Patent GB-190711825-A (GB)
Title: Improvements in Friction Controlling Apparatus
Inventor: PINARD CLAUDE
Filed: 1907-05-21
Granted: 1908-03-19
Abstract: 11,825. Pinard, C. May 23, 1906, [date applied for under Patents Act, 1901]. Self - sustaining gear; overwinding, preventing. - Comprises several forms of gear, in which the two parts of the frictional clutch or brake are normally maintained in engagement by a spring, or equivalent means, and can be disengaged, when required, by means of inclines or screws. The apparatus is stated to be applicable to hoists, to the actuating- levers of brakes, and as a safety device for preventing backward motion in machines generally. It is shown as applied to hoists in a double-acting form, and in a single. acting form; in one modification, the mechanism is operated by a hand-lever, through a pawl and ratchet, so that normal oscillations raise the load, and an oscillation beyond this releases the load. The application of a centrifugal governor is also shown, by means of which the speed of descent of the load, when released, is regulated. Fig. 1 shows a form which is selfsustaining in both directions of rotation. A stationary casing b, or its equivalent, in which are fixed ratchet rings j, j<1>, surrounds the driving-axle a. Mounted on the axle is a sleeve e longitudinally slidable along the shaf but revolving with the same. Between the sleeve e and the fixed casing b are inserted clutch or brake members d, f, g and d<1>, f<1>, g<1> of the multiple-disk or other type, and normally kept in engagement by springs h. Ports d, d' have oppositely-disposed ratchet connexions with the casing b through pawls engaging with the rings j, j<1>. On the shaft a is also mounted a sleeve c<1> capable of slight angular movement thereon ; this sleeve has a screw connexion with the sleeve e, so that, on the handle c being turned either way, an endlong movement of the sleeve e takes place, locking one of the clutching-members, through which the drive then takes effect, and freeing the other. When the handle is free and the load tends to run back, one or other of the brake members, in like manner, prevents the descent. Fig. 5 shows a modification applied to an apparatus for raising loads in one direction of rotation only. The rotation in this case may be effected either by the hand-wheel c<2> or by a lever n<3>. The hand-wheel, keyed to a shaft c<3>, engages a drum a<5> through the inclined surfaces k<2>, k<3>. A ratchet i<3> prevents rotation in one direction ; but rotation of tha hand-wheel in this direction, through the inclined surfaces, slightly releases the clutch, and the load is lowered at a rate determine by the movement of the hand-wheel. A lever m<5>, with inclined surfaces engaging similar surfaces on the fixed portion m<2>, is provided for completely releasing the brake and allowing the load to fall freely. The same effect can be produced by rotating the lever n<3> in the appropriate direction. Overwinding is prevented by means of the stop on the cable p engaging a fixed stop, and thereby bringing the hand-wheel to rest. In the modification shown in Fig. 6, the lever n<4> operates the winding-drum through a pawl-and-ratchet mechanism when moved through a limited distance, but acts to release the clutch or brake when the range is increased so that certain inclines on the boss of the lever and on the collar n<8> are brought into juxtaposition. In Fig. 8 is shown the application of centrifugal weights r<2>, for bringing the brake into action so as to limit the speed of descent.