Patent GB-696638-A (GB)
Title: Braking arrangement for a power vehicle with fluid flywheel and change speed gear
IPC: B60T11/10
Filed: 1949-12-30
Abstract: 696,638. Change-speed gear combinations. MAYBACH, K. Dec. 30, 1949 [Dec. 30, 1948], No. 33312/49. Class 80 (ii). [Also in Group XXXIV] In the transmission between an engine 1 and a vehicle change speed gearbox 20 in which there is interposed a fluid torque transmitter device 2, such as a fluid flywheel, it is arranged for the vehicle wheels to be coupled to the driving member 5 of the torque transmitter 2 in order to brake the vehicle. As shown in Fig. 1, this is done by extending the shaft 10, which forms the input to the gearbox 20, and coupling it by gears 18, 19 to the driving member of the transmission device 2. Friction clutches 11 and 12 are interposed in the drive on either side of the gear wheel 18 and a dog clutch is disposed on the driven side of the device 2. Normal mechanical drive takes place from the engine 1, by clutch 11, gears 18, 19 and shaft 10. Drive through the device 2 is from the engine 1 through clutch 12, device 2, dog clutch 13 and by gears 8, 9 to the shaft 10. If it is now required to brake the vehicle, clutch 13 is disengaged and clutch 11 engaged so that the drive is now from the wheels by shaft 10, gears 19, 18, clutch 11, shaft 3 and clutch 12 to the normal driving member 5. In Fig. 3, is shown an arrangement whereby the operation of the clutch coupling the engine to the transmission device 52 is made dependent on the position of the pedal 91 regulating the output from the fuel pump 50 so that the device 52 automatically becomes operative to brake the vehicle so long as the pedal 91 is in a position corresponding to an engine idling condition. Clutches 65, 66 and 65, 68 transmit the drive from the engine 1 through the fluid transmitter device 52 and the purely mechanical transmission to the output shaft 87 by gears 77, 78 and gears 75, 76 and shaft 80 respectively. The clutches 65, 66 or 65, 68 are alternatively engaged or disengaged according to the setting of valves in a regulating valve box 120. As shown in Fig. 3, the clutch 65, 66 is disengaged and the clutch 65, 68 engaged. If, however, the pedal 91 is allowed to move back to the position shown dotted, which corresponds to the engine idling condition, the movement of a slide valve 96 coupled thereto acts to exhaust pressure from the right hand side of piston 117 in through pipe 106 and port 100 to atmosphere and supplies pressure from pipe 111, through groove 101 and pipe 105 to the left of piston 117 which is thus moved to the right and engages the clutch 65, 66. The transmission is now set so that braking is obtained by drive from the vehicle wheels through shaft 80, gears 76, 78, clutch 65, 68 and clutch 66, 71 to the driving part 53 of the fluid torque transmitter, the free wheel coupling 81, 82 disengaging gears 77, 78. The clutch 65, 68 which determines whether the normal engine drive shall be purely mechanical or by fluid transmisson is also engaged or disengaged by a fluid pressure actuated piston 118 according to the position of the pedal 91. The regulating housing 120 controlling the operation of the piston and cylinder 108, 118, may include an automatic switching apparatus such as that described in Specification 696,637. A further modified fluid pressure control system is also described.