Patent GB-1050283-A (GB)
Abstract: 1,050,283. Change-speed gear and control. BORG-WARNER CORPORATION. April 17, 1964, No. 16086/64. Heading F2D. In a fluid pressure control system for a change-speed gear in trucks or tractors, wherein shift in forward drive is effected automatically by shift valves responsive to vehicle speed and engine load (manifold depression or accelerator position), a hold valve 150, the position of which is controlled by a manual selector valve 349 having a hold, " H," position, is effective to prevent shift irrespective of the forward ' ratio established. Function summary.-The gear provides three forward speeds and one reverse, and includes an hydraulic retarder 17 for hill braking in any forward gear, the hold condition being automatically established when the retarder is applied, a power take-off gear 38 operative whether or not the vehicle is driven, and a rear pump 26 for push starting. An " Inhibited Low " condition (see below), and means preventing Reverse establishment during forward vehicle movement are provided. A modification (described below) provides six forward speeds and one reverse and includes an alternative power take-off position. Gear arrangement.-A planetary gear 10 in series behind a torque converter 15 of the overrun reactor type comprises front and rear planets 47, 53 arranged on a common carrier 54 on the gear output shaft 12 and respectively meshing a sun 46 and a ring 45 and a sun 52 and a ring 51. The ring 45 and the sun 52 are connected together and may be friction clutched at 22 to the turbine shaft 13; the sun 46 may be friction braked at 21 or friction clutched at 23 to the turbine shaft 13; and the ring 51 may be stationed by a sprag-type one-way detent 25 or by a friction brake at 24. In Low, the clutch 22 is engaged for drive through the rear planets 53, the ring 51 reacting on the one-way detent 25 or being braked at 24. In Intermediate, the clutch 22 and the brake 21 are engaged for drive through the front planets 47, the one-way detent overrunning. In High, both clutches 22, 23 are engaged for direct solid 1/1 drive. In Reverse, the clutch 23 and the brake 24 are engaged for compound drive through both trains. Hydraulic retarder.-For hill braking in any forward gear kinetic energy is absorbed by filling the fixed cavity 40 of the hydraulic retarder 17 which comprises vanes 41, 42 respectively attached to the turbine shaft 13 and mounted within the fixed cavity. Power take-off.-The power take-off gear 38 is slidable into engagement with a gear 36 meshing a gear 35 on the turbine shaft 13 for take-off whether or not the planetary gear 10 is driving. Friction clutches and brakes.-The clutches 22, 23 and the brake 21 are multi-disc clutches actuated respectively by a servomotor 78 through a Belleville washer lever 76 functioning as a return spring, directly by a spring-returned servomotor 85, and by a servomotor 65 the flexible wall 66 of which carries a presser plate 64 and functions as a return spring. The brake 24 is a band brake actuated by a servomotor 87. Fluid supply system.-A front pump 20 supplies a pressure main line 165 through a line 166, a retarder apply valve 136, a line 167, a cooler 122, a line 160 and a filter 121 which, if blocked, may be by-passed by a check valve 133. For push-starting, the rear pump 26 supplies the line 165 through a check valve 134. Fluid system components also include a primary regulator valve 131 exhausting to the converter; a secondary (converter) regulator valve 132 exhausting to a transmission lubricating line 164 and, through a check valve 135, to sump; retarder apply and manual valves 136, 137; a retard valve 138; the manual selector valve 139 providing Park, Reverse, Neutral, Drive, Hold and Inhibited Low (P, R, N, D, H, L); a throttle valve 140 controlled by manifold depression or by accelerator pedal position and providing engine load or throttle variable (" TV ") pressure in a line 185; a modulator valve 142 supplying TV pressure limited to a maximum (Modulator pressure) in a line 187; a centrifugal governor valve 27 (Fig. 7, not shown) mounted on the output shaft 12 and supplying output speed responsive pressure (Governor pressure) in a line 200; a compensator valve 143 subjected to opposed Modulator and Governor pressures and supplying Compensator pressure in a line 188 to act on the primary regulator valve 131 so as to increase clutch engaging pressure for initially setting the vehicle in motion; 1-2 and 2-3 shift valves 147, 148 responsive to Governor. spring, TV and main line differential pressures; reverse, rear brake, front brake and rear clutch apply valves 145, 149, 151, 152; rear brake, rear clutch and front brake gate valves 153, 154, 155; a low range valve 144; a reverse inhibitor valve 146; and a " throttle control " valve 141 which, when able, supplies a constant " Inhibited Throttle " pressure which is less than line pressure. Operation.