pallet jack lowering by itself

The manual pallet truck experiences automatic lowering of the forks during use, meaning that the forks slowly or suddenly lower on their own without operating the lowering handle. This phenomenon may lead to damage to goods, unstable equipment, and even safety accidents, and needs to be promptly investigated and dealt with.

Possible reasons and solutions:

Hydraulic system malfunction
Reason: Insufficient hydraulic oil, aging or damaged sealing rings, and internal wear of hydraulic cylinders.
solve:
Check for hydraulic oil leaks and replenish specialized hydraulic oil to the standard level.
Replace damaged seals (such as O-rings, piston seals).
If the inner wall of the hydraulic cylinder is worn, professional maintenance or replacement of the cylinder is required.

Downward valve malfunction
Reason: The lowering valve (handle/switch that controls the lowering of the fork) has not fully returned or the internal spring has failed, resulting in incomplete closure of the oil circuit.
solve:
Clean the linkage mechanism of the descent valve to ensure smooth return of the handle.
Check the spring elasticity and replace the lowering valve assembly if necessary.

Safety valve failure
Reason: The safety valve (relief valve) pressure setting of the hydraulic unit is too low or the valve core is stuck, causing abnormal oil reflux.
solve:
Adjust the pressure of the safety valve to the standard value (refer to the equipment manual).
Clean or replace the safety valve components.

Load exceeding or biased
Reason: Long term overloading or biased use can lead to excessive fatigue of the hydraulic system and accelerated wear of seals.
solve:
Strictly use according to the rated load (such as 2.5T, 3T) to avoid overloading.
Check if the fork is deformed and correct or replace it if necessary.

Air pockets or oil contamination
Reason: Hydraulic oil mixed with air or impurities affects the sealing and pressure stability of the system.
solve:
Exclude hydraulic system air (multiple no-load lifting operations).
Replace with clean specialized hydraulic oil and perform regular maintenance.

Prevention and maintenance suggestions:

Regular inspection: Check the hydraulic oil level, seal condition, and valve flexibility monthly.
Standardized operation: Avoid rapid descent or collision with the fork, and ensure that the descent valve is reset after operation.
Professional maintenance: Conduct a comprehensive hydraulic system inspection once a year and replace worn parts.
Environmental precautions: Avoid using in extreme temperatures or dusty environments to prevent seal aging.