Patent GB-422871-A (GB)
Title: Automatic control mechanism for variable speed gear boxes
Filed: 1933-10-18
Abstract: 422,871. Controlling variable-speed gearing. HAYCOCK, G. W., 294, Kingsbridge Drive, Bankhead, Rutherglen, and CAMPBELL, D., 7, Beech Avenue, both in Glasgow. Oct. 18, 1933, No. 28779. [Class 80 (ii)] A torque governor O, P between sections B, C of a divided driven shaft is used for varying the speed ratio, say, on a vehicle automatically with the load, and the control may be effected jointly between that governor and a centrifugal governor K<1>, Fig. 1, on the driving-shaft. This control may be operative through a selector valve D<2> or switch with a manual auxiliary valve Y<2> to effect reversed driving and braking by the engine. A neutral catch J<4> may be provided for free-wheeling, releasable by the accelerator. The torque governor comprises two parts 0, P rigid respectively with the two parts B, C of the shaft driven by the variable-speed gearing. These governor members 0, P are held in relative position by pairs of springs Q, Fig. 2, in chambers connected by passages so that grease or oil in the chambers have a dash-pot damping effect on vibration as relative turning takes place between the members 0, P due to variations in torque. Such relative turning causes a bevel pinion V carried by the member 0 to roll on a segmental track Y carried by the member P so that a spur pinion W causes a rack B to move axially carrying with it a central sleeve Z, Fig. 1. The relative turning of the members 0, P is limited by interpenetrating central dogs T, U which are specially necessary on reversed driving. The sleeve Z acts through a bearing F<1>, a lever H<1>, and a link Ul on a lever T<1> the upper end of which is connected through a bearing R<1> with the muff O<1> of the speed-responsive governor K<1> on the driving-shaft A. The lower end of the lever T <1> acts through opposed springs B<2> on a control slide A<2> connected through a rod C' with the selector valve D<2> in a valve chest N<2>. Pressure oil enters the chest N<2> at D', passes through apertures E<4> and centrally through the valve system and through apertures F' to a terminal chamber G' whereby the pressure on the system is balanced. The central auxiliary valve Y<2> is normally fixed with its four ports C<3> &c. opposite four ports P<2> &c. in the chest N<2> which lead to four cylinders J, K, L, M for operating, say, a solid drive clutch D and three reduced forward speed brakes E, F, G in epicyclic change-speed gearing, but any other type of variable-speed gearing is contemplated. The auxiliary valve Y<2>, when used, is moved manually to admit oil through a pipe X<2> to a cylinder N to apply a brake H for reversed driving, or alternatively through a pipe W<2> to the first-speed cylinder M when the engine is to be used for braking the vehicle. As the selector valve D<2> is moved to the right from the position shown, oil is admitted successively through pipes T<2>, U<2>, V<2>, W<2> for applying speeds in descending order, but the joint control applies the speeds in the opposite order in starting from rest. Exhaust oil passes through one of a set of annular ducts K<2> and a long connecting duct R<3> to an exhaust port S<3>. A spring bowl V<3> acts to lock the control slide A<2> with the valve D<2> in proper positions for engaging the ports. With the parts all at rest, the governor K<1> is collapsed, the lever T' is on line 3-3 and the bowl V<3> engages a notch Y<3> corresponding to neutral setting of the valve D<2>. The accelerator, not shown, being released, a rod S<4> is pressed into a cylinder Q<4> and stresses a spring R<4> which causes the neutral catch J<4> to engage a notch K<4> in the control slide A<2> and lock it even after the engine has been started by a hand throttle control and is running free so that the governor K<1> stresses the springs B<a>. On depression of the accelerator, the catch J<4> is released, whereupon the springs B<2> bring the slide A<2> to the position shown with the roller V<3> in a notch Z<3>. Oil admitted to the cylinder J tends to bring in fourth speed, but the high torque resistance moves the sleeve Z and link U<1> and pulls the lever T<1> so that eventually the first-speed notch C' is engaged by the roller V<3>. As the vehicle gains momentum, the slide A<2> is moved left to bring in higher speeds which are changed in accordance with the loading of the governor 0, P. To obtain free-wheeling, the accelerator is released and the engine and shaft A slowed down causing the vehicle to overrun effecting reversal in the action of the torque governor so that the slide A<2> is moved to a position in which it is engaged and locked by the neutral catch J<4> until after the accelerator has been depressed. Instead of oil, water, steam, or air may be used, or vacuum. Or electric currents may be used with selector and hand switches in place of the valves D<2>, Y<2>, and solenoids in place of the cylinders J, K &c. Rotary valves and switches may be substituted for the sliding ones.