Troubleshooting Weak Travel Power in a 4WD Rough Terrain Forklift During Winter

Customer Complaint:
A customer reported that their 4WD rough terrain forklift and wheel loader had weak travel power, especially in winter. In cold weather, the machine required 10–30 minutes of warming up before it could move properly. Sometimes, it would not move at all.

Inspection Process & Findings:

1. Transmission Oil Check
   • The transparent observation window of the gearbox was checked. The oil level was low, which can directly lead to loss of driving power. Dirty or insufficient transmission oil causes poor lubrication and hydraulic pressure problems.
2. Transmission Filter Screen
   • The filter screen located at the oil outlet of the gearbox was inspected. A blocked filter restricts oil flow, reducing hydraulic pressure and travel power. In this case, the filter was partially clogged.
3. Coupling (Torque Converter / Steel Wheel) Check
   • The gearbox coupling was examined. If damaged or leaking, it will fail to transmit power effectively. This was not the main issue in this case.
4. Travel Hydraulic Pump (Gear Pump) Inspection
   • The travel pump supplies hydraulic pressure to the transmission system. If worn out, it will cause low oil pressure. The pump in this machine was functioning normally.

Final Solution:

• The transmission oil was drained and replaced with clean oil.
• The filter screen was cleaned and reinstalled.
• After maintenance, the forklift was tested in cold weather conditions and regained full travel power.

Result:
The 4WD forklift operated smoothly with strong traction. The customer confirmed the issue was completely resolved.