SANY SRT95C Off-Highway Truck. Service Manual

of steering cylinder and flows into the oil tank

from the port ‘T’.
During the manual steering operation, if the
engine and the pump are faulty, the steering
valve will be automatically switched over to the
manual steering system. When the steering
wheel is rotated, the oil liquid meter becomes
the rotating manual pump and the pressure oil
directly flows to the steering cylinder via the
corresponding port.
In the case that the steering control unit  is
operated  in  the  mid-position:  In  the  mid-
position or non-steering position, the valve
spool  and  the  bush  are  kept  in  a  proper
position due to the mid-position spring. The
spring maintains the relatively small preload
so that the valve is just kept in the mid-position
and it can be within its limit and be released
at any time. In such a way, when the truck
temporarily  stops  with  the  power  steering
system in the loading state, the system can be
protected against overheating.

Hydraulic Steering Pipeline Of Operator’s Cab

Disassemble

See Fig.9.1-1 for the numbers in brackets.

WARNING

To prevent personal injury and property

loss, rotate the steering wheel in two

directions for several turns and release the

system pressure.

Prevent personal injury and property loss,

and ensure that the wheels are chocked

properly and the chock and the hoist

device have sufficient capacity and work

safely.

1. Place the truck in a flat working area, lower

down the body completely, apply the parking
brake and shut down the engine.
2. Rotate the steering wheel in two directions
for several turns and release the pressure of
accumulator and steering system. Chock the
wheels, and set the main switch of battery into
the ‘OFF’ position.
3. Before the steering control unit is  removed,
clean the valve block and cover pipeline in its
surrounding to prevent ingress of dust.
4.  Ensure  that  the  hydraulic  pipelines
connected to the steering control unit  are
properly marked to facilitate the installation.
Place a proper container in the position of
oil liquid leakage. Disconnect the hydraulic
pipelines and block all hydraulic pipelines to
prevent ingress of dust.
5. Support the steering control unit  (2) and
remove the screw (1).
6. Carefully remove the steering control unit
until the spline shaft is disengaged from the

steering column and the cab firewall. Move the

steering control unit to a clean working area
to facilitate disassembly.

Installation

Note

: Tighten all fasteners according to

Hydraulic Steering Pipeline Of Operator’s Cab

Section 36.2, ‘Technical Conditions for
Tightening Torques of Standard Bolts and
Nuts’.

Note

: Tighten all hydraulic pipelines with the

O-ring end face seal and replace all 'O'rings.

WARNING

To prevent personal injuries and property

loss, ensure that the wheels are chocked

properly. The chock and hoisting device

should have sufficient capacity and be well

fixed to work safely.

1. Ensure the installation area is clean.
2. Carefully lift up the steering control unit
until the spline shaft of steering column goes

through the cab firewall and connects with the

steering column.
3. Through the steering column, use the bolts
to fix the steering control unit onto the cab

firewall.

4. Remove all of covers from the valve ports of
the steering control unit. Connect the pipelines
to the steering control unit according to the
signs made during disassembly.
5. Inspect hydraulic tank level which provides
oil to steering or brake system.
6. Remove the chock under the wheels,
set the main switch of battery into the ‘ON’
position, start up the engine, operate the
steering system, check the hydraulic pipeline
for leakage, and tighten the pipeline and joint
if necessary.

7. Inspect hydraulic oil tank level again. Refill

oil if necessary.

Hydraulic Steering Pipeline Of Operator’s Cab

Filling and draining the steering system

WARNING

Don' start up the truck. It can be started

up only after the air in the oil is completely

vented out.

1. Fill the steering and brake system oil tank to
the maximum liquid level. Start up the engine
and prepare to refill oil. The oil level isn’t
allowed to fall down to below the oil suction
pipe of pump to prevent the air from entering
the system.
2. Start up the engine at the idle speed. Fill
oil to the tank of steering and brake system
according to requirement immediately. If no
more oil is required and the oil becomes
clear, perform the operation according to the
following steps:
a. Rotate the steering wheel to the left and the
right to release the gas in the steering cylinder
and pipeline.

Note

: Rapidly move the valve spool, and refill

oil to the steering and brake control oil tank
to make up for the oil liquid circulating in the
system.
b. If the oil in the oil tank becomes clear
(without turbidity or emulsion), it will indicate
that the air in the system is completed
removed.

