Dr. Pulley HiT clutch has stronger grip force, minimal slippage

Publish Date: 
Feb 18, 2008

DEALER EXPO, Indianapolis - Union Material Co., otherwise known as Dr. Pulley, is debuting at the 2008 Dealer Expo the HiT clutch, whose grip force comes from not only the centrifugal force of clutch weight, but from the power of the engine itself.

Using a compression mechanism, the HiT clutch has a stronger grip force with next to no slippage. Riders should also see an increase in transmission efficiency and throttle response, and an improvement in hillclimbing and overtaking scenarios.

The strength of grip force provided by the HiT is effected by the contact angle between the push pin and the contacting surface of pillow. A pillow with a higher angle can provide a stronger grip force that reduces or even eliminates clutch slippage, according to Paul Wu at Dr. Pulley.

When the rotating speed of the HiT clutch is high enough to make the centrifugal force of the clutch weight overcome the tension of the clutch spring, the clutch weight will centrifugally fly outward to touch the clutch bell to proceed with the initial slippery clutch-in. Friction resistance is produced between the clutch wear pad and the inner surface of the clutch bell during this stage. When the friction resistance is higher than the predetermined distortion strength of pillow spring, the pillow spring will be deformed or extended and the push pin will thrust into the pillow. This compresses the clutch weight so it grabs the clutch bell very tightly.

The design of the HiT clutch is "totally different from the conventional clutch," says Wu.