Patent GB-190719181-A (GB)
Title: Improved Safety Devices for Lifts and Hoisting Purposes.
Inventor: SCHWEDER KURT
Filed: 1907-08-26
Granted: 1908-02-06
Abstract: 19,181. Schweder, K. Aug. 26. Safety suspending-apparatus. - In safety devices for lifts and the like of the kind in which the breaking of the cable causes the application of pneumatically -controlled brake jaws to the shaft guides, mechanism is provided whereby the release of the brakes is prevented in the event of the broken cable catching on the shaft timbers. The invention also comprises means for preventing the action of the safety device during hoisting, and means for locking the cage if the gas pressure should fail. Fig. 2 is a sectional elevation, and Fig. 3 a plan of one form of the suspending and braking devices. The cage a is suspended by a bent rod b connected to a plate b<1> which compresses a spring against a fixed plate a<3>. A lever a<2> is pivotally mounted on the cage at a<3> and is connected by links to the plate b' and the valve e respectively. The valve e, which may be fitted with a small pilot valve also operated by the lever e<2>, is adapted to put a reservoir f of compressed air into communication with the brake cylinders g mounted in the frame a<2>, which is adapted to be drawn towards the frame a', thus causing the rails d' to contact with the guide beams d. The valve e also allows pressure gas to pass to a cylinder h arranged within the spring c so as to prevent the plate b<1> from rising in the event of the broken cable catching on the shaft timbers. The special cylinder h may be dispensed with by the arrangement shown in Figs. 7 and 8. A shaft i is mounted in bearings connected to the cylinders g and is rotated by the action of the pistons on curved lugs i<1> when the brakes are applied. The shaft i carries a lever i<2> connected to the hoisting-shackle, which is thus locked when the brakes are applied. The brake beam a<2> is pivotally connected to the pistonrods g<1>. In the modification shown in Fig. 12, toggle-levers k are used for transmitting the movement of the brake beams a', a<2> to the hoisting- shackle b. Figs. 13 and 14 show the mechanism for preventing the brakes from acting during raising of the cage. The lever e<2> is connected to the valve e, as before, and is also connected to a second valve o by means of the links m, m<1>. The outer end of the link m is connected by the rod n to a pair of levers l, l<1>, mounted on a pin l<4> on the cage and having their outer ends bent round and projecting through the slots l<3> in the guide-rail d' into proximity with the fixed guide d. The levers l, l<1> are connected respectively to a cylinder g<10> and a frame g<4> carried by a piston-rod g<11>, so that the ends of the levers are brought into engagement with the guide d when pressure gas is admitted to the cylinder through the pipe e<17>, which is connected to the valve e. The valves e, o are connected in series so that in order to admit gas to the brake cylinders g both valves must be open. During downward movement of the cage, the levers l, l<1> are in the position shown, so that both valves are opened by the lever e<2> in the event of the cable breaking. If, however, the lever e' is actuated during upward movement of the cage, the valve e is opened thus admitting gas only to the cylinder g<10>. The levers l, l<1> are pressed against the guide and the ends l<2> are swung into their lowest position, so that the valve o is lifted so far that it cannot be released by the downward movement of lever e<2>. Should the cage commence to fall, the valve o is immediately opened by the levers l, l<1> and rod n. Fig. 16 shows an arrangement for locking the cage if the gas pressure should fall below a certain minimum during the application of the brakes. The gas reservoir communicates with a cylinder in which is mounted a spring-controlled piston p. In the event of a fall of pressure, the spring moves the piston and admits pressure gas behind a piston s<1> connected to a wedge s<2>, or roller, adapted to lock against the guide. The brake cylinder pistons are packed by U- or L-shaped leathers or by means of membranes u, Fig. 22, which also act as stuffing- boxes for the rod g<1>. The pistons may be arranged so that they act directly on the guides, or, as shown in Fig. 26, the piston may be provided with vertical pins g<7> adapted to move in slots g<6> in the cylinder. The pins g<7> carry the cross-beam a', the other beam a<1> being fastened to the cylinder g. When rope guides are used, the guiding and gripping rails d<1> are replaced by jaws shaped to fit the rope.