The present invention relates to a brake, which has a fixed seat, a friction brake shoe, a braking part, a braking spring, an acting block, and a driving block. The acting block is connected with a driving member and matched on an acting face of the driving block. The driving block is connected with the braking part. The braking spring has a first end connected with a driven member and a second end connected to the braking part. The braking part is articulated on the driven member by a support pin. The braking part can be engaged with the friction brake shoe or disengaged from the friction brake shoe, and connected with a driven member. In a normal operation or still state, the brake is capable of braking or releasing braking without additional power.
CROSS REFERENCE
This application is a division of U.S. application Ser. No. 08/765,994 filed Apr. 14, 1997, which was the U.S. National stage of International Application No. PCT/CN95/00055 filed Jun. 30, 1995, now issued as U.S. Pat. No. 6,374,963 on Apr. 23, 2002.
Priority Data
Jul 02, 1994 [CN] 94111061 A Jun 28, 1995 [CN] 95106603 A
A shaft coupling unit is disclosed, which comprises a coupling disk (1), a disk (2), a spring (3), a concave member (4), a convex member (5) and a draw lever (14). The concave member (4) is press fitted against the convex member to rotate circumferentially and to move axially with respect to one another. The concave member (4) is axially press fitted against the disk (2) to rotate circumferentially with respect to one another. An external coupling member (6) is disposed between the concave member (4) and a transmission member (7). The external coupling member (6) is radially press fitted against the concave member (4) to axially slide each other. The convex member (5) is mounted on the coupling disk (1). The spring (3joined to the disk (2) at an end, and joined to the draw lever (14) at the other end. The draw lever (14) is linked up with t coupling member (1) through the disk (2). The coupling disk (1) is mounted on an external transmission shaft (8), or at the latter through a shaft joining member (9) so as to form the shaft coupling unit of the invention for coupling the transmission member (7) with the external transmission shaft (8).
