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1t-3.5t R Series Internal Combustion Counterbalanced Forklift Truck. Manual - part 8

1 slide valve

2 valve body

3 plug

4 flexible straight pin 4×40 5 spring

6 flexible straight pin 4×35

7 plug

8 spring 9 spring 10 piston

11 drain plug

12 spring

13 steel ball 14 spring

15 valve core

Fig. 2-10 control valve

Main pressure valve: also called fixed pressure valve, the oil pressure for controlling
the hydrodynamic clutch is at 1.1MPa ~1.4MPa, assigns the oil to the relief valve, then
to torque converter.
Buffer valve: also called adjustment valve, between the inching valve and the
shift-control valve. When the control valve is all opened, the buffer valve begins to
work, for reducing the impact when the hydrodynamic clutch is connecting.
Shift-control valve: assign the pressure oil to the forward or reverse clutch, so as to
make the gear box change the gear ratio.

Structure of Automatic shift valve（used for automatic shift type）

1t-1.8t

2t-2.5t

3t-3.5t

Automatic shift
hydraulic
transmission
gearbox

YQXD18HA

YQXD18E

YQXD18H1

YQXD18HB

（the same of all

except connect shell）

YQXD25A
YQXD25A

YQXD25H

YQXD25H1

YQXD25G1（the

same of all except

connect shell）

YQXD30A
YQXD30A

YQXD30H

YQXD30H1

YQXD30G1（the

same of all except

connect shell）

similarities and
differences

Electrical shift

compare with YQX18

Electrical shift

compare with

YQX25

Electrical shift

compare with YQX30

characteristic

Automatic shift valve: Electrical shift

1．Shell body cover

2.interior hex bolt of taper pipe

3.pin

4.paper gasket

5.tube tie-in

6. electromagnetic shift valve

7.pin

8.small piston

9.spring

10.combine seal

11. relief valve cover

12.piston

13.small spring of fixed pressure valve

14.big spring of fixed pressure valve

15. elasticity columnar pin

16. round plug of fixed pressure valve

17. round plug of control valve

18. big spring of control valve

19. small spring of control valve

20.reel

21.bolt

22.shell body

23.gasket

24. interior hex bolt of taper pipe

5. Notice about installation and usage

5.1 Before installation, first clean oil of oil seal on surface of hydraulic gearbox, to

avoid leaking when working, no disassemble freely hydraulic gearbox.

5.2 To avoid affecting precision of installation and usage must prevent every

installation surfaces, torque converter and out gear knocking.

5.3 Guarantee no more than 0.15mm runout for installation hole of engine flywheel, no

more than 0.1mm for flywheel end surface, no more than 0.2mm for installation
end surface of flywheel, no more than or equal to Ф0.1mm for location position of
2 location pins on installation surface.

5.4 Truck control mechanism must guarantee correct stroke of inching valve lever,

and secure location. Inching valve lever can return its initial location when operator
loosens pedal. Inching valve characteristic graph,see Fig.2, inching valve lever
can move together with brake pedal, must guarantee cut off the oil to clutch
before braking ,and the stroke of inching valve lever is equal to or more than
14mm(less than 22mm) ,when shifting, close inching valve first ,and then shift.

5.5 When hoisting, keep level, ensure gearbox and reduction gearbox calm, and avoid

torque converter sliding out.

5.6 Prohibit changing oil system of the gearbox. To ensure gearbox work regularly,

lubricate well, the circular oil of gearbox can not be used for other purpose, and the
oil should accord with required trademark.

5.7 Keep work oil clean and no other impurity, replace new oil after 50 hours usage for

new truck, and after every 1000 hours,or reuse after long depositing.

5.8 Fill in work oil, run at neutral shift for5 minutes, then check oil height, and the

height should be within the specified range.

5.9 New hydraulic gearbox should breaking in 50 hours after it is installed,and the load

is no more than 70% in breaking in process, note oil temperature ,oil pressure and
bolts loosen or not usually, replace new oil after breaking in .

6. Cause and solutions

Faults

Causes and remedy

Efficiency deceased

and oil temperature

too high

1. Friction discs seized or worn out. Check friction discs for

agglutination, uneven contact or warp.

2. Insufficient oil for torque converter. Check oil pump for worn part

and check the oil level.

3.  Bearing damaged. Replace the bearing.
4.  Check lubricant line for blocking.
5.  One-way clutch of torque converter seizure. Replace the torque

converter.

Oil leakage

1.  Sealing washer wear. Replace the worn sealing washer.
2.  Ageing or damage of rubber parts. Replace the parts.
3.  Parts damaged and cracks. Replace.

Clutch pressure low

and excessive

vibration

1. Oil level too low. Check oil level and refill oil to proper level.
2. Sealing ring on clutch shaft and piston worn out or joint jammed

when assembling. Replace sealing ring and pay attention to
joint when assembling.

3.  Oil pump worn. Replace oil pump.
4.  Oil strainer blocked. Clean or replace.
5.  Check if the inching valve spool returns.

Ⅲ. Driving axle

1. Date

Driving axle type

Full floating, axle and truck body direct

install, front wheel driving

Tire pressure

(7±0.2)×10

Wheel hub rotation starting torque at hub blot

10 N～29 N

Axial play of wheel bearing mm

less 0.08

2. Trouble diagnoses and corrections

condition

Probable cause

Corrective action

Abnormal noises

loose driving axle and body connecting

blots.

loose wheel nut

worn or damaged wheel hub bearing.

wheel hub bearing not properly adjusted.

worn axle shaft spliner.

insufficient lubrication

Tighten.

Replace.

Adjust.

Replace.

Lubricate.

Unstable driving

loose wheel nut.

deformed wheel.

worn or damaged wheel hub bearing.

loose driving axle and body connecting

blots.

wheel hub bearing not properly adjusted.

improper tire pressure.

Tighten.

Replace.

Tighten.

Adjust.

Oil leakage

worn or damaged axle shaft oil seal.

final drive improperly installed.

loose drain plug.

Replace

Replace gasket.

Tighten.

Content .. 6 7 8 9 ..