A beverage distributor faced a chronic issue with a Crown EPE20 electric walkie pallet jack. After about 45 minutes of continuous use, the truck would suddenly lose all drive power. The operator noted that the drive motor area was extremely hot to the touch, and the truck required a 30-minute cooldown period before it would operate again.
The Crown EPE20 utilizes a 24-volt DC drive motor controlled by an EV100 traction controller. The technician connected a laptop to the controller to read the fault history. The log repeatedly showed a "Motor Thermal Cutout" fault, meaning the controller was shutting down to prevent the motor from melting its internal windings.
The technician lifted the drive wheel and attempted to spin the motor by hand. It exhibited severe resistance and a grinding feel. The drive motor was removed and disassembled. The front bearing, located nearest to the drive wheel, had completely seized. The bearing race had shattered, and the balls had welded themselves to the inner race due to extreme friction. This mechanical drag was forcing the motor to draw massive amounts of current just to turn the wheel, which rapidly generated heat and tripped the thermal sensor embedded in the motor windings.
While replacing the drive motor bearing, the technician also noticed the steering chain was loose. The EPE20 uses a steering potentiometer (a variable resistor) to tell the controller which direction the drive wheel is pointing. The pot was tested, and it showed dead spots in its rotation. When the operator turned the handle, the dead spots caused the controller to momentarily lose the steering angle signal. This resulted in erratic, jerky steering inputs, forcing the operator to constantly fight the handle, which placed excessive side-loading stress on the drive motor and exacerbated the bearing failure.
The repair involved installing a new, high-speed sealed bearing in the drive motor and replacing the worn steering potentiometer. The steering chain was adjusted to the correct tension, and the controller was recalibrated to recognize the new pot. After the repair, the pallet jack ran continuously for a full 8-hour shift without a single thermal cutout, and the steering responded smoothly and predictably.
