In warehousing, logistics, and factory workshops, Manual Stackers (also known as manual hydraulic lift trucks) are invaluable tools for short-distance goods handling and stacking due to their simple structure, ease of operation, and low maintenance costs. However, with increased use, the equipment is inevitably prone to some malfunctions.

1. Forks Cannot Reach the Highest Point

This is one of the most common malfunctions of Manual Stackers, usually caused by the following reasons:

• Insufficient hydraulic oil: Check whether the hydraulic oil in the cylinder meets the specified standard.
  
  
• Impurities in the hydraulic oil: Dirt or debris may block the oil circuit; replacing the oil is recommended.
  
  
• Air entering the hydraulic system: Air in the pump body prevents proper pressure buildup.
  
  

Solution: Open the relief valve and pump the handle quickly several times to expel air from the pump body.

2. Forks Automatically Descend After Lifting

If the forks cannot stay at the lifted height, it usually indicates internal or external leakage in the hydraulic system:

• Aging oil pump seal ring: Long-term use can cause seal wear and oil leakage.
  
  
• One-way valve not closing properly: Foreign matter may block the valve core, allowing oil to flow back.
  
  

Solution: Inspect and replace worn seals and thoroughly clean the valve assembly.

3. Forks Do Not Rise When Pressing the Handle

When pressing the handle does not raise the forks of the manual pallet stacker, check the following components:

• Adjustment bolt misalignment: If the bolt at the handle base is too tight, the relief valve may stay open.
  
  
• Damaged oil inlet valve ball: This prevents the system from building hydraulic pressure.
  
  

Solution: Re-adjust the handle bolt clearance to ensure the valve fully closes in the “up” position.

4. Forks Cannot Descend

If Manual Stackers cannot descend after lifting heavy loads, efficiency and safety are both affected:

• Piston rod deformation: Overloading or uneven loads can bend the piston rod.
  
  
• Insufficient lubrication: Mechanical joints may seize due to lack of lubrication.
  
  

Solution: Straighten or replace the piston rod and regularly lubricate all moving parts.

Daily Maintenance Suggestions for Manual Stackers

To minimize malfunctions and extend service life, follow these daily maintenance guidelines:

• Avoid overloading: Always operate within the rated load to protect the hydraulic system.
  
  
• Operate smoothly: Apply steady force when lifting or lowering; avoid sudden impacts.
  
  
• Keep the environment clean: Regularly inspect wheels and remove hair, tape, or debris to ensure smooth movement.
  
  

By mastering these basic troubleshooting and maintenance techniques, operators can effectively handle minor issues and ensure safe, efficient operation of manual stackers.