SECTION 3 POWER TRAIN SYSTEM

GROUP 1 STRUCTURE AND FUNCTION

1. POWER TRAIN COMPONENT OVERVIEW

Transmission Upper drive shaft Engine

Front axle Center drive shaft Rear axle

Front drive shaft Rear drive shaft

The power train consists of the following components :

şTransmission
şFront, upper, center and rear drive shafts
şFront and rear axles
Engine power is transmitted to the transmission through the torque converter.
The transmission is a hydraulically engaged four speed forward, three speed reverse countershaft type
power shift transmission. A drum type parking brake is located on the front of the transmission housing.
The transmission outputs through universal joints to three drive shaft assemblies. The front drive shaft
is a telescoping shaft which drives the front axle. The front axle is mounted directly to the loader frame.
The front axle is equipped with limited slip differential.
The rear axle is mounted on an oscillating pivot. The rear axle is equipped with limited slip differential.
The power transmitted to front axle and rear axle is reduced by the pinion gear and ring gear of
differential. It then passes from the differential to the sun gear shaft(Axle shaft) of final drive.
The power of the sun gear is reduced by a planetary mechanism and is transmitted through the
planetary hub to the wheel.

3-1
1) HYDRAULIC SCHEMATIC

1-2-3
Declutch
To transmission
lube
Oil cooler(Option)
FR

From master
cylinder Charging
Filter pump
assembly

Vent
Converter Clutch
safety valve regulator
Torque
converter Removable
screen
Oil sump

3-2
2) HYDRAULIC CIRCUIT

Modulation Modulation
valve FWD valve REV

Torque REV
converter Clutch
regulator valve

FWD,LO
Hose B

FWD,H/4
A
Converter
safety
Oil cooler valve C 2
(Option)

D
1
Filter E

Hose Pump
Lubrication

Suction screen

Air breather

Oil sump

Forward Reverse Neutral

Speed
1 2 3 4 1 2 3 1 2 3
B X X X
C X
A X X X X
E X X X X X X
D X X X
X : Solenoid activated

3-3
2. TORQUE CONVERTER

Stator

Input side Output side

Turbine Impeller

Torque converter is a stemless transmitting system to transmit engine power by means of hydraulic
force. As usual, this system(Torque converter) is consisting of three elements(Impeller wheel, turbine
wheel, stator wheel).... the impeller wheel connected to input shaft, the turbine wheel connected to
output shaft and the stator wheel(Guide bland) fixed to the housing.
The above impeller wheel and turbine wheel face each other and also, the stator wheel is located
between these two elements. These three elements are enclosed in the oil filled housing.
As the impeller wheel is turned by the engine, centrifugal force causes oil to strike the turbine wheel at
high velocity and forces it to turn.
The stator is provided to change the direction of oil flow after it has gone through the turbine wheel and
send it back to the impeller wheel. At that time, reaction torque is caused and this is added to the
torque of turbine wheel. As a result, the output torque is increased to several times of engine torque.
The output torque becomes the largest when the output shaft is stopped(The torque of output shaft at
that time is called the stalling torque). When the load on the output side decreases, the reaction torque
also decreases and, in contrast with this, the output speed increases.
As explained the above, the torque converter has the working to change output torque automatically in
accordance with strength of load.
Besides, transmitting of torque is done by oil and that results it is possible to slip between the engine
side(Output side) and at the same time, mechanical shock can be absorbed.

3-4
3. TRANSMISSION
1) TYPICAL CROSS SECTION

FWD

REV 2nd 1st

4th 3rd

3-5
2) TRANSMISSION LAYOUT

B A

F
H
N
G L
K

A Torque converter F Reverse clutch K 3rd clutch

B Charge pump assembly G 1st clutch L 4th clutch
C Pump drive idler gear H 2st clutch M Output shaft
D Pump drive gear J Idler shaft N Solenoid control valve
E Forward clutch

3-6
 3) OPERATION OF TRANSMISSION
(1) Forward
‫ ڸ‬Forward 1st
In 1st forward, FWD clutch and 1st clutch are engaged.
FWD clutch and 1st clutch are actuated by the hydraulic pressure applied to the clutch piston.

INPUT

FWD

REV 2nd 1st

4th 3rd

Idler

OUTPUT

3-7
 ‫ ڹ‬Forward 2nd
In 2nd forward, FWD clutch and 2nd clutch are engaged.
FWD clutch and 2nd clutch are actuated by the hydraulic pressure applied to the clutch piston.

