GB748707A - Improvements in and relating to mine hoists and like winding gear - Google Patents

Abstract

748,707. Lift cages. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. May 19, 1954 [May 20, 1953], No. 14203/53. Class 78 (3). A mine hoist or like winding gear provided with keps has an electrical circuit for preventing starting of the winder to lower the cage with the keps in operative position which comprises interlocking switch means responsive to the position of the cage relative to the keps and operable by movement of the cage on to the keps. Keps 3 are pivoted at 4 to a mineshaft 2. The keps have a notch 5 and support a lever 7 pivoted at 8 to the keps. The lever has a roller 10 co-operating with the notch 105 and is pivoted to links 11, 12 connected to interlocking switch mechanism 13. The cage 1 has an abutment 6 in alignment with the roller 10 and notch 5 whereby when the cage is lowered the abutment 6 contacts the roller 10 to operate the switch 13. The switches 13R, 13L for right-hand and left-hand cages are in series with full-wave rectifiers 26, 27 shunted by operating coils OCTD1, OCTD2 of time delay relays TD1, TD2. Power is supplied by A.C. lines 24, 25. A winding motor M is connected to a Ward Leonard generator G driven by an induction motor IM supplied by a three-phase line 20. The motor has field winding MF energized by D.C. lines 21, 27. The generator has a field winding GF in series with a rheostat 23 and forward contacts FC1, FC2 of a controller for the winder in circuit with reverse contacts RC1, RC2 and normally open contacts of auxiliary relay AR which controls also the coil OCB of a mechanical brake for the drums. Relay AR has an operating coil DCAR which has limit switches LS1, LS2 and overwind switch OS. Contacts FC3, RC3 shunt relays TD1, TD2. With the right-hand cage on the keps contacts 13R are opened and relay OCTD1 de-energized the safety circuit is completed since contacts FC3 are closed. If the controller is operated for forward movement contacts FC3 open, coil OCAR is de-energized and contacts AR open, thus preventing movement of the cage onto the keps. It is necessary first to lift the cage before withdrawing the keps. Power is applied as for reverse wind the safety circuit is maintained through contacts FC3 and contact TD2. It is only necessary to release the brake if the load is tending to move the cage in that direction. When the cage is lowered onto the keps, the kep switch is operated and the time-delay relay opens after a short delay, sufficient for the drive to put the control lever to " off " and thus reclose contacts AR, thus maintaining the safety circuit. A circuit controlling a ram for ejecting tubs from the cage may be under the control of the kep switches. The lever 7 may have instead of the roller 10 a shoe.