SERV1792

November 2004

SERVICE TRAINING
TECHNICAL PRESENTATION

914G WHEEL LOADER /

IT14G INTEGRATED TOOLCARRIER
TIER II EMISSIONS UPDATE

Meeting Guide 792

(STMG)
 914G WHEEL LOADER /
IT14G INTEGRATED TOOL CARRIER
TIER II EMISSIONS UPDATE
AUDIENCE

Level II - Service personnel who understands the principles of machine systems operation,
diagnostic equipment, and procedures for testing and adjusting.

CONTENT

This presentation provides update information on machine components and system operation of
the power train hydraulic system, the brake hydraulic system, and the steering hydraulic system,
for the 914G Wheel Loader and the IT14G Integrated Toolcarrier with Tier II Engines. This
presentation may be used for self-paced and self-directed training.

OBJECTIVES

After learning the information in this presentation, the serviceman will be able to:
1. locate and identify changes to the operator's station, power train, and machine
hydraulic systems;
2. trace oil flow through the hystat transmission and brake system; and
3. explain the operation of the power train components and brake systems.

REFERENCES

914G Wheel Loader/IT14G Integrated Toolcarrier Service Manual RENR6490

914G Wheel Loader Parts Book SEBP3756
IT14G Integrated Toolcarrier Parts Book SEBP4016
914G Wheel Loader/IT14G Specalog AEHQ5560
STMG "Cat Machine Security System" SERV1794

PREREQUISITES

STMG 740 "914G Wheel Loader/IT14G Integrated Toolcarrier–Update to

SESV1670" SESV1740
CD ROM version of SESV1740 SERV1740
Interactive Video Course "Fundamentals of Mobile Hydraulics" TEMV9001
STMG 546 "Graphic Fluid Power Symbols" SESV1546

Estimated Time: 2 Hours

Illustrations: 52
Handouts: 8
Form: SERV1792
Date: 11/04

© 2004 Caterpillar Inc.

STMG 792 -3- Text Reference
11/04

TABLE OF CONTENTS

INTRODUCTION ........................................................................................................................5

OPERATOR'S STATION..............................................................................................................9

ENGINE COMPARTMENTS AND ADDITIONAL SERVICE POINTS ...............................17

STARTING AND CHARGING SYSTEM.................................................................................22

ENGINE SPEED CONTROL SYSTEM....................................................................................24

HYSTAT TRANSMISSION SYSTEM ......................................................................................27

STEERING AND BRAKE SYSTEM ........................................................................................50

IMPLEMENT HYDRAULIC SYSTEMS .................................................................................69

ADVANCED OPTIONAL SYSTEMS.......................................................................................75

CONCLUSION...........................................................................................................................77

HYDRAULIC SCHEMATIC COLOR CODE...........................................................................78

HANDOUTS...............................................................................................................................79

NOTE: The Reference Materials have information on systems with no significant

changes.
STMG 792 -4- Text Reference
11/04

NOTES
STMG 792 -5- Text Reference
11/04

914G WHEEL LOADER /

IT14G INTEGRATED TOOLCARRIER
TIER II EMISSIONS UPDATE

© 2004 Caterpillar Inc.

INTRODUCTION

Caterpillar is introducing updated 914G Wheel Loaders and IT14G Integrated Toolcarriers with
Tier II Engines. The new machines are equipped with Caterpillar 3054CT engines.

The updated machines retain the same nomenclature as the previous machines they are
replacing. The machine Serial Number will change to denote the emission compliant status.

The CAT 3054CT engine provides 17.5% higher torque with a 4% increase in peak power over
the CAT 3054T engine it replaced. These increases result in an 8-12% increase in speed on
grades.

The cab is designed for visibility, operator comfort, and convenience. The standard ROPS cab
is sound suppressed, sealed, pressurized, air conditioned, and resiliently mounted to the frame.
A fully adjustable air suspended seat, with side-to-side shock absorption, provides maximum
operator comfort. Conveniently placed switches, gauges, information display, and controls
improve operator comfort, awareness, and efficiency.

Improvements have also been made to various machine systems to enhance customer value.
The IT14G can be equipped with a "brush cutter" ready option.

NOTE: The "HYDRAULIC SCHEMATIC COLOR CODE" is located after the

"CONCLUSION" of this presentation.
STMG 792 -6- Text Reference
11/04

914G/IT14G VS 914G/IT14G WITH TIER II ENGINES

SIMILARITIES AND DIFFERENCES
FEATURES DIFFERENT SIMILAR SAME

Machine Appearance X
Operator's Station X
Basic Engine X
Fuel System X
Air Intake and Exhaust X
Cooling System X
Hystat Transmission X
Hystat Tests X
Implement Hydraulic System X
Steering and Brake System X
Maintenance Items X

The machine appearance has stayed the same. The most significant changes are related to the
engine.

The engine CAT 3054T engine has been replaced with the CAT 3054CT engine. The fuel
system changes include a non-metallic fuel tank, an electric fuel priming pump, fuel filter with
built in water separator, improved fuel sender, improved fuel lines routing, and glow plugs for
cold start. The electric fuel priming pump is also used on the B Series Telehandlers.

The cab has undergone limited changes. Several controls and switches have been improved to
increase operator comfort.

The radiator and hydraulic cooler have been improved for better cooling capacity. The cooler
has changed from steel to aluminum. The crank case breather has changed from open-breather
to closed for EAME. A drip collection system is being developed for the crank case breather.

The hystat system has undergone limited changes. The changes include the previously
mentioned oil cooler, a change to a single hydraulic oil filter, and a redesign of the large motor
signal displacement valve.
STMG 792 -7- Text Reference
11/04

The steering and brake system manifold valve group changed for those machines that are
configured as "brush cutter ready." The brush cutter option provides brush cutter ready
hydraulic and electrical connections direct from the factory.

Maintenance intervals have been increased to 500 hours for the engine oil, engine oil filter, and
fuel filters. This change reduces the cost and time required for engine maintenance. A number
of other maintenance intervals have also been increased.
STMG 792 -8- Text Reference
11/04

Current 914G 3054CT Mechanical

Engine Specs Perkins Perkins

Rated Power 71.5kW/96 hp gross @ 2200 rpm 74.5kW/96 hp gross @ 2200 rpm
Peak Torque 350.5 Nm @ 1400 rpm 412 Nm @ 1400 rpm
Displacement 4.4 L 4.4 L

227 (g/k Wh) @ full load rated 238 (g/k Wh) @ full load rated
Fuel Consumption speed speed
Cooling
SHR 60% 68.5%
% Increase in heat
rejection over current 19%

The chart above shows a performance comparison between the previous 914G and the latest
one with the CAT 3054CT engine.

The basic engine changes include:

- Three piston rings versus two provide longer service life and reduce oil consumption.
- The cylinder block is made of high strength cast iron alloy and offers improved durability
and reduces engine noise.
- The cylinder head is made of high strength cast iron alloy with extra deck thickness.
- The intake and exhaust ports are precision cast to promote optimum combustion, resulting
in more net horsepower and reduced engine noise.
- A direct injection fuel system provides better fuel consumption over an indirect fuel
injection system.
- Improved front and rear crankcase seals reduce leaks.
- A heat treated crankshaft provides longer engine life.
STMG 792 -9- Text Reference
11/04

3
1

OPERATOR'S STATION

A wide choice of seats is available for the 914G/IT14G machines. All seats include an
anti-cinching and retractable seat belt to provide the operator with safety and comfort inside the
cab. The standard seat is fully adjustable for the fore and aft positions, seatback angle, bottom
cushion height, armrest angle, and suspension stiffness. An optional Caterpillar "Contour" seat
also features an adjustable upper backrest and adjustable lumbar support. The Contour seat
may be equipped with an electrically adjusted air suspension system.

Either a 2 inch (51 mm) or a 3 inch (76 mm) wide seat belt is available for the 914G/IT14G
machines.

The parking brake lever (1) is to the left of the seat. An optional 12 volt auxiliary socket (2) is
shown below the parking brake lever.

The door latch release button (3) is also shown. Depress the button to release the door latch.
STMG 792 - 10 - Text Reference
11/04

4
5
3

6
2

The transmission directional control lever (1) is on the left side of the steering column. Pushing
the lever forward from the center NEUTRAL position selects FORWARD, while moving the
lever to the rear of center selects REVERSE. If an attempt is made to start the machine in a
direction, the machine will not start. If the parking brake is ENGAGED and the lever is moved
to a direction, the hystat system is neutralized. The parking brake lever must be RELEASED,
the directional lever must be moved back to NEUTRAL, and then moved to a direction before
the machine will move. If the machine is equipped with optional turn signal lights, the turn
signal switch (7) is on the right side of the steering column.

The steering column tilt lever (8) is below the steering column. The horn (9) is in the center of
the steering wheel. In the center console individual, vented, round gauges with dial faces show
the conditions of the various machine systems:
- hydraulic oil temperature (2)
- coolant temperature (3)
- speedometer location (optional) (4)
- fuel level (5)
- voltmeter (6)
STMG 792 - 11 - Text Reference
11/04

1 2

6
3

4 5

On the left side of the front console are additional control switches.

Machine system monitoring lamps (1) include: engine coolant temperature, hydraulic oil
temperature, engine oil pressure, hydraulic oil filter, and brake oil level.

The headlamp switch (2) has the following positions: OFF, PARK (panel/tail lamps),
ROADING (front headlamps), WORK 1 (front cab floodlamps), and WORK 2 (rear cab
floodlamps). Each position adds the additional lamps to the previous positions.

A spare switch location is provided for additional accessories (3), Start Aid (4), and an optional
rotating beacon (5).

The service hour meter meter (6) and the left service brake pedal (7) are also shown in this
illustration.

NOTE: This front console is used with other wheel loaders. Some options may not be
available on all wheel loaders, such as, the transmission neutralizer override switch.
STMG 792 - 12 - Text Reference
11/04

2 3
4
1

6 5
8

Right front console components include:

- key start switch (1)

- dimmer switch (optional) mounting location (2)

- washer/wiper controls (3)

- indicator lamps (4)

- supplemental steer switch (optional) (5)

- lighter (6)

Indicator lamps include: alternator, park brake, cab floodlamps, and (if equipped) supplemental
steering motor ON lamp, and a primary steering flow fault lamp.

