903,498. Controlling locomotives. ROLLS-ROYCE Ltd. March 3, 1961 [Dec. 3 1959], No. 41065/59. Class 79(5). In a self-propelled rail vehicle or train set having drive reversing means and a lever operated by the driver to control the speed, a change-over of the drive direction from forward to reverse and vice versa is initiated by moving the speed control lever or handle in the speed-reducing direction beyond the normal idling or "off" position. The vehicle may be driven by an internal combustion or steam engine or an electric motor and the engines of two or more units of a train set may be so controlled. With an electric motor, movement of the speed control lever beyond the "off" position may initiate the operation of relays to reverse the direction of rotation of the motors and speed increases are obtained by movement of the handle in the same direction for forward and reverse movements. As shown in Fig. 1, the wheels 5 of a locomotive are driven from a compression-ignition engine 1 through a hydraulic torque converter 2, plate-clutch 3 of the "over-centre" type which is stable in engaged and disengaged positions, gearbox 4 having sliding dogs enabling forward or reverse gears to be engaged, and chains 6. The vehicle controls are duplicated for operation from either side of the cab and include throttle control levers 11 and 12 connected together by a rod 13 in a manner that movement of the control inwardly of the vehicle increases the speed, and to the fuel injection control through rods 14 and 16 and bell crank 15. The forward or reverse direction of gearbox 4 is determined by pre-selector levers 17, the gear being selected according to the position of the handle when the throttle control lever is moved beyond the idling position. The selection of reverse and forward gears and operation of the clutch is effected in a pneumatic circuit, Fig. 4, in which air under pressure is fed through a filter 20 and lubricator 21 to a line 22. The lever 17, shown in forward position, is moved to select reverse gear: the valve 23 is normally spring-loaded to the position shown, but when the throttle lever 12 is moved beyond the idling position (full lines), the valve 23 admits air to a line 24 which is vented to atmosphere through a device 25 except when the vehicle is stationary, when the pressure in line 24 operates a valve 26 to exhaust line 27 and admit air to line 28, changing over a pilot valve 29. Air from line 28 passes through relay valve 30 and line 31 to a spring-loaded pilot valve 32, whereby air is admitted from the pressure line 22 through a line 33 to a double acting clutch actuating cylinder 34 to disengage the clutch. After a time delay caused by a restriction 35 and a device 36, pressure air is applied to the lower end of valve 30 whereby line 31 is cut off, valve 32 returns to its rest position thereby cutting off the supply to line 33, at the same time allowing air from line 27 to pass to line 37 and spring-loaded relay valve 38. The lever 17 having been moved to select reverse gear, valve 37 is changed from the position shown so that air passes through line 39 to change over a relay valve 40 so that air may be admitted from line 22 to the appropriate one of single acting cylinders F and R the operation of which engages forward or reverse gear respectively. Micro switches on the gear-change mechanism cause an indicator light to be illuminated when the appropriate (gear is engaged when the driver returns the throttle lever 12 to return to its normal idling position. This allows valve 23 to return under its spring-loading to the position shown, exhausting line 24 thereby returning valve 26 to the position shown whereby lines 28, 37 and 39 are exhausted and air is admitted to line 27. Relay valve 30 is returned to the position shown and air is passed through the pilot valve 29 to a line 41 to operate a spring-loaded valve 42 and so admit air from line 22 through line 43 to the other end of the clutch operating cylinder 34, so reengaging the clutch. After a time delay determined by a restriction 44 and a device 45, air is admitted to the lower end of valve 29 to return it to its rest position, cutting off line 41 and valve 42, so isolating line 43 from supply 22 so that all the parts are in their original positions except that valve 40 is changed over. If the lever 17 is moved to the "forward" position, any subsequent movement of lever 12 beyond the idling position will initiate a change-over sequence to re-engage forward gear, air passing from valve 38 through line 46 to return valve 40 to the position shown. If the lever 12 is unintentionally moved beyond the idling position when the gear engaged is already that selected by the lever 17, the clutch is merely disengaged and re-engaged when the lever 12 is restored to the idling position. A valve 47 in the path from supply line 22 allows both lines 27 and 28 to be simultaneously vented to atmosphere so that when the lever 12 is moved beyond the idling position the clutch is held withdrawn, to allow maintenance work on the engine. A spring- loaded plunger 48 controlled by valve 23 prevents valve 47 from being operated except when the lever 12 is in the beyond idling position. In a modification, Fig. 5, the lever 17 and valve 38 are replaced by a relay valve 49 and two spring-loaded pilot valves 50 and 51. When air is admitted to line 37, both valves 50 and 51 cut off their associated ends of valve 49 from lines 52 and 53 leading respectively to the cylinders R and F, but air passes through valve 49 and line 39 to change-over valve 40. When the change-over sequence is completed, valves 50 and 51 are opened and line 52 is under pressure so that air is admitted to the left hand end of valve 49 to change it over. Next time the line 37 is under pressure, air passes through line 46 instead of line 39, to change the gear back again. The use of hydraulic and electric circuits instead of pneumatic apparatus is mentioned.