Note

: The slight creeping movement or

hysteresis of steering wheel is normal.
c. Fill the steering and brake system oil tank to

the specified oil level.

Special tools

No requirement for special tools is present
in the steps described in this chapter. These
tools can be purchased from the agent.

Hydraulic Steering Pipeline Of Operator’s Cab

9.2 Steering Valve Group

Overview

The  steering  valve  group  consists  of
three  valves  as  follows:  a  check  valve,
an  accumulator  save  block  and  a  system
pressure protection valve.
The accumulator save block is installed in
the middle part of valve  block. The hydraulic
pump  keeps  pressure  of  the  accumulator
normally, as shown in Fig.2; pressure oil will
goes back to the tank of steering and brake
control system via the block and the whole
process about 3-5 minutes when the pump is
turned off.
The safety valve is installed in the bottom of
valve block. Its setting pressure is 21MPa
(3050psi). If any fault occurs to the pressure-
compensated  valve  of  steering  pump,  this
valve can be used as the auxiliary protection.
If the pressure-compensated valve makes the
steering system pressure exceed the setting
pressure of safety valve, the safety valve will
be opened to depressurize the oil liquid and

allow it to flow back to the oil tank.

Operating principle

The oil from the steering pump enters into
the steering valve group from the port ‘A’ and
the pressure is generated to open the check

valve. The oil flows to the steering control unit

via the port ‘B’ and then it is supplied to the
accumulator via the port ‘E’.
The pressure oil runs to the pressure switch
via the port ‘G2’ and reaches the fault
detection point via the tee fitting of port ‘G2’.
See Fig.2.
In the truck running process, the transmission
pilot pressure runs through the hole ‘D’ and
keeps the save block closed. Consequently,
the oil leakage from the accumulator is cut
off. The return oil of steering valve enters into

the port ‘C’ and then flows into the oil tank via

the port ‘R’. The port ‘G1’ is blocked. If the

Fig.9.2-1 Assembly drawing of steering valve
group

1. Screw

2. Steering valve group

Steering system accumulator

Pressure mea-

suring port

Gearbox lubri-

cation system

Slewing and

automatic sy-

stem oil tank

Port ‘T’ of st-

eering gear

Port ‘P’ of st-

eering gear

Pipeline filter Port ‘P’ of automatic

valve group

PS7

21MPa

Hydraulic Steering Pipeline Of Operator’s Cab

pressure in the oil circuit exceeds the preset
pressure in the safety valve, the valve will be
opened to allow the oil to be discharged back
to the oil tank via the port ‘T’. After the engine
stops, the pilot pressure of transmission
disappears and the spring switches over the
save block to the open position, so that the oil

in the accumulator is allowed to flow into the

internal passage via the port ‘E’ and then be
discharged from the port ‘T’ to the steering and
brake system oil tank via the piston.

Disassembly

WARNING

The pressure is dangerous. Before the

operation, the steering wheel should be

rotated back and forth for several times

to release the pressure in the system. If

the pressure isn’t released, it will lead to

personal injury and property loss.

Prevent personal injury and property loss,

and ensure that the wheels are chocked

properly and the chock and the hoist

device have sufficient capacity and work

safely.

1. Park the truck in a horizontal working area,
and apply the parking brake. Shut down the
engine.
2. Rotate the steering wheel in two directions
for several times to release the pressure of
steering system and accumulator. Chock all
wheels and set the main switch of battery in
the ‘OFF’ position.
3. Clean up the steering valve group and its
surrounding area and make the corresponding
marks on the hydraulic pipelines installed on
individual ports of this valve.
4. Remove all hydraulic pipelines from the
steering valve group and drain oil into a proper
container. Cover all hydraulic pipelines and

Hydraulic Steering Pipeline Of Operator’s Cab

steering valve group port to prevent ingress of
dust.
5. Remove the steering valve group from the
truck. Use a proper solvent to clean the outer
surface of multi-way safety valve assembly.
Then move it to a clean area to facilitate
disassembling.

Installation

Note

: Perform the tightening according to the

specified value in Section 38.2, ‘Technical
Conditions for Tightening Torques of Standard
Bolts and Nuts’.

