Patent GB-546821-A (GB)
Title: Improvements in and relating to mechanical power transmission systems
IPC: F16H61/02
Filed: 1940-06-10
Abstract: 546,821. Controlling change-speed gearing. HIGGS. G R.. and METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. June 10, 1940, No. 10107. [Class 80 (ii)] [Also in Groups XXVI and XXXVII] Relates to mechanical power transmission systems for coupling a prime mover to a load, of the kind providing a plurality of separated velocity ratios which are selectively engageable to match the speed and torque of the prime mover with 'the load conditions. According to the invention, control means are provided responsive to the engine speed being above or below higher and lower limits respectively for initiating respectively a change to a higher or or a lower gear and for automatically synchronizing the engine speed with the speed of the load having regard to the transmission ratio provided by the gear about to be engaged, and means responsive to the attainment of such synchronism for completing the gear change by reengaging the drive from the engine to the load with the new gear, and a manually operated or like control means arranged to allow acceleration and change of gear up to any one or all or some of the several gears provided by the transmission according to the setting of said manually operated or like control means, and thereafter to limit the speed of the engine with that gear engaged. The driver, in the case of rail cars, is thereby relieved of the duty of deciding when the conditions are such that a change of gear should be effected. The invention is described in connection with a diesel engine drive for a rail vehicle in which speed ratios are varied automatically step-by-step and the engine speed is synchronized with the vehicle speed prior to changing the gear ratio by means which are differentially responsive to the speeds of two elements one of which is driven from the engine and the other of which is driven from the load through a pilot gear box comprising a small scale replica of the main gear box, the gear ratio obtaining in the pilot gear box corresponding with that about to be engaged in the main gear box. The apparatus' includes differential mechanisms 1, 2, Fig. 1, for initiating gear changes upwards and downwards respectively, synchronizing means shown at 3, Fig. 1, an electrical wiring system, Fig. 3, controlling the operation of the speed gear, and a checking mechanism comprising switches controlled by differential mechanism, Fig. 2, which ensures that gear changing only occurs when synchronism is reached. A main governor which is ineffective between engine speeds of 800 and 1.250 r.p.m. acts on the fuel pump to prevent the engine speed, when idling, from falling below 800 r.p.m., and to prevent the engine speed exceeding 1,275 r.p.m., at any time. The up and down change mechanisms respectively have shafts 7, 30 rotating at engine speed and shafts 8, 31, driven from a constant-speed motor 9. Gears 13, 35 splined to shafts 7, 30 mesh with gears 14, 36, on threaded parts of shafts 8, 31, the gears being carried by slidable housings 15, 37. The arrangement is such that the housing 15 will move to the right or left according as the engine speed is greater or less than 1,200 r.p.m. while the housing 37 will move to the left or right according as the engine speed is less or greater than 750 r.p.m. The housing 15 is connected to a slidable bar 42 by a rack and pinion 16, 20, and rod 21, the bar having a notch 44 with which co-operates a latch bar 46 connected by a link 47 with a spring-loaded rod 6 controlling the engine fuel supply. Movement of the rod 6 to the right decreases the fuel supply and also moves a contact 22 into engagement with contacts 23, 24, 29 when conditions are suitable for a gear change up. A manual fuel regulator 5 through racks 17, 26, and pinions 20, 27, 28 modifies the positions of the rod 6 and contact 24. Movement of the housing 37 to the left controls contacts 40, 41, when conditons are suitable for a gear change down. A bar 43, on which the latch 46 rests, may be moved to the right by a piston 52, thus permitting the latch 46 to engage an abutment 58 connected to the synchronizing mechanism 3 so that the latter controls the bar 6 which is then set to engine idling speed. The abutment 58 is linked to a sliding housing 65 having intermeshing gears 63, 64, splined to an engine-driven shaft 60 and screwthreaded on a shaft 61 respectively. The shaft 61 is the driven member of the pilot gear box 67 the driving shaft 68 thereof being driven by the vehicle wheels. The housing 65 has a screwed sleeve 81 through which passes a shaft 78 with abutments 79, 80, pinion 88, and a contact 77 actuated from the housing 65 through -lost-motion and adapted to engage a contact 77a and also, in succession fixed contacts I ... IV, corresponding to the four gears of the main gear box. The sleeve 81 may be moved to the dotted line position to vary the lost motion between the housing 65 and the abutments 