1,090,274. Change-Speed gear. HANS GLAS G.m.b.H. ISARIA - MASCHINENFABRIK. Jan. 11, 1965 [Jan. 24, 1964], No. 1207/65. Heading F2D. In an automatic control system for a motor vehicle change-speed gear, transistors are successively rendered non-conducting or conducting by the action of a regulating voltage dependent on vehicle speed, accelerator position, and possibly road gradient, to control, by means of relays or other switching means, solenoid valves regulating the supply of a pressure medium to piston-cylinder arrangements which shift the gear to the next lower or higher ratio respectively. Function summary.-Automatic or manual gearshifts between the forward ratios are accompanied by automatic main clutch and engine throttle valve control, and gear control may be switched from automatic to manual at any time. Automatic shifts are always to the next higher or lower ratio. Reverse is manually engaged only, again with automatic clutch and throttle control. The accelerator position signal to the transistors may be overridden by a hill switch. The engine starter is cut out when any gear other than neutral is engaged. If, in automatic gearshift conditions, the gear springs out, it is automatically re-established. When the engine speed falls to its idling value, declutching is automatic. Gearshift mechanism.-Gearshifts are effected by a shift-bar 37 which is turned to select between 1-2 and 3-4 shift rails by a doubleacting rotary piston 36 and moved axially for gear establishment by a double-acting piston 39 secured to the shift-bar 37. Alternative manual operation is provided by a direct-acting ball-mounted lever 40 which also is the sole means for obtaining reverse against a spring bias. The hydraulic circuit is identical to that in Specification 1,065,358. Pressure from a line 4, supplied by a pump 1 and regulated by a spring-loaded regulator valve 12, is controlled by a solenoid valve 5 which when de-energized is held by a spring 7 in a position venting the line 4 to a return line 11 through a port 9. When energized, the valve 5 closes the port 9 causing a pressure build-up which moves a piston 16 leftwards (Fig. 1) to disengage the main clutch 18 and, via a line 20, to move two spring-returned pistons 23, 24 rightwards to locate an engine throttle valve lever 25, pivoted at 26, in a position corresponding to a low engine speed which is still above the idling speed. The function of the lower piston 23 is to prevent the throttle closing to idle position during a shift, should the driver release the accelerator pedal linkage 27 which is spring- connected to the throttle lever 25. If this were to occur, the clutch would not otherwise reengage automatically after the shift. When the clutch is fully disengaged, the piston 16 admits pressure through a line 19 to a solenoid valve 30 which, during automatic shifts, is energized to connect the line 19 through a line 32 to solenoid valves 33, 34 which respectively control admission of pressure to the pistons 36, 39. Electric circuit components (Fig. 3).-The base voltages of transistors 59, 60, 61, acting as switches for the windings of relays R 1 , R 2 , R 3 , respectively, are taken from a point 57 of a potential divider 54, 55, 56 connected across a battery 51, through a line 58 and adjustable resistors 62, 63, 64 respectively. The resistance 55 of the potential divider is varied from zero at full accelerator depression to a maximum at the accelerator idling position, so that the base voltages decrease with increasing accelerator depression. An alternator 68 driven from the output shaft provides, through a rectifier 69 and respective resistors 65, 66, 67 regulating voltages to the transistor bases which increase with increasing vehicle speed. The resistors 62-67 are arranged so that as the vehicle speed, and hence the regulating voltages, increase, the transistors 59-61 are blocked in succession. For example, with the accelerator at idling, the transistors 59, 60, 61 are blocked at 15, 30, 45 km./hr. respectively, while with full accelerator depression the blocking speeds are 36.5, 73.5, 110 km./hr. Automatic operation of the gearshift control is selected by closing a switch 78 to energize a relay R 6 to move a contact K 6 rightwards, to extinguish a lamp 80 indicating manual control, and to illuminate a lamp 81 indicating automatic control, and to close a contact K<SP>1</SP> 6 . Starting.