GB684239A - Improved method and means for the operation of change speed gearing - Google Patents

Abstract

684,239. Change-speed gearing; operating clutches. NALLINGER, F. Sept. 30, 1949 [Nov. 19, 1948], No. 25263. Class 80 (ii). The main clutch of a motor vehicle, arranged either ahead of or behind the change-speed gear, is automatically partially relieved during a gear change, the degree of relief depending on the position of the gear control means or on the torque being transmitted. In the arrangement shown in Fig. 1, a gear lever c operates in a gate d, each branch of which has a pair of electric contacts such that an electromagnetic main clutch e is fully engaged when any gear is engaged, while, as the lever c is moved towards neutral position, a resistance l is brought into the circuit, so as partially to relieve the clutch e prior to actual disengagement of the gear, and, as the lever reaches neutral, the circuit is broken. The resistances l vary for the various gear positions, being smallest for top gear and largest for reverse or first speed. A pedal f controls a variable resistance i, so that by depression of the pedal the clutch can be partially or completely relieved at will. As shown in Fig. 3, where gear changes are made by hydraulic means (not shown) under the control of a rotary valve 5, the latter also controls supply of pressure oil to a cylinder z, the piston z' of which controls the main spring-engaged clutch e and which exhausts via the valve 5 and one of a series of restrictions 9 which vary for the particular gears. If, for example, the valve 5 is moved clockwise towards second gear position from the position shown, in which first gear is engaged, the valve first allows pressure oil to pass to the cylinder. Due to the restricted outlet, pressure builds up in the cylinder and the piston moves to relieve the clutch to an extent depending on the restriction associated with the first gear, which latter now disengages. As the valve continues to move, oil is still supplied to the cylinder but the latter now exhausts through the restriction associated with second speed, so that the degree of clutch relief is varied. Second speed now engages, and finally valve 5 cuts off supply of oil to the cylinder and the clutch is fully engaged. In the form shown in Fig. 2, wherein gear changes are controlled by a rotary arm m, the latter, in moving out of any gear position, completes an electric circuit including a solenoid q and a variable resistance p controlled by a torque-responsive spring coupling n arranged between the main spring- engaged clutch e and the gear, the armature of the solenoid acting to relieve the clutch e to a degree depending on the torque. The armature also acts through a link t to reduce the fuel supply to the engine.