1. A certain gear of the 3 ton wheel loader is weak or unable to walk, and the other gears are normal.

Judgment points:When the loader does not walk or walks slowly, the main drive shaft rotates quickly and powerfully. When the engine speed is increased, the increase in the speed of the main drive shaft is obviously disproportionate to the front and rear drive shafts.

The transmission oil pressure in neutral and other gears is normal, and the pressure drops significantly after engaging this gear.

cause of issue:

1) The bearing cap or nylon ring is severely worn.

2) If the bearing cover or nylon ring is good or slightly worn, confirm that the inner and outer seal rings of the clutch are not well sealed.

Method of exclusion:

Replace the corresponding damaged parts, that is, the bearing cap or nylon ring, the inner and outer seal rings, and readjust the clearance between the shaft sleeve and the bearing cap.

Failure analysis: If a certain gear is weak or unable to travel, the problems of the common oil circuit and components of each gear, such as torque converter, travel pump, pressure reducing valve, etc., can be eliminated. On the oil circuit between the clutch pistons. After the weak parts such as bearing caps, nylon rings, and inner and outer seal rings are worn, the oil supplied to the clutch piston chamber leaks from the worn parts in large quantities, resulting in a drop in oil pressure. In neutral or other gears, the oil pressure is normal because the oil does not flow through the worn parts.

⒉. Neutral gear automatically moves forward, and the machine can drive normally when it is engaged in the forward gear. When the reverse gear is engaged, the machine stops and cannot walk. The working pressure of each gear is normal.

cause of issue:

The main and driven plates of the forward clutch are sintered and locked

The forward clutch piston is stuck and the seat check valve is blocked
Method of exclusion:
Disassemble the forward clutch, clean the oil passages, replace the main and driven friction plates and related damaged parts, clean all related parts, replace the outer seal ring, clean and dredge the check valve, replace the clutch friction plate, inner and outer seal rings

3. During the normal driving process of the whole machine, it suddenly does not work after the second gear is engaged. Check that the working pressure of this gear and other gears are normal.

cause of issue:

The clutch shaft is broken
Method of exclusion:
Replace clutch shaft, readjust bearing clearance

4. The whole machine suddenly does not move forward or backward while driving, and the working pressure of variable speed is normal.
cause of issue:
1). The transmission valve is faulty or the (40F, 50D, 50F) accumulator is damaged. The air control valve stem of the transmission valve is stuck or damaged.
2). The oil inlet is blocked
3). The accumulator oil circuit is blocked
4). Failure of the air control globe valve
Method of exclusion:
Clean the isolation valve stem of the shift valve or replace the air-operated valve to clear the relevant oil circuits, and repair or replace the air-operated shut-off valve

5. The whole machine works normally, but suddenly there is no turning, no lifting, no walking, the elastic connecting plate is damaged or the connecting wheel is toothed
cause of issue:
The elastic connecting plate is broken, the fixing bolts of the elastic connecting plate are damaged, and the connecting wheel is beaten
Method of exclusion:
Replace the elastic connecting plate, replace the connecting wheel

6. The working pressure of variable speed is normal. When the whole machine is under heavy load, the main drive shaft rotates quickly and powerfully. However, the whole machine cannot work normally during shovel operation and there is metallurgical powder in the transmission fluid.

cause of issue:

The high and low speed levers are not reversed at the low speed position or the shift valve is not in place, the 1:3 clutch is damaged, and the forward clutch is damaged
Method of exclusion:

Hang the high and low-speed levers to the low-speed position, re-adjust the pull rods, replace the clutch friction plates and damage related parts

7. Torque converter top breather bleeds oil

cause of issue:

Transmission valve air control valve stem "O"", air leakage, torque converter oil return filter is blocked, torque converter internal oil circuit or guide wheel seat oil circuit is blocked, torque converter to gearbox oil return line is blocked

Method of exclusion:

Replace the "O" ring of the air control valve, clean the oil return filter element or replace the filter element, clean each oil circuit or replace the guide wheel seat, clean or replace the oil pipe

8. The torque converter has abnormal noise
cause of issue:
The torque converter coupling teeth are beaten or the rubber teeth are damaged, the torque converter elastic coupling plate is cracked, the 3OF, 30D torque converter is damaged by the gear shaft or bearing, the main drive shaft splines do not correspond or the universal joint bearing has large clearance

