A Self-Actuating Traction-Drive Speed Reducer

Abstract

Traction-drive speed reducers offer certain advantages over geared speed reducers. In particular, they generally run quieter than geared units and provide an opportunity for higher efficiency by eliminating sliding motion between contacting elements. In order to generate a sufficiently high output torque, some means must be provided to create a normal force between the rolling elements. This normal force, along with the friction coefficient, enables the device to transmit torque from one rolling member to the next. The speed reducer proposed here is designed so that the configuration of the rolling elements creates the needed normal force in response to the torque exerted back on the system by the downstream loading. Thus the device is self-actuating. Since the normal force is only present when needed, the rolling elements of the device can readily be disengaged, thus eliminating the need for a separate clutch in the drive system. This feature can be exploited to design a transmission with several distinct speed ratios that can be engaged and disengaged in response to changing speed requirements.

Relative fatigue life estimation of cylindrical hollow rollers in general pure rolling contact

“…A good example of the traction drives using cylindrical roller bearings is the self-actuating traction drive designed by Flugrad and Qamhiyah. 2 This traction drive is used as a basis for this work. Even so, the results can be generalised for cylindrical rollers used in roller bearings and other traction drives.…”

Fatigue life investigation of solid and hollow rollers under pure normal loading

“…A good example of the traction drives using cylindrical rollers is the self-actuating traction drive designed by Flugrad and Qamhiyah. 2 …”

Highly efficient traction drive system with a normal force controller using a piezoelectric actuator

“…7 These systems have low efficiency because of the excessive normal force at low oil temperatures because their design is optimized for high oil temperature conditions. 8 Actuator-type adjusting methods include a system using hydraulic pressure, 9 but their efficiency is still low in principle because of losses caused by oil viscosity.…”