Summary of Common Malfunctions of Hydraulic Forklifts

As a core equipment in logistics and warehousing, hydraulic forklifts have a direct impact on operational efficiency and safety due to hydraulic system failures. According to industry data and maintenance cases, common faults can be classified into the following seven categories, with specific manifestations and solutions attached:

1、 Hydraulic oil leakage

Performance: Oil leakage in the return pipe of the lifting cylinder, oil leakage in the pipeline joint, and oil on the piston rod of the cylinder.

Reason:

Oil seal aging or damage (such as broken oil seal of lifting cylinder).

Loose or damaged hydraulic pipeline connections.

Scratches on the surface of the oil cylinder piston rod resulted in seal failure.

Solution:

Replace damaged oil seals or seals, and use a flexible hard iron fixing ring during installation to prevent deformation of the oil seal.

Tighten the pipeline joints and replace the broken hydraulic pipes.

Repair or replace the cylinder on the surface of the piston rod.

2、 Abnormal lifting function

Performance:

Forks cannot lift or lift slowly.

Shaking or automatic descent during the lifting process.

The lifting speed is significantly lower when fully loaded than when unloaded.

Reason:

Insufficient or contaminated hydraulic oil (including impurities and bubbles).

The safety valve of the multi way valve is stuck or the pressure adjustment is improper.

The volumetric efficiency of the gear pump decreases (such as when the shell temperature rises too quickly).

The speed limiting valve spring of the lifting oil cylinder is broken.

Solution:

Supplement or replace hydraulic oil, eliminate pipeline air (by repeatedly lifting and lowering the oil cylinder).

Clean the safety valve of the multi way valve and adjust the pressure to the standard value (with a pressure gauge attached).

Replace the gear pump or speed limiting valve spring.

Check the oil cylinder seals and replace worn parts.

3、 Steering system malfunction

Performance:

Turn towards heavy or bouncing hands.

The steering wheel is not flexible when turning.

Reason:

The diversion safety valve is not tightly closed or the valve core is stuck.

The positioning spring of the steering gear is broken.

Internal leakage of steering cylinder (damaged oil seal).

Solution:

Clean the diversion safety valve and adjust the pressure.

Replace the positioning spring or steering cylinder oil seal.

Check the pipeline connections of the steering system and tighten any loose parts.

4、 Braking system lag

Performance: After lifting the brake pedal, some or all of the wheel brakes cannot be released.

Reason:

Brake master cylinder malfunction (such as poor oil return).

The wheel brake is stuck or the sealing ring is aging.

Solution:

Check the free stroke of the brake master cylinder and adjust it to the specified value.

Replace the brake seal ring or master cylinder component.

Test the return oil condition of the brake system to ensure there is no blockage.

5、 Vibration and noise of hydraulic system

Performance:

Forklift generates abnormal vibrations during operation or lifting.

Hydraulic pumps, valves, or pipelines make noise.

Reason:

Excessive hydraulic oil temperature causes component expansion.

The pipeline is not firmly fixed or the components are loose.

Internal wear or air intake of hydraulic pump.

Solution:

Check the cooling system and lower the oil temperature.

Tighten the pipeline connections and replace worn parts.

Clean the oil inlet filter of the hydraulic pump to prevent air from entering.

6、 Multi way valve jamming and abnormal noise

Performance:

Multi way valve operation is stuck or unable to return to its original position.

The valve body makes a whistling sound (especially when debugging a new valve).

Reason:

Poor oil cleanliness leads to valve stem sticking.

The clearance between the valve hole and the valve stem exceeds the standard.

The opening pressure of the safety valve is too high.

Solution:

Clean the interior of the multi way valve and replace the contaminated hydraulic oil.

Adjust the clearance between the valve stem and the valve hole, and replace the multi way valve if necessary.

Re calibrate the pressure of the safety valve (to avoid excessive pressure).

7、 Hydraulic oil temperature too high

Performance: The temperature of the hydraulic system continues to exceed 82 ° C.

Reason:

Hydraulic pump wear leads to internal leakage.

The cooler is blocked or the fan is malfunctioning.

The viscosity of hydraulic oil has decreased (not replaced for a long time).

Solution:

Replace worn hydraulic pumps or seals.

Clean the cooler and check the fan operation.

Regularly replace hydraulic oil (according to the manufacturer's recommended cycle).

The main equipment produced by Hebei Makita: stage electric hoist, electric chian hoist, wire rope electric hoist，Hand chain hoist, lever hoist, pneumatic hoist and other lifting equipment