Also, shown is the right service brake pedal (7) and the governor pedal (8).
STMG 792 - 13 - Text Reference
11/04

1
2

The 914G and IT14G will have one of several different implement hydraulic control
arrangements depending on the machine configuration:

- joystick (multi-function) control lever (1) for BUCKET RAISE/LOWER and

DUMP/TILTBACK, equipped with an optional F-N-R switch (2)

- third function control lever (3)

- multi-function control lever (4)

- creeper control lever (5)

- hydraulic control lock (pilot shutoff) lever (6)

Reduced lever efforts and shorter lever throws are achieved by using pilot-operated implement
controls resulting in decreased operator fatigue. A decal (7) illustrates the lever functions.
STMG 792 - 14 - Text Reference
11/04

The pilot valves contain normally energized solenoids which hold the lever in detent for the
loader FLOAT position, the bucket kickout circuit, the loader lift kickout circuit, or the third
function lever "rearward position." A hydraulic control lock (pilot shutoff) lever (6) is located
between the seat and the right console. The lever controls a valve which interrupts the flow of
oil to the pilot valves and also deactivates the implement valve solenoid detents if moved out of
the fully unlocked position. To shut off the pilot system, fully raise the lever.

The F-N-R (FORWARD-NEUTRAL-REVERSE) switch allows the operator to change the

direction of the machine without taking his hand off of the joystick. For the F-N-R Switch to
function on the control lever, the shift lever must be in NEUTRAL. To start the machine both
the F-N-R switch and the shift lever must be in NEUTRAL.

The creeper valve is used to control machine speed. A typical application for the use of the
creeper valve is with a broom.

The creeper function works in either the the LOW or HIGH speed range. The speed range
selector switch to select between the two ranges is located on the right console behind the pilot
controls.

For normal operation, the creeper control lever should be moved fully forward into "detent." If
the creeper valve is adjusted correctly and moved fully to the rear, the machine will not move.
STMG 792 - 15 - Text Reference
11/04

2
1
3

Switches mounted on the right console are used to control certain machine functions. The icon
on the switch indicates the function that the switch performs. Since some of the switches are
for optional equipment, not every machine will have all the switches. The cab heater and air
conditioner controls are also located in the console.

The switch (1) on the upper left is used to disable the joystick F-N-R switch.

The engine speed control switch (2) is used on machines equipped with an engine speed control
positioner.

The coupler switch (3) is used to control the coupler in the cylinder. The red button on the
switch is used to maintain the coupler in the locked position.

The speed select switch (4) is used to select the high or low machine travel speed.
STMG 792 - 16 - Text Reference
11/04

10

The fuses and relays (1) are located in the right console.

The diagnostic connector (2) is used to interface with a computer equipped with Caterpillar
Electronic Technician (CAT ET).

The diagnostic connector, harness code identifier connector, option code connector, and
diagnostic indicator (action lamp) (3) are located below the fuse and relay panels.
STMG 792 - 17 - Text Reference
11/04

1 4

2 6

12
5 8

3 11
9

13

10

11

ENGINE COMPARTMENT AND ADDITIONAL SERVICE POINTS

A number of components can be identified in the engine compartment:

- coolant overflow and fill container (1)
- radiator (2)
- hydraulic oil cooler (3)
- air conditioning compressor (4)
- fuel pump and governor (5)
- electronic governor positioner control (6) (optional)
- fuel filter with built in water separator (7) with an electric priming pump (8)
- engine oil fill tube (9)
- engine oil filter (10)
- disconnect switch (11) (optional)
- engine block heater (12) (optional)
- hystat pump (13)
STMG 792 - 18 - Text Reference
11/04

12

The fuel pump is protected by a cover (arrow). The decal on the cover is in a number of
languages. The decal warns NOT to wash the fuel pump when hot.

The fuel pump is the same one used with the previous engine.

The starting aid system has changed. Glow plugs are used instead of an air inlet heater.
STMG 792 - 19 - Text Reference
11/04

13

A single hydraulic oil filter (1) is located on the left side of the machine. An S•O•S tap (2) is
mounted to the filter housing.

The fuel tank fill tube (3) is also shown. The fuel tank, fill tube, and cap design have changed
to a non-metallic design.
STMG 792 - 20 - Text Reference
11/04

2
3
1

14

The two 12 volt batteries (1) are mounted at the rear of the machine on the right side along with
a 12 volt power inverter (2) and circuit breakers (3) for the alternator and the auxiliary electrical
components.

Mounted to the rear of the panel (4) are the glow plug relay and the starter relay.
STMG 792 - 21 - Text Reference
11/04

4
2

15

A shutoff valve (1), used to block the hystat signal from going to the brake valve, is located on
the right side of the machine below the engine hood. The valve is used during machine tests to
prevent the brake valve from bleeding the hystat signal to the tank when the brakes are applied.

The hydraulic fluid level sight gauge (2) has changed so it is easier to read.

Radial seal air filters (3) are used on these machines.

The hydraulic oil fill tube (4) is located on the right side of the machine.

The air conditioning condenser (5) is located on the rear of the cab.
STMG 792 - 22 - Text Reference
11/04

ELECTRICAL STARTING AND CHARGING SYSTEM

RUN POSITION
To To Alt. Lamp
Shift Neutral-
Handle Start 2 1 3 403-GN-18
P915-PK-18
I L P
Relay
Service
B+
Meter
308-YL-18 ALT
Alternator
Main
Breaker
R
60 117-RD-6 112-PU-10 To Accessories Neutral
Main Power Start C OFF
Start S ON
109-RD-6 Relay Aid Relay B ST
15 A 306-GN-18 307-OR-18
Key Start
Lamp Breaker Switch
Aux. Breaker
30 115-RD-10 15
Key Start Switch
109-RD-10 115-RD-14 10 A 105-RD-16

188-WH
Alt. Breaker 109-RD-4
60
Fuel
101-RD-2 Shutdown A 1
B 2
109-RD-6 304-WH-10 Solenoid

NEG POS NEG POS G S 200-BK Start Aid

Switch
399-OR
109-RD-10 MTR BAT

T°
Disconnect Starter Starter MOTOR Cold Coolant
Switch Relay Start
Switch
(Optional) Advance
Motor
FROM
RD-0 LAMP
SWITCH
109-RD-8
310-PU-18
384-BU-8

310-PU-18
Glow
Plug
Relay
Glow Plugs

16

STARTING AND CHARGING SYSTEM

The electrical schematic is shown in the RUN condition. The red coded wires have battery
voltage with the key start switch in the OFF position. When the key start switch is turned to
the START position, power from the batteries flows through the auxiliary breaker to the key
start switch.

When the key is in either the START or RUN position, the fuel shutoff solenoid is energized
and allows fuel to flow through the fuel injection pump. Thus, the solenoid is "energized to
run." When the shift handle of the transmission control is in NEUTRAL, the neutral-start relay
is closed, completing the circuit to the starter relay.

When the starter relay closes, power from the battery energizes the starter solenoid and motor.
The starter then engages the flywheel ring gear and starts the engine.
STMG 792 - 23 - Text Reference
11/04

For cold starts, the start aid switch can be used while cranking the engine. The switch will
energize the glow plugs in the cylinder head. The switch receives battery voltage from the
main power relay. As the machine warms up after starting, the coolant switch will close
sending power to the cold advance motor. The wax in the cold advance motor will melt and
permit full movement of the timing advance mechanism in the fuel pump.

With the key start switch in the RUN position, the main relay is closed and power is directed to
the accessories. The batteries are charged by a belt-driven alternator. The alternator is located
on the right side of the engine. Also, the service hourmeter is powered by the alternator.

When the key start switch is in the RUN position, power from the battery goes through the
switch to the "D+" terminal of the alternator to "excite" the alternator field. When the
alternator field is "excited," the alternator will charge the batteries. A resistor inside the
alternator limits the amount of current needed to excite the alternator field. A diode inside the
alternator permits current flow in only one direction. The diode and resistor also allow the
engine shutoff solenoid to de-energize and the power relay to shut off when the key start switch
is moved to the OFF position. Without the diode, the alternator would keep those components
powered up, and the engine would not shut down.

If starter, battery, or alternator tests are being made, remove the 396-PK wire on top of the fuel
injection pump. Removing the wire will prevent the shutoff solenoid from being energized,
thus preventing the engine from starting.
STMG 792 - 24 - Text Reference
11/04

ENGINE SPEED CONTROL SYSTEM

ENGINE ON / ENGINE SPEED CONTROL SWITCH OFF

Engine C585-BR-18 103-YL-18 To Power

Engine C975-WH-18 Distribution
N941-YL-18
Speed Block
X740-BU-18
Control G879-OR-18 Speed C978-BR-18
C807-BU-18 788-YL-18
Actuator C586-GY-18 Engine Speed
Control 776-YL-18 Control Switch
776-YL-18

ECM

776-YL-14

Engine
Speed 103-YL-18
Control Electronic
Relay F796-GY-18 To Transmission
Distributor ECM
450-YL-18 To Engine
Group
Speed Sensor

604-OR-14 604-OR-14 To Brake Limit Switch

Engine Speed Control

Pressure Switch

17

ENGINE SPEED CONTROL SYSTEM

The engine speed control system is shown in the OFF condition. The engine speed control
system is used to set engine rpm. This feature allows the operator to maintain a constant flow
rate to the attachments.

When the engine speed control switch is depressed, the current engine rpm is sent to the Engine
Speed Control ECM by the electronic distributor group. The ECM sends the engine rpm to the
engine speed control actuator. The actuator then moves the cable that controls the governor.
The actuator adjusts the governor to the correct engine rpm.

The engine speed control switch can increase the engine rpm. If the switch is depressed in the
forward position, the actuator will increase the engine rpm until the switch is released or high
idle is reached.

To deactivate the engine speed control system, turn the engine speed control switch off or
activate the engine speed control pressure switch. The engine speed control pressure switch is
activated by pressing the brake pedal.
STMG 792 - 25 - Text Reference
11/04

18

The Engine Speed Control ECM is located on the right side of the cab below the heating and air
conditioning controls. The Engine Speed Control ECM is used with the engine speed control
switch and the engine speed control actuator to set the position of the governor.

