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VNA Forklift Lifting System Failure Analysis And Solutions

Jan 19, 2024

3-way pallet stacker forklifts, also known as VNA forklifts, include man-up type VNA pallet stacker, VNA electric articulated forklift, and other types. Their lifting system consists of an outer mast, an inner mast, a three-way fork and a cargo fork. The lifting cylinder of the fork drives the inner mast, and the inner mast drives the inner slide frame through the chain. A motor and a rack cylinder are installed on the three-way fork head, which push the fork head sideways or rotate under the action of hydraulic pressure to realize three-way stacking of goods. Today I will show you the general fault analysis and treatment of the three-way forklift lifting system.


1. The fork lift is not smooth

(1) Reason: Improper adjustment of fork frame assembly

     Troubleshooting: Adjust the gap between the channel steel guide rail and the side roller

(2) Reason: Insufficient clearance between the roller and the mast slot

     Troubleshooting: Adjust the roller gap

(3) Reason: Dirt between moving parts

     Troubleshooting: eliminate foreign matter

(4) Reason: Insufficient lubrication

     Troubleshooting: Apply grease on the guide rail contact surface

(5) Reason: The inner mast is skewed or the fork frame is bent.

     Troubleshooting: Repair or replace

2. Three-way forklift forks lift unevenly

   Reason: The lifting chain is not adjusted properly

   Troubleshooting: Adjust the tightness of the chains on both sides to be consistent

3. The lifting roller does not rotate

(1) Reason: Grease is hardened or the roller is stuck with dirt.

     Troubleshooting: Clean and lubricate the rollers

(2) Reason: The lifting roller is incorrectly adjusted

     Troubleshooting: Adjust

4. The mast makes too much noise during the lifting process

(1) Reason: Insufficient lubrication

     Troubleshooting: Lubrication

(2) ReasonThe upper side rollers of the fork frame are unevenly adjusted.

     Troubleshooting: Adjust the adjusting shims of the rollers and side rollers

5. Inability to lift or unable to lift

(1) Reason: The oil pump gear and pump body are excessively worn and have large gaps.

     Troubleshooting: Replace wearing parts or oil pump

(2) Reason: Lifting cylinder piston seal ring wear and internal leakage

     Troubleshooting: Replace the sealing ring

(3) Reason: Multi-way valve and safety valve spring failure

     Troubleshooting: Replace the spring

(4) Reason: The valve stem and valve body of the multi-way valve are greatly worn and oil leakage.

     Troubleshooting: Replace

(5) Reason: Oil leakage between the valve bodies of the multi-way valve

     Troubleshooting: After grinding, reassemble and assemble in order

(6) Reason: Oil leakage in hydraulic pipeline

     Troubleshooting: Check and trim

(7) Reason: The oil temperature is too high, oil is too thin, and the flow rate is insufficient.

     Troubleshooting: Replace unqualified hydraulic oil and check the cause of excessive oil temperature

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