GB292178A - Improvements in and relating to self-propelled vehicles - Google Patents

Abstract

292,178. Ord, L. C. Dec. 13, 1926. Automatic speed or power control; controlling different functions by same handle or lever. - Rotates to vehicles having an epicyclic gear serving as the lowest or first gear and associated with a variable resistance such that with increase in engine speed up to a given point the torque transmitted to the driving wheels will increase. According to the present invention, (1) the resistance is at first controlled by hand and at a predetermined, point is automaticallv controlled in accordance with the engine speed, or (2) the variable load is dependent on the throttle opening and a plurality of constantly meshed gears controlled by a dog or like clutches is provided. Means for synchronizing the speeds of the dog clutch parts may be provided. In the construction shown in Fig. 2, the engine shaft i drives the propeller shaft j through any one of the pairs of gear wheels e<2>, e<1>, f<1> f<2>, g<1>, g<2>, according to which of the clutches e<3>, f<3>, g<3> is operative. The lowest gear e<2>, e<1> drives through an epicyclic gear b, one driven member of which can drive the shaft j through gearing h<1>, h<2>, while the other member drives an hydraulic pump or other resistance (not shown) by means of a connecting rod d. A valve in the hydraulic circuit is adapted to be actuated by the engine throttle controlling means, so that when the throttle is practically closed the valve is open and the engine turns idly without driving the vehicle. To start the vehicle the throttle is opened and the valve gradually closed; this causes a gradually increasing resistance to the movement of the pump member of the differential gear until finally the torque transmitted to the other member h<1> is sufficient to set the vehicle in motion. At a predetermined point the hand control of the resistance ceases and control is then automatically dependent upon the engine speed, e.g. by a suitable governor. Instead of the hydraulic resistance, a band brake, friction clutch, magnetic clutch, or electric generator may be employed. The higher gear ratios may be brought into use by hand or automatically and the gears may be controlled as described in Specification 290,687. 'Where a non- reversing engine is employed two sets of gears may be employed, one set being disconnected when the other set is in use. A main friction clutch is dispensed with, but a spring coupling (not shown) is preferably provided between the engine and the gearing, and the relative movement of the two parts of this coupling may be used to operate a switch controlling the engine throttle and gear-changing means so as to accelerate or decelerate the engine as required when speed changes are being made and so relieve the dog clutches from load and allow them to be readily disengaged. Mechanical means may be employed to control the engine throttle so as to facilitate the engagement and disengagement of the dog clutches. In the construction shown in Fig. 3 one member of the dog clutch carries a loose sleeve having T-slots n engaged by pins n' on the clutch member. This sleeve has a coned end l<1> adapted to engage a corresponding cone l<2> on the driving member of the clutch. When the clutch is disengaged the cone faces are also separated but the sleeve l, being acted upon by a spring m, extends beyond the dog teeth of the driven clutch member and the pins n<1> are in the heads of the T-slots, thus permitting relative rotation between the sleeve and its clutch member. On movement of the driven dogs towards the driving dogs the coned faces first engage each other, and the sleeve l is driven and transmits the drive to the clutch member when the pins n' reach the ends of their slots. The relative rotation of the sleeve and the clutch member causes axial movement of a ring p having pins p' engaging diagonal slots o in the sleeve and other slots in the clutch member parallel to the axis, and this ring is connected to the engine throttle so that the engine speed is increased or decreased by the axial movement of the ring. It is stated that by these means the speeds of the two members of the dog clutch synchronise and are brought into engagement, the ring being then returned to its central position. In a modification the two parts of a spring coupling carry a floating lever, connected by a bell-crank lever to a sliding ring which controls the throttle, so that relative movement between parts of the spring coupling, when it is under load in either direction, causes the engine speed to be increased or decreased as required to allow the corresponding dog clutch to be readily disengaged. One-way dog or toothed clutches may be employed, the only synchronizing control required in this case being to accelerate the engine when gear changing under load.