ELASTISCHES ZAHNRAD

A silk hat flexible engagement gear device (1) has first and second end plates (2 and 3) and an input shaft (4) is rotatably supported, with their ends supported, between the two end plates. A cylindrical body part (61) of a silk hat flexible external gear (6) is disposed on the outer circumference of the input shaft (4). A cross roller bearing (8) which also functions as a device housing and a rigid internal gear (5) are provided on the outer circumference. An annular boss (64) of the flexible external gear is held between the outer ring (81) of the cross roller bearing and the second end plate (3) and these three members are coupled with each other with second fixing bolts (9). The rigid internal gear (5) is held between the inner ring (82) of the cross roller bearing and the first end plate (2) and these three members are coupled with each other with first fixing bolts (11). An additional member which is used as a device housing is not necessary. The members are temporarily fixed and fastened and, further, attached to a housing on the motor side or on the load side with the fixing bolts (9 and 11) only. Therefore, the number of components of the device can be reduced and the size of the device can be reduced.