Method of exclusion:

Replace the coupling wheel or rubber teeth, replace the elastic connecting plate, replace the main and passive gears or bearings, re-adjust or adjust the clearance

9. The whole machine works normally, the oil temperature is high, the output power is insufficient and there is aluminum foam in the transmission oil

cause of issue:

The oil return filter is blocked, the mechanical oil radiator is blocked, the oil return pipeline is not smooth, the bearing is damaged, and the three wheels of the torque converter are worn
Method of exclusion:
Clean the filter element or replace the filter element, replace the radiator, clean and dredge each oil circuit or replace, replace the bearing, replace the three wheels and adjust the clearance

10. Low or high speed out of gear
cause of issue:
The clearance of the control part is too large or the tie rod is adjusted improperly, the sliding sleeve and the high and low speed gears are worn, the meshing amount is too small, the clearance between the high and low speed gear bushing and the output shaft is too large, the fork is deformed or the positioning spring of the fork shaft is broken

Method of exclusion:

Adjust the clearance of each relevant tie rod, replace the damaged sliding sleeve and gear, replace the gear bushing and adjust the clearance, replace or repair the fork and replace the spring
11. The hydraulic oil in the gearbox increases and the hydraulic oil in the working hydraulic oil tank decreases
cause of issue:

The oil seal of the working pump or steering pump is aging, and the axial clearance or radial barrier of the working pump or steering pump shaft is too large
Method of exclusion:
Replace the working pump or steering pump oil seal, repair the calibration oil pump or replace the oil pump
12. The hydraulic oil in the gearbox is reduced, and the hydraulic oil in the working hydraulic oil tank is increased
cause of issue:

The oil inlet filter of the working oil tank is blocked or the suction pipe of the oil pump is blocked
Method of exclusion:
Clean or replace the oil inlet filter and replace the oil pump suction pipe

