Abstract: Apparatus for controlling the torque delivered to pipe connections by power tongs by utilizing the reaction torque to cause a proportional fluid by-pass to be bled from the drive motor fluid power supply to slow the motor as torque increases, and to stop the motor at some preselected torque quantity. The torque is maintained as long as the operator provides fluid power to the motor circuit to overcome brief torque resistances due to such as pipe wobble.

Abstract: A hydraulically driven mower having a mower deck with conduit means in contact with the deck for flowing hydraulic fluid which powers hydraulic motors for driving cutting blade means positioned below the mower deck so that air flow created by the cutting blade means will provide heat transfer from the hydraulic fluid in the fluid conduit means through the deck member to provide cooling of the hydraulic fluid and a hydraulic drive system having a pressure relief means to direct hydraulic fluid supplied to a first hydraulic motor in series to the next hydraulic motor in series when the first hydraulic motor overloads to maintain sufficient hydraulic power to the second motor.

Abstract: A mower mounting apparatus for mounting an offset mower to a vehicle having a plurality of parallel links pivotally mounted about first pivot axis to maintain the mower at the same inclination upon pivoting of the links to raise and lower the motor and pivotally mounted about second pivot axis lying in vertical planes for horizontal swinging movements of the links to allow rearward non-rotational translation of the mower when the mower strikes an obstacle.

Abstract: A hydraulic impact device has a hammer member carrying a piston which is reciprocally disposed in a cylinder chamber to form an expansible chamber. When the expansible chamber is pressurized, the hammer is retracted against an air spring or other energy storage device by the high pressure. A sleeve valve is reciprocally disposed in the cylinder chamber between the piston and the energy storage device and is held against the piston by an imbalanced fluid pressure as the hammer is retracted against the spring. When the piston and sleeve valve have been retracted to a predetermined position, high pressure fluid is ported between the sleeve valve and piston to hydraulically separate the two members.