Patent GB-1101943-A (GB)
Title: Change-speed power transmission mechanisms
Inventor: STUART DUNCAN JAMES KEITH
IPC: B23Q5/14
Filed: 1964-06-24
Abstract: 1,101,943. Change-speed control; valves. EDWARD WILLIAMS HOLDINGS Ltd. 23 June, 1965 [24 June, 1964], No. 26075/64. Headings F2D, and F2V. A preselector change-speed gear for a lathe providing twelve forward and twelve reverse ratios has a selector valve 76 operable only when servo pressure is not supplied to it, servo pressure being supplied under the control of a valve 89 operated by pilot pressure supplied by a pump 100 to a vane type hydraulic motor 98 which is connected by step-up gearing and a one-way clutch 97 (Fig. 3) to the change-speed gear input shaft 30, the one-way clutch 97 permitting drive from the hydraulic motor 98 to the shaft, but the shaft in normal operation being driven faster from an input pulley 24 than it would be by the motor so that the pilot pressure is low. On operation of a control for gear establishment, a clutch 25 between the input pulley 24 and the input shaft 30 is disengaged and a brake 28 is applied to retard the shaft 30 so that the hydraulic motor 98 is also retarded and the pilot pressure rises until the valve 89 is actuated and servo pressure is supplied to the selector valve to effect ratio shift. On the completion of shift the servo pressure rises and actuates a switch 120 controlling a solenoid valve 101 which alters the connections to the clutch and brake servos so that they can now be controlled by a manual valve 103 which in a central position lightly engages both the clutch 25 and brake 28 and on displacement to one side or the other increases engagement of one and reduces engagement of the other. Gearing.-Input shaft 30 has a gear cluster 31 slidably splined thereon with gears 32-34 selectively meshable with gears 35-37 fast on a layshaft 38. A shaft 39 equidistant from shafts 30, 38 has a shift sleeve 40 splined thereto and formed with a gear 41 meshable with the gear 32 and with clutch splines 42 engageable with clutch teeth of a loose gear 44 which meshes a gear 45 fast on the shaft 38. The shaft 39 can thus be driven at six ratios, and a sleeve 46 is splined thereto and has gears 47, 48 meshable with a gear 49 and with a reversing gear 51. The sleeve 46 can also assume a central neutral position. The gear 49 is fast with a gear 53 which meshes the reverse gear 51 and which is engageable with clutch teeth 57 of a sleeve 56 splined to a shaft 50. The shaft 50 is formed with an output gear 54 driving the lathe spindle. The reverse gear 51 is fast with a gear 61 meshing a gear 59 which can be clutched to the shaft 50 by the sleeve 56 to provide a further reduction ratio. Control circuit elements.-The shift sleeves 56, 40 are controlled by simple double-acting pistons 62, 64, and the sleeves 31, 46 by pistons 63, 65 which can assume a mid position defined by a stop piston 65e. Servo liquid is supplied to the pistons 62-64 by the selector valve 76 and to the piston 65 by first and second solenoid valves 87, 88. The selector valve 76 has a rotary valve plate 78 (Fig. 2) with bores selectively alignable with ports 81a-81g in a stationary plate and is formed with a recess 78b connected to drain. Servo pressure when supplied through a line 79 to the valve enters a chamber 77a and presses the valve plate 78 on to the stationary plate and thus prevents adjustment of the valve plate. The circuit also includes a servo pressure pump 102, a pilot pressure operated valve 90, the solenoid valve 101, a servo pressure operated valve 104, and the manual clutch-brake control valve 103. The valve 103 (Fig. 8) has a shaped needle 131 co-operating with four restrictions 124a between a central inlet port 128, ports 129, 130 on either side leading, through the valves 101, 104 to the brake 28 and clutch 25, and drain ports 126, 127. In the central position of the needle 131 all the restrictions 124a are equally open, by moving the needle to one side or the other the supply to the clutch or brake is increased and to the other is reduced so that the workpiece may be rotated slowly or the clutch or brake be fully engaged. Operation.-On starting, the pumps 100, 102 are driven and the valves 87-90, 101, 104 are in the positions shown so that the clutch 25 is disengaged, and the brake 28 is applied by servo liquid supplied through the valve 104, a line 91 and valves 89, 101. The input shaft 30 and the hydraulic motor 98 are thus stationed so that pilot pressure builds up in a line 93 until the valves 89, 90 are actuated, whereupon the valve 89 supplies servo pressure from the line 91 to the line 79 whence the selector valve 76 distributes it to the gear selector-sleeve servos to effect ratio shift as preselected. Servo pressure is supplied through the valves 87, 88 to either side of the pistons 65, 65e to shift the sleeve 46 to its neutral position, and pressure is also supplied from the line 91 through valves 90, 89, 101 to the brake 28 which remains applied. On completion of shift the servo pressure in line 79 rises and closes the pressure actuated switch 120 which actuates the valve 101. Servo pressure is now supplied through the valve 101 to actuate the valve 104 through which servo pressure is now supplied to the inlet port 128 of the clutch-brake selector valve 103, and the clutch and brake can now be controlled by this valve. For forward drive a switch 118 is actuated which energizes a relay controlling the valve 87 and de-energizes a relay controlling the valve 101. The valves 101, 104 are thus returned to the positions shown so that the brake 28 is applied and the hydraulic motor 98 is decelerated and pilot pressure builds up until the valve 89 is actuated. Servo pressure is then supplied through the valve 88 to shift the piston 65 to the left to give forward drive, and is supplied through the selector valve 76 to effect any necessary gear shifts. During shift the brake 28 is disengaged (since the valve 90 has not been actuated) so that the motor 98 can drive the input shaft 30 slowly to prevent gear or clutch tooth abutment during shift. On completion of shift the pressure actuated switch 120 closes and the actuation is as before. For reverse drive both valves 87, 88 are actuated.