INPUT

FWD

REV 2nd 1st

4th 3rd

Idler

OUTPUT

3-8
 ‫ ں‬Forward 3rd
In 3rd forward, FWD clutch and 3rd clutch are engaged.
FWD clutch and 3rd clutch are actuated by the hydraulic pressure applied to the clutch piston.

INPUT

FWD

REV 2nd 1st

4th 3rd

Idler

OUTPUT

3-9
 ‫ ڻ‬Forward 4th
In 4th forward, 4th clutch and 3rd clutch are engaged.
4th clutch and 3rd clutch are actuated by the hydraulic pressure applied to the clutch piston.

INPUT

FWD

REV 2nd 1st

4th 3rd

Idler

OUTPUT

3-10
 (2) Reverse
‫ ڸ‬Reverse 1st
In 1st reverse, REV clutch and 1st clutch are engaged.
REV clutch and 1st clutch are actuated by the hydraulic pressure applied to the clutch piston.

INPUT

FWD

REV 2nd 1st

4th 3rd

Idler

OUTPUT

3-11
 ‫ ڹ‬Reverse 2nd
In 2nd reverse, REV clutch and 2nd clutch are engaged.
REV clutch and 2nd clutch are actuated by the hydraulic pressure applied to the clutch piston.

INPUT

FWD

REV 2nd 1st

4th 3rd

Idler

OUTPUT

3-12
 ‫ ں‬Reverse 3rd
In 3rd reverse, REV clutch and 3rd clutch are engaged.
REV clutch and 3rd clutch are actuated by the hydraulic pressure applied to the clutch piston.

INPUT

FWD

REV 2nd 1st

4th 3rd

Idler

OUTPUT

3-13
4) ELECTRIC SOLENOID CONTROL VALVE

Direction Solenoids Clutches

& speed energized pressurized

Forward 1st V X Y Forward & 1st

Forward 2nd V X Forward & 2nd
Forward 3rd V Forward & 3rd 2P

Forward 4th V Z 4th & 3rd

RC RP 2C
Reverse 1st W X Y Reverse & 1st
Reverse 2nd W X Reverse & 2nd
1P
Reverse 3rd W Reverse & 3rd
FHP
Pilot and clutch pressure check points V Z Y
1P 1st pilot FWD 4th 1st
2P 2nd pilot
2C 2nd clutch
4P(FHP) 4th clutch W X
RP Reverse pilot REV 2nd
RC Reverse clutch

Energized
Inlet

Pilot pressure
Vent

De-energized

Vent

3 - 14
4. EGS LEVER
1) SHIFT LEVER OPERATION
EGS lever applications share the principle of selecting direction and gear positions.
Direction is selected by placing the lever in one of three detented positions(Neutral, Forward or
Reverse).
Gear shifts are made by bringing the lever either in the upshift position or in the downshift
position. These positions are spring returned.
With the EGS, shifts are made relative to the previous position : The EGS remembers the selected
gear position and shifts either to a higher gear or to a lower gear.
The EGS display always shows the selected shift lever position, the selected direction, the gear
position and the gear direction.
This operating principle accounts for the flexibility of the EGS system : It makes possible to control
any(Electric) powershift transmission with the same shift lever, provided the correct software(A
program for the EGS computer) is installed.
It also facilitates features such as kickdown, automatic powerup in neutral, preset gear selection
after a direction change, etc..

Forward
LOCK
Heatsink
Upshift
SPRING RETURN

Neutral

Downshift
SPRING RETURN

Reverse Display - LEDS

LOCK

The froward driving direction is selected by pushing the lever away from the driver(This usually
corresponds with pushing it to the normal driving direction).
The reverse driving direction is selected by pulling the lever towards the driver.
The neutral can be selected by placing the lever into its central detented position.
An upshift is requested by rotating the shift lever counter clockwise.
A downshift is requested by rotating the shift lever clockwise.

3 - 15
2) FUNCTIONAL DESCRIPTION
(1) Automatic powerup in neutral
When power is first applied to the EGS, neutral is always selected.
This is regardless of the position of the shift lever(It can be in either forward, neutral or reverse
position).
In order to start driving, the driver first has to place the shift lever into the neutral(Central detented)
position before a specific direction can be selected.
(2) Neutral start protection
Each EGS can have an output signal, which is deactivated whenever the shift lever is in the
neutral position.
This signal can be used to control a normal closed relay preventing engine start up whenever the
shift lever is not in the neutral detented position.
If during powerup the shiftlever is in forward or in reverse, the neutral start protection will not be
activated(Due to the function automatic powerup in neutral). Only after leaving this function
automatic powerup in neutral the neutral start protection will be activated.
(3) Kickdown
This EGS lever is also available with a shift lever integrated push button, which is used for the
kickdown function.
Usually it's used for requesting a downshift from 2nd to 1st gear, which is dropped after a direction
change : F2ơKickdownơF1ơR2
This is called kickdown.
If however the speed is too high, the kickdown request is stored for a certain time. If during this
time the speed has not slowed down sufficiently, the request is dropped.

