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22nd July 1924, Page 12
22nd July 1924
Page 12
Page 13
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The Latest Requirements of the War Office for a 30-cwt. Vehicle Which Can Be Fitted with Pneumatic Tyres When Required.

THE new specifications (covering constructional details and required performances) for the War Department's subsidy-type light lorry was published last week. They define the type of vehicle the War Office is enrolling under the subsidy scheme, and it is officially stated that it is the intention of the Department to utilize this specification not only in respect of vehicles subsidized, but in respect of vehicles purchased by the War Office.

The subsidy-type light lorry will now differ very little from the light chars-h-bancs and 30-cwt. and 2-ten lorries of the latest British-made types of commercial use. Although the specificp,tion describes a pneumatic-tyred vehicle with 38-in. by 7-in. or 34-in. by 7-in, giant tyres, the subsidy may be granted in connection with vehicles which normally operate on solid or twin pneumatic tyres, but are so designed that a quick change-over can be effected, when desired, to the War Department standard pneumatics.

Provision is made for electric lighting, a speedo

meter, and a power-driven tyre pump, but these items need not necessarily be fitted to the vehicles accepted for subsidy.

Below we give in full the specification of construction details and, very briefly, some of the requirements under the head of specification of performance. In addition, the document includes full details of Professor Dalby's engine tests, a note on the properties of W.D. lubricating oils, a list of all that is required under the heads of (1) chassis, (2) body, (3) W.D. equipment, and (4) manufacturer's equipment, a table giving standard sections of steels for laminated springs, a set of blue prints giving dimensions of certain wheel and hub fittings, and a series of general notes.

Copies of the specification, and particulars of manufacturers building vehicles which comply with it, can be obtained from the Chief Inspector of Subsidize'd Transport, Caxton House, Tothill Street, Westminster, London, S.W.1.


Minimum swept out volume 3.500 c.c. Suitable arrangements must be Made so that in the event of the gudgeon pins working loose they cannot score the cylinder walls.

Where timing chains are employed, satisfactory adjustment for wear or stretch must be provided. A large and efficient oil filter to be fitted in the oil system in an easily accessible position for withdrawal and cleaning purposes, and it is desirable that this withdrawal shall not involve a loss of the main body of the crank-chamber oil. A lubrication indicator must be fitted within reach of the driver's hand when in the driver's seat, so that the driver may feel whether the system is working.

Test cocks to indicate high or low level of oil to be fitted in crankcase sump.

A positively driven 12 volt lighting dynamo is to be provided complete with accumulator, switchboard, wiring, two headlamps, two side lamps, one tail lamp. The whole to be of approved design (this item may be omitted on civilianowned vehicles enrolled under the subsidy scheme).


Ignition to be by high-tension magneto of a type standardized by the 1S.E.S.A., report No. 80, dated 1917, or any subsequent B.E.S.A. report superseding this.

In order to limit the variety of magnetos fitted to W.D. and subsidy vehicles contractors will be required to submit a list of magnetos they are able to re, one or more of which will be chosen by the W.D. A hand control for advance and retard must be fitted.

To enable the timing of the ignition to be readily set, the flywheel is to be clearly marked to a fixed pointer, with stamped directions.

Starting Handle.

A locking device to keep the handle vertically above the centre when not in use to be fitted.

Folding or detachable types of starting handles will not be accepted.

Cooling System.

Provision must be made so that the cooling capacity of the radiator can be reduced for use in cold climates.

The drain cock must he of not less than On. bore, and arranged so as to preclude the danger of accidental opening.

The radiator to be of the vertical straight-tube type, with detachable top and bottom tanks.

Tubes to be not less than 5-16-m. bore.

Filler-cap opening to be at least 2i-in. diameter or the equivalent area, with a cap of the hinged type secured by a screw adjustment without loose parts. Overflow pipe should be of not less than i-in. bore, and must be suitably baffled to prevent loss of water.

B30 Radiator to be protected from possible injury in case ofcollision by a stout bar or tube of at least 1i-in. diameter supported from the frame and not the radiator.

