A short-circuiting, brush-lifting device coupled within an asynchronous motor that includes a slip-ring rotor having a central axis and a plurality of slip rings, said short-circuiting, brush-lifting device comprising:
- a plurality of short-circuit contacts statically mounted to said slip rings of said slip-ring rotor;
- a short-circuiting ring having a central axis substantially coincident to the central axis of said slip-ring rotor, said short circuiting ring coupled around said slip-ring rotor and capable of movement in an axial direction, said short-circuiting ring capable of being electrically coupled to said short-circuit contacts;
- means for triggering an axial displacement of said short-circuiting ring into electrical contact with said short-circuit contacts, such that electrical contact between said short-circuit contacts and said short-circuiting ring causes said slip rings of said slip-ring rotor to become short-circuited;
- a rotatably supported actuating ring having a central axis substantially coincident to that of said slip-ring rotor, said actuating ring coupled around said slip-ring rotor and capable of rotational movement from a starting position to an operating position in a circumferential direction around the central axis of said actuating ring, said actuating ring also capable of movement in an axial direction from said starting position to said operating position;
- a plurality of brush-actuating guide rods, each being substantially equal in length and including a first articulated joint and a movable articulated joint, each brush-actuating guide rod coupled to said actuating ring via said first articulated joint;
- a plurality of brushes capable of being coupled to said slip rings of said slip-ring rotor;
- a plurality of holder studs coupled to said plurality of brushes;
- a plurality of levers coupled between said plurality of holder studs and the first articulated joints of said brush-actuating guide rods, such that movement of said brush-actuating guide rods is capable of causing said holder studs to rotate and said brushes to become lifted and disconnected from said slip rings when said slip rings have been short circuited, such that when said actuating ring is moved from said starting position to said operating position said short-circuit contacts electrically contact said short-circuiting ring and said brushes are disconnected from the slip rings of said slip-ring rotor;
- a plurality of axially aligned axial guide rods, each being substantially equal in length and each including a fixed articulated joint and a movable articulated joint, each movable articulated joint of said axial guide rods being coupled to and uniformly distributed over an outer circumferential surface of said actuating ring, said brush-actuating guide rods being aligned perpendicularly to said axial guide rods;
- a plurality of rollers, each having a radial axis and being uniformly distributed over an inner surface of said actuating ring, a surface area of each roller abutting against an end face of said short-circuiting ring that faces said slip rings on said slip-ring rotor in said starting position;
- a plurality of springs coupled to said short-circuiting ring, said springs urging said short-circuiting ring towards said rollers and said short-circuit contacts;
- such that the movable articulated joints of said brush-actuating guide rods are capable of being deflected to a first point of maximum excursion where the movable articulated joints of said brush-actuating guide rods are at a maximum distance from said actuating ring;
- such that the movable articulated joints of said axial guide rods are capable of being deflected to a second point of maximum excursion where said actuating ring is at a maximum displacement in an axial direction from said starting position;
- such that said brush-actuating guide rods and said axial guide rods are positioned such that the movable articulated joints of said brush-actuating guide rods are deflected through said first point of maximum excursion before the movable articulated joints of said axial guide rods are deflected through said second point of maximum excusion;
- and
- such that an axial displacement of said actuating ring in said operating position is larger in magnitude than a displacement between said short-circuit contacts and the end face of said short-circuiting ring in said starting position.