Tham khảo tài liệu 'advanced vehicle technology episode 1 part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Fig. Laycock double epicycle overdrive large planet gear absorbs the driving torque reaction and in the process is made to revolve around the braked sun gear. The overdrive condition is created by the large planet gears being forced to roll walk about the sun gear while at the same time revolving on their own axes. As a result the small planet gears also revolving on the same carrier pins as the large planet gears drive forward the annular ring gear at a faster speed relative to that of the input. The overall gear ratio step up is achieved by having two stages of meshing gear teeth one between the large pinion and sun gear and the other between the small pinion and annulus ring gear. By using this compound epicyclic gear train a 92 relatively large step up gear ratio can be obtained for a given diameter of annulus ring gear compared to a single stage epicyclic gear train. Direct drive Fig. Direct drive is attained by releasing the double-sided cone clutch member from the stationary conical brake and shifting it over so that it contacts and engages the conical frictional surface of the annulus ring gear. The power flow from the input shaft and planet carrier now divides into two paths the small planet gear to annulus ring gear route and the large planet gear sun gear and double-sided clutch member route again finishing up at the annulus ring gear. With such a closed loop power flow arrangement where the gears cannot revolve independently to each other the gears jam so that the whole gear train combination rotates as one about the input to output shaft axes. It thereby provides a straight through direct drive. It should be observed that the action of the unidirectional roller clutch is similar to that described for the single stage epicyclic overdrive. Clutch operating Fig. Engagement of direct drive and overdrive is achieved in a similar manner to that explained under single stage epicyclic overdrive unit. Direct drive is provided by four powerful .