3 - 16
3) DISPLAY FUNCTION
The EGS has an internal bicolor LED display for displaying the selected shiftlever position, the
selected shiftlever direction, the transmission position and the transmission direction.
Application specific details are described in a separate document : EGS functional description.
This EGS functional description can be requested for each EGS unit. This description overrules
the below description wherever applicable.
(1) Displayed information
Typically four types of information about the EGS and the transmission can be of interest to the
driver :
Selected shiftlever position and transmission position
Selected shiftlever direction and transmission direction
Application specific information
Diagnostic information
‫ ڸ‬Selected position and direction
The difference between shift lever position and transmission position might not be immediately
clear, but when one remembers that the EGS can protect the transmission(Example : By not
allowing a downshift), it becomes clear that the requested position(The shift lever position) can
be different from the actual engaged position(The position of the transmission).
Both shift lever position and transmission position can be divided in two subcategories:
Gear position (1st, 2nd, 3rd, 4th)
Driving direction (Forward, neutral, reverse)
Application specific information
This can be anything(Whatever the customer wants to see).
As an example : On an EGS automatically controlling the lockup clutch, it's interesting to see
whether or not the converter is in lockup. This can be indicated on the EGS
display by using the LED 7-yellow.
‫ ڹ‬Diagnostic information
Two types of diagnostic information are considered :
ON LINE diagnostics
This information is given during normal driving when something special happens.
In most applications, the LED 8 is used to indicate standstill. This helps to spot problems with
the speed sensor in an early stage before the lack of protection resulting from the failure can
produce damaged to the drivetrain.
Which on line diagnostic functions are provided is detailed in the application specific EGS
Functional description.
OFF LINE diagnostics
There are three selftest modes built into the EGS. Details about their function and usage are
described in clause 5), Selftest functions.

3 - 17
(2) Display layout
The EGS uses LED's(Light Emmitting Diodes) to give information to the driver.
It consists of eight multicolor LED's :
Labelled 1 to 8 and can light up in red, green and yellow.

1 2 3 4 5 6 7 8

N T F N R

These numbered LED's are used for displaying both the shift lever selection and the transmission
engagement.
They also used to indicate diagnostic information in the different test modes.
The red LED is labelled N and when this lights up it indicates that the transmission is placed in
neutral(This is possible even while the shift lever is not in neutral).
The yellow LED is labelled T which stands for troubleshooting. This LED is ON while working in
one of the three selftest modes described in clause 5), Selftest function.
(3) Display method
Basically the gear position is shown by turning ON the LED that corresponds with the selected
position. In 1st gear, LED 1 is ON, in 2nd gear, LED 2 is ON etc..
The selected direction is shown with the color of the LED :
Red Indicates Neutral
Green Indicates Forward
Yellow Indicates Reverse
Additionally LED N(Red) is ON while the transmission is in neutral.
The position shown is always the selected shiftlever position. Most of the time, the actual
transmission position will be the same as the shown one, and in that case that's all there is.
However if, because of an active protection or because of some internally generated delay, there
is a discrepancy between transmission position and shift lever position, a 2nd LED will indicate the
transmission position(Color indicates direction).
To let the driver know the difference between both indications, the transmission LED blinks while
the shift lever LED stays ON all the time.
While this may seem a bit confusing at first, it's very easy to understand the shown information in
reality.
Example : Driving in 4th gear forward at high speed. ơ LED 4 - Green
When the driver is making a downshift, but due to a
too high speed the EGS will protect the transmission
and will not allow the requested downshift. Thus the
transmission will stay in 4th gear forward, while the
shiftlever is in 3rd gear forward. ơ LED 3 - Green &
LED 4 - Blinking green

3 - 18
4) CONNECTOR PIN DESIGNATIONS
Below table lists the function of each EGS connector pin for the transmission :

Pin Comment

1 Battery plus
2 Battery ground
3 Neutral start signal
4 CV Solenoid 1
5 CV Solenoid 2
6 CV Forward solenoid
7 CV Reverse solenoid
8 Null
9 Speed 5km/hr
10 Speed sensor input HOT
11 Speed sensor input GND
12 Travel speed signal
13 CV High / Low solenoid
14 Declutch
15 Extension kick down
16 Shield ground(Internally connected to wire 2)
CV stands for control valve.

