Greenwood & Batley, Ltd.
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Exhibit:—One 35h.p. Petrol-Electric Bus Chassis.
After experimenting with a smaller vehicle employing the same system of transmission, Greenwood and Batley, Limited, has been tempted to enter into the battle between steam, petrol and Electricity for the transmission of power for motor omnibuses. The result is a vehicle, the trial of which we await with interest, as many of its lines are distinctly novel.
The engine as fitted to the chassis on exhibition is a 4-cylinder, vertical Mute], with cylinders 125mm. diameter a the bore, and with a pistonstroke (If momm. It develops 4oh.p. at 1,mo r.p.m., hut, as it normally runs at a lower speed than this, the power is stated to be 35h.p. The engine has bearings between each pair of cylinders ; it is fitted with a Xemà automatic carburetter, and with lowtension magneto ignition. Although there has been no time to lit it, a system of forced lubrication, the invention of the company, will be used. This combines sight feed with pressure feed, but the oil is under pressure right up to the point of its application to the journals or moving parts. Instead of the oil being visible, the feed is indicated by the stems of checkvalves, each of which, in turn, allows a charge of oil to pass to its particular bearing. The moving stems or plungers of these valves, worked by the oil pressure, clearly indicate whether any oil is passing. Should the pump be delivering too much oil, some of it may return through a relief-valve provided for that purpose. There is a comparatively small flywheel, to equalise the torque to a certain extent, and this is further assisted by the kinetic energy of the revolving armature, which is directly coupled to the engine shaft.
The dynamo is capable of generating an output of 2o kilo-watts for con tinuous running, but will, for short periods, give an output of 27 kilowatts, and is compound wound. The connection between engine and dynamo may be unshipped by simply removing one bolt, and the dynamo may then be taken away without disturbing any other parts. The armature, tat), may he taken out, when the dynamo is in position, without disturbing any other parts, and, by easily removable covers, free access to the commutator brushes is obtained. The leads from i be dynamo are cOnveyed, in rubber ahd canvas tubes, to the two
motors. These motors have one common field-casting with two separate armatures : they are series-wound, and are mounted on a bridge-piece and trunnions, the bridge-piece being connectod to the back live axle, by a large tubular radius rod. Being connected in this manner, the back axle and armature shafts are always in perfect alignment ; this is not affected, even should one wheel be raised considerably higher than the other. The motor armatures are coupled to two worm shafts, running in the bottom of wormgear cases on the back axle, by cardan shafts.
Although plain shafts could here be used by reason of the single tubular radius rods above described, it has been thought desirable to make a universal connection between armature and worm. The cardan shafts are enclosed by sheet-metal, tubular, hinged cases (see supplement) in order to protect the joints from mud. Each worm drives a separate worm-wheel, mounted on one end of the divided rear axle, and the gear ratio is 12 to I. The armature shafts and worm shafts all run on ball bearings. The worm gears are very easy running, and, although the weight of the chassis is tons, two men find no difficulty in pushing it along the level with the worm wheels driving the worms. These gears are designed and cut by the company. The outer tubes of the axle, which take all the weight, are of chrome-nickel steel with flanges forged out of the solid. The ends of the axle-shafts have dog clutches to mesh with similar clutches on the cast-steel road wheels. The method of driving by two worms dispenses with the necessity for differential gear.
The controller is a series-parallel one, as used an trams, and has no external resistances. The need for external resistances is obviated by an arrangement of the shunt-winding of the dynamo, by which the act of breaking the main circuit reduces the voltage of the dynamo about 50 per cent., so that, on the circuit's being re-made, the application of the load is gradual. No additional switch contacts are necessary. The controller handle is fitted under the steering wheel, on the steering pillar.
The engine is controlled by the usual levers on the steering wheel, but they do not revolve with it. The throttle valve is inter-connected with the single foot-pedal, so that, whatever the position of throttle or control lever, a slight depression of the pedal throttles down the engine and breaks the main circuit, whilst a further movement of the pedal applies the brakes on the propeller shafts. On releasing the pedal, the previous condition of gas supply is resumed. No solenoids are used in the control system. The foot brakes are of the locomotive type, and provision is made for water cooling if necessary. The lever brakes are of the internal-expanding type, and are compensated; they are 'very easily adjustable, as shown in the sketch herewith. All parts are provided with means of lubrication by greases, or by ample oil wells.
The chassis presents quite a unique appearance and, at first sight, gives one the impression of great weight, but this is really not the case. It is the first of its type, and is well worth a careful inspection. The adjustment of the side-lever brake is in a very handy form, and quite accessible. The brake tension rod has a swelled, threaded end which passes through a trunnion, at each side of which is a weightdd lock-nut as shown in the accompanying sketch. The chassis abounds in details of a novel character, and it is the object of much attention from visitors, who are at a loss to understand the strange lines of the chassis. The makers' address Is Armley Road, Leeds, and its experience in the construction of " electromobile " chassis has been turned to good account in the model under notice.