Patent GB-877114-A (GB)
Title: Change gear system
Filed: 1959-01-06
Abstract: 877,114. Change-speed control. EATON MANUFACTURING CO. Jan. 6, 1959 [Feb. 10, 1958], No. 536/59. Class 80 (2). The input and output shafts of a change-speed gear drive a signalling unit having blocking means to prevent the transmission of a shift signal until the gears next to be engaged approach synchronism. Gearing.-A five-speed and reverse gear-box 1 driven from a main clutch 3 and having a countershaft brake 27 has sliding positive clutches 18, 19 and gears 12, 13 controlled by pneumatically actuated shift rods 33, 34, 35. The rods 33, 34, 35 carry collars 37, 38, 39 which, in conjunction with a stop 52 and plates 50, 51 under the action of a cylinder 57 and piston 56 enforce neutral when pressure is applied to line 253. The input 4 and output 8 shafts are connected to a shaft 92 and a gear sleeve 126 of a signalling unit 91. Signalling unit.-The shaft 92 carries gears 93 ... 97 selectively clutchable to the shaft, under the action of shift rods 101, 103, to provide with gears 113 ... 117 the same ratios between shafts 92 and 112 as may be obtained between shafts 4 and 8 of the main gear 1. The sleeve 126 drivingly carries two gears 127, 128 meshing with gears 131, 132, free on shaft 112, which latter gears are driven slightly faster and slightly slower than the shaft 112. The gears 131, 132 have axially extending splined tongues which co-operate with a sliding sleeve 119, splined to shaft 112, to form a baulking dog blocking mechanism allowing axial movement of sleeve 119 for half distance only when synchronous speeds for upshift is approached, and for whole distance when synchronous speed for downshift is approached. The sleeve 118 is urged axially towards the blocker mechanism 133 by pressure in line 222 acting on a signalling valve 123 and is urged in the opposite direction by a spring 120. Selector valve.-A manual selector lever 361 rotates, by Bowden cable 359, a cylindrical valve core 63 having internal passages 346, 347 connected respectively to liner 223, 203. The passage 346 is selectively connectible with ports 82, 75 ... 71, 76 controlling the supply of air for the engagement of neutral, 5th, 4th, 3rd, 2nd, 1st and Reverse ratios respectively, and the passage 347 is simultaneously respectively connected with a blank, parts 77 ... 81 and a blank for the corresponding engagement of the appropriate gears of the signalling unit 91. The lever 361 carries a knob 364 actuating an impulse valve for initiating a change in ratio after selection by lever 361 by supplying a pressure pulse to clutch relay valve 226 and neutral cylinder relay valve 234. A hand trip valve 372 is provided for obtaining reverse since no reverse synchronism signal can be fed from the unit 91. Operation.-With the selector valve 61 turned to the neutral position, pressure air from a source 202 reaches passage 347 by line 203 but does not continue to any of the signalling unit shift rod pistons 104, 106 ... 109. Pressure will also flow to neutral valve 58, passage 346, 82 and 246 to neutral relay cylinder 234. Spring 55 between the plates 50, 51 urges the neutral cylinder casing and valve 58 to the right causing exhaust of liner 218 and 222 ensuring the signal valve 123 moves to the left under action of spring 120. Pressure is also exhausted from clutch cylinder 28 through 230 and clutch relay valve 226, thus engaging the clutch 3. Movement of the lever 361 to 1st gear position rotates the selector valve 63 to connect passage 347 with port 81 and passage 346 with port 71. This applies pressure to the signalling unit first gear cylinder 108 to engage gear 97 with shaft 92, and on operation of the pulse control 364, which moves valves 226, 234 rightwardly, applies pressure to the first gear shift cylinder 44. At the same time air from 201 passes through 216, 249, valve 234, 252 and 253 to neutral cylinder 57, it also passes to line 251, clutch valve 226 and line 230 to disengage the clutch 3. Since the neutral cylinder is larger than the cylinder 44 the gear remains in neutral and the neutral valve 58 is opened to allow air to flow by line 222 to the left end of the signal valve 123 which it urges rightwardly until blocked by the mechanism 133. In this position the valve 123 connects line 222 to brake cylinder 28 to retard the countershaft. As it is unlikely that synchronism will be reached to allow the mechanism 133 to unblock, the manual valve 372 is opened to pressurize the right end of the neutral relay 234 to exhaust the neutral cylinder 57 and allow pressure in cylinder 44 to engage 1st gear. Movement of the shift rod 33 rightwardly causes movement of the plate 50 to move the neutral valve 58 to exhaust lines 218, 223 but a check valve 224 prevents exhaust of line 210. Since the gears have been engaged, subsequent movement of the signalling valve will not interfere with the completed shift. Shifts from one gear to another are attained in a similar manner, but unblocking of the mechanism 133 on the approach of synchronism allows corresponding rightward movement of the signalling valve 123 to complete the change, without the use of the manual valve 372, at the correct synchronizing speeds of the main gears. Provision may be made for manual control of the clutch 3 in addition to the pneumatic control if desired. Specifications 851,996 and 854,031 are referred to.