Note

: Tighten the hydraulic pipeline equipped

with the O-ring seal and replace the O-ring.
1. Install the steering valve group assembly
onto its fixing support. Use the fasteners

removed during disassembly to fix it.

2. According  to  the  signs  made  during
disassembly,  connect  all  oil  pipes  to  the
steering valve group and fasten them.
3. According to the stipulations in Chapter 15,
‘Hydraulic Oil Tank Assembly’, check the oil
level of oil tank. Add the oil to the proper oil
level according to the stipulations.
4. Remove the chock, set the main switch
of battery into the ‘ON’ position, start up the
engine  and  operate  the  steering  system.
Check  the  steering  system  for  leakage.  If
necessary, tighten the connecting piece and
recheck the oil level.

Maintenance

The maintenance of steering valve group is
limited to the replacement parts only.

Special tools

No requirement for special tools is present
in the steps described in this chapter. These
tools can be purchased from the agent.

Hydraulic Steering Pipeline Of Operator’s Cab

10 OPERATOR’S CAB BRAKE

PIPELINE AND JOINT

10.1 Foot Valve

Overview

The foot valve is a mid-position cut-off valve.
It controls the hydraulic oil pressure value of
front and rear brakes as well as the maximum
brake pressure applied into these pipelines.
Such valve is controlled by the foot pedal
inside cab. It operates along with the engine
and the brake valve group can automatically
apply brake.
The different maximum operation pressures
required by the front and rear brakes can be
provided by the foot valve. These pressures
can be adjusted according to test and
regulation. When being actuated by the foot
valve, the pressure switch of stop light will
send a signal to rear brake light to turn on the
brake light.

Operation

Apply the traveling brake

See Fig.2.
When the foot valve is pressed down by the
operator, the slide valve will move downward
to push the regulating spring, which will then
push the regulating spool downward. When
the regulating spool moves downwards, the
current limiting groove will move away the oil
groove and shut down the exits of 'B1', 'B2'
to port 'T'. The regulating spool will move
downward continuously till the current limiting
groove completely aligns with the pressure
inlet. Such action opens ports 'P1', 'P2' and
exits 'B1', 'B2'.
After the pressure of hydraulic oil in the brake

is built up, the oil flow enters the cavity under

the spool via the small orifice of adjusting
spool. When the pressure in the brake rises
up, the pressure in the cavity under the
spool correspondingly increases to move the

Fig.1 Assembly drawing of foot valve

1. Foot valve

2. Screw

PS6

PS5

Fig.2 Hydraulic principle of foot valve

Operator’s Cab Brake Pipeline And Joint

adjusting spool upwards to close the outlet of
interfaces ‘B1’ and ‘B2’. The regulating spool
keeps balance between brake pressure and
regulating spring pressure. Such pressure is
produced when the operator presses down
the foot pedal. If the footplate is not pressed
down, the adjusting valve will close the inlet,
outlet and oil tank interface. The spool will be
kept in this position. If the operator continues
pressing down the footplate, the adjusting
valve will move downwards to build up the
higher pressure in the brake until it balances
the action of footplate.

Releasing normal traveling brake

See Fig.2. When the operator releases
the footplate, the adjusting spool loses the
balance. It moves upwards, and the outlet
of interfaces ‘B1’ and ‘B2’ connected to the
interface ‘T’ of oil tank is opened. The oil in the
pipeline of ‘B1’ and ‘B2’ is released into the oil
tank via the interface ‘T’ of oil tank. The brake
is released.

Applying/releasing emergency brake

See  Fig.2.  Press  the  emergency  brake
switch  to  de-energize  the  brake  multi-way
electromagnetic valve. It makes all pressure
enter the interface ‘PX’ on the foot valve. It is
equivalent to the complete and rapid pressing
down of foot valve. For example, push the
adjusting  spool  downwards  and  apply  the
maximum brake.
See  Fig.2.  Release  the  emergency  brake
to switch on the multi-way electromagnetic
brake valve and enable the pressurized oil in
'PX' pipeline to return to the oil tank and the
pressure will drop accordingly. Exits 'B1', 'B2'
will be connected to oil tank port 'T' to return
the oil in pipelines 'B1', 'B2' to the oil tank and
release the brake.