Petrol Tank.

The tank must be constructed of non-ferrous metal. For capacity see sub-para. (ii). Feed must be by gravity and a two-way cock fitted so as to retain 21 gallons in nokmal position, and to release this to carburetter in the third position of cock.

Filler Cap to be same as on radiator, but with suitable removable gauze strainer. An accessible filter of ample dimensions to be fitted between the tank and carburetter, so arranged that leaks of petrol cannot fall on exhaust pipe.


Multiple-disc or leather-lined clutches will not be accepted.. Clutch stop must be provided.


Vehicles are to be fitted with four speeds forward and one reverse.

Gate change to be employed. Safety catch for reverse to be fitted on change-speed lever.

A legible diagram showing the arrangement of slots to be fitted to the dashboard, unless slots themselves are clearly and permanently marked. A speedometer of approved design, positively driven from the transmission, is to be provided. The instrument to be mounted on the dashboard.

(This item may be omitted on civilian-owned vehicles enrolled under the subsidy scheme.) Gearbox easing to be fitted with a test plug or cock to indicate oil level.

Final Drive.

Rear axle to be of the fully enclosed type without tie-rod. Chain drive will not be accepted.

Jack Platforms.

Front and rear axles to have suitable platforms near the ends to receive the head of a jack, unless the shape of the axles is such that, in the opinion of the C.I.M.T., platforms are unnecessary.

With all tyres removed the platform or jacking place to be not less than 9* ins, from the ground.


Front and rear hubs and studs to be in accordance with the standard W.D. hub fitting and to he suitable for wheels 34 ins. by 7 ins. or 38 ins. by 7 ins., with 1.25 ins, offset, as described on one of the drawings accompanying the specification.

An alternative road-wheel equipment, which permits the substitution of the standard W.D. wheel on mobilization, will be considered in respect of civilian-owned vehicles enrolled under the subsidy scheme.


Tyres will be of the giant straight-wall type of approved British make. The same size will be used on all four wheels.

The nominal size to be either 34 ins. by 7 ins. or 38 ins. by 7 ins.

An alternative tyre equipment which permits the substitution of the standard W.D. wheel on mobilization will be considered in respect of civilian-owned vehicles enrolled under the subsidy scheme.

Tyre Pump.

A positively driven power inflator to be an integral part of the design. Inflators operated by the pressure in engine cylinders will not be accepted. A pressure gauge to be fitted. An efficient oil filter to be fitted.

(The first three requirements under this head may he omitted on civilian-owned vehicles enrolled under the subsidy scheme.)

Wheel Lock.

Front-wheel stops must be provided to prevent the tyres from fouling the chassis, Chassis Details.

The chassis weight is not to exceed 35i. cwt., but preference will be given to those firms who are able to reduce this weight. The items to be included when weighing the chassis are specified in an appendix.

Fitted and driven bolts must be used in place of rivets throughout the chassis for parts which are liable to replacement owing to wear or fracture, such as road-spring brackets. All boles must he drilled, not punched.

Minimum road clearance at all parts must not be less than 103, ins.

Frame to be suitably designed to take the standard W.D. towing-hook attachment.

'Springs to be constructed of one or more of the standard sactions for road-spring leaves described in one of the appendices accompanying the specification.

Engine and gearbox units must be mounted on a threepoint suspension system to avoid damage from frame distortion on rough ground. Chassis frames must not be weakened by holes in the flanges at positions subject to severe stress. Maximum overall width must not exceed:7 ft.

Tho track of both front and rear wheels measured from centre to centre of tyre should be the same, but a maximum difference not exceeding 2 ins, will be considered. Towing hooks or shackles of subatantial design must be provided at the front and rear.

The chassis frame to be braced against horizontal distortion, due to a direct or diagonal pull in any direction up to 20 degrees with the longitudinal axis of the vehicle. TJndershield, if fitted, to be provided with spring clips, so as to be readily removable without tools.


Clutch pedal on left, brake pedal on right. Foot throttle-control pedal must be fitted. Clutch and brake pedals are to work independently of each other.

