B230 Hydraulic Knowledge

TOUGH WORLD. TOUGH EQUIPMENT.

 目 录

ØSteering hydraulic system

ØTransmission hydraulic system

ØCooling lubrication system

ØWorking hydraulic system

Bulldozer chassis hydraulic system
推土机底盘液压系统简介

Function: Realize the driving and steering braking of the bulldozer, also known as the variable speed and
steering hydraulic system.
Composition: Rear axle box, pump, transmission valve, steering brake valve, gearbox, steering clutch, brake
booster, pipeline and other components. It can be divided into variable speed walking, steering braking,
cooling, pressure measuring oil circuit and other parts.
Ø S t e e r i n g h yd r a u l i c s y s t e m
Steering hydraulic system components:

1.primary filter 2.Steering Pump 3.Steering filter 4.steering safety valve

5.steering brake valve 6.brake booster 7.Steering lines, etc.

6 4 1 2 3

5
 St e e r i n g h y d r a u l i c o i l c i r c u i t

The oil in the rear axle box is pumped up by the steering pump and passes through the magnetic filter to the steering
pump, enters the steering filter element and is filtered again, then passes through the safety valve to ensure the
pressure (2.4MPa) and reaches the steering valve to supply the steering clutch and steering brake. Finally, it is
released into the rear axle box. ((Note: B230 bulldozer transmission oil and steering box share the oil of the rear axle
box and a magnetic filter element)
Brief description of the working oil circuit of steering control valve, steering clutch and brake:
When the steering lever is not pulled and the brake is not applied: the hydraulic oil reaches the safety valve, steering
control valve and brake booster from the steering pump. Since the steering control valve and the brake oil circuit are
cut off, the circuit pressure rises, and when the set pressure of the safety valve exceeds 2.4MPa, the oil is released and
returned to the rear axle box.
Brief description of steering control valve, steering clutch and brake
working oil circuit:

When the steering lever is pulled to the first stroke: the

hydraulic oil will flow from the steering control valve to the
steering clutch through the pipeline to push the piston to
disengage the clutch

When the brake pedal is pressed, the hydraulic oil flowing

to the brake booster pushes the piston to achieve braking
and the machine turns.
Brief description of steering control valve, steering clutch and brake
working oil circuit:

If you do not step on the brake pedal and continue to pull the steering lever to the second stroke, the hydraulic
oil will flow through the steering valve and the brake valve to the brake booster. Hydraulic oil pushes the piston
to achieve braking and mechanical steering.
Gearbox, steering hydraulic system pressure measuring points

left steering left brake

pressure pressure
Torque converter inlet Transmission control valve
pressure pressure

right steering right brake Torque converter outlet

pressure pressure pressure
Gearbox, steering hydraulic system pressure measuring points

symbol pressure point Normal working range (Mpa)

RC Right steering pressure 1.3～1.9

RB Right brake pressure 2.0～2.25

LC Left steering pressure 1.3～1.9

LB Left brake pressure 2.0～2.25

IN Torque converter inlet pressure 0.87～0.9

OUT Torque converter outlet pressure 0.2～0.5

T/M Transmission control valve pressure 2.7～3.7

St e e r i n g P u m p

Type: gear pump

Speed: 1696r/min

Flow: 106.7L/min

Set pressure: 3Mpa

Rotation: right
Ø Tr a n s m i s s i o n h yd r a u l i c s y s t e m

Transmission hydraulic system components:：

1.Primary filter 2.Transmission pump 3.Gearbox filter 4.Transmission control valve
5.Torque Converter Safety Valve 6.Torque converter regulator valve 7.Transmission lubrication valve
8.Transmission lines, etc.

3 2 6 7 4

5 1
Tr a n s m i s s i o n h y d r a u l i c o i l c i r c u i t
The oil passes through the suction of the transmission pump from the rear axle box, passes through the primary
coarse filter-transmission pump-transmission filter element-enters the transmission valve (pressure regulating
valve), firstly meets the transmission clutch oil, and then enters the torque converter through the transmission
valve. device. The gearbox adjusts the opening pressure of the safety valve to 3.4MPa, and the opening pressure
of the pressure reducing valve (first gear pressure) to 2.3MPa.
out torque converter
regulator valve

Inlet torque converter

safety valve
Transmission control valve

Lubrication Transmission
valve control valve

Main pressure
regulator
调压阀

Quick return
快回阀
valve

First gear pressure reducing

valve
Introduction to the role of transmission control valve

Main pressure regulating valve:

The opening pressure is: 3.4MPa, which ensures the combination of all rows of clutches except the first gear.
After reaching this pressure, supply oil to the torque converter.

Quick return valve

combined with the main regulating safety valve, it can make the clutches of each row of the gearbox combine
smoothly and separate completely. The pressure drops sharply at the moment of operating the shift gear, so
that the clutch is completely disengaged. Then the pressure rises slowly, so that the clutch is combined stably,
avoiding the shock and helping to improve the life of the transmission system.

Pressure reducing valve

It is specially set for the first gear clutch, and its opening pressure is: 2.3MPa.