NOTE: The rear compartment of the right console has been removed.
STMG 792 - 26 - Text Reference
11/04

19

If the engine speed control switch is pressed while the governor pedal is depressed, the engine
speed is communicated to the engine speed control actuator (1). The actuator (1) moves the
cable (2) to the governor to regulate the engine speed.
STMG 792 - 27 - Text Reference
11/04

HIGH SPEED HYDROSTATIC TRANSMISSION ELECTRONIC

CONTROL SYSTEM
F•N•R
Switch

Shift Diagnostic Buffered Speedometer

Lever Indicator Driver
(Action LED)
Ride Control/ Ride Control/
Load Check Switch Load Check Relay

Parking Brake Motor Signal

Switch Control Valve Solenoid

Key Start Reverse

Switch Solenoid
Electronic
Harness Code
Forward
Connector
Control Solenoid

Options Code Module

Solenoid Common
Connector
Interrupt Relay

Main Steering
Flow Switch Secondary Supplemental
Steer Relay
Creeper Switch or
Speed Switch Service
Connector
Engine Speed
Sensor
Primary Steering
Drive Shaft Flow Lamp
Speed Sensor

20

HYSTAT TRANSMISSION SYSTEM

The Hydrostatic Transmission Electronic Control System (HYTEC) is used on all machines.

The HYTEC consists of the following components:

Electronic Control - senses various inputs and sends signals to control hystat
Module (ECM) functions and other machine functions.
Shift Lever - allows the operator to choose transmission direction.
F-N-R Switch - is an attachment built into the implement control lever that
allows the operator to choose transmission direction.
Ride Control switch - allows the operator to choose ON, OFF, or AUTO for Ride
Control. A separate ON/OFF switch is used with a load
check system.
STMG 792 - 28 - Text Reference
11/04

Parking brake switch - neutralizes the transmission when the parking brake is
engaged.
Service connector - allows the mechanic to use CAT ET for performing
diagnostics.
Harness code connector - establishes the machine identity for the ECM.
Options code connector - establishes identities for the options used for the machine
configuration for the ECM.
Main steering flow switch - provides input from the steering system. When the switch
opens, the ECM activates the primary steering flow lamp.
Speed select switch - selects the HIGH or LOW speed range.
Creeper valve - selects the speed range and provides variable speed control
for the LOW speed range on machines built prior to August
of 2000. On current machines, the valve provides variable
speed control in both LOW and HIGH speed ranges.
Engine speed sensor - senses engine speed from the engine flywheel.
Drive shaft speed sensor - senses drive shaft speed which is automatically converted to
motor speed by the ECM.
Diagnostic indicator - or "action LED" displays fault codes through a series of
flashes.
Buffered speedometer - provides a signal from the ECM to the speedometer
driver
Ride Control/load - is used to activate the Ride Control or a load check solenoid
check relay
Transmission solenoids - control transmission speed and direction. They include
Reverse and Forward solenoids, which are part of the F-N-R
valve, and a proportional solenoid, which is part of the
motor signal control valve.
Ground interrupt relay - is energized for 1.5 seconds at machine start-up to verify
proper operation. If either the Forward or Reverse solenoid
is shorted to battery, the ground interrupt relay will energize
and permit the machine to return to Neutral.
Secondary supplemental - will close after the loss of primary steering flow. This relay
steering relay then closes the main supplemental steering relay which will
then turn on the supplemental steering pump and the
supplemental steering lamp. The relay is controlled by the
ECM.
STMG 792 - 29 - Text Reference
11/04

21

The machine ECM is located on the right side of the machine below the cab.

The electronic control system stores fault information and displays the fault information as a
series of light flashes at the diagnostic indicator. When the electronic control system contains a
fault, the diagnostic indicator LED flashes ON and OFF.

The indicator LED flashes a two digit code associated with the faults in the electronic control
system. When conveying a fault, the indicator LED flashes a number of times in sequence,
then pauses for approximately one second before flashing again. The number of flashes before
the one second pause indicates the first digit in the fault code and the number of flashes after
the one second pause indicates the second digit in the fault code.

The electronic control system can log more than one fault at a time. A three second delay
separates the two digit fault codes. To interpret the fault codes, count the number of flashes
before and after each one second pause. Refer to the chart in the service manual module for an
explanation of the fault associated with the codes.

The CAT Data Link can be used to troubleshoot the system. The CAT Data Link permits
communication between the electronic control system and the CAT ET. When connected to the
service connector of the electronic control system, the CAT ET can register and display
electronic control system faults.
STMG 792 - 30 - Text Reference
11/04

HIGH SPEED HYSTAT SYSTEM

Shutoff Creeper
Motor Valve Valve
Signal Control
Valve M2
To Implement To
Pilot System Brakes
PS1 G1 PC AB

From Brake
Accumulators
Large
X1 Motor

Brake
Valve
X3
X4 Pump

X2

To
Flushing
Bypass
Small
Block
Motor
To Tank
Return Check
Valve

To Hydraulic
Tank
Filter
Group M1
Oil
Sampling

22

The hydraulic components of the hystat system include:

- the pump group,
- two motor groups,
- the filter group,
- the motor displacement control,
- the brake valve, and
- the shutoff valve

The system shares the hydraulic tank with the implement and steering systems.

The two motors are mounted to a gear box which mounts to the rear axle. Each motor has an
input gear on its shaft that meshes with the output gear in the gear box. The output gear
transmits power to both the front and rear axles.
STMG 792 - 31 - Text Reference
11/04

The optional creeper valve drains the signal oil from the speed sensing valve to the tank. This
action limits the machine speed and can also limit rimpull.

As the brake pedals are depressed, the brake valve allows signal oil to go to the tank, which
causes the motor to upstroke (if not already at maximum angle) and the pump to destroke.
Engaging the brakes will not reduce the engine speed. This feature allows faster implement
speeds due to higher flow from the implement pump.

The shutoff valve is used when testing the hystat system. The shutoff valve, when closed,
prevents the signal from bleeding off to the tank through the brake valve.

NOTE: The small motor displacement varies from 35 to 80 cc (2.13 to 4.88 cu. in.) per
revolution. The large motor displacement varies from 0 to 107 cc (0 to 6.52 cu. in.) per
revolution.
NOTE: The motor signal control valve design has changed. The motor signal control
valve will be discussed later in the presentation.
STMG 792 - 32 - Text Reference
11/04

OS
To Motor Displacement
Control Valve
Motor Signal
Control Valve

To Implement
Pilot System

Pump PS1 G1 PC AB To Brake / Inching Valve

To Motors
Pressure
X1 Override MB
Orifice
Valve
Speed
Sensing
Valve

Charge
Pump X3
Charge Relief
Valve
X4

X2
HIGH SPEED HYSTAT SYSTEM
Crossover
Relief and PUMP WITH MOTOR SIGNAL
Makeup CONTROL VALVE
Valves

MA
To Motors

FWD

FNR
Valve To Hydraulic
Tank

Oil
Filter Bypass
Sampling
To Motor Switch
Shuttle Valve

23

The pump group consists of the following components:

A variable displacement, over-center piston pump provides flow to drive two bi-directional
motors. The actuator piston controls the angle of the pump swashplate.

The charge pump charges the system at start-up and provides makeup oil. Oil is directed by
the charge pump through the filter group, which filters the oil before entering the drive pump
and motor. The charge pump also provides the source for signal pressure to control the pump
and small motor. The signal pressure will vary proportionally to the engine speed. The higher
the engine speed, the higher the signal pressure.

A speed sensing valve senses the charge flow and converts some of it to signal oil. The orifice
in the speed sensing valve creates a pressure differential which is proportional to engine speed.
This pressure differential is then multiplied by the speed sensing valve and becomes signal oil.
This signal is then used to control the pump and the small motor. The large motor is controlled
by the motor signal control valve.
STMG 792 - 33 - Text Reference
11/04

The speed sensing valve sends the signal to the Forward-Neutral-Reverse (F-N-R) valve and
the small motor displacement control valve. The speed sensing valve sends oil not used for
signal oil to the remainder of the charge circuit.

An orifice in the signal line above the speed sensing valve allows the pressure override valve
and the brake valve to function as designed. Without the orifice, the speed sensing valve would
compensate for flow loss through the brake valve, thereby negating the braking capability of
the valve. The orifice would also decrease the ability of the pressure override valve to limit the
maximum drive loop pressure.

The combination crossover relief and makeup valves will open to protect the system by either
maintaining a minimum pressure or reducing pressure spikes in the drive loop. At machine
start-up, the valves open to direct charge pump oil to both sides of the pump and motor.

The charge relief valve limits the pressure of the oil not sent through the speed sensing valve.
The valve also limits the maximum hystat system pressure in NEUTRAL and the maximum
implement pilot system pressure.

The Forward-Neutral-Reverse (F-N-R) valve consists of a spool and two solenoids. When
one of the solenoids is energized by the ECM, the spool is shifted and sends signal oil to
actuate the pump to provide flow for the direction selected.

The Pressure Override valve (POR) limits the maximum drive loop pressure. A ball resolver
senses the highest drive loop pressure. When this pressure reaches a specified limit, the
override valve will open and send oil in the signal line to case drain, reducing the signal
pressure and causing the motor to upstroke and the pump to destroke. When the motor is
upstroked or the pump is destroked, machine speed is reduced.

A filter bypass valve and switch are part of the filter group. If the filter is plugged, the bypass
valve opens and the switch closes to turn on an indicator lamp in the operator's compartment.
The indicator lamp stays on as long as the valve is open. With cold oil, the bypass valve opens
and the indicator lamp lights temporarily. The lamp goes out as the oil warms up.

The motor signal control valve varies the signal to the large motor to control the speed of the
motor. In the HIGH speed range, the motor signal control valve is controlled by the ECM. At
approximately 500 rpm motor shaft speed, the ECM causes the motor signal control valve to
start destroking the large motor. At 2000 rpm, the large motor is fully destroked. In the LOW
speed range, the motor signal control valve is not energized and the large motor stays upstroked
to limit vehicle speed so the higher engine speed can be used to improve implement
performance. The LOW speed range can be obtained by moving the optional creeper control or
by the speed selector switch.
STMG 792 - 34 - Text Reference
11/04

SPEED SENSING VALVE

STARTUP / CHARGING NEUTRAL OR ACCELERATING DECELERATING
To POR Valve and To POR Valve and To POR Valve and
Brake / Inching Valve Brake / Inching Valve Brake / Inching Valve

To F-N-R To F-N-R To F-N-R

Valve Valve Valve
To Charge To Charge To Charge
Circuit Circuit Circuit

From From From

Charge Pump Charge Pump Charge Pump

24

The speed sensing valve regulates the signal pressure oil (based on engine speed) to the F-N-R
valve, the hystat motor, and the brakes. The speed sensing valve is shown in three different
states.

