436,652. Controlling change-speed gearing. DEMOCRATIS, A., 38, St. Augustines Road, and ROSTON, J., 24, High Holborn, both in London. March 16, 1934, Nos. 8401, 32676, and 33876. [Class 80 (ii)] Automatic control mechanism for changespeed gearing suitable for vehicles comprises means 22, Fig. 1 translating the speed of the engine into a proportional force, means 36 for translating the load torque into a resisting force, and balance mechanism 30, Fig. 2, between these forces which effects the speed changes automatically and which is held against excessive movement when the load torque reverses. There is alternative manual operation by a lever 113, Fig. 17, and when a lever 112 is set at left to " automatic," changes are made automatically by servo means in the speed range above the speed set by the manual lever 113. A pump 22, Fig. 1, driven by a driving-shaft 1 delivers oil through a pipe 23, Fig. 2, past a relief valve 24 and through a pipe 25 to a valve chamber 26, Fig. 3, where a rotary valve 27 directs the oil, for automatic changes, into a cylinder 28 behind a plunger 30. The speed responsive force is thus directed on a lever 41 which is thrust by it left of Fig. 2. The load torque at 36 is communicated to the balance lever 41 as a pull in the opposite direction, and the resultant force is passed on through a link 128 and arm 127, Fig. 13, to one side driver disc 120 of a differential clutch 130 the other side driver disc 121 of which is, through a resilient arm 126 and lever 115, connected to the manual lever 113, Fig. 17. The middle driven disc 122, Fig. 14, of the differential clutch 130, Fig. 2, is connected by an arm 123 and a link to an arm 124, Fig. 6, on a selector cam shaft 51 for the speed changes. When the lever 112, Fig. 17, is set to "automatic," the valve 27, Fig. 3, is turned to deliver the oil to the cylinder 28 whereby the speed and torque responsive forces are brought into balanced relation upon the lever 41 and so as jointly to control the shaft 51. If the torque in the load shaft 12, Fig. 2, reverses, the lever 41 tends to swing over to right of Fig. 3 but is prevented from doing so because oil in the cylinder 29 closes a valve 31<x> and then resists any rightward throw of the plunger 30. When the lever 112, Fig. 17, is thrown away from " automatic ", the valve 27, Fig. 3, is turned to direct the pressure oil into the cylinder 29 instead of the cylinder 28, whereby the plunger 30 is thrown hard over into the cylinder 28 and the automatic action is disabled. The manual control is then operative alone. Each of the driver discs 120, 121, Fig. 13, of the differential clutch has a projecting shoulder 133, Fig. 15, adapted to engage the flank of a dog 130 pivoted transversely upon the middle disc 122. In the position shown in Fig. 13, the driver disc 121 has engaged the dog 130 with its shoulder and the other end of the dog 130 has ridden up on the automatic disc 120 so as to depress the dog into a notch 131 in the manual disc 121. The manual disc 121 thus carries the disc 122 and therefore the selector shaft 51 with it until it is overtaken by the automatic disc 120, which then engages the tilting dog 130 alone and carries the disc 122 on to higher automatic speeds than according to the setting of the manual disc 121. The torque in the shaft 12, Fig. 1, is translated into a thrust on the sleeve 36 by means shown in Fig. 4. The member which moves axially on change of torque is a screw 34 which slides on feathers 33 on the driven shaft 10 of the change speed gearing. The screw 34 screws inside a nut 35 fast on the tail shaft 12 and the screwing displacements are passed on to the sleeve 36 by pins 37 passing through helical slots 38 in the hollow nut 35. A planetary torque responsive device is described with reference to Fig. 5, not shown. As the shaft 51 is tilted to effect a speed change, a cam 67, Fig. 9, tilts a beam 65 so as to turn a lever 60 from a stop 62 to a stop 61, and so tilt the spindle 59 of a valve 58, Fig. 7, to admit pressure oil into a cylinder 56 and so tilt the beam 52 of an executive control shaft 50, Fig. 6, to the gear disengaged position. An electric contact 161 then completes a circuit from a battery 160 which circuit by a solenoid 149 decelerates the engine suddenly and speeds it up again slowly as described in Specification 436,714. This current also passes through a solenoid 64, which turns the lever 60, Fig. 9, back against the stop 62 thereby admitting oil to another cylinder 55, Fig. 7, and throwing the executive shaft 50, Fig. 6 back to the gear engaged position. A helix 76 and a cam 74 between them operate a solid-driving dog clutch 21, Fig. 1, by means shown in Fig. 10, (not shown), and described in the Specification referred to. A double helix 76<1>, 76<2>, Fig. 6, and double cam 74<1>, 742 operate a sliding stop dog or brake 17, Fig. 1, with two engaging positions, to effect two reduced speeds in the epicyclic gearing. Cams 87, 87<1> co-operate with notches 86, 86<1> by means illustrated in Fig. 12, (not shown), and described in the Specification referred to, to close brakes alternatively upon drums 18, 19, Fig. 1, to bring in first speed and reversed drive, respectively. Electric contacts 88, 96, Fig. 6, are associated with means for facilitating the engagement of the brakes and dog members as described in the Specification referred to. Electric lamps 118, Fig. 17, are arranged to light up to show which gear is in use. These lamps are operated by means, (not shown), associated with the clutch forks &c.