A concrete product factory reported that a Lonking FD35T (3.5-ton) diesel forklift had excessive play in the steering wheel-nearly 45 degrees of rotation before the wheels turned. There was also a "clunking" sound coming from the rear of the machine when changing direction from forward to reverse.
The technician inspected the "Steer Axle Assembly" (a steer-over-drive design common in heavy forklifts). He jacked up the rear of the truck and checked the wheel play. He found that the "Pivot Kingpin Bearings" (the bearings that allow the wheel hub to pivot) were dry and worn. The grease zerks were plugged with cement dust, preventing lubrication. This caused the "clunking" noise as the weight of the truck shifted on the worn bearings.
He then checked the "Steering Cylinder" (a double-acting cylinder that pushes the wheels left and right). The cylinder mount bolts were loose. The cylinder rod eye (bearing) had elongated holes. When the operator turned the wheel, the cylinder moved in its mount before pushing the wheel, causing the steering lag and freeplay.
The repair involved pressing out the old kingpin bearings and installing new heavy-duty tapered roller bearings. The steering cylinder mount was reinforced with larger diameter bolts and thread-locking compound. The cylinder rod eye was replaced with a new hardened steel bushing. The steering system was bled, and the steering wheel play was reduced to less than 5 degrees, restoring precise control.
