Patent GB-1105416-A (GB)
Title: Improvements in means for controlling hydraulically-operated clutches for conveying rotary motion
IPC: F16D48/02
Filed: 1965-08-16
Abstract: 1,105,416. Change-speed and clutch control. ERWIN HENGSTLER, [trading as E. HENGSTLER]. 16 Aug., 1965 [11 Sept., 1964], No. 34955/65. Headings F2D and F2L. A clutch control includes a pressure-increase valve whereby the fluid pressure in a clutch gradually increases to avoid sudden application. A body 2 includes the pressure-increase valve 4 and control valve spools 3, 59; when spool 59 is not in neutral, pressure fluid from pump 20 enters chamber 13 via groove 62 or 73, the spool 3 being biased by spring 24 to the shown neutral position. With spool 3 in position I or II lands 8, 9, 10 direct fluid to chambers 12 or 14 connected to conduits 44, 49. Fluid from chamber 13 also passes via passage 16 to throttle 27 and to bore 34 to act on pistons 26, 29 against spring 31, the working area 39 of piston 26 is four times the working area 40 of piston 29. In operation, when pressure in passage 16 reaches e.g. 3 atmospheres, the piston 29 is forced back to connect passage 16 to vent passage 35 to prevent further pressure rise. At the same time, pressure fluid acts via throttle 27 on piston 26 which after a certain time rises to re-inforce the action of spring 31 and cause a corresponding pressure increase in passage 16, chambers 13 and 12 or 14, until at e.g. 8 atmospheres the piston engages the end of its cylinder and prevents the uncovering of passage 35, the pressure rising further until safety valve 59a in pump 20 opens. The gradual rise in pressure acts via chamber 12 or 14 and conduit 44, 49 in clutch 54 or 53 for a gradual application. The clutches 53, 54 drive gear 57 and shaft 58, respectively, from shaft 46, a shaft 69 being driven from gear 57 or gears 66, 67, 72 on shaft 58, a gear 70 splined to shaft 69 being movable by rod 61 and including a fret-wheel device 71. The rod 61 has grooves 64, 74 and extends into a device 60. In an agricultural tractor gear 70 has three positions S, A, R corresponding to road operation, field operation and reverse. With gear 70 in field position A as shown.- Valve spools 3, 59 are moved to position I and pump output passes via groove 62 to chambers 13, 14 and passages 16, 17; the pressure increase from valve 4 acts via conduit 49, groove 50 and passage 51 in shaft 46 to gradually engage clutch 53 to drive gear 57 and shaft 69. At the same time, the fluid passes via conduit 61, device 60, conduit 65, groove 47 and passage 48 in shaft 46 to gradually apply clutch 54 to drive gear 66, the device 71 preventing jamming of the gears. With spools 3, 59 in position N the spool 59 blocks flow from pump 20, clutch 53 is released by fluid escaping past lands 8, 9, 10 of spool 3 and clutch 54 is maintained engaged with fluid from pump 20 passing via passage 63 and device 60. Movement of spools 3 and 59 to position II connects chamber 13 to pump 20 via groove 73 and clutch 54 is maintained engaged via conduit 63. Movement of the spools to position III leaves chamber 13 connected to pump 20 but the fluid vents via chamber 14 and the lower end of spool 3 so clutches 53, 54, deliver no torque but a power take-off shaft, not shown, could be driven whilst the tractor is stationary. With gear 70 in position S for road work rod 61 blocks conduit 63 and connects conduits 44, 65. In position I, the clutch 53 is gradually applied as before; in position N the flow from pump 20 is blocked and neither clutch is engaged; in position II clutch 54 is gradually engaged via passage 15 and conduits 44, 65. With gear 70 in position R for reverse, the clutch 53 is gradually engaged as in position I above. A spring-pressed ball holds spool 3 in each position. In Fig. 1, not shown, the pump is connected directly to chamber 13 with spool 59 omitted as is the gear mechanism 66-71; clutch 54 is engaged in position I of spool 3 and clutch 53 engaged in position II.