Fault 1: The hydraulic system cannot reach the required working pressure, and the throttle of the engine cannot be increased. Phenomenon: The legs cannot be retracted, the luffing boom cannot be raised, and the turntable cannot rotate. From the pressure gauge, the pressure of each mechanism is very low.
Reason: 

(1) The opening pressure of the relief valve is too low. 
(2) The oil level of the fuel tank is too low, or the suction pipe is blocked. 
(3) The pressure pipeline and the oil return pipeline are connected or leaked too much, so that a large amount of oil flows back to the fuel tank without participating in the work. 
(4) The oil pump is damaged or leaked too much.
Remedy: 

(1) Adjust the opening pressure of the relief valve 
(2) Add new oil or check the oil suction pipe 
(3) Check the oil circuit, especially various valve locks, motors, etc. 
(4) Check the oil pump, repair it, or replace it with a new one.

Fault 2: Failure to control gears
Reasons:(1) joystick failure(2) fork damage (3) positioning bead spring failure
Exclusion method: or repair or replace

Fault 3: Oil leakage from hydraulic system
Reasons: (1) loose joints (2) damage to seals (3) pipe edge cracks or oil sand holes in welded pipe joints
Remedy: (1) Tighten (2) Replace with new ones (3) Repair welding or replace with new ones

Fault 4: The throttle control valve does not work
Reasons: (1) the wire rope in the system is stuck (2) the spring is damaged (3) the stroke changes due to the loosening of the rope card (4) the lack of lubricating oil
Remedy: (1) Maintenance (2) Replacement (3) Adjust the stroke; tighten (4) Lubricate each P position

Fault 5: The pressure gauge oil does not indicate, or the pressure does not rise
Reasons: (1) The liquid level of the fuel tank is too low or the oil suction pipe is blocked. (2) The adjustment pressure of the relief valve is too low.
Remedy: (1) Refuel and remove foreign objects (2) Properly adjust the pressure according to regulations

Fault 6: Serious noise and vibration in the oil circuit
Reasons: (1) There is air in the pipeline (2) The components are out of order (3) The components on the side of the pipe are not fastened (4) The reversing is too fast and too fast. (5) The oil temperature is too low. (6) The oil is insufficient. (7) The pipeline is blocked.
Remedy: (1) Each mechanism acts repeatedly for many times to remove the internal gas and overhaul the oil pump. (2) Repair or replace (3) Tighten the pipe-adding card (4) Slow operation (5) No-load operation for heating (6) Oil filling (7) Unblocking

Fault 7: Oil temperature is overheated
Reasons: (1) Excessive internal leakage (2) Too high pressure (3) Long continuous operation time and high ambient temperature (summer)
Remedy: (1) overhaul components (2) adjust pressure (3) stop after rest and cool down before working.

Fault 8: The cylinder and motor move unevenly, and there is a phenomenon of climbing
Reasons: (1) After the air load exists in the hydraulic system, it is significantly compressed, making the movement uneven. (2) Lack of lubrication between the moving friction surfaces. (3) The gap between the moving parts and the non-parts is too small, or the moving working parts are deformed.
Remedy:(1)Add enough oil to the fuel tank and reciprocate each cylinder at high speed and full stroke several times.(2)often add grease lubrication. (3) Check and adjust the tightness of the gap between the moving parts.

Fault 9: The outrigger moves slowly, fails to retract or even does not move
Reason: (1) The overflow valve fails or the pressure is too low. (2) Oil leaks in the oil cylinder, the oil seal is damaged and the volume efficiency of the oil cylinder is reduced, the displacement of the oil pump is insufficient, the reversing valve fails or the internal leakage is serious. (3) There are foreign objects or scars between the spool valve cone surface and the valve seat contact line in the two-way hydraulic lock. ⑷ There is air in the cylinder.
Remedy: ⑴ overhaul, replace or adjust the pressure. (2) Replace the oil seal, the displacement of the oil pump is insufficient, do not increase the throttle, increase the engine speed, and the reversing valve fails. (3) Disassemble and clean, if it is heavy, replace it, if it is light, re-grind it. (4) Reciprocate several times to remove air.