When the machine is started, the speed sensing valve is in the start-up or charging position.
The charge pump provides oil flow to the speed sensing valve. Initially, no signal (drive signal)
is sent to the F-N-R valve, the hystat motor, and the brakes. From the speed sensing valve, oil
flows through the crossover relief valves and makeup valves to charge the closed loop drive
system.

After the drive loop is charged, the higher charge pump oil pressure on the left side of the speed
sensing valve, with assistance from the spring, causes the speed sensing valve to shift to the
NEUTRAL position allowing signal oil to flow to the F-N-R valve, POR valve, hystat motor,
creeper valve (if equipped), and the brakes.

The speed sensing valve increases the signal to the F-N-R valve and the hystat motor when
engine speed is increased to accelerate the machine if the machine is in FORWARD or
NEUTRAL. The machine ground speed will increase and decrease with changes in engine
speed.
STMG 792 - 35 - Text Reference
11/04

When the machine decelerates, the charge pump sends less flow to the speed sensing valve.
The charge oil pressure is lower on the left side of the speed sensing valve than on the right
side causing the speed sensing valve to shift to the left, directing the signal to the tank. With a
reduced signal, the hydrostatic pump begins to destroke. The loss in signal pressures will also
cause the motor or motors to upstroke.

The charge relief valve limits the maximum charge pressure in the closed loop. As pressure in
the charge circuit increases, the charge relief valve opens to control the charge pressure.

NOTE: The three positions of the speed sensing valve shown here are to improve
comprehension of the operation of the valve. The single position envelope shown on the
system schematics represents all three of these positions.
STMG 792 - 36 - Text Reference
11/04

Speed
Charge Sensing
SPEED SENSING VALVE Pressure Signal

From
START-UP / Charge
CHARGING Pump

Spring Orifice
Speed
Charge Sensing
Pressure Signal

NEUTRAL OR From
Charge
ACCELERATING Pump

Spring Orifice

25

During start-up or charging, the speed sensing valve directs charge oil to fill both drive loops.
Initially, the speed sensing signal passage is open to the tank.

After the drive loops are charged, the pressure differential across the orifice increases and the
valve shifts to the left, which provides the speed sensing signal for the hydrostatic system. The
charge pressure will remain relatively constant, but the speed sensing signal will vary with
changes in the engine rpm.
STMG 792 - 37 - Text Reference
11/04

Creeper
Shutoff Valve
From Motor Valve
Signal Control
Valve M2
To
Brakes

From Speed Throttle From Brake

Sensing Valve Flushing Pin Accumulators
Valve

Large Motor
Motor
HIGH SPEED HYSTAT SYSTEM Displ.
Control
MOTORS AND INCHING VALVES Valve
Brake
Valve

From Overspeed
Valve

From Pump
Shuttle

Throttle
Small Motor Pin
To
Flushing
Motor Actuator Bypass
Piston Block

Motor Displacement
Control Valve
To Tank Return
Check Valve

From Pump

M1 From FNR Valve

26

The small motor group consists of the following components:

A bi-directional, variable displacement, bent-axis piston motor and actuator convert hydraulic
power into mechanical power. The motor actuator piston controls the motor displacement by
changing the angle of the rotating group relative to its output shaft. The higher the stroke or
displacement, the higher the torque and lower the speed. The lower the stroke, the lower the
torque and higher the speed.

A throttle pin with two orifice grooves controls motor stroking time. The larger orifice groove
slows the actuator movement from minimum stroke to maximum stroke. The smaller orifice
groove slows the actuator movement from maximum stroke to minimum stroke.

A motor displacement control valve senses the signal from the speed sensing valve. The
valve compares the signal with the drive loop pressure to control the motor actuator piston.
When the accelerator is depressed more, the signal pressure increases to destroke the motor. If
the drive pressure increases, the motor upstrokes.
STMG 792 - 38 - Text Reference
11/04

A shuttle valve sends the active drive line pressure (either FORWARD or REVERSE) to the
motor signal control valve and actuator. By stroking the motor with the higher drive loop
pressure, hystat driving response is improved and, during hydrostatic braking, system stability
is maximized.

The large motor group consists of the following components:

A bi-directional, variable displacement, bent-axis piston motor and actuator convert hydraulic
power into mechanical power. The motor actuator piston controls the motor displacement by
changing the angle of the rotating group relative to its output shaft.

A motor displacement control valve senses a variable signal from the motor signal control
valve and meters the highest drive loop pressure to the motor actuator piston to destroke the
motor. When the accelerator is depressed more, the signal pressure increases to destroke the
motor. If the drive pressure increases, the motor upstrokes.

Two check valves sense the drive loop pressures. The highest drive loop pressure opens one
check valve and seats the other. The drive loop pressure then flows to the motor displacement
control valve. By stroking the motor with the higher drive loop pressure, hystat response is
improved during driving and braking.

A flushing valve continuously drains some oil from the low pressure side of the drive loop
through the motor bearings to case drain. This action purges heat, debris, and air from the
drive loop. The relief valve in the flushing valve maintains a minimum pressure in the low
pressure side of the drive loop.

A throttle pin (orifice check valve) controls motor stroking time. The orifice slows the
actuator movement from minimum stroke to maximum stroke.
STMG 792 - 39 - Text Reference
11/04

HIGH SPEED HYSTAT SYSTEM OS Large Motor Creeper

NEUTRAL Shutoff Valve
Motor Signal Valve
Control Valve
M2
To
To Implement Brakes
Pilot System
Throttle
Pump PS1 G1 PC AB
Flushing Pin From Brake
Valve Accumulators

MIN

Pressure
X1 Override MB
Valve Motor
Speed Displ.
Sensing Control
Valve Valve
Brake
Valve
X3
Charge Relief
Valve
X4

X2
Crossover
Relief and Shuttle
Makeup
Valves Throttle
Pin
To
Flushing
Bypass
MA Block
MIN

FWD To Tank Return

Check Valve

FNR
Valve
To Hydraulic
Tank

M1 Motor Displacement Small Motor

Control Valve

27

At machine start-up with the shift lever in NEUTRAL, the charge pump, mounted to the hystat
pump, sends oil through the filter group to the speed sensing valve and the motor signal control
valve. The motor signal control valve blocks the oil in NEUTRAL.

Most of the charge oil to the speed sensing valve enters the charge circuit and goes to the
crossover relief and makeup valves, the charge relief valve, and the implement pilot system.
The makeup valves in each crossover relief open and charge oil flows through the drive loop to
the hystat pump, both hystat motors, the flushing valve, and the shuttle valve.

Charge oil in the drive loop also flows through the ball resolver in the pressure override valve.
Drive loop pressure can be checked at test port "AB." In NEUTRAL, this pressure is the same
as charge pressure.

Charge oil also flows to both motor displacement control valves and motor actuators. (The
small motor may upstroke, but since no pump flow is produced, no power is transferred to the
hystat gear box.) Pressure on the left side of the motor actuators can be checked at test ports
"M1" and "M2." In NEUTRAL, "M1" and "M2" equal tank pressure.
STMG 792 - 40 - Text Reference
11/04

When the system is charged, the charge relief valve opens and most of the charge oil goes to
the pump case and then to the tank. Charge pressure can be checked at test port "G1."

In NEUTRAL the speed sensing valve creates a signal which flows to the pressure override
valve, the FORWARD-NEUTRAL-REVERSE (F-N-R) valve, the brake valve, and the motor
signal control valve. Signal pressure can be checked at test port "PS1." With the F-N-R valve
in NEUTRAL, signal oil is blocked preventing the pump from upstroking. When the
accelerator is depressed, the speed sensing signal increases.

A small amount of charge oil sent to the motor signal control valve flows through an orifice
and the solenoid to the tank.

Pump case pressure can be checked at test port "PC."

NOTE: Always use at least a 60000 kPa (8500 psi) pressure gauge (such as 8T0861)
when checking the drive loop pressure at test ports "AB" and "M1" unless a pressure
limiter (such as 1U9161) is used to protect the gauge.
STMG 792 - 41 - Text Reference
11/04

HIGH SPEED HYSTAT SYSTEM

FORWARD / LOW OS Large Motor Creeper
Shutoff Valve
Motor Signal Valve
Control Valve
M2
To
To Implement Brakes
Pilot System
Throttle
Pump G1 Flushing Pin From Brake
PS1 PC AB
Valve Accumulators

MIN

Pressure
X1 Override MB
Valve Motor
Speed
Sensing Displ.
Valve Control
Valve
Brake
Valve
X3
Charge Relief
Valve
X4

X2
Crossover
Relief and Shuttle
Makeup
Throttle
Valves
Pin
To
Flushing
Bypass
MA Block

MIN

FWD To Tank Return

Check Valve

FNR
Valve
To Hydraulic
Tank

M1 Motor Displacement
Control Valve Small Motor

28

When the operator moves the transmission control lever to FORWARD and the speed selector
switch is set for the LOW speed range, the F-N-R valve moves to the left and signal oil from
the speed sensing valve flows to the pump actuator and to the shuttle valve in the small motor.
The signal pressure acts against the pump centering springs; but, since the signal pressure is too
low, the pump will not upstroke and the machine will not move. The signal causes the shuttle
valve to shift and allows the signal pressure to reach the small motor displacement control
valve.

In FORWARD/LOW, the motor signal control valve is not energized and the large motor will
not destroke.

As the operator depresses the accelerator pedal, engine speed increases causing the signal
pressure to increase. The increase in signal pressure causes the pump to upstroke and increase
flow, which causes the small motor to turn faster and the machine speed to increase.
STMG 792 - 42 - Text Reference
11/04

As the engine speed continues to increase, the signal pressure from the speed sensing valve also
continues to increase. Eventually, the signal pressure will move the motor displacement control
valve (small motor) to the left and allow drive loop pressure oil to flow to the motor actuator to
destroke the motor.

Destroking the motor causes the motor to rotate faster. When the motor is fully destroked, the
pump is fully upstroked and the engine is at maximum rpm, the machine speed is maximum for
the LOW speed range.

The large motor stays fully upstroked to limit the maximum machine speed.

