Patent GB-158867-A (GB)
Title: Improvements in or relating to brakes for hauling machines, lifts and similar hoisting apparatus
IPC: B66D5/26
Filed: 1920-11-22
Abstract: 158,867. Siemens-Schuckertwerke Ges. Feb. 11, 1920, [Convention date]. Electric plant. - In winding- gear adapted to raise a loaded cage or the like by a direct pull on the suspending-rope, or by a system of " tail-rope haulage " having two cages and loads partly balancing each other, the braking-power is varied by hand or automatically so as to secure the same retardation in each case. When the variation is automatic, it may be controlled by a signal which indicates that a change-over from one system of working to the other has been effected, or by the mechanism for clutching or unclutching the loose drum, when changing from the single-drum direct-haulage to the double-drum tail-rope haulage. The variation in the braking-power may be obtained in various ways, for example, by varying the air pressure in the case of pneumatic brakes, modifying the electric circuits of electric brakes, or mechanically, by bringing additional braking-meaus into action. When the variation is semi-automatic, various locking-devices may be used with the object of preventing easy use of the winding-gear with the wrong set of brakes in action. For example an additional brake, used for main-rope haulage, may be locked in the " on " position with the lock only releasable by the handgear for setting the brakes for tail-rope haulage, or the throw of a brake-operating lever may be limited by locking-means so that the full force of the brakes cannot be applied when the winding- apparatus is set for tail-rope haulage. Fig. 1 shows the invention applied to a winding-gear in which two equal coaxial drums I, I<1> are used for tail-rope haulage, while the drum 1<1> is held stationary by a brake 3 and the drum 1 used alone for main-rope haulage. The drum 1 is braked by a pair of blocks 2 which are applied during tailrope haulage by a pneumatic cylinder 5. The application of the brake 3 by the hand-wheel 4, to change over from tail-rope to main-rope haulage, also opens a valve 9 to bring an additional pneumatic cylinder 6 into action to increase the braking pressure on the drum 1. In the event of overwinding, the brake-blocks 2 are applied automatically by one falling weight 12 in the case of tail-rope haulage, and by both weights 12, 13 in the case of main-rope haulage. The weight 12 is released by the automatic opening of a limit switch 15 which de-energizes the magnet 17 and allows the armature to be lifted by the spring 17<1> to release the lock 18. The lifting of this armature also breaks the main circuit of the magnet 19 and releases the weight 13. In the case of tailrope winding, a supplementary circuit is closed by a switch 21, operated by the hand wheel 4, to prevent the release of the weight 13. Fig. 2 shows a modified arrangement in which, during tail-rope haulage, a link 22 actuates both pairs of brake-blocks 2, 3 in unison through the link 24. For main-rope haulage the hand wheel 4 is operated to put the brakes 3 hard on, to fix the drum 1<1>, the rods being provided with pin-andslot connections to enable this to be done without disturbing the link 24. This movement locks the link 24 by means of the bar 28. In consequence, the brakes for main-rope haulage cannot be applied until the rod 24 has been moved to a new position 29 which gives the necessary increased leverage for working under main-rope haulage. Reference is made also to the electrical control of motors to produce a braking effect in the event of overwinding, and to the introduction of a timefactor into the braking action to vary the intensity. The method suggested is the use of a liquid damping-device or dash-pot controlled by a valve to vary the rate of exit of the liquid from the dash-pot under the two systems of winding, and thus to vary the time taken by the motor switch arm to moving over the switch contacts.