THE G.M.C. ONE-TONNER.
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An American Model Built on British Lines.
THE G.M.O. one-ton chassis, for which the con.. cessionnaires are the Ancona Motor Co., Ltd., Brompton Road, London, S.W. is a fine example of American construction. SW., all chassis which hail from the States appeal to users in Britain, but this is an example which should do so, as it is constructed on British lines in many respects. In calling it a one-tonner, the makers under-state rather than over-state its capacity, but this is due to the bad habit of overloading which prevails in America, where vehicles have to he constructed for/ practically double the load for which the are
nominally built. .
The one-tonner is similar in many respects to the 15-ewt. model previously marketed, and whose plain this later model takes. The 15-cwt. vehicle,was very successful and became the standard chassis for the British Red Cross Society. The Main difference between the new model and the old is in the construelion of the •torque arrangement. On the 15-cwt. model this consisted of a central torque tube, but in ihe one-tonneOradius. rods have been substituted, these enabling the semi-elliptic springs to be shackled at both ends; in the 15-cwt. full elliptic springs were used. The new springs are long and flexible and should make the vehicle a veryteasy riding one. An engine of the well-known Continental make is
provided. This has a g in. bore and 5 in, stroke. ltis.in.unit construction with the gearbox, of course,. incorporating,the clutch casing.
Continental., engines are now being used by a large number of makers, and they appear to give ,general satisfaction. The'oneldn question is &four cyliudered monobloc, all the.valv\es being•on-one.side.and totally enclosed. The water pump is of the centrifitgal type driven from the timing gear, the magneto being driven from the same shaft through a flexible disa. coupling
The engine is provided With a Marvel carburetter, fitted with a long, flexible, metallic hot-air inlet.pipe, which passes round the back of the:cylanders and obta,iiia its heat from a muffle round the exhaust.
Above the'carburetter, and between .it,and the engine, is fitted a Monarch governor, which controls the :speed of the engine by closing the throttle as the suction,increases. An oil level gauge °Wile floating type is fitted ir4o the crankcase.
A plunger-type oil pump is driven from a earn on the camshaft and oil is fed directly to the main bearings and to the big-endttroughs. An oil indicator is provided on the dash; this consists of a plunger fitted to a diaphragm in:the oil•circuit which is forced out when the oil is under pressure. The ..drive from the engine is taken through a multiple disc clutch, which consists of five driving plates and six driven; tile driving plates are plain steel, but the..driven are lined on both sides with copper asbestos material. A large cover above tho clutch allows for inspection.
The gearbox is compact and strong, and the shafts are kept .as short as possible. It gives three forward speeds and a reerse, The change-speed and brake levers are mounted direct on the gearbox, the change speed working on what is known as the "invisible gate " system ; they are thus situated at the left side of the.driver.
The.frame is of .A in. channel steel, the side members being parallel. Itsis :of one depth up to the front, Where it tapers up towards the dumb-irons. From its centre,to a point which is about a foot from the radiator, each side member is reinforced by a channel steel liner, which is a very good fit in the member.
The engine and gearbox unit,has a three-point suspension, the front enclAeing mounted on a trun..non bearing.. The cardan shaft has double universal joints of the star type, which are totally enclosed by oil-tight metal covers. These covers are pressed up to their work by stout springs, and can rock owing to being provided with ball and socket joints. It is not often that such care is taken in protecting the universal joints, the usual casings being of leather. Throughout the chassis splined shafts are used instead of square, these being, of course, far more satisfactory and less liable to cause slackness.
The back axle is a substantial piece of work. The final drive is by bevel gearing, and the differential is also of the bevel type. A point in the design is that the bevel pinion is provided with ball bearings at each end so that there is no overhang, chattering and wear on the bearings being thus greatly; reduced.
The axle is of the three-quarter floating type, the wheels being supported on the axle tubes by large diameter New ,Departure double row ball races. The inner ends of the driving shafts are supported on Hyatt roller beirings, and the whole axle is so arranged that the driving Shafts can be withdrawn quite easily without removing the wheels.
At each side of the differential casing is a small plate which, when removed, allows for adjustment of the thrust ball races. The adjusting nut is locked into position by a projection which is in one with each cover.
Both brakes act on the same drums, the hand brake working on the inside of the drums, and the foot brake on the outside. These brakes are provided with butterfly nut adjustment. The whole chassis exhibits considerable care in respect to detail. For instance, in the, springsall the leaves are ground and polished, so that lubrication is a simple matter. The fan is on a swing bracket so that it can be easily adjusted. The footboards are mounted on substantial brackets and are joined together by a tie rod which passes right across the vehicle under the frame. Large lubricators are provided at all important points.
We have said nothing yet of the radiator. This is of the tubular type with horizontal gills: The wheels are all provided with detachable rims and 8-20 by 120 tyres.
The price of the chassis complete is at present 2550.