GB616873A - Improvements in and relating to automatic change speed devices - Google Patents

Abstract

616,873. Automatic change-speed gearing. SOC. FRANCOIS CONTE. March 2, 1940, No. 3975. Convention date, March 29, 1939. [Classes 80 (ii) and 80 (iii)] In an automatic change-speed gear controlled jointly by load and engine speed acting respectively through a torque screw on the output shaft and a centrifugal governor on the input shaft, the governor masses have cam-shaped operating surfaces so designed that the force exerted by the governor corresponds to the driving power of the engine. As shown applied to a motor vehicle transmission gearing, the masses k, Fig. 4, have an operating face n divided into separate operative cam sections o ... o3 corresponding to gear ratios up to direct drive and separated by grooves corresponding to the speed changes, the torque screw-thread 32, Fig. 10 (developed view), being similarly divided on its bearing flank into operative sections 33 ... 36 of individually constant but successively increasing pitch connected by transition zones 37 ... 39 of low pitch. Interaction of the governor and torque screw controls the engagement of nested clutches f ... f3, Fig. 1, giving three reduced speeds and a direct drive respectively, the reduced speeds being through nested sleeves s ... s2, pinions u ... u2 and countershaft pinions v ... v2 having cumulative free-wheel connections x ... x2 with a pinion v3 meshing a pinion u3 on the direct drive shaft t. The clutches are driven by the driving shaft a and are controlled by axial movement of rods g fixed in one driving clutch plate d3 and having stepped abutments against which the other driving plates d2 ... d bear under the action of their clutch springs. Axial movement of the rods g to the right, to bring in successively higher gear ratios, is caused by the reaction of the masses k, pivoted on a spider h fixed to the rods, against an axially fixed driving ring e. Axial movement of the rods g to the left, to bring in successively lower gear ratios, is effected by the thrust of the torque screw 20 which is splined on the shaft t and acts thereon through a stop ring 22 to cause a shoulder on the shaft to move the plate d3 through a thrust bearing d4. The torque screw 20 coacts with a nut 23 free on the output shaft 24 and connectible thereto by a friction synchronized dog clutch member 27 splined on the shaft. The member 27 is movable through a neutral position to engage for reverse drive a gear 30 meshing through an idler with a countershaft gear 31. The coacting threads 32, 41 of the torque screw and nut may be of trapezoidal section and of single or multiple start, the thread 41 having a locating cam portion 44 on its bearing flank. The variable-pitch torque screw may be replaced by a screw of constant pitch and variable diameter or by one of constant pitch and constant diameter connected to the nut directly or through a suitably-shaped cam. Specification 616,883 is referred to. The Specification as open to inspection under Sect. 91 comprises also the subject-matter of Specification 620,295. This subject-matter does not appear in the Specification as accepted.