79, 80, upon rotation of the pinion 88 by a rack 87 operated by a piston 82. The checker mechanism comprises a pair of differentials 100, 101 driven by shafts -105, 108, connected to the engine shaft and to the shaft 61, Fig. 1, respectively. The shafts 105, 108, are rotated in opposite directions and the gearing is such that if the speeds of the shafts 105, 108, are equal then the suns 106, 103 rotate faster than the suns 102, 107. Contacts 111, 114 are frictionally. connected to the planet carriers. In operation the contacts 111, 112, and 114, 115 are closed only when the speeds of the shafts 105, 108 are equal or vary by less than a predetermined value, and such closure establishes electrical circuits permitting gear changing up or down. The control system. Fig. 3 includes a lever controlling a drum MC1 associated with wires 200 controlling the fuel regulator 6, and a lever MC2 movable in a notched gate 201 to the four gear positions and to a neutral position. When the lever MC2 is moved into a notch corresponding with any particular gear, i.e. III, that gear and any lower gear may automatically become established. The main supply lines 202, 210, are connectable through the lever MC2 with lines 203 ... 207. The line 203 leads to the contact 77a, and the contacts I ... IV have lines 211 ... 214 leading to gear relays GR1 .. GR4, controlling various smaller normally open and closed contacts. The gears of the pilot gear box 67, Fig. 1, are actuated upon energization of the corresponding gear relays GR1 .. GR4. The four clutches in the main gear box are actuated upon energization of coils G1 ... G4. The change up, change down, and checker mechanism coils OCCU, OCCD, and OCCH respectively control various normally open and closed contacts. The wiring system also includes a running relay coil OCRR which is energized during normal running conditions, a clutch relay coil OCCL controlling means for engaging the main clutch between the engine and the main gear box, a coil 232 controlling a supply of pressure fluid to the piston 52, Fig. 1, a coil OCBR controlling a supply of pressure fluid to the piston 82, Fig. 1, and various normally opened and closed contacts controlled by these coils. Operation. With the vehicle at rest, the engine idling, and the main clutch disengaged, the drum MC1 is moved in accordance with the acceleration desired and the lever MC2 is engaged with one of the notches, I.. IV, according to the maximum speed desired. A coil OC 75 is energized to release a brake 75 on the pilot gear-box shaft 61, coil 232 operates piston 52 to engage latch 46 with the abutment 58, relay GR1 is energized through contact I and G1 is energized through the normally closed contacts 221 (RR) of the running relay. The first gear of the main gear box, and the main clutch are thus engaged. Thereupon contacts 231 (CH) open, and the control of the fuel rod 6 is transferred to the regulator 5 and the train accelerates in first gear. If the engine speed exceeds 1,200 r.p.m. the housing 15 closes contacts 23, 24, 29. whereby the control of the fuel rod 6 is transferred to the synchronizing mechansm 3. Also energization of the coil OCBR operates piston 82 to project the sleeve 81 from the housing 65. Movement of the housing 65 to the left causes the contact 77 to engage the contact II. Coil GR2 is thus energized, the gear in the pilot gear box is changed, and the mechanism 3 acts to synchronize the speeds of the shafts 60, 61. When this occurs the checking mechanism acts to introduce the second speed in the main gear box and the control of the fuel rod 6 is transferred to the regulator 5 to accelerate the engine in second gear. Other up-changes are similarly effected. When conditions are such that a change down is necessary the housing 37 of the change-down mechanism operates the contacts 40, 41 resulting in disengagement of the effective clutch in the main gear box: Thereupon housing 65 moves to the right, Fig. 1, to make contact 77 engage a lower gear contact after which the synchronizing mechanism functions and eventually causes the introduction of a lower gear in the main gear box. During this change, the fuel-control transfer operation is effected as during an up-change. In an alternate form of change-up mechanism, Fig. 4, the main governor 302 of the engine is employed in place of the differential mechanism of Fig. 1 for initiating upward gear changes. The governor is unaffected by engine speeds between 800 and 1,200 r.p.m. A fuel regulator corresponding to 5 in Fig. 1, is coupled directly to the bar 42 of the fuel-control transfer mechanism. The link 47, Fig. 1, is coupled to a crank 300 pivoted at 301 on the governor casing 302 having a shaft 303 driven by the engine. A floating lever 304 is pivoted at 305 to the crank 300, and at its upper end is coupled by a rod 306 with the control member 307 of the fuel pump 308. Its lower end is coupled with the changing speed responsive member 309 of the governor. The change-up contacts corresponding with 22..24 of Fig. 1, are a