Patent GB-1442206-A (GB)
Title: Tooth meshing
IPC: B66C13/22
Filed: 1973-06-02
Abstract: 1442206 Change-speed control; toothed gearing CLARKE CHAPMAN Ltd 3 June 1974 [2 June 1973] 26426/73 Headings F2D and F2Q [Also in Division H2] Means for facilitating mesh of pairs of toothed gears, establishing ratios in a two-speed remotecontrolled winch drive on a ship, comprises an electric motor, drivingly coupled to one of the gears and energized alternately in one and another mode by uni-directional current to oscillate the gear about its axis of rotation during its movement into mesh with the other gear, the amplitude of oscillation of the motor being less than one revolution. The motor may be A.C. or D.C., and in each case is energized by rectified current from an A.C. source for the oscillations. For an A.C. motor, Figs. 1 and 2, threephase winding terminals 30, 32, 34 of the motor, which drives the winch-barrel through the change-speed gear, are supplied with current in alternating different pairs to produce the oscillatory movement, the winch-barrel being braked during shift. Current is supplied by a nominally 12-volt transformer winding 10, rectified at 12, and energizing the phase terminals 30, 32, 34 through contacts 36, 38, 40, closed by energizing respective contactors C, X, Y in a circuit fed at a rectified 110 volts at 50, 52 by another winding of the transformer. Shift sequence, following disconnecting the main supply to the winch-drive motor and braking the winch, is initiated by closing a respective upshift or downshift switch 56, 58, which energizes an electrically driven screw thrust device for de-meshing the off-going gear and shifting the on-going gear towards mesh, at the same time feeding the contactor bus-bar 54, which energizes the contactor C, closing contacts 36 to energize the motor phase 30 continuously throughout the sequence. In the initial state shown, the contactor Y is also energized to close contacts 40, connecting together motor phases 30, 34 for a first mode of operation. At the same time energization of the contacts Y closes contacts Y1, which, after a time delay, set by a resistor 60 and capacitor 62, energizes a relay AR, closing contacts AR1 energizing the contactor X, which closes motor contacts 38, so that, for a transition state, all the motor phases 30, 32, 34 are connected together. Energization of the contactor X de-energizes Y at X1, leaving only motor contacts 36, 38 closed, thereby connecting together phases 30, 32 for a second mode of operation of the motor. The deenergization of the contactor Y opens contacts Yl, producing a delayed de-energization of the relay AR, which opens the contacts AR1 for a transition in which both X and Y are de-energized and no current is supplied to either motor phase 38, 40. The opening of contacts AR1, following the opening of Y1, restors the circuit to its initial condition and the four-stage sequence then repeats. If a restraining torque is applied to the motor by inability of the gear to mesh, an oscillating torque is thus applied to it and the connected shift gear, which continues until the contactor circuit is broken by a limit switch on completion of gear engagement. A resistor 18 is provided for varying the oscillatory torque. The transformer may supply shift control for additional winches, as well as slewing and lifting controls of cranes. In an equivalent D.C. motor control, Figs. 3 and 4, not shown, the contactors control reversing contacts (100 ... 106) in the armature circuit of a shunt wound, compound or series motor.