• 1. The recommended shaft tolerance is h6 or h7.
• 2. Always use parallel keys and keep a clearance between the top of key and keyway. Use JIS B1301-1996 (new JIS) parallel keys (standard type).
• 3. When inserting the shaft, apply pressure only to the face of the inner race only. Never hit the outer race.
• 4. When using on a pitching machine, attach a balance weight to the arm shaft to balance it with the arm. Unbalance may cause large vibration loads.
• 5. Use rubber or other cushioning material at the fixed portion of the torque arm to absorb vibration loads.
• 6. Refer to the following for installation reference drawings and usage instructions.
• 7. For more information on lubrication and maintenance, click here.

Backstopping due to reciprocating shock loads

This is a backstopping use of repetitive momentary and shocking vibration loads, such as the reaction force of a spring. Typical examples are those used for tennis machines and pitching machines.

The sprocket (with bearings) which is constantly rotating due to the reduction motor has a claw on its side which comes into contact with the claw on the end face of the boss of the arm (keyed to the shaft) and pushes up the arm.

The spring, one end of which is attached to an eccentric plate (keyed to the shaft), is extended as the arm shaft rotates and suddenly contracts when it passes the top dead center. At this point, the arm throws the ball.

Even after the throw is complete, the arm will continue to rotate past the bottom dead center due to its own inertia, stretching the spring and reaching a certain angle (θ). During this time the cam clutch continues to overrun.

After rotating to θ degrees, the arm tries to suddenly reverse due to the contraction force of the spring, but the cam clutch engages to prevent this reversal.

The reversing torque that occurs at this time is an impactful vibration torque. This is the load characteristic of the backstop with repeated loading.

Points of Caution

Attach a balance weight to the arm shaft to maintain dynamic balance. If it remains unbalanced, excessive vibration will occur when the cam clutch engages. Please note the following points to minimize shock when reverse torque is applied.

• (1)Where the tip of the torque arm is fixed to the frame, insert a cushioning material such as rubber to absorb vibration loads.
• (2)The tip of the torque arm should be flexible and not completely fixed with bolts or other fasteners. If it is completely fixed, it may cause twisting inside the cam clutch and result in damage.
• (3)To always keep the clearance between the surface at the end of the torque arm that receives the reverse torque and the cushioning material to a minimum, apply a reverse moment to the torque arm using a weak spring or similar.