3 - 19
5) SELFTEST FUNCTIONS
The EGS has special circuitry to help verifying its operation.
Three selftest modes are built into the EGS control programs :
Input test
Speed sensor test + Lamptest
Output test
The EGS furthermore has the ability to check for possible problems while driving(On line
diagnostics).
As described in clause(2), Display layout at page 3-18, the T LED is used for identifying different
troubleshooting modes. This is done in combination with the status of the N LED.
(1) Operation of the N and T LED's
‫ ڸ‬Overview

Situation LED

In normal situations(Driving, no problems) T LED is always OFF

When error is detected T LED is ON or BLINKING
In selftest mode T LED is always ON

‫ ڹ‬Detailed operation

Situation N LED T LED

Normal operation On when transmission neutral OFF

Internal fault ON Blinking SLOWLY
Input test Blinking SLOWLY ON
Output test Blinking FAST ON
Speed sensor test OFF ON

(2) Selftest operation

Selftest modes can only be started while powering up the EGS.
Invocation of a certain mode is done by moving the shift lever to a specific position while switching
on the power of the EGS.
Leaving the selftest mode is done by switching OFF the power of the EGS.
‫ ڸ‬Selftest mode invocation
Below table lists what conditions must be satisfied during powerup to get into a specific selftest
mode :

Selftest mode To enter mode

Input test FWD & UP

Speed sensor test REV & UP
Output test FWD & DOWN

3 - 20
‫ ڹ‬Input test
When EGS shiftlever is held in the forward up position while power is applied, input test mode
is activated.
In this mode, driving is not possible, since all EGS outputs remain OFF until the testmode is left.
This test is used to verify operation of the shiftlever and its inputs.
The LED's(Gear position indicators) on the EGS top cover are used to display test information :

Shift lever position LED Color LED Number

Neutral RED 4
UP RED 5
DOWN RED 3
FWD GREEN 4
FWD & UP GREEN 5
FWD & DOWN GREEN 3
REV YELLOW 4
REV & UP YELLOW 5
REV & DOWN YELLOW 3
Wire 14 = GROUND RED 1 (Together with above LED)
Wire 15 = GROUND GREEN 1 (Together with above LED)
ƓIf wire 14 and wire 15 are grounded simultaneously LED 1 lights up yellow.

‫ ں‬Speed sensor test

When EGS is held in the reverse up position while power is applied, speed sensor test mode is
activated.
In this mode, driving is possible.
The test begins with a lamp test and then displays the speed sensor information.
‫ ڻ‬Speed display
The LED corresponding with below table burns to indicate converter turbine speed :

Turbine rpm LED Number(Green)

0 1 BLINKS
0 - 249 1 ON
250 - 499 2 ON
500 - 749 3 ON
750 - 999 4 ON
1000 -1249 5 ON
1250 - 1499 6 ON
1500 - 1749 7 ON
1750 -1999 8 ON
Above 2000 8 BLINKS

3 - 21
‫ ڹ‬Output test
When EGS is held in the forward down position while power is applied, output test mode is
activated.
In this mode, driving is not possible, since all EGS outputs remain OFF until the testmode is left.
LED's 1 - 8 light up sequentially during output test :
First LED 1 is switched on shortly, then LED 2 etc..
When LED 8 is switched off, LED 1 is again switched on and so on.
The color of the LED indicates its status :

Color Status

GREEN Output OK
YELLOW Output NOT connected or shorted to battery plus
RED Output shorted to ground(or to another output)

The LED numbers correspond to output wires as follows :

LED Number Output wire

1 6
2 7
3 4
4 5
5 9
6 13
7 8
8 3
ƓTo find the function of the corresponding output wires - See EGS functional description

3 - 22
5. AXLE
1) OPERATION
ş The power from the engine passes through torque converter, transmission and drive shafts, and is
then sent to the front and rear axles.
ş Inside the axles, the power passes from the bevel pinion to the bevel gear and is sent at right
angles. At the same time, the speed is reduced and passes through the both differentials to the
axle shafts. The power of the axle shafts is further reduced by planetary-gear-type final drives and
is sent to the wheels.
(1) Front axle

