Patent GB-1362424-A (GB)
Title: Transmission
IPC: F16H63/30
Filed: 1971-08-11
Abstract: 1362424 Friction clutches; change-speed gear; full-face disc brakes BORG WARNER CORP 11 Aug 1971 [27 Aug 1970] 37788/71 Headings F2C F2D and F2E In an automatic change speed gear a clutch 21 is actuated by a servomotor comprising a chamber 82 housing a piston 80 and a smaller chamber 83 housing a piston 81 which can engage the larger piston 80, and a brake 25 can be actuated by a similar servomotor having a larger piston 100 and a smaller piston 111 (see Fig. 2), the smaller piston of each servomotor being actuated except when reverse gear is selected, when the larger pistons are also actuated so that the clutch and brake can cope with greater torque.  Clutches.-The clutch 21 is actuated by fluid supplied through passages 93 and 94 to the larger and smaller chambers 82 and 83 respectively, the larger piston 80 being urged by a spring 90 to the clutch disengaged position and, when actuated (either directly by fluid from port 93 or by pressure from piston 81) engaging clutch plates 74 and 76 to couple the input shaft 12 via drum 79 of clutch 20 to a sleeve 34 on which the sun gears 36 of the planetary gear 27 are formed. Included in each of the pistons 80 and 81 in a ball valve (98 and 99 respectively), these ball valves being closed by pressure applied to the chambers but opened (by centrifugal force) when the clutch is disengaged to relieve the pressure.  Brakes.-The transmission includes multiplate brakes 23, 24 and 25 as well as one way brakes 60 and 62. The brake 25, which brakes the planet carrier 38 of the planetary gear 27, is actuated via an annular thrust transmitting member 103 against which the larger piston 100 of the servomotor 58 abuts. This piston 100 is actuated by fluid under pressure supplied through a passage 117, a smaller annular piston 111 being actuated by fluid under pressure supplied through passage 118, so that an increased actuating force is obtained when fluid is supplied through both passages to that when fluid is supplied through passage 117 alone. A spring 105 serves to disengage the brake. Change-speed gear.-This comprises the planeary gear 27, having a sun gear 36 mounted on a sleeve 34 attached to the drum 71 of clutch 21 and to the drum of clutch 20 (and so to the input shaft 12) when clutch 21 is actuated. Brake 24 can be used to hold sun gear 36 stationary. The planet carriers 38 and 40 respectively have planetary pinions 39 and 42 respectively which mesh with ring gears 44 and 31 respectively. In first gear the clutch 20 is engaged to connect shaft 30 with the input shaft 12, thereby driving ring gear 31 in the forward direction, the planet carrier 40, connected to the output shaft 13, providing the output, one-way brake 60 holding the planet carrier 38. Engagement of brake 25 bridges the brake 60 and establishes two way drive, this being manually controlled. Second gear is provided by clutch 20 remaining engaged and brake 24 being applied to hold sun gears 36 stationary, one-way brake 62 here being optionally bridged by brake 23. Direct drive is established by engaging both of clutches 20 and 21, and reverse by applying clutch 21 and brake 25, the planet carrier 38 being held stationary to allow ring gear 44 to run in the reverse direction. In reverse the actuators for clutch 21 and brake 25 are actuated so that these are engaged as firmly as possible, fluid being supplied to both chambers of each.