-In Drive, " D," the manual selector valve 139 connects line 165 pressure, through line 180, to the servomotor 78, whereby the clutch 22 is engaged, for Low, and remains engaged for all forward drive conditions, to the valve 145 to prevent shifting into Reverse, and to the valves 149, 151, 152 where it is blocked; through the line 182 to the valve 141 to move it into a port blocking condition; through the line 180, valve 150, line 204, valve 148, line 203, valve 147 and line 201 to the valve 149 to shift the latter and admit line pressure in 180 through line 190, valve 155 and line 208 to hold the valve 151 blocking, line 190, valve 154 and line 209 to hold the valve 152 blocking, and line 190 to valve 144 where it is blocked, line pressure having been admitted to shift the valve 144 through line 181, valve 138 and line 193. When Governor pressure predominates, the 1-2 shift valve 147 upshifts to admit line pressure in 203 through line 202 to shift the valve 151 and admit line pressure in 180 through line 207 to the servomotor 65 to engage the brake 21 for Intermediate, the one-way detent 25 overrunning. Line pressure in 207 is also admitted through valve 153 and line 206 to return shift the valve 149, the line 201 being exhausted, to exhaust the line 190, and, through the valve 154 and line 209, to hold the valve 152. When Governor pressure further predominates, the 2-3 shift valve 148 upshifts to admit line pressure in 204 through line 205 to shift the valve 152 and admit line pressure in 180 through line 195, valve 145 and line 196 to the servomotor 85 of the clutch 23. Although the lines 203, 202 are exhausted, the valve 151 remains shifted due to Modulator and line pressure applied thereto until line pressure 195 through valve 155 and line 208 acts to overcome these pressures and return shift the valve 151 to exhaust the servomotor 65 of the brake 21, the delay in disengagement of the latter providing a controlled overlap. The line pressure in 195 is also applied through the valve 153 and line 206 to the valve 149 to hold the latter. 3-2 and 2-1 downshifts are produced in the reverse manner to that described above. With the manual selector valve 139 set to Inhibited Low, " L", upshift from Low is prevented, 3-2 and 2-1 downshifts occur only below predetermined vehicle speeds, and an upshift subsequent to a 3-2 or 2-1 downshift is prevented. In " L," line pressure in 165 is connected through the line 180 for forward Low as previously described, but lines 181, 182 are exhausted. Exhausting the line 181 allows the return shift of valve 144 so that line pressure in 190 is connected through line 189, valve 145 and line 197 to the servomotor 87 to engage the brake 24. Exhausting the line 182 allows the valve 141 to supply " Inhibited Throttle " pressure through the line 186, valve 144, and lines 191, 192 to lock valves 147 and 148 in their downshifted positions. If the valves 147, 148 are already upshifted the line 192 is blocked and pressure in line 191 acts against Governor pressure to produce downshifts at predetermined speeds. Once either of the valves 147, 148 downshifts, pressure in line 192 is effective to retain it downshifted. In Hold, " H", the manual selector valve 139 connects main line pressure to lines 180, 182. Since pressure in the line 193 is exhausted through the valve 138 and the line 181 and since pressure is connected to a line 194, through the line 182 and the valve 138, the valve 150 is shifted whereby the connection between the line 180 and the shift valves 147, 148 is cut off so that shift to any other ratio is prevented, and the connection between the lines 188 and 161 is cut off so that Compensator pressure is prevented from acting on the primary regulator valve 131 which then supplies maximum line pressure for maximum torque transmission. Retarder.-When the retarder is applied for any forward condition the hold condition is automatically established. Shifting the retarder manual valve 137 connects the line 160 to the retarder 17 through a line 170. The outflow from the filled retarder, in line 171, then shifts the valve 136 so that flow from line 166 is redirected through line 170, retarder 17, line 171, valve 136, line 167, cooler 122 and line 160 to cool the retarder heated fluid before it is supplied to the remaining control system elements. Pressure in line 170 also shifts the valve 138 thereby exhausting line 193 and connecting line pressure in 165 to the line 194 so that the hold valve 150 shifts. In Reverse, " R", the manual selector valve 139 connects main line pressure through a line 183 to the valve 145 where it is initially blocked and to the valve 146, where, if no Governor pressure is present in line 200, it acts to hold the valve 146 open and is directed through line 198 to the shift valve 145 and allow 183 pressure to pass through lines 196 and 197 to the servomotors 85 and 87 for respective engagement of the clutch 23 and the brake 24. If the vehicle is moving forwardly, Governor pressure in line 200 closes the valve 146 to pre