Any resistance to the motor rotation increases the drive pressure, which acts on the left end of
the motor displacement control valve (small motor). This higher pressure moves the motor
displacement control valve to the right and drains oil in the motor actuator to the tank. The
motor actuator then moves to the left, causing the motor to upstroke and reduce machine speed.

The motor displacement control valve (small motor) continuously balances the signal and drive
loop pressures to prevent excessive engine lug.

NOTE: The pump will upstroke almost completely before the small motor starts to
destroke.
STMG 792 - 43 - Text Reference
11/04

HIGH SPEED HYSTAT SYSTEM Solenoid Valve Spool

OS
FORWARD / HIGH Large Motor Creeper
Shutoff Valve
Motor Signal Valve
Control Valve
M2
To
To Implement Brakes
Pilot System
Pump Throttle
PS1 G1 PC AB
Flushing Pin From Brake
Valve Accumulators

MIN

Pressure
X1
Override MB
Valve Motor
Speed
Displ.
Sensing
Control
Valve
Valve
Brake
Valve
X3
Charge Relief
Valve
X4

X2
Crossover
Relief and Shuttle
Makeup
Throttle
Valves
Pin
To
Flushing
Bypass
MA Block

MIN

FWD To Tank Return

Check Valve

FNR
Valve
To Hydraulic
Tank

M1
Motor Displacement
Control Valve Small Motor

29

When the operator moves the transmission control lever to FORWARD and the speed selector
is set for the HIGH speed range, the F-N-R valve moves to the left and signal oil from the
speed sensing valve flows to the pump actuator and to the shuttle valve in the small motor. The
signal pressure acts against the pump centering springs but, since the signal pressure is too low,
the pump will not upstroke and the machine will not move. The signal causes the shuttle valve
to shift and allows the signal pressure to reach the motor displacement control valve in the
small motor.

In the HIGH speed range, the Transmission ECM energizes the motor signal control valve and
the large motor will destroke after a certain ground speed is reached.

When current is sent to the motor signal control valve, the solenoid valve shifts proportionally.
The solenoid valve restricts the charge oil from going to the tank. The pressure to the left of
the orifice increases and shifts the spool to the right directing signal oil to the large motor. The
spool will shift between the left side and right side regulating the amount of signal sent to the
large motor.
STMG 792 - 44 - Text Reference
11/04

The motor signal control valve sends signal oil to the motor displacement control valve (large
motor). The signal pressure will move the motor displacement control valve (large motor) to
the left and allow drive loop pressure oil to flow to the motor actuator to destroke the motor.
As engine speed increases, the signal pressure increases. The signal pressure causes the pump
to upstroke and increase flow, which causes both motors to turn faster and the machine speed to
increase. As the engine speed continues to increase, both motors will begin to destroke at the
same time but at different rates.

Small Motor: As the engine speed continues to increase, the signal pressure increases from
the speed sensing valve. Eventually, the signal pressure will move the small motor
displacement control valve to the left and allow drive loop pressure oil to flow to the motor
actuator to destroke the small motor. Destroking the motor causes the motor to rotate faster.
When the small motor is fully destroked (which occurs after the large motor is destroked) the
machine speed is nearly maximum for the HIGH speed range. As engine speed continues to
increase, the maximum machine speed will be achieved.

Any resistance to motor rotation increases the drive pressure, which acts on the left end of the
motor displacement control valve (small motor). This higher pressure moves the motor
displacement control valve to the right and drains oil in the motor actuator to the tank. The
motor actuator then moves to the left, causing the motor to upstroke, thus reducing machine
speed. The motor displacement control valve (small motor) continuously balances the signal
and drive loop pressures to prevent excessive engine lug.

Large Motor: As the ground speed increases, the ECM sends a variable electrical signal to the
motor signal control valve. As the motor signal control valve (proportional solenoid) opens, the
spool shifts, and the valve begins to send a variable hydraulic signal to the large motor
displacement control valve and eventually moves the valve to the left.

This movement allows drive loop pressure to flow through the spool to the motor actuator to
destroke the motor. When the large motor speed reaches a specified design limit, the motor
stays fully destroked. An additional increase in machine speed is caused by destroking the
small motor.

If the machine starts to overspeed, the ECM will communicate with the motor signal control
valve. The valve will reduce the hydraulic signal to the motor displacement control valve and
cause the large motor to upstroke to limit the machine speed. The motor signal control valve
continuously limits the machine speed on favorable grades in the HIGH speed range and
prevents excessive engine overrun.

Operation in REVERSE is similar to operation in FORWARD except that the F-N-R valve and
the shuttle valve move to the right. High pressure oil is then sent from the opposite side of the
drive loop and the motors rotate in the reverse direction.

NOTE: When the machine speed increases from NEUTRAL to maximum speed, the
pump will upstroke almost completely before the motors start to destroke. When
FORWARD/HIGH or REVERSE/HIGH is selected, the machine speed ranges from 0
kph (0 mph) to maximum.
STMG 792 - 45 - Text Reference
11/04

30

The hystat motors are shown in this illustration.

The M2 pressure tap (1) can be connected to the large motor to provide a signal to the large
motor to determine stroking points of the large motor.

The sensor (2) monitors the drive shaft speed. The harness to the sensor can be unplugged
from the connector and then connected to a signal generator to perform diagnostic tests on the
hystat system to determine the stroking points of each motor.
STMG 792 - 46 - Text Reference
11/04

31

CAT ET must be used to access the machine ECMs.

The ECM Selector Screen shows this particular machine is equipped with two ECMs.
STMG 792 - 47 - Text Reference
11/04

32

Additional information about the selected ECM can be found on the ECM Summary Screen.
STMG 792 - 48 - Text Reference
11/04

33

Different Status Screens can be created using CAT ET. These Status Screens are used to
display various machine conditions.

The Status Screens can be beneficial in troubleshooting the machine.

STMG 792 - 49 - Text Reference
11/04

34

When the "Hydrostatic Transmission" ECM is selected from the ECM Status Selector Screen
using CAT ET, the technician can gain access to the Power Train Configuration Screen.

The technician has some limited capabilities to change parameters for the Power Train ECM.
Highlight the parameter and then use the "Change" button on the lower left to change the
parameter. The parameter for "Ride Control Activation Speed" can be used to establish what
speed Ride Control turns on.

Refer to the Service Manual for more information on the configuration screen.
STMG 792 - 50 - Text Reference
11/04

Steering
914G STEERING AND BRAKE SYSTEM
Cylinder ACCUMULATORS CHARGING / BRAKES RELEASED

HMU

LS Line
Brake
Front Axle
Accumulators Valve

Cut-In/
Cut-Out
Spool
Flow
Orifice
Control
Valve
Relief
Valve

Rear Axle

Steering and Brake Hystat

Manifold Valve Group Signal

Steering and Implement

Brake Pump Pump

35

STEERING AND BRAKE SYSTEM

The steering and brake system used on the current 914G/IT14G uses a fixed displacement
pump to provide flow.

A steering and brake manifold valve group is used to charge the brake accumulators. Once the
accumulators are charged, the valve group directs oil not used by the steering system to the
tank.

The cut-in/cut-out spool controls the pressure in the accumulators. The check valve seats to the
left once the accumulators are charged.

The flow control valve provides pressure compensation for the Hand Metering Unit (HMU) to
maintain the desired flow to the HMU.

The relief valve limits the maximum steering signal pressure. By limiting the maximum signal
pressure the maximum steering pressure is controlled.
STMG 792 - 51 - Text Reference
11/04

The orifice in the steering and brake manifold valve group provides dynamic signal bleed for
the steering system to improve steering response. With the steering in HOLD, the dynamic
signal bleed orifice directs oil through the LS line and HMU back to the tank. When the
steering wheel is turned, this signal bleed oil shifts the flow control valve to direct pump supply
oil to the HMU resulting in faster steering response than systems without dynamic bleed.

The brake valve, when engaged, first bleeds the hystat signal to the tank before directing oil to
the brake disks in the front and rear axle on the machine.

The flow switch informs the operator of insufficient steering flow.

When the machine is started, oil from the pump flows to the steering HMU and to the steering
and brake manifold valve group. The oil to the HMU is blocked unless the steering wheel is
turned.

When the accumulators are charging, oil from the pump is directed through the flow control
valve, the check valve, and to the accumulators.

As the accumulators charge, pressure is sensed on both sides of the cut-in/cut-out spool and on
both sides of the flow control valve.

The flow control valve stays to the left during the charging cycle due to the spring and the
pressure on the right side of the spool. The cut-in/cut-out spool is held up during the charging
or cut-in cycle.
STMG 792 - 52 - Text Reference
11/04

STEERING AND BRAKE MANIFOLD VALVE GROUP

ACCUMULATORS CHARGING
To HMU
LS Passage
From Pump
To HMU
Cut-in/
Cut-out
Spool

Check
Valve

Orifice

Relief Flow Control

Valve Valve
To Accumulators To Tank

36

When the machine is started the accumulators begin to charge. Oil from the pump flows to the
steering HMU and to the steering and brake manifold valve group. The HMU blocks the oil
from the pump.

The flow control valve and the cut-in/cut-out spool are held to the left by their respective
springs during the charging cycle.

Oil from the pump flows around the flow control valve and moves the check valve to the left.
The oil then flows to the accumulators. Some of the oil flows through the orifice to the right
side of the flow control valve to work with the spring in keeping the flow control valve to the
left. Oil through the orifice is blocked from going to the load sense (LS) passage by the
cut-in/cut-out spool.

As the accumulators charge, the pressure increases on the left side of the cut-in/cut-out spool.
STMG 792 - 53 - Text Reference
11/04

Steering 914G STEERING AND BRAKE SYSTEM

Cylinder
ACCUMULATORS CHARGED / BRAKES ENGAGED

HMU

LS Line
Brake
Front Axle
Accumulators Valve

Cut-In/
Cut-Out
Spool
Flow
Orifice
Control
Valve
Relief
Valve

Rear Axle

Steering and Brake Hystat

Manifold Valve Group Signal

Steering and Implement

Brake Pump Pump

37

In this illustration the accumulators have been charged. As pressure increased in the system,
the cut-out pressure was reached moving the cut-in/cut-out spool down.

When the cut-in/cut-out spool moved down, pump supply oil through the orifice is allowed to
flow through the LS line to the HMU. At the HMU, the oil in the LS line flows through
another orifice to the tank.