13. After the gearbox is in neutral or in gear, the shifting pressure is low and the whole machine is powerless to walk
cause of issue:
Insufficient transmission oil in the gearbox, blockage of the gearbox oil pan filter, damage to the travel pump, low volumetric efficiency, improper adjustment of pressure by the pressure reducing valve or inlet pressure valve, aging or serious bending of the oil suction pipe of the travel pump
Method of exclusion:
Add enough hydraulic oil in the gearbox to the center of the oil mark at idle speed, replace or clean the filter screen, replace the travel pump, re-adjust the pressure to reach the specified range, and replace the oil pipe.
14. During normal driving, the loader suddenly has no steering, and the steering wheel can be easily turned.
cause of issue:
Steering cylinder piston falls off
Broken or damaged steering column and steering gear connecting sleeve
Method of exclusion:
Replace the steering cylinder
15. During normal driving, the loader suddenly has no steering, and the steering wheel cannot be moved.
Method of exclusion:
The steering pump roll key or the spline of the connecting sleeve is damaged, the one-way valve of the steering gear falls off (in the valve block) The 8mn steel ball (one-way valve) in the steering gear fails, replace the steering pump or connecting sleeve, and replace the valve block or one-way valve
16. Automatic steering, the steering wheel cannot automatically return to the neutral position.
cause of issue:
The return spring in the steering gear is broken
Method of exclusion:
Replace return spring or steering gear assembly
17. When the steering wheel encounters uneven ground, the direction will automatically deviate to the concave side of the ground.
cause of issue:
Damaged two-way overload buffer valve
Method of exclusion:
Replace steering gear, clean repair or replace valve block
18. Steer heavy
cause of issue:
The oil filter or oil pipe of the steering pump is blocked, the gap between the steering column and the steering gear is small or there is no clearance, the steering gear spool and the valve sleeve, the stator and the rotor are too tight, the monostable valve or the relief pressure is too low or Stuck, low volumetric efficiency of steering pump
Method of exclusion:
Clean the filter element or replace the oil pipe, adjust its clearance, replace the steering gear or clean and grind, adjust its pressure to the specified value, and replace the oil pump
19. Steering without a sense of finish
cause of issue:
The spring of the two-way buffer valve on the steering gear valve block is broken or the adjustment pressure of the two-way buffer valve is lower than the pressure of the steering safety valve, the fueling path of the steering safety valve is blocked, the clearance of the steering gear valve body, valve sleeve, valve core or the rotor and stator pair is seriously worn out. Big
Method of exclusion:
Replace the spring or adjust its pressure to the specified value, clean and unblock the pipeline, and replace the steering gear
20. 50F loader suddenly no lift, no steering during work
cause of issue:
The roller key of the pilot pump or the shaft of the pilot pump is broken, and the bearing at the connection between the torque converter and the pilot pump is damaged
Method of exclusion:
Replace the pilot pump or #shaft key with the shaft, replace the bearing
21. The steering wheel turns but the steering action is very slow, the steering wheel turns lightly, and the number of revolutions increases
cause of issue:
Steering cylinder piston seal damage Bidirectional overload buffer damage
The wear gap between the rotor and the stator is too large, and the efficiency of the steering pump is low
22 When the loader turns, there is abnormal sound on the front axle or rear axle, and the sound disappears when driving in a straight line
cause of issue:
The differential planetary gear and the axle gear are not matched, the meshing is poor, the differential planetary gear is beaten or the surface is damaged, the planetary gear and the differential cross shaft are stuck or the clearance is poorly adjusted
Method of exclusion:
Replace planetary gears or cross shaft gears, adjust clearance or replace gears
23. There is noise on the drive axle of the loader, and it does not disappear when sliding
cause of issue:
The lubricating oil in the drive axle housing is insufficient, the meshing clearance of the main and driven helical bevel gears is too small, and the clearance between the differential case and the cross shaft planetary gear is too large
Method of exclusion:
Add enough lubricating oil according to the standard, and adjust the gap to reach the specified value
24. Fault phenomenon: suddenly the front axle and rear axle have no drive during walking
cause of issue:
Half shaft broken
Method of exclusion:
Replace the half shaft
25. The loader is running normally, and the four wheels produce abnormal noise
cause of issue:
The fixed tapered roller bearing on the wheel side is damaged, the needle roller bearing of the planetary wheel shaft is damaged, the broken teeth of the sun gear and the planetary gear are damaged, the inner gear ring is beaten, and the connecting bolt between the inner gear ring and the inner gear ring support frame is broken
Remedy: replace the bearing, adjust its clearance, replace the needle bearing, replace the sun gear and planetary gear, replace the inner gear ring, and replace its bolts 10×75
26. Suddenly the boom does not lift, does not retract the bucket, and does not tip the bucket.
cause of issue:
The work distribution valve main safety valve is stuck.
Approach:
Open the main safety valve for cleaning, and pay special attention not to loosen the pressure regulating nut at the rear end of the safety valve.
Failure Analysis:
After the safety valve is stuck, all the oil of the working pump flows into the oil return circuit, and the oil circuit of the lift cylinder and the tipping cylinder cannot build up the required working pressure, thus causing the corresponding boom and bucket to not move. Such failures are generally caused by poor cleanliness of the hydraulic system. For machines that have been used for a long time, the hydraulic oil and oil suction filter elements should be fully inspected or replaced.

27. Fault phenomenon:
1) The lifting speed of light load is normal. After a certain weight is exceeded, it suddenly does not lift or lifts very slowly. The fault phenomenon of hot and cold cars is basically the same.
2) Can be lifted, but cannot reach the maximum lifting height.
cause of issue:
1) Overload
2) The set pressure of the main safety valve of the work distribution valve becomes lower.
Approach:
1) Eliminate overload.
Overloading can cause early damage to the main safety valve and working pump!
2)Clean the main safety valve and re-calibrate the pressure.
Note: The set pressure must meet the requirements of the manual. Too high set pressure may cause serious damage to the working pump, working valve and high-pressure oil pipe!

