Critical Tests Ensure Service Vehicle Efficiency
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The Mechanization Inspection Department is an Important Branch of War Organization. How Its Inspectors Work at Leading Commercial vehicle
Factories is outlined By a Special Correspondent
TlIE initialc A.I.D. are now as well known as any combination of letters of that nature, but, rather strangely, those that signify the Mechanization Inspection Department are far from being so familiar. Of similar ultimate importance, the M.I.D. probably has an equally exacting job, but, maybe, its value in certain branches is overshadowed by the very thoroughness of the efforts of manufacturers of the various commodities.
In particular, this is so with the building of heavy transport vehicles, for the normal peace-time standards of tests were high enough to make any further check almost superfluous. Nevertheless, that a relentless inspection is carried out was obvious when I recently visited a famous commercialvehicle factory in the North of England. Here, inspectors are always on the alert, but one imagines that, ultimately, they must suffer from a semewhat frustrated feeling in view of the fact that their " bag " is relatively small. But matters do occasionally go adrift and the M.I.D. inspector is the man who sees that only sound machines are sent out to take their places in the service of the Army, Royal Navy or Royal Air Force.
Replete are Rare The chief M.I.D. inspector at this factory says quite frankly that the manufacturers' own machinery, for ensuring that they attain the necessary standard, functions so efficiently that there is little comeback in the way of rejects. However, his confidence in the works test department has not resulted in any abatement of his desire for perfection. Hels one of those wfm knows from practical experience the far-reaching effects of some quite minor trouble if it occurs when a vehicle is in the field.
When an engine unit is completed the factory's own inspectors put it through severe routine bench tests, after which the unit is passed over to the M.LD. inspector for testing to specification, which takes place on the same bench. These tests follow normal procedure, except that in each report the barometer reading is recorded so that due allowance can be made for any atmospheric variations.
After the bench tests the engine is stripped down and the various parts tested for any sign -of fault. Then comes the time for the engine to be supplied with all incidental equipment.
, Meanwhile, a bare chassis is gradually acquiring springs, wheels, brakes, fuel system and steering. The engine unit is mounted in the chassis; then a cab is fitted as well as any bodywork called for in the contract. At every stage the work is checked by the manufacturer's own inspectors.
Finally, the complete machine goes to the running shop and is handed over to the firm's road-test staff, the actual testing being supervised by the chief tester and observed by the M.I.D. inspectors. The first vehicle of each contract is given a strictly observed 100-mile run for road-test, purposes. Fuel consumption and turning circles are checked, braking and hill-climbing powers are observed and the general
• roadworthiness of the machine is noted. Throughout the remainder of the contract every 50th machine. is giveli a 60-mile test and the same procedure is followed.
The remainder of the vehicles receive • the manufacturer's standard tests, such as are given to their own ordinary commercial vehicles, but this time they are specially checked by the M.I.D. staff. After the road test any defects or shortages have to be made good before the vehicle is released as fit for Service conditions and placed in readiness for delivery to, or collection by, the Army, Navy or R.A.F.
Features of the Special Trials Before I went out to take part in an actual road test I traced out the route followed by the 'more extensive special trials. Whilst the latter are mostly on give-and-take roads they include sections of considerable severity. My own trip was a regular routine run consisting of a shorter circuit which, nevertheless, included the main 'features of the special trial. When we got on to the road it was apparent that the speed was controlled, the governor being set to 32 m.p.h. with a permissible tolerance of 2 m.p.h.
During every test a substantial overload is carried, nominal 10-ton vehicles being given ballast of 12 tons and nominal 3-tonners taking ballast of at least four tons. With such overloads, it is necessary that the machines shall climb a 1-M-10 gradient at not less than 9 m.p.h.; also they must stop and restart without running back on a gradient of 1 in 4. Actually, we did this in third gear with the auxiliary gearbox in action.
Most impressive of all are the braking tests, because exceptional -efficiency is demanded. Either hand brake or foot brake, independently applied, must be capable of holding the vehicle on a gradient of 1 in 4. Each brake, independently, must be able to control the machine at a speed of 8 m.p.h. on a half-mile descent of 1 in 10, also without aid from the engine.
Further, each brake used independently, without any assistance through engine compression, must be capable of bringing the vehicle to rest -from 20 m.p.h. in not more than 40 ft.
During these tests a careful check is kept on petrol consumption and where a unit fails to reach the prescribed standard it is sent back to the shops for further examination. As has already been made clear many faults make their appearance from time to time, but it is a commendable record that throughout the war there has. never been a vehicle towed back after. being sent out for road test.
For the purpose of articulation tests the worst imaginable conditions are reproduced at the works, a series of blocks and wells giving a rise and fall of over 9 ins, each way for the rear • bogie of a six-wheeler. Where winches are fitted the pull is tested against a powerful spring balance.
All these machines for the Services are built to a shipping height and, at the one-in-50 examination, the upper part of the cab is removed, so as to see that this objective is attained with the ease intended by the designer. When the cab top is removed for shipping purposes the windscreen can be folded down.
Tools Selected with Care Since the Service driver is not in the happy position of being able to slip round to the local agent when he needs repairs, careful thought is devoted to the question of tools and spares.. Each tool considered necessary , is inspected, checked, packed and, finally, sealed in the kit. Following each contract to its destination go an extra percentage of spare engine units and one per cent, each of axles and gearboxes for replacement purposes. Even so, calls come from all parts of the world for spares and, in view of the great delay that may ensue as a result of error, every care is taken to see that the parts are actually suitable in respect of material and correspond precisely with the components they are replacing. Before final packing all of them are treated with an anti-rust preparation. In the spares department it was interesting to note that women inspectors were apparently working with complete efficiency after a relatively brief training. The particular factory that we visited is not a newcomer to the job of making Service vehicles and quite recently the spares department dealt with an order for a machine produced in 1916, that is still functioning well. A further reminder of this maker's connection with the 1914-18 war was the presence of an Army chassis, repurchased in the 'twenties, which is now engaged in towing its modern successors around the works.