A distance (D.sub.1) between a rotation center (O) of an input member (3) and a contact portion (P.sub.in) between an input side engaging portion (9) and an input side engaged portion (17) in a second direction is set to be shorter than a distance (D.sub.2) between a rotation center (O) of an output member (4) and a contact portion (P.sub.out) between an output side engaging portion (12) and an output side engaged portion (14) in the second direction in a state in which a pair of pressing surfaces (13) is pressed against a pressed surface (6) in accordance with a rotation of the output member (4) in a predetermined direction and the input side engaging portion (9) engages with the input side engaged portion (17) in accordance with a rotation of the input member (3) in a direction opposite to the predetermined direction. In a locked or semi-locked state, a contact portion (C.sub.1) between the output side engaging portion (12) and the output side engaged portion (14) is located on the side closer to the rotation center (O) of the output member (4) in a first direction in relation to a virtual line (L) connecting the rotation center (O) of the output member (4) and a contact portion (C.sub.2) between one pressing surface (13) of the pair of pressing surfaces (13) and the pressed surface (6).

The reverse input shutoff clutch includes: an input member, an output member coaxially arranged with the input member, a pressed member having a pressed surface, and an engaging element. The engaging element, when rotational torque is inputted to the input member, moves in a direction away from the pressed surface due to engagement with the input member and transmits the rotational torque to the output member, and when rotational torque is reversely inputted to the output member, moves in a direction toward the pressed surface due to engagement with the output member, and prevents or suppresses relative rotation between the output member and the pressed member.

There is provided an indicator system for a torque limiter. The system comprises a first component extending around an axis (A) and comprising one or more radially extending cam surfaces, and a second component in combination with a third component. The third component is fixed against rotation relative to the second component, but is axially movable relative to the second component. The third component comprises one or more notches, each receiving one of the radially extending cam surfaces. Upon relative rotation between the first component and the combination of the second component and the third component, a surface of each of the notches is configured to ride up a corresponding cam surface of the first component, causing the third component to move axially away from the second component.

There is provided an indicator system for a torque limiter. The system comprises a first component extending around an axis (A) and comprising one or more radially extending cam surfaces, and a second component in combination with a third component. The third component is fixed against rotation relative to the second component, but is axially movable relative to the second component. The third component comprises one or more notches, each receiving one of the radially extending cam surfaces. Upon relative rotation between the first component and the combination of the second component and the third component, a surface of each of the notches is configured to ride up a corresponding cam surface of the first component, causing the third component to move axially away from the second component.

An actuating device for a coupling/braking device is provided with at least one actuating piston that is axially slidable relative to a shaft and, in an actuating state, exerts an axially acting contact pressure on coupling/braking parts of the coupling/braking device. At least one control piston is provided that axially displaces the at least one actuating piston into the actuating position. A coating is provided in a contact region between the actuating piston and the control piston, wherein the coating is disposed at the actuating piston or at the control piston or at both the actuating piston and the control piston. The actuating piston can also be designed as a control piston that interacts immediately with the coupling/braking parts of the coupling/braking device.

An actuating device for a coupling/braking device is provided with at least one actuating piston that is axially slidable relative to a shaft and, in an actuating state, exerts an axially acting contact pressure on coupling/braking parts of the coupling/braking device. At least one control piston is provided that axially displaces the at least one actuating piston into the actuating position. A coating is provided in a contact region between the actuating piston and the control piston, wherein the coating is disposed at the actuating piston or at the control piston or at both the actuating piston and the control piston. The actuating piston can also be designed as a control piston that interacts immediately with the coupling/braking parts of the coupling/braking device.

In a predetermined first state, a distance (D.sub.1) in a second direction between a contact portion (P.sub.in) between a input-side engaging part (9) and an input-side engaging part (17) and a rotation center (O) is larger than a distance (D.sub.2) in the second direction between a contact portion (P.sub.out) between an output-side engaging part (12) and an output-side engaged part (14) and the rotation center (O). In a locked state or a semi-locked state, a contact portion (C.sub.1) between the output-side engaging part (12) and the output-side engaged part (14) is located closer to the rotation center (O) of the output member (4) in a first direction than an imaginary straight line (L) connecting a contact portion (C.sub.2) between one pressing surface (13) of the pair of pressing surfaces (13) and a pressed surface (6) to the rotation center (O) of the output member (4).

A reverse-input blocking clutch, comprising a pressed member, an input member, an output member, and an engaging element, the pressed member including a first pressed member element having a pressed surface around an inner peripheral surface thereof and a second pressed member element having a mounting portion fixed to a portion that does not rotate during use, the engaging element configured to transmit rotational torque input to the input member to the output member by moving in a direction away from the pressed surface and to completely block rotational torque reversely input to the output member or transmit a part of the rotational torque reversely input to the output member to the input member and block a remaining part thereof.

A rotary drive device includes a housing element, a drive shaft and a driven shaft, both rotatably mounted in the housing element, a transmission device that transmits torque from the drive shaft to the driven shaft, and a braking device configured to counteract rotation of the drive shaft. The braking device includes a drive shaft input element, a braking element connected to the housing element for conjoint rotation, and a coupling element adjustable with respect to the input element. A braking force exerted by the braking device is greater when the coupling element is located in a first position than when located in a second position, and the coupling element assigned to the driven shaft so that adjustment from the first position to the second position is triggered by exceeding a threshold value of the difference in torque between the drive shaft and the driven shaft.

A rotary drive device includes a housing element, a drive shaft and a driven shaft, both rotatably mounted in the housing element, a transmission device that transmits torque from the drive shaft to the driven shaft, and a braking device configured to counteract rotation of the drive shaft. The braking device includes a drive shaft input element, a braking element connected to the housing element for conjoint rotation, and a coupling element adjustable with respect to the input element. A braking force exerted by the braking device is greater when the coupling element is located in a first position than when located in a second position, and the coupling element assigned to the driven shaft so that adjustment from the first position to the second position is triggered by exceeding a threshold value of the difference in torque between the drive shaft and the driven shaft.