28. The tipping bucket is normal, the boom lifts slowly, and the heavier the material loaded by the shovel, the slower the lifting speed, and the degree of failure is aggravated after the hot car.
cause of issue:
1) Early wear of the lift cylinder piston seal. Judgment method: lift the boom to the highest position, disassemble the oil inlet connector of the piston rod cavity of one of the lift cylinders, put the boom lever of the work distribution valve in the "lift" position, and step on the medium and high speed accelerator, Observe the leakage at the interface of the lifting cylinder, there is a slight leakage normally, and the same is true for judging the other lifting cylinder.
(2) The efficiency of the working pump is reduced. After eliminating the first cause, it can be basically determined that the efficiency of the working pump is reduced.
Failure Analysis:
The lifting speed of the boom is mainly determined by the speed, efficiency and leakage of the lifting oil circuit of the working pump. If the piston seal of the lift cylinder is damaged or the efficiency of the working pump decreases, the leakage will increase accordingly, and it will increase with the increase of the working pressure, that is, the heavier the material, the slower the lifting.
29. The boom stops at a certain position, and it cannot stop and sinks
cause of issue:
The seal on the lift cylinder piston is damaged, and the fitting clearance between the work distribution valve stem and the valve body is out of tolerance
Method of exclusion:
Replace the seal on the piston, and check that the gap between the valve stem and the valve rest is too large, and the work distribution valve should be replaced.
30. During the normal operation of the loader, the working hydraulic device (lifting, dumping) suddenly does not work at the same time
cause of issue:
The working oil pump is damaged, the splines on the working oil pump and the keyway of the connecting sleeve are damaged or the driving oil pump shaft is broken
Method of exclusion:
Replace oil pump, replace damaged parts
31. The joystick of the work distribution valve (lifting linkage, boom linkage) cannot be positioned
cause of issue:
The positioning sleeve is damaged, the positioning steel ball is damaged, and the positioning spring is broken
Method of exclusion:
Replace the positioning sleeve, replace the positioning steel ball, replace the positioning spring
32. When the loader is working, the bucket is unable to retract the bucket or it automatically turns down after the bucket is retracted and the bucket is automatically recovered when there is resistance at the bottom of the bucket
cause of issue:
The seal in the tipper cylinder is damaged, the large-cavity over-cut valve is stuck or damaged, and the small-cavity overload valve is stuck or damaged
Method of exclusion:
Replace the seal on the piston, clean or replace the corresponding parts
33. When the loader is working, no matter the hydraulic system of lifting or closing the bucket produces noise
cause of issue:
There is little hydraulic oil in the working oil tank, the vacuum valve of the 30-type working hydraulic oil tank is damaged or not tightened, the oil suction pipe of the working oil tank is old and chemically flattened, the oil pipe clamp of the working device is loose, the oil pump suction pipe is inhaled, and the main word full valve on the work assignment is not working properly
Method of exclusion:
Add enough hydraulic oil to reach its standard value, tighten or replace the vacuum valve, clean the filter element or replace the oil pipe, clean and repair the main safety valve, and replace the main safety valve if necessary
34. Oil leaks from the small hole at the rear of the positioning sleeve when the valve stem of the lift and tipper is operated
cause of issue:
Damaged stem and spring seat "O" ring
Method of exclusion:
Replace "O" ring and tighten
35. Low brake air pressure causes brake failure or no brake
cause of issue:
The air compressor is damaged, the pipeline is leaking, the compressed air pressure is insufficient, the multi-function unloading valve is damaged or adjusted, and the pressure is low
Method of exclusion:
Check and replace the damaged parts or replace the assembly, check and tighten the air leakage, adjust the shovel unloading valve or adjust the pressure to its standard value
36. The brake air pressure is normal, resulting in poor braking effect or no braking
cause of issue:
The brake chamber cup is damaged or the air-controlled shut-off valve is damaged, the brake valve exhausts less, and the brake hub and brake pad wear too much
Method of exclusion:
Replace the leather cup or air control shut-off valve, adjust its clearance or replace the brake valve, and replace the damaged parts
37. Abnormal noise when braking
cause of issue:
The hardness of the brake shoe friction plate is too large or the rivets are exposed, the metal debris is sandwiched between the brake hub and the friction plate, and the surface of the friction plate is hardened due to the overheating of the brake.
Method of exclusion:
Eliminate the above phenomenon.
38. When braking, lean to one side
cause of issue:
The gaps between the two front wheel brake discs and the friction pads are different, the contact areas of the two front wheel friction pads are different, there is air in the piston of a front wheel, the brake caliper of a front wheel is deformed, the air pressure of the two front wheels is inconsistent, and a certain side Wheel friction plate oily sewage wet