Speed ​valve
used to manipulate the action of each row of clutches in the gearbox to obtain different speeds.

Directional valve:
used to control the action of the first clutch and the second clutch of the gearbox, so that the bulldozer can
move forward or reverse.
Tr a n s m i s s i o n p u m p

Type: gear pump

Speed: 1953r/min

Flow: 78.5L/min

Set pressure: 4Mpa

Rotation: left
Ø CO O L I N G LU B R I C AT I O N S YS T E M
The oil from the gearbox enters the torque converter safety valve through the torque converter safety valve
(opening pressure: 0.87~0.9MPa), and the oil after working by the torque converter regulating valve (opening
pressure: 0.2~0.5MPa) is After being sent to the cooler to cool, it enters the gearbox lubrication valve (opening
pressure: 0.125MPa) to lubricate all parts of the gearbox.

To transfer case
lubrication valve

Back axle box Into the oil cooler

Outflow oil cooler

From torque converter

return pump
Schematic diagram of transmission and steering hydraulics
Ø W O R K I N G H Y D R AU L I C S YS T E M

The working device hydraulic system mainly includes:

Lift cylinder, lift pipeline, tilt cylinder, tilt pipeline, ripper pipeline, ripper cylinder, working
pump, working valve, hydraulic oil tank, etc.。
O P E R AT I N G H A N D L E

Blade operating handle

Ripper operating handle

WORKING PUMP

The working pump is a double pump. During

bulldozing or leveling operations, the oil of the
small pump directly flows back to the oil tank,
reducing engine power loss and improving
efficiency.

l Avoid starting the pump with load and stopping it

Rated displacement: 80/36.5mL/r
with load
Rated pressure: 19.5MPa
l When the pump is used for the first time or when it
Rated speed: 1700rpm
will not be used again for a long time, it should run
for about 5 minutes without load; check the noise,
external leakage and oil level at the same time!
W O R K I N G VA LV E

l The working valve is external, and it is not

necessary to open the working oil tank during
repair

Blade Control Valve Ripper Control Valve

B L A D E C O N T R O L VA LV E

The B230 blade control valve is composed of a blade lift valve and a blade tilt valve, and integrates a check
valve, oil supply valve and relief valve inside the valve body

Supplement
valve

T：To working tank

Rated flow
Check valve
Blade lifting valve: 198L/min

Blade tilt valve: 62L/min

Rated pressure: 19.5MPa

Overflow valve
B L A D E C O N T R O L VA LV E

D
P: The oil inlet port of the blade
control valve (from the outlet of the
large pump of the working pump)

PCo: Oil inlet port of blade lifting

valve (from Co port of scarifier B1
Supplement
control valve) valve
A1
A1: To blade lift cylinder

B1: To blade lift cylinder PCo

A2: To blade tilt cylinder

B2: To blade tilt cylinder

A2

D: to fuel tank B2
check valve
(small pump）
R E L I E F VA LV E

When the 230 bulldozer is configured

without a ripper, an overflow valve
protection system needs to be added
separately
R I P P E R C O N T R O L VA LV E ( T H R E E T E E T H )

Three-tooth ripper control valve: Realize the lifting operation of the three-tooth ripper, integrating overflow
valve, check valve and safety valve

DA
T：To tank

DA: To tank

DB：To tank T
Co：To blade control valve PCo

DB
• Ripper Control Valve

• Rated flow: 136L/min

• Rated pressure: 19.5MPa

Co
 R I P P E R C O N T R O L VA LV E ( T H R E E T E E T H )

check valve Safety valve

A：To the large chamber of the opening pressure
23MPa
A
ripper cylinder

B：To the small cavity of the B

ripper cylinder

Relief valve opening

pressure 19.5MPa

P
P：From working pump large pump outlet
L I F T C Y L I N D E R - Q U I C K D R O P VA LV E

The function of the quick-drop valve is to reduce the vacuum generated inside the hydraulic cylinder, which
is generated when the blade's lowering speed increases.
Q U I C K D R O P VA LV E - B L A D E U P
Q U I C K D R O P VA LV E - B L A D E D O W N

Basic principle: oil return regeneration

When oil is fed into the large cavity of the cylinder, if the oil in the large cavity is too fast and the oil supply of
the pump is insufficient, the oil in the small cavity can be directly supplied to the large cavity through the check
valve.
WORKING PUMP HYDRAULIC CIRCUIT

Blade Control Valve Ripper Control Valve

Working pump
 LIFT CYLINDER HYDRAULIC OIL CIRCUIT

Mainly includes
Lifting cylinder, lifting pipeline, tilting cylinder, tilting pipeline, working pump, working valve, hydraulic oil tank

Blade Control Valve

cylinder lift
T I LT C Y L I N D E R O I L C I R C U I T

Cylinder
extended
RIPPER HYDRAULIC OIL CIRCUIT

液压油箱

Mainly includes
工作阀
Cylinders, pipelines, working

pumps, working valves,

油缸
hydraulic oil tanks

工作泵
 TOUGH WORLD. TOUGH EQUIPMENT.

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