The 80 degree constant velocity universal joint.

The 80| Constant Velocity Universal Joint

THE HIGH-ANGLE constant velocity universal joint with a center slider has been shown in patents as early as 1903, has been applied in European agricultural machinery since the 1960s, and in this country since the 1980s.

Investigation of current 80| CV joints indicated a need to improve the lubrication system and reduce ball stud breakage; our objective was to solve these problems, increase the joint's life, and design a guarding system to fit within the ASAE minimum size tractor shield.

To obtain surface contact and subsequent long wear life, a ball and socket design was chosen, with the ball supported in the yoke by the socket, which is an integral part of the yoke forging.

A large amount of material supports the ball socket to resist high radial loads imposed by telescoping thrust forces and secondary couples that pass through the centering mechanism. The center cardan is two forgings welded together. The wear surfaces between the center cardan and the center slider are hardened and ground, with carefully balanced wear rates of the center slider surface and the mating center housing to durability.

Constant output velocity is achieved by dividing the yoke-to-center-cardan angles precisely through the center slider and balls. When one yoke is moved in an angular direction, that movement causes the center slider to move in a radial direction. The center slider pivots about the other ball and forces the center cardan into an equal angle.

Division of angles is very accurate because all controlling surfaces are hardened and ground, and experience very little wear over the life of the CV joint.

Lubrication system

A unique lubrication system is used for the ball and socket.

It begins will a grease passage drilled on the centerline of the yoke intersecting the bushing cup bore. Next, an extra ring groove is machined into the bushing bore of the yoke, allowing the grease to pass around the bushing cup.

The second passage, is drilled radially on the centerline of the socket, which permits the grease to pass from the ring groove into the rear portion of the socket.

The center slider has a hole drilled through the pins, enabling grease to pass to both sockets.

Weasler has constructed the socket to prevent grease from passing backward through the passages if the zerk fitting is removed.

The grease passages are drilled such that a centrifugal check value is created to prevent grease from backing out, but allowing lubricating through a readily accessible hole in the guard when the CV joint is attached to the tractor pto shaft.

Two annular cavities in the center cardan forging hold up to one-half pound of grease. On the center slider are grooves that travel back and forth across the cavity during operation, carrying grease across the wear surfaces when the joint is angled, providing relubrication every time the CV joint is moved through an angle.

Guard construction

Guards for the new joint were designed to let the user install the CV joints on a tractor without removing the tractor master shield.

The guard is a two-piece articulated construction. The bell journaled to the rear yoke of the double cardan universal joint is spherical.

For geometrical clearances, the centerline of the sphere is displaced from the centerline of the rear cross kit. The guard extension is journaled on the spherical surface on the center cardan and has a spherical inside diameter that mates with the sphere on the rear shield.

This shield-within-a-shield provides minimal lateral movement when the CV joint is angled to 80| and remains within the confines of the minimum size pto master shield permitted by ASAE standard 203.10.

Photo: Cutaway shows some of the primary internal features of the new Weasler 80| CV joint.