This Curtis alloy steel double pin-and-block universal joint with bored hubs is designed to connect two rotating shafts at angles up to 70 degrees in applications requiring higher torque transmission than needle bearing joints. This universal joint compensates for both parallel and angular misalignments, and its double joint configuration provides two points of flexion to help minimize speed fluctuations and torsional vibration during operation. The hubs, center block, and pins are made of alloy steel for strength, wear resistance, and machinability. Each hub end is ground on center and bored to one-half of the outer diameter, and fits onto shafts without the need for machining. The joints are permanently assembled with a small bearing pin that is riveted in place. Joints with an outer diameter size of 7/8-inch and larger can be taken apart and reassembled without special tools (TakeApart feature) in order to replace worn parts or custom machine the hubs. The large bearing pin in the assembly includes a lubrication passage for distributing lubricant in the joint's moving parts. Joints with an outer diameter of 1 to 4 inches also include a ball-spring oil fitting that helps retain lubricant. A lock ring (Tell-Tale Lock Ring) provides positive lock-up of the entire assembly. This Curtis steel double universal joint meets military specification MIL-U-20625A, Class A, and is used in a variety of military, commercial, industrial, and medical applications including conveyor equipment, clean room robotics, and hospital equipment.

Universal joints (also called U-joints, universal couplings, Cardan joints, Hooke’s joints, or Hardy-Spicer joints) are used to transmit motion and rotational power, or torque, between two shafts that are offset at an angle. Most universal joints consist of two yokes and a middle assembly; the hub end of each yoke attaches to a shaft while the yoke ears attach to and pivot around the middle assembly to accommodate shaft misalignment. The type of middle assembly determines its usage—pin and block joints are suitable for transmitting high torque, needle bearing joints are used to handle high rotational speeds, and ball and socket joints are used in applications requiring low backlash (play between moving parts). The body of the universal joint may include a single joint to accommodate only angular misalignments between shafts, or two joints to accommodate both angular and parallel misalignments. Available in a variety of materials and configurations, universal joints are used in applications including motor vehicles, conveyors, medical and optical devices, forestry and mining equipment, robotics and space exploration, and aeronautics, among others.

Curtis Universal Joint Company manufactures universal joints and assemblies for military, commercial, industrial, and medical applications. The company, founded in 1935, is headquartered in Springfield, MA.