A logistics warehouse reported that a Heli CPCD25 (2.5-ton) forklift's forks would "stick" (jam) when raising the mast between 2 and 3 meters height. The operator had to force the joystick to make it move, causing the hydraulic system to groan.
The technician inspected the mast rails. The bronze "Wear Strips" (shims) on the inner rail were dry and scored. He lubricated the rails, but the sticking persisted. He then examined the "Lift Cylinder Rods." The left cylinder rod had a visible "bluing" (heat discoloration) mark and a small bend (dent) near the middle of the stroke.
The bend was caused by a previous collision where the fork carriage hit a cross-beam. When the cylinder extended past the bent section, the rod rubbed against the cylinder gland bushing, creating friction. This friction was so high that it stalled the lift cylinder.
Additionally, the "Lift Chains" were not tensioned equally. The left chain was tight, and the right chain was loose. This imbalance pulled the inner mast frame sideways, exacerbating the binding on the bent rod.
The repair involved removing the left lift cylinder. The rod was straightened using a hydraulic press (if the bend was minor) or replaced (if major). In this case, the rod was replaced. The cylinder gland bushing and rod seals were also replaced. The chains were re-tensioned to equal slack, and the mast rails were greased. The mast then operated smoothly without sticking.
