Patent GB-619423-A (GB)
Title: Improvements in variable speed power transmission
IPC: B60K17/06
Filed: 1946-12-09
Abstract: 619,423. Change-speed gear. FORD MOTOR CO., Ltd. Dec. 9, 1946, No. 36355. Convention date, Dec. 22, 1945. [Class 80 (ii)] [Also in Group XXXIV] A three speed and reverse planetary gearing in which changes of ratio are produced automatically by two governor-controlled clutches has a manual forward and reverse control comprising two toothed members moving into and out of engagement with teeth on a planet carrier and a clutch carrier selectively. The gearing is similar to that described in Specification 615,175 in which a drive from an engine shaft 13 passes through a fluid coupling 16, a main shaft 14 and planetary gears 29, 26, 27, 31 to a driven shaft 15 for low speed, the planet carrier 23 of the gear train being held from backward rotation bv a oneway clutch 32, the stationary member of which is held by a positive brake 33. For reverse drive the brake 33 is released and a similar brake 43 is engaged to hold a clutch carrier 21 which causes the sun gear 28 to become the reaction member of the train, and the torque from the main shaft 14 is reversed in direction as applied to the driven shaft 15. The positive brakes 33, 43 comprise yokes 51, 65 pivoted on the base of the gear casing 12 and having teeth 56 engageable with corresponding teeth 57 on the members 32 or 21. The yokes are coupled by a link 77 so that pivoting movement imparted from a hollow spindle 62 through a spring detent held plate 61 to a shifting fork 59 integral with the yoke 51, causes respective engagement and disengagement of the gear teeth. The hollow spindle 62 is operated from a control on the stearing column of the vehicle through a lever 64, having a cam plate 157, and a linkage system 60. An anticreep friction brake band 96 encircles a drum 93 rigid with the clutch carrier 21, one end 98 of the band being located on a horizontal wall 101 of the gear casing 12 and the other end connected through a bell crank lever 104 with an engine suction operated diaphragm 109. The diaphragm chamber 111 in the valve body 107 is in communication through a bore 149 with an arcuate recess 137 in a rotatable disc valve 128, the recess 137 being in communication with a passage 125 when the valve is in the extreme anticlockwise position and the end 138 of the recess 137 overlaps the sector shaped recess 127. The passage 125 leads to a valve having a stem 117 normally urged off its seating 116 by a spring 118 to allow engine suction to pass from an inlet 114 to the passage 125. Under all conditions when the driven shaft is rotating, the valve 117 is held shut by the oil pressure from the gear actuating pump 38, led through a connection 122 to a bellows 124 so that the brake cannot be applied when the vehicle is moving at more than very slow speeds. To prevent the application of the anti-drag brake with engine speeds greater than idling the valve disc is operated by a linkwork from the accelerator pedal, and the length of the recess 137 and the positioning of the two sectorshaped ports 127, 144, which latter is open to the atmosphere, is such that only approximately 4 degrees of valve motion is available for applying the brake, this motion corresponding to the normal backlash in the throttle control mechanism. Having regard to the positive brakes 33, 43, the anti-drag brake is released during movement of the lever 64 by the cam 157 which co-operates with a lever having a lost motion connection with the valve 128, this arrangement momentarily releases the brake during the shift from neutral to forward and maintains the brake released when the the reverse is engaged.