This action results in a pressure drop on the right side of the flow control valve and the pressure
on the left side of the flow control valve moves the valve to the right to direct pump supply oil
to the tank. Supply pressure drops and the check valve seats to the left due to the higher
pressure in the accumulators.

When the brake pedal is depressed, the brake valve moves down. Initially, the hystat signal is
bled to the tank to hydrostatically brake the machine. As the valve moves down further, the
valve directs oil in the accumulators to the brakes to ENGAGE the brakes.
STMG 792 - 54 - Text Reference
11/04

STEERING AND BRAKE MANIFOLD VALVE GROUP

ACCUMULATORS CHARGED / STEERING NEUTRAL

To HMU
LS Passage
To HMU From Pump
Cut-in/
Cut-out
Spool

Check
Valve

Orifice

Relief Flow Control

Valve Valve
To Accumulators To Tank

38

When the cut-in/cut-out valve moves to the right due to the pressure on the left, supply oil
through the orifice is able to flow through the LS passage to the HMU.

Pressure in the spring chamber on the right end of the flow control valve is reduced. The flow
control valve moves to the right opening up a passage for the supply passage to go to tank.

The check valve moves to the right due to the accumulator pressure being higher than supply
pressure.

After multiple brake applications, the pressure in the accumulators will fall below the cut-in
pressure. The cut-in/cut-out spool moves up and the charging cycle will begin again as
previously described.
STMG 792 - 55 - Text Reference
11/04

Steering 914G STEERING AND BRAKE SYSTEM

Cylinders ACCUMULATORS CHARGED / STEERING ACTIVATED

HMU

LS Line
Brake
Front Axle
Accumulators Valve

Cut-In/
Cut-Out
Spool
Flow
Orifice
Control
Valve
Relief
Valve

Rear Axle

Steering and Brake Hystat

Manifold Valve Group Signal

Steering and Implement

Brake Pump Pump

39

When the steering wheel is turned, the HMU blocks oil through the LS passage from going to
the tank. Due to the orifice, the LS pressure on the right side of the flow control valve is able
to shift the spool rapidly to the left, blocking the supply oil from going to the tank.

Full pump supply oil is directed to the HMU.

Also, when the HMU is turned it connects the LS passage to the steering cylinder to sense the
actual steering load, which limits the signal pressure sensed at the flow control valve.

As steering flow needs are met, pressure increases on the left side of the flow control valve and
moves the valve back to the right to meter the oil not needed by the HMU to the tank.

If the relief valve opens, the valve directs some of the signal oil to the tank. The flow control
moves fully to the right and directs supply oil to tank. This action protects the steering
components.
STMG 792 - 56 - Text Reference
11/04

STEERING AND BRAKE MANIFOLD VALVE GROUP

ACCUMULATORS CHARGED / STEERING ACTIVATED

To HMU
LS Passage
From Pump
To HMU
Cut-in/
Cut-out
Spool

Check
Valve

Orifice

Relief Flow Control

Valve Valve
To Accumulators To Tank

40

When the steering wheel is turned a pressure drop occurs in the supply passage to the HMU.

Dynamic bleed signal oil in the flow control valve spring chamber works with the spring to
shift the flow control valve to the left preventing supply oil from going to the tank. Full pump
supply oil is directed to the HMU.

As the flow needs are met, pressure increases on the left side of the flow control valve and
shifts the valve back to the right. The flow control valve meters the oil not required by the
HMU to the tank.
STMG 792 - 57 - Text Reference
11/04

Quick
Steering Coupler
Cylinder

HMU Coupler
Control
Valve

LS Line

Brake
Front Axle
Accumulators Valve

Cut-In/
Cut-Out
Spool

Flow
Control Orifice
Valve
Relief
Valve

Rear Axle

Hystat
Steering and Brake
Signal
Manifold Valve Group
Supplemental
Steering Flow
Switch IT14G STEERING AND BRAKE
M Steering and
Brake Pump Implement
Pump
SYSTEM
ACCUMULATORS CHARGED / BRAKES ENGAGED

41

The IT14G Steering and Brake System also supplies oil to control the quick coupler. If one of
the quick coupler solenoids is selected in the coupler control valve, supply oil from the steering
and brake pump flows to the quick coupler cylinder.

Some of the oil flows to the resolver and then flows to the steering and brake manifold valve
group. This oil shifts the flow control valve to the left to restrict the supply oil from flowing to
the tank. Most of the supply oil is directed to the coupler cylinder.

In this illustration the quick coupler is being RETRACTED. Some of the supply oil to the
quick coupler is used to unseat a check valve to allow oil to return to the tank.

Supplemental steering and the flow switch are separate options on either the IT14G or 914G.
STMG 792 - 58 - Text Reference
11/04

SERVICE BRAKE VALVE

Plunger

Springs

Upper
Ball Spool
Check

To Brakes To Brakes

From From
Accumulators Accumulators

Hystat Hystat
Signal Signal

Lower
Spool

BRAKES RELEASED BRAKES ENGAGED

42

When the brakes are RELEASED, the spring below the lower spool holds both spools up. The
springs below the plunger hold the plunger up.

The lower spool blocks the hystat signal from the tank. The upper spool blocks the supply oil
from the accumulators and opens the passage to the brakes to the tank.

When the brake pedal is depressed, the plunger moves down. As the plunger moves down, the
plunger compresses the uppers springs, which move the spools down against the lower spring.
As the lower spool moves down, the spool starts to bleed off the hystat signal to the tank. This
action results in the pump destroking and the motors upstroking to provide hystat braking for
the machine.

As the spools continue to move down, the upper spool closes the passage to the tank and allows
oil from the accumulators to flow to the brakes to engage the brakes.

The amount the brake pedal is depressed determines how far the plunger is moved down. The
distance the plunger moves determines how far the spools move down.
STMG 792 - 59 - Text Reference
11/04

Once the upper spool allows oil from the accumulator to flow to the brakes, it acts as a variable
pressure reducing valve. Back pressure from the brake application is felt between the two
spools and moves the upper spool away from the lower spool. The upper spool then meters the
accumulator oil to the brakes to maintain the desired braking force.

For INCHING, the operator depresses the brake pedal enough to just bleed off the hystat signal
to neutralize the hystat system. This action allows more engine horsepower for the implement
system.

The ball check prevents a hydraulic lock below the plunger and prevents return oil from the
brakes from entering the chamber below the plunger.
STMG 792 - 60 - Text Reference
11/04

Steering
Cylinders
Quick
HMU Coupler

Coupler
Control
LS Line Valve

Steering and Brake

Manifold Valve Group Brake
Valve Front Axle

Cut-In/
Cut-Out
Spool
Flow
Control Orifice
Valve

Relief
Valve

Rear Axle

Hystat
Signal

Steering and
Brake Pump
Implement
Pump
IT14G STEERING AND BRAKE SYSTEM
BRUSH CUTTER READY
ACCUMULATORS CHARGING / BRAKES RELEASED

43

The IT14G can be equipped with a "brush cutter ready" option. This option requires the use of
a different steering and brake manifold group.

The flow control valve is a different design and the relief valve senses supply oil before the
flow control valve. The relief valve limits the maximum supply pressure instead of the
maximum steering signal (load sense) pressure.

When the machine is started, oil from the pump flows to the steering HMU and to the steering
and brake manifold valve group. The oil to the HMU is blocked unless the steering wheel is
turned.

When the accumulators are charging, oil from the pump is directed through the flow control
valve, the check valve, and to the accumulators.

As the accumulators charge, pressure is sensed on both sides of the cut-in/cut-out spool and on
both sides of the flow control valve.

The flow control valve stays to the left during the charging cycle due to the spring and the
pressure on the right side of the spool. The cut-in/cut-out spool is held up during the charging
or cut-in cycle.
STMG 792 - 61 - Text Reference
11/04

STEERING AND BRAKE MANIFOLD VALVE GROUP

ACCUMULATORS CHARGING

To HMU Relief Valve

From Pump

Load Signal
To HMU

Cut -In/
Cut -Out
Spool

Check
Valve

Flow Cont rol

To To
Valve
Accumulat ors Orifice Tank

44

When the machine is started the accumulators begin to charge. Oil from the pump flows to the
steering HMU and to the steering and brake manifold valve group. The HMU blocks the oil
from the pump.

The flow control valve and the cut-in/cut-out spool are held to the left by their respective
springs during the charging cycle.

Oil from the pump flows around the flow control valve and moves the check valve to the left.
The oil then flows to the accumulators. Some of the oil flows through the orifice to the right
side of the flow control valve to work with the spring in keeping the flow control valve to the
left. Oil through the orifice is blocked from going to the load sense (LS) passage by the
cut-in/cut-out spool.

As the accumulators charge, the pressure increases on the left side of the cut-in/cut-out spool.
STMG 792 - 62 - Text Reference
11/04

Steering
Cylinders

Quick
HMU Coupler

Coupler
Control
Valve
LS Line

Steering and Brake

Manifold Valve Group Brake
Valve Front Axle
Accumulators
Cut-In/
Cut-Out
Spool
Flow
Control Orifice
Valve

Relief
Valve

Rear Axle

Hystat
Signal

Steering and
Brake Pump
Implement
Pump
IT14G STEERING AND BRAKE SYSTEM
BRUSH CUTTER READY
ACCUMULATORS CHARGED / BRAKES ENGAGED

45

In this illustration the accumulators have been charged. As pressure increased in the system,
the cut-out pressure was reached moving the cut-in/cut-out spool down.

When the cut-in/cut-out spool moved down, pump supply oil through the orifice is allowed to
flow through the LS line to the HMU. At the HMU, the oil in the LS line flows through
another orifice to the tank.

This action results in a pressure drop on the right side of the flow control valve and the pressure
on the left side of the flow control valve moves the valve to the right to direct pump supply oil
to the brush cutter. Supply pressure drops and the check valve seats to the left due to the higher
pressure in the accumulators.

When the brake pedal is depressed, the brake valve moves down. Initially, the hystat signal is
bled to the tank to hydrostatically brake the machine. As the valve moves down further, the
valve directs oil in the accumulators to the brakes to ENGAGE the brakes.