Brake lever to pull on, to be well away from change-speed lever.

Both levers must have their movement independent of that of the steering wheel. Both levers to move forward to increase speed of engine. Both levers to move on a rack and to have an index plate marked to show what their movements will effect.

Throttle to be operated by hand lever, combined with foot-control pedal, in such a way that, on releasing the footcontrol pedal, the throttle returns to the position set by the hand lever.

All connections for throttle, governor, ignition, etc., to be by means of rods or tub-es, not wire or chain.


All wearing surfaces to be of large dimensions and easily enewable.

Brake shoes to be fitted with easily detachable and renewable wearing surfaces. Brakes operating on brake drums fixed to the driving wheels must be compensated. They must not be operated by wire, rope or chain.


Oil lubrication throughout the chassis is desired, although consideration will be given to an injector system employing a thin grease lubricant.

Wick-feed type of lubricator to be adopted wherever possible.

Loose caps to lubricator to be avoided. All lubricators must be readily accessible, and not require special tools for their operation. Engine lubrication system to be of sufficient capacity to last for a run of at least 200 miles with the vehicle fully loaded.

All lubricators for engine and gearbox to be of such a type that they will work efficientlywith the War Department standard lubricants. The main properties of these lubricants are shown in an appendix. A lubrication diagram, engraved on metal, to be attached to the inside of the dashboard to indicate essential parts requiring attention. The order of ignition also to be shown on this plate.

Spare Parts.

Illustrated detailed spare-parts lists to be provided for each type of vehicle, with a view to the provision of a supply of spare parts. Part numbers to be shown on the list. To facilitate identification, wherever passible the part numbers themselves are to be stamped with the spare part number referred to in the catalogues. All spare parts -which cannot be marked clearly with the part number during the process of manufacture to have the7part, numbers etched on afterwards by the readiest means asailable. The second and third standards, -when supplied, will be distinctly marked in addition to the part number.

With regard to case-hardened parts, such as gudgeon pins, the part number may, instead, be painted on in hard enamel, With regard to nuts, small bushes and such items as could not possibly be dealt with in the above manner, these will be strung on wire, and a metal disc with the respective part numbers securely attached.

In all cases the part number will be preceded by a symbol or initials (of not more than three letters) denoting the make of the vehicle to which the part belongs. It is further required that when high-tensile steels are employed the part he stamped where possible with the letter " T," followed by figures representing the ultimate tensile strength of the material ; thus, for a " 50-ton " steel the marking would be " T.50." The following main units, namely, engine, frame, gearbox, and back axle to be clearly marked with an assembly part number.


Full sets of cloth or process tracings of drawings -with loading dimensions are to be supplied with every type of vehicle.

Instruction Handbook.

A -handbook of driver's instructions for maintenance, together with a lubrication chart, is to be provided with each chassis, the book to be illustrated where necessary to show methods of carrying out roadside and garage adjustments likely to he met with by drivers in charge of vehicles. A specification of performance of the various parts of the chassis and the complete vehicle is included, from which we extract some of the salient features. Obviously a full copy of the specification mus1, be obtained by makers who desire to build to it.

The engine will be required to pass Professor Dalby's engine test,including a 5 hours' run without stop. Decarbonization must be possible in 5 hours, and big-end and main bearing examination in the ,same time. Petrol consumption must not exceed 1 gallon per 12 yehiciie-miles. The petrol tank most hold enough fuel for 120 miles, The clutch must permit starting loaded on top gear on a level road. The gearing must enable a vehiele loaded to climb a gradient of 1 in 44, or an average gradient of 1 in 10 at 8 m.p.h. for a quarter of a mile, The maximum speed required is 30 m.p.h. for one mile and an average of 22 m.p.h. A useful load of 30 cwt. must be carried. The turning circle most not exceed 45 ft. diameter for each lock. The vehicle must be capable, of running through soft sand up .to 10 ins. deep. Water 18 ins, deep must, not affect engine running. Accessibility is laid down as being of considerable importance, and not only as regards parts subject to roadside adjustment.


Organisations: War Department
Locations: London

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