Disc Brake for a Hoist, Combining a Positive Brake and a Negative Brake

A hybrid brake for a hoist, intended to cooperate with a disc of the hoist extending in a plane orthogonal to an axial direction, the hybrid brake comprising:

• two plates (2, 3) extending parallel to the disc on both sides thereof, the two plates forming a clamp operable between an open-brake position where the plates are at a distance from the disc and a closed-brake position where the plates clamp the disc, each plate (2, 3) provided with one or more friction pads (7)
• a rigid body (4, 5) comprising an upper tubular part (4), called upper half-caliper, located on one side of the disc, one of the plates (2), called upper plate, being carried by a shoe (6) mounted to slide in the axial direction in a central through recess (40) in the upper half-caliper,
• a stack of spring washers (10) arranged in the central recess (40) of the upper half-caliper about a central axis (X100) parallel to the axial direction, the stack of spring washers (10) being configured to be compressible beyond a level, called emergency braking compression, wherein said stack exerts a force on the shoe (6) corresponding to a desired emergency clamping force on the disc,
• a negative actuator (8), comprising a negative piston (80) driven by a first power source, which negative piston has a face (83) whereupon a lower end of the stack of spring washers (10) rests, the negative piston (80) being mounted so as to slide in the axial direction in the central recess (40) of the upper half-caliper between an upper, open-brake position where the negative piston (80) compresses the stack of spring washers (10) beyond the emergency braking compression, and a lower, closed-brake position, where the brake is closed and where the negative piston (80) holds the stack of spring washers (10) at the emergency braking compression on one side and bears directly or indirectly on the shoe (6) on the other side, the negative piston being placed in its upper open-brake position when the first power source is activated and in its lower closed-brake position when said first power source is inactive, the negative piston (80) comprising an upper cylindrical cavity (82) receiving a lower part of the stack of spring washers (10), the negative piston further comprising a lower end (85) configured to bear directly or indirectly on the shoe (6) when the negative piston is in the lower closed-brake position,
• a positive actuator (9) comprising a positive piston (90) driven by a second power source, the positive piston being axially slidable between an upper open-brake position where the brake is open and a lower closed-brake position where the brake is closed, the positive piston being in its upper open-brake position when the second power source is inactive and being movable to its lower closed-brake position when the second power source is activated, the positive piston (90) comprising a shaft (904) extending along the central axis (X100) through the stack of spring washers (10), which shaft has a lower end configured to mate with the shoe (6) and an upper end which projects from the upper half-caliper (4) regardless of the position of the positive piston.
• the hybrid brake being characterized in that it comprises a positive piston return spring (98), configured to return the positive piston (90) to its upper open-brake position and in that the brake comprises a wear compensation device (13) between the stack of spring washers (10) and the shoe (6) to compensate for friction pad wear.

A hoist, comprising:

• a disc extending in a plane orthogonal to an axial direction;
• and,
• a hybrid brake comprising:
• two plates (2, 3) extending parallel to the disc on both sides thereof, the two plates forming a clamp operable between an open-brake position where the plates are at a distance from the disc and a closed-brake position where the plates clamp the disc,
• a rigid body (4, 5) comprising an upper tubular part (4), called upper half-caliper, located on one side of the disc, one of the plates (2), called upper plate, being carried by a shoe (6) mounted to slide in the axial direction in a central through recess (40) in the upper half-caliper,
• a stack of spring washers (10) arranged in the central recess (40) of the upper half-caliper about a central axis (X100) parallel to the axial direction, the stack of spring washers (10) being configured to be compressible beyond a level, called emergency braking compression, wherein said stack exerts a force on the shoe (6) corresponding to a desired emergency clamping force on the disc,
• a negative actuator (8), comprising a negative piston (80) driven by a first power source, which negative piston has a face (83) whereupon a lower end of the stack of spring washers (10) rests, the negative piston (80) being mounted so as to slide in the axial direction in the central recess (40) of the upper half-caliper between an upper, open-brake position where the negative piston (80) compresses the stack of spring washers (10) beyond the emergency braking compression, and a lower, closed-brake position, where the brake is closed and where the negative piston (80) holds the stack of spring washers (10) at the emergency braking compression on one side and bears directly or indirectly on the shoe (6) on the other side, the negative piston being placed in its upper open-brake position when the first power source is activated and in its lower closed-brake position when said first power source is inactive,
• a positive actuator (9) comprising a positive piston (90) driven by a second power source, the positive piston being axially slidable between an upper open-brake position where the brake is open and a lower closed-brake position where the brake is closed, the positive piston being in its upper open-brake position when the second power source is inactive and being movable to its lower closed-brake position when the second power source is activated,
• the hybrid brake being characterized in that it comprises a positive piston return spring (98), configured to return the positive piston (90) to its upper open-brake position.