US Patent 7472762 Top drive oil flow path seals

A top drive system including, in certain aspects, a motor, a gear system below, and driven by the motor, a space between the top drive motor and the gear system, a seal assembly for inhibiting oil for lubricating parts of the gear system from flowing into the space, the seal assembly having a movable rod piston, a sealing arm projecting from the rod piston, at least one removable seal secured to the sealing arm, a seal member releasably secured to the gear system, and the movable rod piston movable to move the sealing arm to bring the at least one removable seal into sealingly contact with the seal member to inhibit oil from flowing into the space.