Patent GB-968537-A (GB)
Title: Improvements in or relating to gear change mechanism
Inventor: NICKOLS IAN HAROLD
IPC: B23Q15/00
Filed: 1960-05-23
Abstract: 968,537. Change-speed control. IAN NICKOLS Ltd. July 20, 1961 [May 23,1960], No. 18081/60. Heading F2D. Gear change in a sliding gear-wheel type change-speed gear for the headstock of a lathe or like machine tool is effected by fluid pressure means under the control of an electric circuit such that the gearing is first moved to a neutral position and a brake applied to station the gearing, and then a gear-wheel is moved towards its position for meshing with another gear-wheel while at the same time the brake is released and torque applied to the gearing to facilitate meshing of the gears. As described, a three-position rotary speed selector, a fast/slow lever and a forward/brake/reverse lever are all actuated by pneumatic motors, controlled by solenoid-operated valves which are controlled in turn by the circuit shown in which energization of a relay coil moves the associated switches (which are given the same reference) from the positions shown to their alternative positions. Microswitches LM/S, HM/SA, MM/S, are associated with the gear change mechanism, and when a gear-wheel is fully in engagement the associated microswitch is moved from the position shown to its alternative position. Operation is controlled by eight push buttons or sockets labelled reverse, stop, forward, slow, fast, low, high and medium. Assuming that the gear is in the low position and the medium button is pressed: relay RM closes its switches so that relay R1 is energized. Current now passes to the slow solenoid SV3 and the forward solenoid SV2, and via switches MM/S, LM/S (which is in its alternative position) to the reverse solenoid SV1. Energization of both the forward and reverse solenoids moves the associated lever to its stop position, applying the brake to station the gearing. This causes the brake microswitches M/SA to be actuated energizing a self-latching relay R2 which energizes the medium gear solenoid SV5, and through the closed contacts U1 U, V1, V energizes the low gear solenoid SV6, causing the gear change motor to move towards its high position. As the gears shift, the microswitch LM/S is released, de-energizing the reverse solenoid SV1 and thus moving the forward/ reverse lever to forward, and the gears are moved into mesh, whereupon the microswitch HM/SA closes, thus energizing the reverse solenoid SV1 to bring the forward/reverse lever back to stop. A microswitch HIGH M/SB is closed with the switch HM/SA, so that when the brake switch M/SB closes, a relay R3 is energized, which opens the contacts U1, U and V1, V so that the solenoid SV6 is de-energized and the gear change motor is moved towards its medium position. Release of the microswitch HM/SA cuts off the reverse solenoid so that the forward/reverse lever moves to forward, and as soon as the gear teeth engage the switch MM/S closes, de-energizing the relay R1 and de-energizing the forward and reverse solenoids SV2, SV1. The medium button can now be released, and forward or reverse, fast or slow can be selected as required. If for some reason the gears refuse to engage an additional relay R5 is energized by the closing of a switch FOR M/S which is operated by the forward/ reverse lever at some position after the forward clutch has begun to pick up, this gives an intermittent engagement of the forward clutch until the gear engages.