Method of exclusion:
Check the brake disc and friction pads if they are damaged and replace them, check and replace the friction pads, exhaust the air in the correct way, replace them, the air pressure in the air chamber is specified and the air pressure is the same, clean and dry
39. When the brake pedal is pressed to the bottom while driving, the brake suddenly fails
cause of issue:
The sealing ring of the afterburner master cylinder is damaged or overturned, there is no brake fluid in the afterburner master cylinder, no brake air pressure, the brake pipeline is severely ruptured or the pipeline joint is disconnected
Method of exclusion:
Replace the damaged seal, add enough brake fluid to the standard value, drain the air in the oil circuit, and replace the damaged brake pipeline
40. When walking continuously, the brake disc is seriously heated. After releasing the brake pedal, the loader is difficult to start, and the brake caliper piston does not return.
cause of issue:
The brake pedal of the loader has no free travel or poor return, the seal ring of the afterburner is expanded or the piston is deformed or the piston is stuck with dirt, the return spring of the afterburner is broken, the rectangular ring on the brake caliper piston is damaged or the piston is stuck or raw. Rust, the gap between the brake disc and the friction plate is too small, the brake pipe is concave and blocked, and the oil return is not smooth, the viscosity of the brake fluid is too large or too dirty, making the oil return difficult, and the brake valve cannot be exhausted instantaneously
Method of exclusion:
Adjust the clearance to the normal value, clean or replace the damaged parts, replace the return spring, clean or replace the rectangular ring piston, adjust the clearance or replace the friction plate with thinner friction plates, replace and clear the oil circuits, clean the afterburner pump or replace it The same type of brake fluid, replace the brake valve or its clearance at high speed
41. After the manual control valve is connected, it is easy to pop up
cause of issue:
The air pressure is too low to reach 0.35MPa, the manual control valve is damaged, the sealing is not strict, the air control stop valve is damaged, and the seal on the piston of the parking air chamber is damaged.
Method of exclusion:
Check whether the air compressor works for air leakage in the pipeline, and replace the damaged seals
42. After turning on the start switch, the starter does not turn
cause of issue:
The starter is damaged, the starter switch knob is in poor contact, the wire connector is loose, the battery charge is insufficient, the electromagnetic switch contacts are not in contact or burned out
Method of exclusion:
Repair or replace the starter, repair or replace the starter switch, check and fasten the connecting wire and charge, repair or replace the electromagnetic switch
43. After the starter switch is turned on, the starter runs idly and cannot drive the engine to run together
Causes of failure: The stroke of the electromagnetic switch iron core is too short, the armature moves or the auxiliary coil is short-circuited or open, the one-way mesher slips, and the flywheel teeth are severely worn or broken
Remedy: check and repair the electromagnetic switch or replace, repair or replace the coil, replace the flywheel
44. The engine is idling or running at a high speed, and the ammeter indicates that no electricity is allowed.
cause of issue:
Generator armature and field wiring insulator damage, slip ring insulation breakdown, silicon diode breakdown, short circuit or open circuit, voltage regulator contact burnout, stator or rotor coil grounded or open circuit
Method of exclusion:
Check and repair damaged parts, replace slip rings, replace diodes, replace regulators, repair stator or rotor coils
45. After the starter switch is turned on, only the starter has a "scare" sound, but it cannot be turned
cause of issue:
Insufficient battery storage or loose starting circuit wires, damage to the starter bearing, bending of the armature shaft (rotor part) and collision (stator part), short circuit of the armature and the magnetic field coil Remedy:
46. Poor cooling effect or no cooling
cause of issue:
The electromagnetic clutch is not pressed or the compressor belt is too loose, the refrigerant is low, the condenser fan or fan does not rotate, and the intake pipe is blocked
Method of exclusion:
Check whether the electromagnetic clutch is damaged, adjust the belt, add refrigerant to its standard value, check the fan or circuit, check the intake line to remove blockages
47. The air conditioning system is noisy
cause of issue:
The drive belt is too loose or severely worn, the compressor mounting bracket is loose, the blower motor is loose or worn, the electromagnetic clutch slips and makes noise, and the internal parts of the compressor are worn
Method of exclusion:
Adjust or replace the belt, re-adjust the loose parts, replace the motor or repair, check and repair the electromagnetic clutch or replace, replace the damaged parts, replace the compressor if necessary
48. There is a "pop" exhaust sound around the cylinder head during engine operation, and water returns at the water tank filling hole and increases with the increase of engine speed
cause of issue:
The cylinder head is deformed due to the uneven tightening torque of the fixed bolts, and the quality of the cylinder head is