-With the vehicle stationary and the gear in neutral, so that contacts K 1 , 73 are in the positions shown, the rightward movement of K, energizes a relay R 5 which moves a contact K 5 leftwards, to energize the solenoid valve 5 for clutch disengagement and throttle valve closure, and, through a contact K<SP>1</SP> 4 , to energize the solenoid valve 34, and closes a contact K<SP>1</SP> 5 to energize the solenoid valves 30, 33. The energized valves 33, 34 cause 1st gear to be engaged, upon which a groove 74 in the shift bar 37 acts on the micro-switch 73 to move the latter leftwards (Fig. 3) de-energizing the relay R 5 , which causes de-energization of all four solenoid valves, with consequent clutch engagement and return of the throttle to manual control. If 1st gear springs out, the switch 73 is moved rightwards, and re-energizes the relay R 5 to cause re-establishment of the gear. 1-2 upshift occurs when the vehicle speed has risen sufficiently for the regulating voltage to block the transistor 59, de-energizing the relay R 1 , and allowing the contact K 1 to move leftward energizing a relay R 4 . This moves the contact K<SP>1</SP> 4 upward to energize the solenoid valve 5 for de-clutch and throttle control, and moves a contact K 4 rightwards to energize the solenoid valves 30, 33 causing 2nd gear to be engaged, upon which the groove 74 of the shiftbar 37 causes the switches 73, 76 to be moved rightwards, the latter de-energizing the relay R 4 for clutch re-engagement. 2-3 upshift occurs when the vehicle speed has risen sufficiently for the transistor 60 to be blocked, de-energizing the relay R 2 , which allows a contact K 2 to open, preventing energization of the valve 33, and a contact K<SP>1</SP> 2 to move rightwards to energize the relay R 1 . This moves K 1 rightwards to energize the relay R 5 , moving K 5 leftwards to energize the solenoid valves 5, 34 and closing K<SP>1</SP> 5 to energize the solenoid valve 30, so that the clutch is disengaged, the throttle held, and 3rd gear is engaged, upon which the groove 74 causes the switches 73, 76 to move leftwards, the former de-energizing the relay R 5 for clutch re-engagement. 3-4 upshift occurs when the transistor 61 is blocked, de-energizing the relay R 3 , allowing a contact K 3 to open, de-energizing the relay R 1 . This moves K 1 leftwards to energize the relay R 4 , to move the contact K<SP>1</SP> 4 upwards to energize the solenoid valve 5 for clutch disengagement and to move the contact K 4 rightwards to energize the solenoid valve 30, causing 4th gear to be engaged, upon which the groove 74 causes the switches 73, 76 to move rightwards, the latter de-energizing the relay R 4 for clutch re-engagement. Downshifts follow a similar pattern, the successive opening of transistors 61, 60, 59 causing shifts to 3rd, 2nd and 1st gears respectively. Manual gearshifts.-Grasping the lever 40 closes a switch 84 to energize relay windings R<SP>1</SP> 6 , to move contact K 6 leftwards to extinguish the lamp 81 and illuminate the lamp 80, and to open contact K<SP>1</SP> 6 to prevent energization of the solenoid valve 30, and R<SP>1</SP> 4 which moves the contact K<SP>1</SP> 4 upwards to energize the solenoid valve 5 for de-clutching and throttle control. Gear-shift control remains manual until the switch 78 is closed again manually. Safety circuits.-When any gear ratio is engaged, either the switch 73 or the switch 76 earths a starter locking circuit 75 to prevent actuation of the engine starter. To maintain the correct ratio sequence when the transistors are blocked or opened in rapid succession, e.g. due to full accelerator depression, or on severe braking, a relay R<SP>1</SP> 1 in parallel with the relay R 5 holds the contact K 1 in the position shown during 2-3 upshift and 4-3 downshift to prevent the energization of relay R 4 until 3rd gear is engaged, even if relay R 1 is deenergized during the shift. The micro-switches 73, 76 serve to prevent direct automatic shifts between 1st and 3rd or 2nd and 4th gears.