Center hole cylinders are available in both single and double acting styles. These cylinders are primarily used for pushing and pulling applications. Both styles have a center tube that allows a rod or cable to pass through the cylinder and assist in tensioning / pulling applications. Both single acting and double acting center-hole cylinders are constructed and operated in a similar manner to their standard counterparts. Single acting center-hole cylinders utilize a spring for retraction. This cylinder type requires a pump source with a 3 way valve for proper operation. Double acting center-hole cylinders are hydraulically extended and retracted.This cylinder type requires a pump source with a 4 way valve for proper operation.