When a dumper truck bed slams down, it’s usually due to missed stages. This issue, known as Mis-Staging, occurs when the cylinder does not extend or retract in the correct sequences as described above. Here’s what dump truck Mis-Staging can look like with a 3-stage cylinder: the largest sleeve extends properly, but the plunger starts extending before the middle (or next larger) sleeve starts to extend. The middle sleeve finally breaks loose and shoots out, causing it and the plunger to collapse or drop back into the cylinder. This creates a loud banging noise as the dump truck cylinder slams down.