Caterpillar Tractor Co.

John E Corwin

Jan B Yates

Jimmy D Myers

Noble G Barker

An improved hydraulic actuator for use as a swing motor in a material handling apparatus of the type having a vehicle mounted boom. Two embodiments are disclosed and each includes a vertically disposed, double-acting cylinder having an internal, vertically reciprocal piston. The cylinder may be disposed between yoke arms mounting a boom and provision is made for securing the cylinder to the vehicle frame. A coupling device is secured to one of the yoke arms and has a first splined surface while means are carried by the piston and movable therewith and include a second splined surface slidably engaging the first splined surface. The piston also carries a third splined surface which is in engagement with a fourth splined surface carried by either the cylinder or a part of the vehicle frame and at least one of the splined surfaces has a helical pitch so that reciprocation of the piston will cause rotation of the coupling device to thereby effect rotation of the yoke to swing a boom attached thereto about a generally vertical axis.

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Portland, IN, United States of America

John E Corwin