After multiple brake applications, the pressure in the accumulators will fall below the cut-in
pressure. The cut-in/cut-out spool moves up and the charging cycle will begin again as
previously described.
STMG 792 - 63 - Text Reference
11/04

Steering
Cylinders
Quick
HMU Coupler

Coupler
Control
Valve
LS Line

Steering and Brake

Manifold Valve Group Brake
Valve Front Axle
Accumulators
Cut-In/
Cut-Out
Spool
Flow
Control Orifice
Valve

Relief
Valve

Rear Axle

Hystat
Signal

Steering and
Brake Pump
Implement
Pump
IT14G STEERING AND BRAKE SYSTEM
BRUSH CUTTER READY
ACCUMULATORS CHARGED / STEERING ACTIVATED

46

When the steering wheel is turned, the HMU blocks oil through the LS passage from going to
the tank. Due to the orifice, the LS pressure on the right side of the flow control valve is able
to shift the spool rapidly to the left, blocking the supply oil from going to the tank.

Full pump supply oil is directed to the HMU.

Also, when the HMU is turned it connects the LS passage to the steering cylinder to sense the
actual steering load, which limits the signal pressure sensed at the flow control valve.

As steering flow needs are met, pressure increases on the left side of the flow control valve and
moves the valve back to the right to meter the oil not needed by the HMU to the tank.

If the relief valve opens, the valve directs the supply oil to the tank. This action protects the
steering components. The flow control does move as was done with the previously discussed
flow control valve.
STMG 792 - 64 - Text Reference
11/04

STEERING AND BRAKE MANIFOLD VALVE GROUP

ACCUMULATORS CHARGED/ STEERING ACTIVATED

To HMU Relief Valve

From Pump

Load Signal
To HMU
Cut -In/
Cut -Out
Spool

Check
Valve

Flow Cont rol

To To
Valve
Accumulat ors Orifice Tank

47

When the steering wheel is turned a pressure drop occurs in the supply passage to the HMU.

Dynamic bleed signal oil in the flow control valve spring chamber works with the spring to
shift the flow control valve to the left preventing supply oil from going to the tank. Full pump
supply oil is directed to the HMU.

As the flow needs are met, pressure increases on the left side of the flow control valve and
shifts the valve back to the right. The flow control valve meters the oil not required by the
HMU to the tank.
STMG 792 - 65 - Text Reference
11/04

Steering
Cylinders
Quick
HMU Coupler

Coupler
Control
Valve
LS Line

Steering and Brake

Manifold Valve Group Brake
Valve Front Axle
Accumulators
Cut-In/
Cut-Out
Spool
Flow
Control Orifice
Valve

Relief
Valve

To Brush
Cutter Rear Axle
From Brush Hystat
Cutter Signal

Steering and
Brake Pump
Implement
Pump
IT14G STEERING AND BRAKE SYSTEM
BRUSH CUTTER READY
FLOW TO BRUSH CUTTER

48

When a brush cutter mower attachment is plumbed into the system, supply oil from the pump is
available first to charge the accumulators, and then the steering system. Flow not required for
these two circuits is directed by the flow control valve to the brush cutter mower attachment.

The relief valve in the steering and brake manifold group will limit the maximum pressure for
the brush cutter.
STMG 792 - 66 - Text Reference
11/04

STEERING AND BRAKE MANIFOLD VALVE GROUP

ACCUMULATORS CHARGED/ STEERING NEUTRAL
FLOW TO BRUSH CUTTER

To HMU Relief Valve

From Pump

Load Signal
To HMU

Cut -In/
Cut -Out
Spool

Check
Valve

Flow Cont rol

To To
Valve
Accumulat ors Brush Cut t er

49

When flow is not required for the steering or brake circuits, oil is directed by the flow control
valve to the brush cutter mower attachment.

The pressure on the left side of the flow control valve moves the valve to the right to direct
pump supply oil to the brush cutter. The brush cutter uses an open-center control valve. When
the brush cutter function is in HOLD, the oil to the brush circuit is directed back to the tank.

If the steering or brake circuits are activated, these circuits have priority over the brush cutter.
Pump oil will flow to the activated circuit to supply the necessary oil. Once the requirements
are met, the brush cutter will then receive full pump supply oil.

If the relief valve opens, the valve directs the supply oil to the tank. This action protects the
brush cutter components.
STMG 792 - 67 - Text Reference
11/04

50

The quick coupler control valve (arrow) is located next to the machine articulation point.
STMG 792 - 68 - Text Reference
11/04

2
1

51

The HMU (1) and brake control valve (2) are located below the cab next to the articulation
point.
STMG 792 - 69 - Text Reference
11/04

914G IMPLEMENT HYDRAULIC SYSTEM

HOLD
To Attachment
Cylinders

Main
Relief
Valve

Inlet Lift Tilt Aux.

Steering Implement Manifold Valve Valve Valve
Pump Pump

Pilot Shutoff
Valve
Orifice
From Hystat
Charge Pump

Pilot
Valves
To Hystat Motor Bearing
From Hystat Pump Case Drain

From Hystat Motor Case Drain

52

IMPLEMENT HYDRAULIC SYSTEMS

The 914G is equipped with an open-center, pilot-operated hydraulic system. The implement
control valves are in parallel as to pump flow. The 914G implement hydraulic system consists
of a tank, a fixed displacement pump, a main relief valve, a tilt circuit with one cylinder, and a
lift circuit with two cylinders. The auxiliary circuit is optional. Each valve is controlled by a
pilot valve. The hystat charge pump supplies oil to the pilot system. The charge relief valve
limits the maximum pilot system pressure. An accumulator provides implement lower
capabilities for a limited time after the engine has been shut down.

Orifices in the pilot lines permit smoother control valve operation. The pilot valves act as
variable pressure reducing valves. The more the pilot valve is shifted, the higher the pilot
pressure is to the individual control valves. The amount of pilot pressure to the control valve
will determine the distance that the spool in the control valve shifts and the amount of pump
flow directed to the cylinders.
STMG 792 - 70 - Text Reference
11/04

The pilot valves are equipped with solenoids which work with the loader and bucket lift
kickouts. Another solenoid in the lift pilot valve will hold the lift circuit in FLOAT. The
auxiliary valve is also equipped with a detent.

The pilot shutoff lever (hydraulic control lever lock) is able to block the pilot oil to the pilot
control valves when applied. The lever also opens the hydraulic lock detent override switch
which cuts the power to all the solenoid detents in the pilot valves.

A manual dead engine lower valve for the loader lift valve can be used after the accumulator
pressure is exhausted. The lift and tilt circuits are controlled by a joystick (multifunction)
control lever.

The tilt circuit is equipped with combination line relief and makeup valves for the rod and head
ends of the cylinder. The lift circuit is equipped with a makeup valve for the rod end of the
cylinders. The auxiliary circuit can be equipped with optional line relief valves for both the
head and rod ends of the cylinders. All valves are equipped with load check valves.

With all the implement control valves in HOLD, the pump supply oil flows through the center
passage of each valve before returning to the tank.

NOTE: Additional orifices have been added to the following circuits: lift cylinder
(lower) and tilt cylinder (lower). The additional orifices improve the modulation of the
pilot oil to the valve spool.
STMG 792 - 71 - Text Reference
11/04

IT14G IMPLEMENT HYDRAULIC SYSTEM

HOLD
Ride
Control

To Attachment To Attachment
Cylinders Cylinders

Dead Engine
Lower

Main
Relief
Valve

Inlet Lift Tilt Aux.

Steering Implement Manifold Valve Valve Valve
Pump Pump

Pilot Shutoff
Valve
Orifice

From Hystat
Charge Pump

Pilot
Valves
To Hystat Motor Bearing
From Hystat Pump
Case Drain

From Hystat Motor Case Drain

53

The IT14G implement hydraulic system is similar in operation to the 914G hydraulic system
except for having two tilt cylinders, an additional optional auxiliary valve, a coupler cylinder,
and a slightly different tilt valve.

The tilt valve has a "regenerative dump" position which permits faster bucket unloading.
Return oil from the rod end of the cylinders is added to the pump supply oil to fill the head end
of the cylinders.

The Ride Control System is optional on either machine. When the Ride Control System is
operating, the solenoid valve opens a passage between the head end of the lift cylinders and the
accumulator. The solenoid valve also opens a passage to allow oil in the rod end of the
cylinders to return to the tank. The ride control accumulators are mounted to the front loader
frame above the implement valve group.

As the operator drives over rough terrain with the Ride Control System ON, the uneven ground
will cause the lift cylinders to extend and retract.
STMG 792 - 72 - Text Reference
11/04

When the lift cylinders retract, pressure in the head end of the cylinders increases. The
cylinder rod movement forces some of the oil in the head end of the cylinders into the
accumulator, and the rod end of the cylinders draws oil from the tank to make up for voiding of
the cylinders. As the lift cylinders extend, oil in the rod end of the cylinders returns to the tank
and pressurized oil from the accumulator flows to the head end of the cylinders. The
accumulator dampens the shocks from external forces to provide a smoother ride.

NOTE: Additional orifices have been added to the following circuits: lift cylinder
(lower) and tilt cylinder (lower). The additional orifices improve the modulation of the
pilot oil to the valve spool.
STMG 792 - 73 - Text Reference
11/04

54

The machines are equipped with magnetic lift (1) and tilt kickouts (2).

The IT14G has two tilt kickouts. One detent is for use with buckets and the other for use with
forks. When activated the detents are use to stop bucket movement when the selected work
tool is parallel to the ground.

A switch on the left console is used to select one or the other.

STMG 792 - 74 - Text Reference
11/04

55

The coupler cylinder is located under the cover (1).

Connectors (2 and 3) are used to plumb worktools to the machine.

STMG 792 - 75 - Text Reference
11/04

56

ADVANCED OPTIONAL SYSTEMS

The updated 914G and IT14G can be equipped with the optional Machine Security System
(MSS). When the anti-theft feature is installed, a microchip is imbedded in the rubber grip of
the key. This microchip responds to a signal sent from an antenna around the start/stop switch
(key slot). Only if the key has the appropriate, pre-programmed microchip can the engine be
started.

The wrong microchip or no microchip will not allow electrical power to be sent to the main
power relay or the starter relay, preventing the engine from being started.

When the "MSS" ECM is selected from the ECM Status Summary Screen using CAT ET, the
technician can gain access to the the the Machine Security System Configuration Screen.

