Manual Hydraulic Forklift Common Malfunction Analysis and Improvement Suggestions

I. Common Malfunctions and Root Causes

Slow or Failed Lifting

Root Causes:

Insufficient Hydraulic Oil: Low oil levels directly affect lifting force.

Air in the Hydraulic System: Air trapped in the pump or oil cylinder reduces pressure transmission efficiency, causing sluggish lifting.

Worn Valve Components: Valve rods, springs, or seals may wear out due to prolonged use or contaminated oil, leading to internal leakage.

Damaged Oil Seals: Aging or cracked oil seals in the oil cylinder result in oil leakage and pressure loss.

Uncontrolled Descent of Forks

Root Causes:

Internal Leakage in Valve Body: Worn valve components allow hydraulic oil to flow back to the oil tank, causing unintended descent.

Contaminated Hydraulic Oil: Impurities in the oil can block or damage the pressure relief valve, preventing it from closing properly.

Failed Seals: Worn seals in the oil cylinder or valve body fail to maintain pressure, leading to oil leakage.

Oil Leakage

Root Causes:

Aging or Damaged Oil Seals: Oil seals in the oil cylinder or valve body degrade over time, causing oil leakage.

Cracked Components: Cracks in the oil cylinder or valve body due to impact or fatigue result in oil leakage.

Difficulty in Steering

Root Causes:

Worn Steering Wheel Bearings: Damaged bearings increase friction, making steering difficult.

Deformed Steering Components: Deformation of the steering arm or connecting rods due to overload or impact affects steering smoothness.

Uneven Fork Height

Root Causes:

Deformed Connecting Rods: Overloading can bend the connecting rods between the forks and wheels, causing height imbalance.

Worn Pins: Wear on the pins connecting the forks and wheel forks leads to instability and uneven lifting.

II. Improvement Suggestions

Regular Maintenance and Inspection

Hydraulic Oil Management:

Check oil levels regularly and top up as needed (using ISO VG32 hydraulic oil is recommended).

Replace hydraulic oil every 6–12 months or if contamination is detected.

Seal Inspection:

Inspect oil seals in the oil cylinder and valve body for cracks or aging, and replace them promptly.

Valve Component Cleaning:

Clean the valve body, springs, and steel balls with diesel or cleaning agents to remove impurities and prevent blockages.

Air Removal from the Hydraulic System

Steps:

Place the forklift on a level surface and ensure the handle is in the neutral position.

Pull the handle to the "lift" position and press it down repeatedly 10–20 times to expel air from the pump.

Check for bubbles in the oil cylinder and repeat the process until no bubbles appear.

Replacement of Worn Components

Valve Rods and Springs:

If the valve rod shows significant wear, consider chrome plating or replacement.

Replace broken or fatigued springs to ensure proper valve operation.

Oil Cylinder Repair:

For minor scratches in the oil cylinder, polish the inner wall to restore smoothness.

For severe damage, replace the entire oil cylinder.

Steering System Maintenance

Lubrication:

Apply grease to the steering wheel bearings and connecting rods regularly to reduce friction.

Component Replacement:

Replace worn steering wheel bearings or deformed steering arms to ensure smooth steering.

Fork Height Adjustment

Connecting Rod Calibration:

Loosen the pins connecting the forks and wheel forks, and adjust the connecting rods to level the forks.

Pin Replacement:

Replace worn pins to prevent height imbalance caused by instability.

Operator Training

Proper Usage:

Train operators to avoid overloading and sudden movements, which can accelerate component wear.

Routine Checks:

Encourage operators to perform pre-use inspections (e.g., oil levels, leaks, steering smoothness) to detect issues early.

III. Preventive Measures

Use High-Quality Hydraulic Oil:

Opt for hydraulic oil with good anti-wear and anti-corrosion properties to extend component life.

Avoid Overloading:

Adhere to the forklift’s rated load capacity to prevent structural damage.

Store Properly:

Keep the forklift in a dry, clean environment to prevent rust and corrosion.

Establish a Maintenance Schedule:

Implement a regular maintenance plan (e.g., monthly checks, quarterly overhauls) to address issues proactively.

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