|Dave S. said: (quoted from post at 11:00:22 08/18/13) Bought new lift cylinder & single groove piston, where does the backing washer go, (in front of o-ring on the oil pressure side, in back of o-ring away from oil pressure or underneath the o-ring)? Shouldn't the piston with o-ring installed fit tight in cylinder?|
The "backup" washer goes to the backside of the o-ring - e.g. the side away from the oil pressure. It supports the back of the o-ring and helps prevent o-ring extrusion. Extrusion occurs when the oil pressure deforms the o-ring into the gap between the cylinder wall and the edge of the o-ring groove in the piston damaging it - see image below. In a double acting cylinder you typically have backup rings on both sides of the o-ring since pressure is applied in both directions.
This post was edited by TheOldHokie at 08:29:39 08/18/13 3 times.