PETROL RAIL INSPECTION CARS.
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A Type of Vehicle Recently Tested by the M.O.M.
IN OUR LAST WEEK'S ISSUE we briefly referred to a new design of petrol rail inspection car built to the order of the Ministry of Munitions, Railways Material Department, by the Motor Rail and Tram Car Co., Ltd., of Simplex Works, Elstow Road, Bedford. We have been fortunate enough to secure details of the constiuctipn of this type of vehicle, so that we are able to fulfil the promise which we made to our readers by amplifying our former somewhat meagre description.
The general appearance of the car can be clearly seen from the illustrations which we reproduce on the next page. So far as the technical detail is concerned, the engine is of the conventional four-cycle two-cylinder type and develops 20 b.h.p. All the bearings are of liberal dimensions, and are automatically lubricated from a gear oil pump in the sump of the crankcase, thts oil being constantly pumped through the oil filters ; an oil-level indicator and a large oil-filling aperture are provided. Ignition is by the standard type of high-tension magneto. The valves are of the poppet type and can be readily adjusted. The engine is cooled by means of a radiator of ample dimensions, situated longitudinally with the power unit, through which water is forced by a directly-coupled centrifugal pump, aided by means of a fan. The cooling effect is, of course, -equally efficient whichever way the car may be travelling. In other details the engine conforms to conventional practice.
The chassis -frame is constructed of 6 ins. by 3 ins. channel steel and is adequately cleated and gusseted so as to form a particularly stout member for the size of vehicle. The engine is centrally mounted in the frame and is of unusually heavy construction for its size and a proportionately large diameter flywheel is
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employed. The clutch is of the inverted cone type. To this component is directly coupled -through a flexible joint a " Dixon-Abbott " gearbox, which provides for two speeds in each direction by using machine-cut and hardened spur gearing only, there being no bevels or worm gear. To facilitate the operation of gear changing the clutch is provided with back stop springs. The control levers are conveniently arranged for the control of the car in both directions. From the gearbox the drive is taken to each axle by means of heavy roller chains, which enable both axles to be driven without the use of connecting rods, special provision being made to enable the chains to be readily adjusted, and in this attachment a spring drive is incorporated, which relieves any sudden strain on the chains.
The bodywork of the coach is of rather unusual construction, in so far as the barge boards are concerned. These boards, which are 6 ins, high, are carried the full length of the vehicle on each side. The seats are so positioned that they can be immediately lifted out in one piece in order to accommodate stores or other 'goods, which may be required to be carried, up to a gross load of two tons. The seats and dashboards themselves are panelled and framed in American ash.
A removable canopy on the Cape cart hood principle is fitted arid is held taut by means of straps. The driver, is accommodated on an independent reversible seat near the centre of the car, so arranged that he is able to have a good view of the signals and track ahead without actually occupying the front seats, which are used by the inspectors. The engine casing is alongside the driver and is so arranged as to provide additional seating capacity if required. Those possessing the front seats are protected from the
elements by dashboards nearly 3 ft. high, above which are swinging windscreens, capable of adjustment at any angle : when not required they can be swung right down so as to fit snugly into the groove in the end dashboards.
So far as dimensions are concerned we would refer our readers to the accompanying side and end view illustrations. The car is 14 ft. 6 ins. eve.head stocks and 6 ft. 5 ins. over main frame. The wheels are 24 ins, in diameter and are arranged so that they can be run on a track of 4 ft. Eg, ins. or 5 ft. gauge: The wheelbase is 7 ft.
, As we intimated in our previous reference the two petrol rail inspection cars which were delivered to the M.O.M. were recently tested on the BedfordHitehin branch line on the system of the Midland Railway. This particular line forms an ideal test track for a vehicle of this description in so far as it provides a wide variety of conditions in a relatively short distance. The line is at first more or less on the flat, then a steady climb for 24 miles of a. 1 in 120 gradient is encountered, as well as a number Of twists and turns and a tunnel which is half a mile long.
The cars had to undergo a thorough inspection at the hands of the district locomotive superintendent of the railway company and other officials before they were permitted on the line. The Motor Rail and Tram Car Co. undertook in their specification to attain a speed of 30 m.p.h. and to accelerate to 40 m.p.h. under favourable conditions of running. The officials were somewhat dubious of this latter figure being attained and held varying opinions as to the manner in which such a compaiatively light vehicle would traverse the points and crossings. As a matter of fact, under actual test, the average speed attained from station to stationwas slightly in excess of 33 m.p.h., and no difficulty was experienced in negotiating the points and crossings. The absence of sway of the vehicles and the ease of control were particularly apparent.
One of the ears was tested on paraffin and the maximum speed in this case was found to be 40 m.p.h., the average speed from station to station working out at 26i m.p.h. It is not intended, however, to operate the cars on this fuel, the demonstration on paraffin simply being. carried out to show what can be done in this direction. The tests proved in every way satisfactory and convinced the somewhat doubtful officials of the -capabilities and efficiency of the petrol-propelled vehicle when employed for inspection and other purposes on a permanent track.