Hydraulic Cylinder End Cap History

[Chris Zavatson]

Older hydraulic cylinders used a thin steel washer as an end-cap to hold the shaft seal in place. When the cylinder is extended and under pressure this washer wants to bow outward. This has two impacts. First, the washer can be permanently deformed. Secondly, this deformation forms a slight ramp encouraging the snap ring to retract out of its groove. A handful of cylinders have disassembled themselves in use.

Below is a slide with a photo of a nose gear cylinder where the snap ring is on its way out. You can make out the witness mark around the perimeter showing how much of the snap ring used to be engaged in the snap ring groove.

Later cylinders used a machine end cap. This machine unit is much stiffer to eliminate the bowing. More importantly, it traps the snap ring once installed. The end-cap needs to be pushed into the cylinder slightly in order to install/remove the snap ring. In operation, the snap ring is physically trapped.

Many cylinders in the field have already been updated. If you need any, I still have end caps available at $15ea.