AGMA 10FTM17

In most of the gear drives, when the driving torque is suddenlyreduced as a result of power off, torsional vibration, power outageor any mechanical failure at the transmission input side, thengears will be rotating either in the same direction driven by thesystem inertia, or in the opposite direction driven by theresistant output load due to gravity, spring load, etc. The lattercondition is known as backdriving. During inertial motion orbackdriving, the driven output shaft (load) becomes the driving oneand the driving input shaft (load) becomes the driven one. Thereare many gear drive applications where the output shaft driving isless desirable. In order to prevent it, different types of brake orclutch devices are used. However, there are also solutions in geartransmission that prevent inertial motion or backdriving usingself-locking gears without any additional devices. The most commonone is a worm gear with a low lead angle. In self-locking wormgears, torque applied from the load side (worm gear) is blocked,i.e. cannot drive the worm. However, their application comes withsome limitations: the crossed axis shafts’ arrangement, relativelyhigh gear ratio, low speed, low gear mesh efficiency, increasedheat generation, etc. The paper describes the design approach aswell as potential applications of the parallel axis self-lockinggears. These gears, unlike the worm gears don’t have suchapplication limitations. They can utilize any gear ratio from 1:1and higher. They can be external, internal, or incorporated intothe planetary gear stage or multistage gear system. Their gear meshefficiency is significantly higher than the worm gears and closerto conventional gears. As a result they generate less heat. Theself-locking can be designed to prevent either the inertia driving,or backdriving, or both. The paper explains the principle of theself-locking process for gears with symmetric and asymmetric teethprofile, and shows their suitability for different applications. Itdefines the main parameters of gear geometry and operatingconditions. It also describes potential self-locking gearapplications and references to related publications.

Edition:

10

Published:

10/01/2010

Number of Pages:

8

File Size:

1 file , 350 KB