3.2 OPERATIONS

1) DOWN position

The fluid from port B pushes up stop ring (9) of poppet(10) until the ring comes into contact with adjust screw(6),as it reaches chamber(R). Consequently,the extent choke (C) is opened is determined by the positioning of adjust screw (6):that is,when adjust screw(6) is screwed in clockwise,the opening of chock(C) decreases and the lowering speed of the lift arm slows down;whereas the opening of choke(C) increases and the lowering speed of the lift is accelerated when the adjust screw is unscrewed counterclockwise.When the adjust screw screwed in completely,the poppet comes into contact with body seat(S) and the choke is closed completely,so the lift arm stops.

2) Up position

The flow port A,overcoming the force of spring(11),pushes up poppet (10) and choke(C)is fully opened regardless of the position of adjust screw(6).Thus the fluid flows to port B and the cylinder,which results in raising the lift arm.

4. MAIN RELIEF VALVE

1)GENERAL DESCRIPTION

This valve regulates the maximum pressure in the whole hydraulic circuit.The regulated pressure can be set with the adjust screw.

2) PRECAUTIONS FOR DISASSEMBLY AND REASSEMBLY

(1)Tightening torque of lock nut (9)5.0∼6.0

(36.2∼43.4 ft.lbs)

(2)Install seat(2)and then tap ball(3)(5/16) lightly so as to provide tight seating.

(3)Wrap the valve threads with sealing tape and tighten the valve up to a specified torque of 5-6Kgf.m(36-43 ft.lbs)

(4)Before disassembly, the current screwing-in depth of the adjust screw should be written down or memorized for later reference.

3) MEASUREMENT OF THE RELIEF PRESSURE

(1)3 POINT TO TEST RELIEF PRESSURE

①Remove the plug in the delivery pipe on the right-hand side of the transmission case and install a compression gauge to measure the pressure. Keep the engine speed at 2600 rpm and shift the position control lever at the highest position.

②Control valve coupler.

③Remove the plug in the hyd. pump flange and engage the pressure gauge and measure it.

Measurement the Pressure must be done 3 times and should be set within specified pressure.

1) GENERAL DESCRIPTION

This pump induces fluid from one side and delivers it from the other side,by rotating two gears meshed with each other. The actual delivery is as mentioned below,considering the consequences of fluid temperature and volume efficiency in accordance with revolution speed. That is dual pump system

This pump induces fluid from one side and delivers it from the other side,by rotating two gears meshed with each other. The actual delivery is as mentioned Fig.9-13, Considering the consequences of fluid Temperature and volume efficiency in accordance with revolution speed.

4)DISASSEMBLY NOTE:

①Before disassembling the pump,wash the outside clean.In the course of disassembling operation,all disassembled parts should be kept aside in a clean place such as on clean paper or cloth and be handled carefully so as to prevent them from becoming dirty or damaged.

Check all disassembled parts for damage and wash undamaged or usable parts in clean diesel fuel or kerosene. Inspect all parts referring to these point,and repair or replace defective parts.

(1)DISASSEMBLY

①Remove the key.

②Hold the pump in a vice with the mounting flange turned downward,and remove the bolts

③Remove front and rear pump

Be sure not to be damaged the o-ring or steel ball

④Remove the rear pump

▶Detach the cover

▶Remove the o-ring

▶Remove the bushing,drive gear,gear and bushing.Take care of removing the bushing which is marked and recorded.

▶Remove the bushing seal from the bushing.

⑤Remove the front pump same as rear pump disassembly.

⑥Remove the snap ring and extract oil seal from the flange.

3) REASSEMBLY

① Install the rear pump.

▶Install the bushing seal to bushing.

▶Install the bushing,drive gear,gear,and bushing to the housing.

▶Install the o-ring to the cover.

▶Install the cover to the housing.

④Tightening sequence and torque of the pump cover tightening bolts.

▶Tightening torque: 2.5∼2.8㎏f·m

②Install the front pump with rear pump.

③After installing the cap ring,and O-ring to the front pump,and install the rear pump.

⑤ Install the oil seal,snap ring,and key.

⑥The gears should turn smoothly with a turning torque of less than 30 kgf.cm (2.2ft.lbs)

(1)Check all disassembled parts for damage and wash undamaged or usable parts in clean diesel fuel or kerosene except rubber parts.Inspect all parts referring to these points,and repair or replace defective parts.

(2) Housing(casing)

①The gear pump is originally designed so that the gears come into light contact with the side of the pump body

②Therefore some evidence of contact can be found around the intake port of a pump once used.

③The normal contact tracing is less than half the length of the gear housing bore and less than 0.05 mm(0.0020 in)in width.If width A is more than 0.1 mm(0.004 in), replace the gear pump set.

(3) Bushing

① With clean working fluid,surfaces are rarely scratched and should be smooth.

② If there are many scratches on the bore walls,or on parts which are in contact with the gears,which can be readily felt or when the latter parts are darkened,the gear pump set should be replaced.

Problem and causes are as below a.contaminated fluid b.overload by relief valve damage c.cavitation or airation d.overheat of fluid.

e.Low density of fluid

④Some evidence of contact can be found around the intake port of a bushing once used.The normal contact tracing is less than half the length of the bushing bore and less than 0.03mm(0,0012 in)in width.If width is more than o.o3 mm (0.0012 in).Replace the bushing.

①With clean working fluid,surfaces are rarely scratched and should be smooth.

②If roughness can be felt by a finger nail,they are darkened,or the shaft diameter is less than 0.03 mm replace the shaft.

③Usable shaft diameter is as below

Gear Shaft

(5) Oil seal

The oil seal prevents oil leaks by its inner seal lip and dust from invading by its outer dust lip.Therefore if an oil seal has damaged or deformed lips,it should be replaced.

(6)MEASUREMENT OF THE PUMP

The best way to measure for the pump is to use a special tester.

But if it's not available,Use installed tractor Remove the plug in the delivery pipe on the righthand side of the transmission case and install a compression gauge to measure the pressure.

Keep the engine speed at 2600 rpm and shift the position control lever at the highest position.

1)GENERAL DESCRIPTION

The tractor is equipped with two oil filters: suction filter(1) and line filter(4),for better filtration.

2)SPECIFICATIONS

-Suction filter

DONAX TD or RPM THF 500

4) REPLACEMENT

Check the O-rings for damage or deformation and replace defective ones.When installing the filters,be sure to install the O-rings properly with grease applied.

DONAX TD or RPM THF 500 Applicable oil

32 Rated flow rate(ℓ/min.)

-30 ∼130℃ Working oil temperature (℃) 80 mesh Filtration density (mesh)