3
2

1 Final drive 2 Differential 3 Axle

(2) Rear axle

3
2

1 Final drive 2 Differential 3 Axle

3 - 23
2) SECTION OF FRONT AXLE DIFFERENTIAL

A A

1
5
SECTION A-A

1 Bevel pinion 3 Sun gears 5 Side gear(Differential)

2 Bevel gear 4 Shaft

3 - 24
3) SECTION OF REAR AXLE DIFFERENTIAL

A A

1
5
SECTION A-A

1 Bevel pinion 3 Sun gears 5 Side gear(Differential)

2 Bevel gear 4 Shaft

3 - 25
4) DIFFERENTIAL

(1) Description 3
When the machine makes a turn, the 2 4
outside wheel must rotate faster than the
inside wheel. A differential is a device
which continuously transmits power to the
right and left wheels while allowing them
to turn a different speeds, during a turn.
The power from the drive shaft passes
through bevel pinion(1) and is transmitted
to the bevel gear(2). The bevel gear
changes the direction of the motive force
by 90 degree, and at the same time
1
reduces the speed.
It then transmits the motive force through
the differential(3) to the axle gear shaft(4).

(2) When driving straight forward

Pinion gear
When the machine is being driven straight
Side gear Side gear
forward and the right and left wheels are
rotating at the same speed, so the pinion Axle gear shaft
gear inside the differential assembly do not
rotate. The motive force of the carrier is
send through the pinion gear and the side
gear, therefore the power is equally Carrier
transmitted to the left and right axle gear Pinion gear
shaft.

(3) When turning Swing

When turning, the rotating speed of the Pinion gear
left and right wheels is different, so the Side gear Side gear
pinion gear and side gear inside the
differential assembly rotate in accordance
with the difference between the rotating
speed of the left and right wheels.
The power of the carrier is then
transmitted to the axle gear shafts. Carrier

Pinion gear Ring gear

3 - 26
5) TORQUE PROPORTIONING DIFFERENTIAL
(1) Function
‫ ڸ‬Because of the nature of their work, 4-
wheel-drive loaders have to work in
places where the road surface is bad.
In such places, if the tires slip, the ability
to work as a loader is reduced, and also
the life of the tire is reduced.
The torque proportioning differential is
installed to overcome this problem.
In structure it resembles the differential of
an automobile, but the differential pinion
gear has an odd number of teeth.
Because of the difference in the
resistance from the road surface, the
position of meshing of the pinion gear
and side gear changes, and this changes
the traction of the left and right tires.

(2) Operation
‫ ڸ‬When traveling straight(Equal Spider rotating
direction
resistance from road surface to left and
right tires)
Under this condition, the distances
involving the engaging points between
right and left side gears and pinion-a and FL FR
a b
b-are equal and the pinion is balanced as Engaging Engaging
point point
FLźa=FRźb. Thus, FL=FR, and the
right and left side gears are driven with
the same force. Left side gear Pinion Right side gear

3 - 27
‫ ڹ‬When traveling on soft ground
(Resistance from road surface to left and
right tires is different)
If the road resistance to the left wheel is
Spider rotating
smaller, the left side gear tends to rotate direction
forward, and this rotation changes the
engaging points between the side gears
and pinion. As a result, the distances
involving the engaging points becomes FL
Small road FR Large road
a>b. The pinion now is balanced as FL resistance a b resistance
źa=FRźb, where FL>FR. The right Engaging Engaging
side gear is driven with a greater force point point
than the left side gear. The torque can
Left side gear Right side gear
be increased by up to about 30% for Pinion
either side gear.
The pinion therefore does not run idle
and driving power is transmitted to both
side gears until the difference between
road resistance to the right and left
wheels reaches about 30%.

3 - 28
6) FINAL DRIVE(Front & rear)

1 Axle shaft 3 Ring gear 4 Sun gear

2 Planetary gear

(1) To gain a large drive force, the final drive uses a planetary gear system to reduce the speed and
send drive force to the tires.
(2) The power transmitted from the differential through axle shaft(1) to sun gear(4) is transmitted to
planetary gear(2). The planetary gear rotates around the inside of a fixed ring gear(3) and in this
way transmits rotation at a reduced speed to the planetary carrier.
This power is then sent to the wheels which are installed to the planetary carriers.

3 - 29
6. TIRE AND WHEEL

4
6

1 Wheel rim 3 O-ring 5 Side ring

2 Tire 4 Lock ring 6 Valve assembly

1) The tire acts to absorb the shock from the ground surface to the machine, and at the same time
they must rotate in contact with the ground to gain the power which drives the machine.
2) Various types of tires are available to suit the purpose. Therefore it is very important to select the
correct tires for the type of work and bucket capacity.

3 - 30