A logistics warehouse reported that a Toyota 8FBEU15 reach truck (2-ton capacity) was making a "clunking" noise when raising the forks. The mast would "jump" or stick at around 3 meters height, then suddenly release and lift quickly.
The technician inspected the lift chains. The left chain was significantly tighter than the right. He also found that the chain rollers were wearing unevenly, with a lip forming on one side. He suspected a "Mast Alignment" issue.
He extended the mast and used a large carpenter's square to check the vertical alignment of the inner and outer rails. He found that the inner rail (stage 2) was tilted 5mm to the left compared to the outer rail. This misalignment was causing the chain sprocket to bind against the side plate.
He traced the root cause to the "Lift Cylinder Gland Nut." The gland nut secures the cylinder rod to the inner mast crossbar. The technician found that the gland nut on the left side was overtightened during a previous repair, pulling the cylinder rod slightly sideways. This bent the inner mast frame slightly.
The repair involved loosening the gland nuts to neutral, shimming the mast rail guides (wear strips) to re-align the rails vertically, and then re-torquing the gland nuts to the correct specification. The lift chains were re-tensioned to equal slack. The "clunking" noise disappeared, and the mast lifted smoothly and evenly. This case emphasizes that hydraulic and mechanical alignment must be checked together, not just the hydraulic pressure.
