Common Fault Analysis and Improvement Suggestions for Manual Forklifts

As a commonly used handling equipment in logistics and warehousing, the stability of the hydraulic system, structural components, and operating mechanism of manual forklifts directly affects operational efficiency and safety. Starting from the core fault types, combined with technical principles and maintenance practices, a systematic improvement plan is proposed.

1、 Hydraulic system malfunction: lifting failure and oil leakage

Fault performance

Slow or weak lifting: Insufficient hydraulic oil, blocked oil circuit, aging seals causing internal leakage, or incomplete air discharge in the oil pump.

Automatic lowering of fork: Failure to tighten the oil discharge valve, worn seals, or impurities in the hydraulic oil can cause the valve body to not close tightly.

Oil leakage: The sealing ring on the joint surface of the oil cylinder has hardened, the piston rod seal has failed, or the pipeline interface is loose.

technical analysis

Hydraulic systems rely on seals (such as O-rings and oil seals) to maintain pressure, and long-term use can accelerate wear due to material aging or oil contamination. For example, the service life of domestic oil seal repair kits is usually several months to two years, while imported parts can last up to 3-5 years.

Failure to exhaust the air from the oil pump can lead to a decrease in compression ratio, manifested as slow lifting and lowering; If the top thread of the oil drain valve is too loose or the valve body is worn, it may cause internal leakage, which needs to be repaired by adjusting the set screw or replacing the valve core.

Improvement suggestions

Regular maintenance: Check the hydraulic oil volume monthly (preferably 2/3 of the cylinder body), replace the hydraulic oil and filter element every six months, and use ISO VG32 standard oil to reduce impurity deposition.

Seal upgrade: using fluororubber or polyurethane material seals to enhance wear resistance and weather resistance; The chrome plating treatment on the inner wall of the oil cylinder can reduce the friction coefficient and extend the sealing life.

Intelligent monitoring: Install pressure sensors and oil pollution monitoring modules to provide real-time feedback on system pressure and oil quality status, achieving warning based maintenance.

2、 Structural component failure: deformation and wear

Fault performance

Arm deformation or breakage: Frequent reciprocating motion can cause metal fatigue, or overloading can lead to fracture.

Unbalanced fork arm: The connecting pin shaft between the square connecting rod and the wheel fork is deformed, or the wheel fork is subjected to lateral force for a long time, resulting in an enlarged opening.

Steering wheel stuck: Bearing damage or axle spring detachment, affecting steering flexibility.

technical analysis

As a load-bearing core component, the material strength and heat treatment process of the pull arm directly affect its lifespan. Overloading or improper operation can accelerate fatigue crack propagation, ultimately leading to fracture.

Unbalanced fork arms are often caused by wear and tear of the pin shaft or deformation of the fork wheel. Under long-term heavy pressure, the opening of the fork wheel may expand, which may lead to the overall detachment of the brick board and roller.

Improvement suggestions

Material optimization: The pull arm is made of high-strength alloy steel (such as 42CrMo) and its fatigue resistance is improved through quenching and tempering treatment; Hard chrome plating on the surface of the pin can reduce wear.

Structural reinforcement: Adding reinforcing ribs to the fork design or using integral casting technology instead of welding structure to enhance deformation resistance.

Dynamic balance adjustment: Adjust the height of the wheels by rotating the square connecting rod or replacing the deformed pin shaft to ensure that the horizontal difference between the two fork arms is ≤ 5mm.

3、 Operating mechanism malfunction: connection failure and gear disorder

Fault performance

Malfunction of the oil drain valve handle: Improper adjustment of the gap between the hard and soft connections resulted in uncontrolled lifting.

Gear misalignment: Wear of the multi way directional valve stem or failure of the reset spring can cause oil circuit interconnection or valve body warping.

technical analysis

The operating mechanism relies on precise coordination to achieve its functions, and the clearance between the valve stem and valve body needs to be controlled within the range of 0.01-0.03mm. Long term use or oil contamination can damage the sealing surface, leading to internal leakage or gear failure.

Insufficient elasticity of the reset spring or uneven tightening torque of the valve body bolts may cause the valve body to warp, further exacerbating the risk of oil leakage.

Improvement suggestions

Standardization of connectors: adopting modular design, integrating the handle of the oil drain valve with the top wire to reduce connection clearance; Add a limit device to the gear adjustment mechanism to prevent misoperation.

Valve body repair process: chrome plated and polished the lightly worn valve stem; Replace the valve body when it is severely worn, and use a torque wrench to tighten the bolts in sequence (refer to the equipment manual for torque values).

Operation training: Standardize the operation process, avoid neutral sliding or overloading, and reduce mechanical impact.

4、 Comprehensive improvement strategy: preventive maintenance and intelligent upgrade

Preventive maintenance system

Establish a "daily inspection weekly maintenance monthly repair" system: inspect oil and connecting components daily, lubricate moving parts weekly, conduct comprehensive maintenance and record data monthly.

Implement "5S management": keep equipment clean, promptly remove oil stains and debris, and prevent corrosion and jamming.

Intelligent upgrade direction

Develop a fault diagnosis app: Connect sensors via Bluetooth, upload real-time data such as pressure and temperature to the cloud, and use AI algorithms to predict fault trends.

Application of AR technology: Displaying repair steps through augmented reality glasses, reducing technical barriers, and improving maintenance efficiency.

Environmental Protection and Safety Enhancement

Choose biodegradable hydraulic oil: reduce environmental pollution caused by oil leakage and comply with RoHS and REACH regulations.

Install safety protection devices such as fork limiters and overload alarms to reduce operational risks.

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