GB1165993A - Improvements in Gear Shift Mechanisms for Change-Speed Gear Boxes - Google Patents

Abstract

1,165,993. Change speed control. ROBERT BOSCH G.m.b.H. 24 Jan., 1967 [25 Jan., 1966], No. 3520/67. Heading F2D. In a gear-shift mechanism, particularly for motor vehicles, wherein a cross-shifting cam and a gear-establishing cam are simultaneously rotated by an electric motor, the cross-shifting cam extends substantially in the form of a helix or spiral each convolution of which corresponds to one gearestablishing element, and the gear-establishing cam has a continuous contour extending 360 degrees. In Fig. 1, the cross-shifting and gear-establishing cams comprise grooves 15, 21 respectively in the periphery and an end face of a cylinder 14 which is driven by a reversible electric motor 13 through reduction gearing in a casing 12. The groove 15 comprises three circumferential portions 16 (reverse), 17 (1-2), 18 (3-4) connected by helical portions 19, 20. The groove 15 is engaged by a pin 26 extending through a slot in a bearing block 24 from a rod 27 longitudinally displaceable in said block. The groove 21 is substantially oval and is engaged by a roller 22 carried by an arm 23 mounted on a hollow shaft 25 rotatably mounted in the block 24. A fork 28 carried by the rod 27 and extending through slots in the block 24 and the hollow shaft 25 engages an annular groove 29 in an actuating rod 30 so as to transmit longitudinal movements thereto. Pivotal movements of the hollow shaft 25 are transmitted to the rod 30 by a cross-pin 31 extending through the latter and engaging longitudinal slots 32 in the hollow shaft. The rod 30 is connected to a gear-box actuating rod moving in accordance with an H - shape with one side branch to provide four forward ratios and one reverse. The two helical groove portions 19, 20 effect axial cross-shifting movement of the rod 30 when the arm 23 is midway of its gear-establishing movement, i.e. in Neutral. In Fig. 3, the ends of the cross-pin 31 selectively engage axially extending grooves 53, 54, 55 in hubs 50, 51, 52 of pivotal arms 46, 47, 48 which are connected by rods to gear-establishing levers (40), (41), (42) pivotally mounted on a gear-box. Since the hub 50 serves only for reverse, the groove 53 therein is made wider to provide circumferential lost motion, so that, with a gear-box in which 1st and reverse are engaged in the same direction, shift therebetween may be effected by a full revolution of the cylinder 14 without interruption. In an alternative embodiment, wherein for cross-shift and gear-establishment a member is respectively rotated and axially shifted, the cross-shift and gear-establishing cams respectively comprise a spiral end-face groove and a peripheral groove which latter may have a centre position detent or notch.