A logistics warehouse reported that a Toyota 8FBEU20 reach truck made a "popping" noise when extending the mast, and the forks would tilt sideways at heights above 8 meters.
The technician inspected the "Lift Cylinders" (located on the sides of the mast). He found that the "Cylinder Anchor Pins" (the pivot pins at the bottom of the cylinders) were not seated evenly. One pin was sticking out 5mm more than the other. This misalignment caused the left cylinder to push the inner mast frame at a slightly different angle than the right cylinder.
He also checked the "Mast Roller Clearance." The inner mast frame was twisted. When extended, the left roller had a 3mm gap to the rail, while the right roller was grinding against the rail. The "popping" noise was the right roller jumping over a wear groove on the rail.
The twist was caused by the "Chain Anchor Bolts" being loose. The lift chains are anchored to the mast frame with high-strength bolts. If one side is loose, the chain tension pulls the frame sideways.
The repair involved re-aligning the inner mast frame using a laser level. The cylinder anchor pins were re-seated and welded in place. The chain anchor bolts were tightened to specification. The worn mast rollers were replaced. The result was a smooth, vertical extension without binding or popping noises.
