A logistics depot reported that a Heli CPCD50 5-ton diesel forklift had severe "wander." The operator had to constantly correct the steering wheel to drive straight, and the rear drive tires were wearing down to the canvas cords in just three months. The tire wear pattern showed "scalloping" (cupping) on the outer edges.
The technician first checked the steering hydraulic cylinder for leaks, which was dry. The steering orbitrol (control valve) was also functioning correctly. The issue pointed to mechanical alignment. The forklift was raised, and the rear steer axle assembly was inspected. The CPCD50 uses a "center pivot" steer axle.
The technician found that the large central pivot pin, which allows the steer axle to oscillate and maintain ground contact on uneven surfaces, was seized. Furthermore, the pivot pin was slightly bent. This prevented the axle from articulating freely and forced the wheels into a "toed-out" position when the machine was lowered to the ground. The bent pin also caused the kingpins (which allow the wheels to turn) to bind, preventing the wheels from returning to the center position automatically after a turn.
The repair was extensive: the entire steer axle had to be removed. The bent pivot pin was pressed out and replaced. The kingpin bushings were replaced, and the new pivot pin was greased thoroughly to prevent future seizure. After reassembly, the wheel alignment was checked and adjusted to a slight "toe-in" (0.5 mm) to account for the play in the steering linkage. The wander disappeared, and the new tires showed a normal wear pattern after one month of operation.
