Patent GB-1058747-A (GB)
Title: A machine tool gear-box speed ratio change apparatus
IPC: F16H61/02
Filed: 1964-09-14
Abstract: 1,058,747. Change-speed control. ATELIERS G.S.P. (GUILLEMIN - SERGOT : PEGARD). Sept. 14, 1964 [Sept. 19. 1963], No. 37492/64. Heading F2D. 3 change speed control for a machine tool gear comprises a preselector valve DS between a pump P and differential stroke hydraulic servomotors PC2, PC3 which act on an axially slidable gear cluster 2 in opposition to a smaller section servomotor PC1 connected directly to the pump P, and an executive switch B5, closure of which de-energizes a main driving motor MP and energizes a secondary motor MPS which drives the gear at an inching speed through a clutch 4, 5 and drives the pump P supplying pressure liquid to the servomotors and after gear establishment the pressure liquid operates a pressure sensitive switch MC causing deenergization of the motor MPS and re-energization of the driving motor MP. The clutch 4, 5 may be electromagnetically operated, centrifugal or, as shown, operated by pressure liquid supplied by the pump P to a servomotor 3. A valve 13 prevents pressure liquid being supplied to the servomotors PC1, PC2, PC3 until the clutch 4, 5 is engaged. To start the machine the executive lever ML closes forward or reverse switch B1 or B2 to energize a relay C1 or C2 which closes a switch C11 or C21 to start the main motor MP in the forward or reverse direction and opens switch C12 or C22 to prevent energization of the other relay C2 or C1. To establish a ratio which has been preselected by movement of the valve DS, the lever ML is moved from the forward or reverse position to operate the switch B5 and returned to the forward or reverse position. Thus the switch B1 or B2 is opened to stop the main motor MP and thereafter closure of the switch B5 completes the circuit to a relay C5 which closes switches C51 to start the secondary motor MPS in a forward direction, closes a holding switch C53 and opens switches C54, C52 which prevent energization of relays C1, C2, C6. The motor MPS drives the pump P which supplies pressure liquid initially to engage the clutch and thereafter through the valve 13 to the ratio establishing servomotors PC1, PC2, PC3. After establishment of the new ratio the liquid pressure rises and closes the pressure-sensitive switch MC which completes the circuit to a relay R. The relay R opens a switch R13 to de-energize the relay C5 and stop the motor MPS. opens a switch R14 to prevent energization of the relays C1, C2, closes a switch R11 to energize a relay C6 which closes switches C61 to re-start the motor MPS in the opposite direction and thus de-pressurize the hydraulic circuit, and after a predetermined delay opens a switch R12 to de-energize the relays R1, C6, whereupon the motor MPS stops and the circuit to one of the relays C1, C2 is completed through the now closed switches C54, R14 and switch B1 or B2 to restart the motor MP. In Figs. 2 and 4 (not shown) a double acting clutch servomotor is connected to the pump P and a reservoir through a flow reversing valve which is spring-biased to normally supply pressure liquid to the clutch engaging side of the servomotor. After ratio establishment the liquid pressure increase overcomes the spring bias and changes the valve to supply pressure liquid to the clutch disengaging side of the servomotor. A cam on the valve spool operates a switch to stop the secondary motor.