Note

: The output pressure generated at the

outlet of ‘B1’ and ‘B2’ when the emergency
brake is applied (in the pipeline of ‘PX’) is

Operator’s Cab Brake Pipeline And Joint

higher than the one generated when the
footplate brake is applied by 5%.

Maintenance standard

Frequently check the valve for leakage or
damage. Check whether the excessive cam
swing occurs to the footplate. If necessary,
replace the component.
If the following phenomena occur, the
component should be repaired or replaced in
time:
1. External leakage occurs.

Note

: Check all hydraulic pipelines and joints

and ensure no leakage.
2. The foot pedal can not restore to the original
position.
3. The footplate is kept in the pressure state
during the idle speed operation.
4. When the footplate is completely pressed
down, the pressure output varies very quickly.
5. The output pressure of pipeline should be
kept constant: ±0.52MPa (±75psi).

Disassembly

WARNING

To prevent personal injury and property

damage, the wheels should be chocked

properly and the hoist device should be

fixed firmly and should have sufficient

capacity for safe work. After the engine is

shut down, the pressure of hydraulic oil

will remain in the system. The operation

can be performed on the brake system

only after the foot brake is continuously

pressed down until the pressure is

released. Otherwise, it will result in severe

personal injuries.

1. Park the truck in a horizontal working area,
apply the emergency parking brake, shut

Operator’s Cab Brake Pipeline And Joint

down the engine, continuously operate the
foot valve and release the pressure of brake
accumulator.
2. Block the wheels. Turn the accumulator
main switch to 'off' position.
3. Use proper solvent to clean the foot valve
and the surrounding area. Dismantle all of the
hydraulic pipelines connected to the foot valve
and mark them to facilitate the installation. Use
a proper container to catch the leakage oil,
and cover all open pipelines and the foot valve
interface to prevent contamination of dirt.
4. Remove and mark the electrical connector
connected to the parking light pressure switch.
5. Remove the installation parts fastening
the foot valve to cab floor. Move the foot
valve assembly to a clean working area for
performing the maintenance operations.

Installation

Note

: Tighten all the fasteners according to

'Tightening Moment Technical Conditions of
Standard Bolt and Nut' in 38.2.

Note

: Tighten all the hydraulic pipelines

equipped with the end face seal. Replace all
'O'rings.
1. Place the foot valve assembly onto the

floor of cab. Use the installation parts to fix it.

Remove the covers.
2. Remove the covers. Connect the hydraulic
pipelines to the foot valve assembly according
to the signs made during disassembly.
3. Connect the electrical connector to the
parking light pressure switch according to the
disassembly signs.
4. Check the oil level of steering and brake
control oil tank. Refill oil conforming to the
stipulations to reach the correct oil level

specified in the ‘Steering and brake control oil

tank’.
5. Set the main switch of accumulator into the
'on' position, remove the chock, start up the
engine and warm up the hydraulic oil to normal
operating temperature.

Operator’s Cab Brake Pipeline And Joint

6. Apply the brake. Check for oil leakage.
Tighten the pipelines and joints.

Note

: To operate Step 7, ensure the applying

and releasing of emergency brake.
7. Press down the footplate and the
emergency brake system. Check the
conditions of brake operation.

Parking light pressure switch

The parking light pressure switch is a normally
open switch. When a testing instrument is
connected to the terminal of parking light
pressure switch, the system will be opened.
When the brake pressure is 0.27MPa or
higher, the system will be closed to signal
the brake indicator lamp to flash; when the
pressure falls down to 0.27MPa, the system
will be opened and the brake light will be off.

Maintenance

General maintenance

Check foot valve hydraulic pipelines and joints
for oil leakage and damage, tighten or replace
if necessary.

Every 1,000 hours

Check the front and rear brake pressure in the
detection points. If the pressure is not in the
specified range, inspect the valve and take
the corresponding measures (adjusting the
pressure; disassembly, repairing or replacing
the valve).

Special tools

No special tool requirement is present in the
steps described in this chapter.

