GB781944A - Improvements in and relating to transmission systems of power driven vehicles - Google Patents

Abstract

781,944. Change-speed gearing. SOC. ANON. FRANCAISE DU FERODO. Jan. 17, 1956 [Jan. 17, 1955], No. 1624/56. Class 80 (2). In a motor vehicle wherein an overdrive gear behind the gear box is normally controlled automatically in accordance with speed but can be changed down from overdrive to direct drive at will by kick-down of the accelerator or by a separate control member, the arrangement is such that the engine clutch is temporarily disengaged during such voluntary change-down. In the arrangement shown in Figs. 1, 3, the overdrive epicyclic gear comprises an input planet carrier 12, an output annular gear 14, a one-way clutch 15 between carrier 12 and gear 14 for direct free-wheel drive, and a sun gear 16 which can be locked for overdrive by a transversely-movable member 20 engageable with teeth 19 on the sun gear. The latter can be moved axially to couple it to the carrier 12 by clutch teeth 17,18 during reverse drive. Member 20 is normally held retracted, as shown in Fig. 3, by a spring 26 and is moved to locking position upon closure of a relay switch 29 causing energization from a battery 31 of both main and holding solenoid windings 23, 22, the holding winding 22 being permanently earthed at 53 and the main winding 22 being connected to earth through a switch 55 which is closed when member 20 is in retracted position but is opened by member 20 when it moves to locking position. The accelerator kick-down switch 46 normally connects contacts 41, 42, whereby relay switch 29 is controlled by a speedresponsive switch 49 in series with a switch 48 which is closed only during forward drive; the switch 49 being opened or closed when vehicle speed is below or above a predetermined value. Upon kick-down of the accelerator during overdrive, contacts 41, 42 are disconnected, so deenergizing the locking solenoid, and contacts 43, 44 are connected, completing a circuit including a spring-closed switch 52 and a relay coil 61 which opens a switch 64 to cause disengagement of the engine clutch 66. A switch 69, controlled by the gear lever, causes the clutch also to be disengaged during gear changing in the main gear box. As the member 20 moves to retracted position, it opens switch 52, so deenergizing the coil 61 and causing re-engagement of the clutch. In the arrangement of Fig. 4, a member 80 is movable axially on the sun 16 so as frictionally to connect the latter either to annulus 14, for direct drive, or to the casing 82, for overdrive, the member 80 being normally held by a spring 83 in direct drive position and being moved to overdrive position by hydraulic means 84. The latter is controlled by a valve 85 actuated by a speed-responsive governor 50 with an overriding kick-down control 86 coupled to a switch 87 controlling the engine clutch, a normally-closed switch 88 being opened by the movement of member 80 or by timing mechanism to cause re-engagement of the clutch.