Method of exclusion:
Re-adjust according to the specified torque and in sequence, replace the cylinder head, re-replace the cylinder head with good quality, adjust the advance angle
49. Drain the oil from the oil filler port and the oil dipstick port
cause of issue:
The oil level in the oil pan is too high, the air pressure in the oil pan is too high (the oil temperature is too high, the oil-water separator is blocked or the ventilation hole of the crankcase is blocked. High pressure gas enters the oil bottom)
50. High engine oil consumption
cause of issue:
Oil leakage, supercharger oil leakage, blockage of air filter, excessive oil filling, oil grade does not meet the requirements, ordinary oil viscosity is too small, oil and gas separator is blocked, air compressor piston, piston ring and cylinder wall are seriously worn , early wear of cylinder liner, blow-by gas
Method of exclusion:
Replace the oil seal or tighten the oil leakage part, replace the supercharger, clean the filter element, put it in the specified position, replace the oil that meets the requirements, clean or replace, replace the piston ring, piston ring and cylinder wall, replace the cylinder liner and other components
51. The oil is mixed with water, and the color of the oil turns white
cause of issue:
The water plug is not tightly pressed, resulting in loose and leaking water or the water plug is rotten, the cylinder gasket is damaged or the cylinder head is cracked, the body has blisters, the engine oil cooler is cracked or welded
Method of exclusion:
Replace the water plug, replace the cylinder head gasket or head, replace the body, check repair or replace the oil cooler
52. Diesel is mixed into the oil and the oil level rises
cause of issue:
The injector of a certain cylinder is damaged, the needle valve is stuck, the cracked oil head is burned, etc., diesel oil leaks from the inside of the high-pressure pump, and the piston sealing ring of the oil transfer pump is damaged
Method of exclusion:
Check, repair or replace the oil cooler, check and calibrate the fuel injector or replace, replace or repair the high pressure oil pump, replace the oil transfer pump
53. The engine emits black smoke and increases with the increase of the engine speed
cause of issue:
Too much fuel injection, uneven or poor atomization, insufficient cylinder pressure, insufficient combustion, oil entering the combustion chamber, and poor diesel quality
Method of exclusion:
Clean the air filter element to ensure the correct gas distribution phase, the advance angle of the fuel supply of the high-speed fuel injection pump, and the piston, piston ring, and cylinder liner are seriously worn. If the valve is not closed tightly, the fuel injector should be replaced. If damaged, it should be replaced, and the diesel oil that meets the label should be replaced.
54. When the ZL50C loader is at idle speed, the lowering and lifting speed of the boom slows down.
Accompanying phenomenon: When the working time is long, the working hydraulic system heats up more seriously.
cause of issue:
Pilot pump relief valve set pressure is low
The pilot pump relief valve spool is stuck or the spring is broken and the pilot pump efficiency is reduced.
Method of exclusion:
Readjust the pressure to the calibrated value of 2.5Mpa and replace the pilot pump overflow valve
Replace the pilot pump
Failure Analysis:
The direct cause of the reduction in the lifting and lowering speed of the loader arm is the drop in the oil flow to the lift cylinder. The reason for the low flow rate of the cylinder is that the efficiency of the working pump decreases and the actual oil supply decreases, the second is that the opening of the working valve stem becomes smaller, and the third is that there is a leakage point. The above faults have the problem of slow movements in both the lifting and lowering states, and the first and third reasons can be excluded. One of the reasons for the smaller opening of the working valve stem is the machining deviation between the valve stem and the valve body. Therefore, this fault exists when it leaves the factory, and with the improvement of machining accuracy, this kind of problem becomes less and less. . The second reason is that the pilot pressure is too low and the valve stem cannot be pushed to the specified position. In the actual measurement, it is found that when the pilot pressure is reduced to 13kgflcm2, the falling speed of the idle speed will slow down to about 17 seconds. In actual maintenance, the relief valve on the pilot pump should be removed first to observe whether the valve core and return spring are damaged. If it is normal, the pressure should be re-adjusted after cleaning. If the adjustment effect is not obvious, it is caused by the reduced efficiency of the pilot pump. Only replace the pilot pump. In addition, due to the decrease in the oil-passing ability of the valve stem, the throttling loss at the valve port will directly lead to an increase in the oil temperature of the system. When this kind of fault occurs, because the throttle is generally at medium and high speed during operation, the fuel supply of the pump is relatively large, so it is generally not obvious when lifting, but it is generally low throttle or idling when descending, and the fuel supply of the system decreases. is small, so the descending speed will be significantly slowed down, which should be paid special attention to when checking.