Patent GB-423425-A (GB)
Title: Improvements in transmission control gear for locomotives and the like
IPC: F16H61/02
Filed: 1934-08-15
Abstract: 423,425. Change-speed and reversing gearing. DUNCAN, F., and REBBECK, F. E., c/o Harland & Wolff, Ltd., Queen's Island, Belfast. Aug. 15, 1934, No. 23509. [Class 80 (ii)] [See also Group XXXI] A locomotive propelled by an internalcombustion engine through change-speed and reversing gearing comprising a plurality of gear trains is controlled by one or more levers movement of which in either direction from a mid position selects the desired gear train and causes movement of the locomotive in that direction and increase of speed of the locomotive in either direction is effected by movement of the lever in that direction farther from its mid position to select a gear train of higher speed. In the construction shown the engine 1 drives an axle 18<a> through a fluid flywheel or slipping clutch 2, two-speed gearing 8, 9, 11, 12 controlled by a clutch 7, and reversing gearing 10, 13, 14 controlled by a clutch 15. The clutches 7, 15 are operated by levers 19, 25 connected through springs and rods 20, 28 to levers 23, 29 having rollers 33, 31 working in cam grooves in plates 32, 30 fixed to an arm 34 pivoted at 35. The arm 34 is operated by either of two hand levers 40, 41 fixed to a shaft 42 having an arm 39 of equal length to the arm 34 and connected thereto by a link 36. The cam grooves are so arranged that when the hand levers and the arm 34 are in mid position as shown, the reversing clutch 15 is disengaged and the clutch 7 is in the low-gear position. Movement of the arm 34 in either direction rocks the lever 29 and shifts the reversing clutch 15 to engage that gear wheel, 10 or 14 which will drive the locomotive in the direction in which the arm 34 and hand levers have been moved. This initial movement of arm 34 does not affect the change-speed clutch since the central part of the cam groove in plate 32 is concentric with the pivot 35 of arm 34. Further movement of arm 34 in either direction rocks the lever 23 to change the speed to top gear but does not effect the reversing gear, both ends of the cam grooves in plate 30 being concentric with the pivot 35. In order to facilitate change of speed and reversal the movement of the hand levers is arranged to apply a brake 6 to the driving or clutch shaft 3 and to close the engine throttle when changing speed. Further, the hand levers are locked in mid position by means which are only released when the locomotive brake is applied, so that the reverse gear cannot be shifted from forward to reverse and vice versa unless the locomotive is stationary. For these purposes the link 36 is formed as an inverted arc of radius equal to the lengths of the arms 34, 39, so that a roller 51 riding on the arc is not moved vertically when the arm 34 is rocked, except when recesses 36<a> in the arc come under the roller. There are five recesses corresponding respectively to the mid position of the arm 34, the two end positions, and two intermediate positions. A rod 47 connects the roller 51 to a spring-closed valve 49, so that when the roller is in one of the recesses the valve is closed, but when the arm 34 is moved the roller is lifted by the arc and the valve is opened to admit compressed air from a pipe 59 to a pipe 55 leading to (a) a cylinder 53 applying the brake 6 on the clutch shaft 3, (b) a cylinder 54 acting on a hand lever 61 to slow down the engine and (c) a cylinder 43 operating a looking bolt 43<a> adapted to lock the arm 34 when it is in mid position, the bolt then passing through a hole 44 in the arc 36 and in a fixed plate 46. Although in the mid position the roller is in a recess and the valve 49 is closed, air is trapped in cylinder 43 by a slow-acting release valve and consequently is able to operate the bolt. The bolt can be released by air supplied to the other side of the cylinder 43 through a pipe 60 connected to the locomotive brake cylinder, so that when the locomotive brakes are applied the bolt 43<a> is withdrawn and the arm 34 can be moved past the mid position. When the valve 49 is closed air is released from the cylinders 53 and 54 so that brake 6 is released and the engine speed is increased. The change-speed and reverse clutches 7, 15 are formed with ratchet teeth to allow the axle and gears to over-run the clutch shaft 3.