| 摘要 |
1469783 Change-speed control CATERPILLAR TRACTOR CO 11 June 1974 [13 June 1973] 25903/74 Heading F2D Means to limit to one, two or more ratiosteps through which a manual selector lever 28 can be pivoted, with a support 34, during ratio selection, comprises a fixed quadrant 36 with locking notches 38 corresponding to the respective ratio settings (sixteen forward, neutral and two reverse) into which the lever 28 is laterally spring loaded about a transverse pivot 32 on the support 34, which latter, 34, carries, for relative pivotal movement about the same selecting axis as that of the lever, a second quadrant 43, having notches 47 corresponding to those 38 of the fixed quadrant, which receive a pin 48 on the lever 28 when the latter is pivoted laterally out of locking engagement with the fixed quadrant 36 prior to making a selector movement, the pin 48 then taking the second quadrant 43 along with the lever 28 in its selecting movement until restricted in either direction by stops 53, 54, whereupon the lever is released to return, under spring load laterally into locking engagement with the fixed quadrant 36, releasing the pin 48 from the second quadrant 43, which is then returned by a centralizing spring 52 back to a central position ready for limiting the next selection. Two springs bias the shift lever 28 laterally into engagement with the fixed quadrant 36, one, 41, a light spring, the other, 42, heavier, which latter must be overcome before the shift lever can be moved over a quadrant stop 39 into the two reverse settings. To override the ratio step limit, the lever 28 can be raised, against springs 74, to lift the pin 48 out of engagement with the second quadrant 43. As shown the stops 53, 54 limit each shift to two ratios steps, and to reduce the limit to a single step between ratios thirteen to sixteen, the fixed housing carries an inwardly-spring- loaded plunger 63, Figs. 3 and 5, which is thrust outwardly into a slot 68 in the quadrant 43, limiting movement of the latter to one step, by a plunger 64 thurst upwardly by a cam plate 69 which pivots with the shift lever 28 in its selecting movement and is effective in ratios thirteen to sixteen. Alternative override means, Figs. 6 to 8, not shown, comprise a retractable telescopic sleeve or rod in the lever 28, or a rod which is depressed by a push button to free the pin 48 from downwardly directed quadrant notches. The gear, Fig. 1, not shown, comprises two countershaft gears in series, the first giving four ratios and reverse, the second four ratios. A main clutch and brake are provided at both the input and output ends of the gear, and shift selection is pneumatic. |