Operator’s Cab Brake Pipeline And Joint

Fig.1 Air conditioning pipeline installation

1. Blast pipe

6. Condensation-storage rubber hose 11.Flow hose

2. Blast pipe

7. Warm water rubber hose

12.Stream-pressure rubber hose

3.Blast pipe

8.Hot water adaptor

13.Storage-steam rubber hose

4.Thimble

9.Hot water adaptor

5. Thimble

10.Pressure-condensation rubber hose

11 AIR CONDITIONING PIPELINE INSTALLATION

11.1 Air Conditioning Pipeline Installation

Air Conditioning Pipeline Installation

Air conditioning system pipeline dis-

assembly

See Fig1 for the number in the bracket.

1. Place the truck in a flat working area. Apply

the parking brake. Shut down the engine. Turn
the steering wheel for a few rounds to release
the pressure of the steering system.
2. Chock the truck wheel. Put the main switch
of the battery at the position of “close”.
3. If necessary, disassemble installation
accessories on the protective cover of the
truck.
4. After the system is completely discharged,
respectively mark flow hose (11), defrosting
blast pipe (1), blast pipe in front of driver’s
seat for face blowing (2), blast pipe in front
of co-driver’s seat for face blowing (3), warm
water rubber hose (7), stream-pressure
rubber hose component (12), condensation-
storage rubber hose component (6), storage-
steam rubber hose component (13), pressure-
condensation rubber hose component (10) for
the convenience of installation.

5. Carefully disassemble the marked flow hose

(11), defrosting blast pipe (1), blast pipe in front
of driver’s seat for face blowing (2), blast pipe
in front of co-driver’s seat for face blowing (3),
warm water rubber hose (7), stream-pressure
rubber hose component (12), condensation-
storage rubber hose component (6), storage-
steam rubber hose component (13), pressure-
condensation rubber hose component (10)
respectively from corresponding systems, plug
joint parts and corresponding pipe fittings to
prevent the entry of foreign substances into
the system.

Air conditioning system pipeline

installation

Numbers in parentheses refer to Fig.11.1-1

Note

: Tighten all the fasteners according to

section 38.2 'technical conditions of tightening
moment for standard bolts and nuts'.
1. Remove plugs from end of storage-steam

Air Conditioning Pipeline Installation

rubber hose component (15) end, receiver
drier (12) and evaporator (6) port; connect
rubber  hoses  according  to  signs  made  at
disassembly.
2. Remove plugs from end of condensation-
storage  rubber  hose  component  (13),
condenser assembly (11) and receiver drie (12)
port; connect rubber hoses according to signs
made at disassembly.
3. Remove plugs from end of stream-pressure
rubber hose component (9) end, compressor
(14)  and  evaporator  (6)  port;  connect
rubber  hoses  according  to  signs  made  at
disassembly.
4.  Remove  plugs  from  end  of  pressure-
condensation rubber hose component (10),
compressor  (14)  and  condenser  (11)  port;
connect rubber hoses according to signs.
5.  Remove  plugs  from  end  of  warm  water
rubber hose (8), evaporator (6) and engine
port, connect rubber hoses according to signs
made at disassembly.
6. Remove plugs from end of  flow hose (7),
blast pipe for feet blowing (4), defrosting blast
pipe (3), blast pipe in front of operator’s seat
for face blowing (2), blast pipe in front of co-
operator’s seat for face blowing (1), evaporator
(6)  and  corresponding  port  in  operator’s
cab,  connect  according  to  signs  made  at
disassembly.

Air Conditioning Pipeline Installation

Fuel Tank And Mounting

4 5 6

5 7 8

8756 5

2627

Fig.1 Oil tank assembly and pipeline installation

1.Connector

16.Fuel supply line

2.Clamp

17.Connector

3.Fuel supply line

18.Washer

4.Bolt

19.Fuel control valve assembly

5.Washer

20.Connector

6.Articulating body

21.Connector

7.Connector

22.Bolt

8.Washer

23.Washer

9.Bolt

24.Damper

10.Washer

25.Fuel tank

11.Primary filter

26.Washer

12.Washer

27.Washer

13.Connector

28.Nut

14.Clamp

29.Core,filter,separator,oil-water

15.Fuel return line

12 FUEL TANK AND MOUNTING

12.1 Fuel Tank and Mounting

SANY SRT95C Off-Highway Truck. Service Manual - page 20