Highlight the parameter and then use the "Change" button on the lower left to change the
parameter. Refer to the Service Manual for more information on this configuration screen and
the Machine Security System.
STMG 792 - 76 - Text Reference
11/04

57

The Machine Security System (MSS) ECM is located in the rear of the cab. The MSS ECM is
used with the Machine ECM and a microchip embedded key to provide a security system for
the machine.

NOTE: The rear panel inside the cab is removed.

STMG 792 - 77 - Text Reference
11/04

58

CONCLUSION

This concludes the presentation on the updated 914G Wheel Loaders and IT14G Integrated
Tool Carriers with 3054CT Tier II engines.

This presentation supports the service manual and previous released training materials. When
used in conjunction with the service manual, the information in this package should permit the
technician to do a thorough job of analyzing a problem in these systems.

For service repairs, adjustments, and maintenance, always refer to the Owner and Operator
Manual, Service Manuals, and other related service publications.
STMG 792 - 78 - Text Reference
11/04

HYDRAULIC SCHEMATIC COLOR CODE

Black - Mechanical Connection. Seal Red - High Pressure Oil

Dark Gray - Cutaway Section Red / White Stripes - 1st Pressure Reduction

Light Gray - Surface Color Red Crosshatch - 2nd Reduction in Pressure

White - Atmosphere or Air (No Pressure) Pink - 3rd Reduction in Pressure

Purple - Pneumatic Pressure Red / Pink Stripes - Secondary Source Oil Pressure

Yellow - Moving or Activated Components Orange - Pilot, Signal or Torque Converter Oil

Cat Yellow - (Restricted Usage) Orange / White Stripes -

Identification of Components Reduced Pilot, Signal or TC Oil Pressure
Within a Moving Group
Orange / Crosshatch - 2nd Reduction In
Brown - Lubricating Oil Pilot, Signal or TC Oil Pressure

Green - Tank, Sump, or Return Oil Blue - Trapped Oil

Green / White Stripes -

Scavenge / Suction Oil or Hydraulic Void

HYDRAULIC SCHEMATIC COLOR CODES

The colors on the hydraulic schematics and cross-sectional views shown throughout this
presentation denote specific meanings. This illustration identifies the meaning of each color.
 11/04

HYDRAULIC SCHEMATIC COLOR CODE

STMG 792

Black - Mechanical Connection. Seal Red - High Pressure Oil

Dark Gray - Cutaway Section Red / White Stripes - 1st Pressure Reduction

Light Gray - Surface Color Red Crosshatch - 2nd Reduction in Pressure

White - Atmosphere or Air (No Pressure) Pink - 3rd Reduction in Pressure

Purple - Pneumatic Pressure Red / Pink Stripes - Secondary Source Oil Pressure
- 79 -

Yellow - Moving or Activated Components Orange - Pilot, Signal or Torque Converter Oil

Cat Yellow - (Restricted Usage) Orange / White Stripes -

Identification of Components Reduced Pilot, Signal or TC Oil Pressure
Within a Moving Group
Orange / Crosshatch - 2nd Reduction In
Brown - Lubricating Oil Pilot, Signal or TC Oil Pressure

Green - Tank, Sump, or Return Oil Blue - Trapped Oil

Green / White Stripes -

Scavenge / Suction Oil or Hydraulic Void
Handout No. 1
STMG 792 - 80 - Handout No. 2
11/04

Machine Walk-around Checklist

Directions: Use this sheet when performing a machine orientation lab exercise.

Place a check in the blank if the fluid level is acceptable.

914G IT14G
Engine oil level
Hydraulic system oil level
Brake system oil level
Cooling system fluid level
Fuel level

Place a check in the blank if acceptable or after task was performed.

914G IT14G
Drain water separator
Check seat belt
Check air filter indicator and precleaner if equipped

Place a check in the blank if the indicator, switch, or control is working correctly.

914G IT14G
Key start switch
Turn signal
Tachometer
Engine coolant gauge
Fuel level gauge
Parking brake light
Turn signal
Horn
Running lights
Front work lights
Rear work lights
Windshield wipers
Heating and air conditioner controls
F-N-R switch
STMG 792 - 81 - Handout No. 3
11/04

Machine Walk-around Checklist - cont'd

Place a check in the blank after locating and reading the following warning labels on the
machine.

914G IT14G
Before operating
Use of ether
Accumulators
Articulation area
Before roading
Loader arm brace
ROPS
Use of Jumpers

Place a check in the blank after locating each of the following controls.

914G IT14G
Front governor pedal
Steering wheel
Directional shifter
Speed selector
Directional or transmission neutral lock
Brake pedals
Parking brake lever
Loader lift and tilt
Attachment lever
Attachment switch for IT machine

Place a check in the blank after locating each of the following identification plates.

914G IT14G
Engine identification plate
Transmission identification plate
Work tool identification plate
Machine identification plate
Starting and Charging System Worksheet
11/04

Directions: Use the machine electrical schematic RENR6499 to complete this schematic. Label the wires with the appropriate
STMG 792

alpha-numerical codes.

ELECTRICAL STARTING AND CHARGING SYSTEM

To To Alt Lamp
Shift Neutral-
Handle start 2 1 3
I L P
Relay
Service
B+
Meter
ALT
Main Alternator
Breaker
R
60 112-PU-10 To Accessories
C OFF
Main Power S ON
Relay Neutral-start B ST
15 A Start
Relay
Aid
Key Start
Switch
Aux. Breaker
- 82 -

30 15
Key Start Switch
Lamp Breaker 10 A

Alt. Breaker 60
Fuel
Shutdown A 1
B 2
Solenoid

NEG POS NEG POS 200-BK Start Aid

Switch

Starter T°
Starter Motor Cold Coolant
Disconnect Relay Start Switch
Switch Advance
(Optional) Motor
From
Lamp Switch

Glow Plug
Relay
Handout No. 4

Glow Plugs
HYTEC System Components Checklist
11/04

Directions: Record a check next to each component after locating it on the machine.
STMG 792

F•N•R
Switch

Shift Diagnostic Buffered Speedometer

Lever Indicator Driver
(Action LED)
Ride Control/ Ride Control/
Load Check Switch Load Check Relay

Parking Brake Motor Signal

Switch Control Valve Solenoid

Key Start Reverse

Switch Solenoid
- 83 -

Electronic
Harness Code
Forward
Connector
Control Solenoid

Options Code Module

Solenoid Common
Connector
Interrupt Relay

Main Steering
Flow Switch Secondary Supplemental
Steer Relay
Creeper Switch or
Speed Switch Service
Connector
Engine Speed
Sensor
Primary Steering
Drive Shaft Flow Lamp
Speed Sensor
Handout No. 5
High Speed Hystat Power Train System Components Checklist
11/04

Directions: Fill in the blanks next to the terms with the correct letter.
STMG 792

Identify Components
Filter group
Large motor
Small motor HIGH SPEED HYSTAT SYSTEM B OS
NEUTRAL O
P Q
Pump
M2
To
Charge pump To Implement Brakes
Pilot System
A PS1 G1 PC AB L From Brake
Accumulators
Pressure override valve N
MIN

Crossover line relief X1

MB
F
valves
C M
Speed sensing valve R
X3
H
- 84 -

Charge relief valve X4

E
X2

Shutoff valve D
Motor signal control valve L To
Flushing
K Bypass
MA Block
Brake valve
MIN

Shuttle FWD To Tank Return

Check Valve

Small motor displacement

G
control valve To Hydraulic
S Tank
I
Large motor displacement M1
J
control valve
Flushing valve
F-N-R valve
Creeper valve
Handout No. 6
STMG 792 - 85 - Handout No. 7
11/04

POSTTEST: MACHINE ORIENTATION

NOTE: Use the provided sales information brochures to answer the following questions.

Directions: Modified True/False. If the question is false, circle the word or words that make
the statement incorrect and replace with the word(s) to make the statement correct.

1. The machines are equipped with the Caterpillar 3054T engine.

2. Both the 914G and IT14G are available with the "brush cutter" ready option.

3. The machines are equipped with a 24-Volt electrical system.

4. For improved engine starting in cold weather, an inlet air heater is used.

5. The engine speed control can be used in conjunction with the creeper control to
achieve optimal work tool performance.

6. The machines are equipped with two hydraulic oil filters.

7. The machines use an open-centered, pilot operated hydraulic system.

8. The creeper control works only in low range.

9. The machines are now equipped with a fully compliant Tier I engine.

10. The "brush cutter" ready option is available from the factory.

11. The machines are equipped with two fuel filters.

12. The Ride Control System is only available on the IT14G.

13. The Hystat Electronic Control (HYTEC) is found on all Tier II machines.

14. The maintenance interval for engine oil, engine oil filter, and fuel filter is 250
hours.

15. The machines can be equipped with the Machine Security System (MSS).

16. For normal travel operation of the machine, the creeper control should be moved
fully forward into "detent."
STMG 792 - 86 - Handout No. 8
11/04

POSTTEST ANSWERS: MACHINE ORIENTATION

NOTE: Use the provided sales information brochures to answer the following questions.

Directions: Modified True/False. If the question is false, circle the word or words that make
the statement incorrect and replace with the word(s) to make the statement correct.

F 1. The machines are equipped with the Caterpillar 3054T 3054CT engine.

F 2. Both the 914G and ONLY IT14G are available with the "brush cutter" ready
option.

T 3. The machines are equipped with a 24-Volt electrical system.

F 4. For improved engine starting in cold weather, an inlet air heater GLOW PLUGS
is used.

T 5. The engine speed control can be used in conjunction with the creeper control to
achieve optimal work tool performance.

F 6. The machines are equipped with two ONE hydraulic oil filters.

T 7. The machines use an open-centered, pilot operated hydraulic system.

F 8. The creeper control works only BOTH RANGES in low range.

F 9. The machines are now equipped with a fully compliant Tier I TIER II engine.

T 10. The "brush cutter" ready option is available from the factory.

F 11. The machines are equipped with two ONE fuel filters.

F 12. The Ride Control System is only available on the IT14G AVAILABLE ON
BOTH MODELS.

T 13. The Hystat Electronic Control (HYTEC) is found on all Tier II machines.

F 14. The maintenance interval for engine oil, engine oil filter, and fuel filter is 250
500 hours.

T 15. The machines can be equipped with the Machine Security System (MSS).

T 16. For normal travel operation of the machine, the creeper control should be moved
fully forward into "detent."