THE "CM." TESTS A S-COMMERCIAL TRUCK.
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First Details of an Entirely New 25-cw and Instructive Results Ob Model, Together with Some Interesting h the Vehicle on the Road.
WE seem, nowadays, to have got beyond the point where man's faithful servant in the past—the horse—is being replaced by the motor (everybody, nowadays, who is at all goahead uses mechanical transport), so that when dealing with a new vehicle the question of how many horsed vehicles one mechanical van or lorry will replace does not crop up. The modern operator—who is, by the way, a very discriminating man—wants to know, first, how any newly introduced vehicle will suit his particular demands, and, secondly, how much it will cost both to purchase and to run. This undoubted fact was firmly implanted in our minds when the pleasant task of examining the mechanical details of the latest product of Morris-Commercial Cars, Ltd., and later, of trying it on the road, was undertaken.
From a specification, a great deal of information with regard to the capacity, performance and road-worthiness of any vehicle cannot effectively be conveyed to the reader, but, when the main constructional features are described, together with a report of a comprehensive road test, the results are not only interesting but they provide a fund of useful information to the prospective user.
Before going into the mechanical details of the new Morris-Commercial truck, it would seem opportune briefly to give the main dimensions and load-carrying capacity of the chassis. The new model is known as the 25-cwt. Super truck and, as its title implies, it is fully up to the work involved in regular transportation of loads up to the amouut stated. in passing, it might be mentioned that a load considerably greater than this was carried throughout our test (described later), and the results were in every way satisfactory.
With wheelbase of 10 ft. 8 ins, and track 4 ft. 8 ins., the chassis is capable of carrying a reasonably large platform, yet, as was proved during our run on the road, the machine can be easily handled. The overall length of the truck complete is less than 15 ft., and the overall width comes within the 6-ft. mark, facts which, combined with a
• turnino.' circle of only slightly greater than 40 ft. diameter, makes for easy manceuvring in confined spaces. The truck body is 8 ft. long and 5 ft. 6 ins, wide, and has a loading height of g ft. 4 ins. The sides and tailboard (1 ft. 9 ins. deep) can IA dropped, whilst the cab (which will be dealt with later) is a really comfortable affair.
In addition to the truck there is a Super van available, which, with iuterior dimensions for the floor of 7 ft. 10 ins. (length) and 4 ft. 8 ins. (width"), is really quite capacious because the inside height is no less than 4 ft. 61 ins. The loading height for the van, by the way, is vary much smaller than that of the truck, being 2 ft. 8i ins. only.
Turning now to a consideration of the chassis details, the main frame appears to be well up to its work, for the channels are 5a ins, deep in the centre and, having wide top and bottom flanges, it forms the basis of a very rigid structure. There are four cross-members, each one of which has a well-splayed-out fitting into the framesides, thereby distributing the load and forming an effective means of bracing to avoid "loxenging" of the chassis as a whole.
B24 • One cross-member struck us as being particularly ingeniously arranged—the tie between the front anchorages for the rear semi-elliptic springs. The member itself is bow-shaped in a transverse plane and a flanged channel in a longitudinal plane, whilst, on each side, ears to carry the pivots for articulating brake levers are formed by sheering and depressing the plate. This interesting form of construction is clearly shown in one of the drawings on the next page. Semi-elliptic springs are used fore and aft, those at the rear being outrigged from the main frame and shackled at their rearmost ends. Because an overhead worm-driven rear axle is employed in conjunction with an enclosed pro peller shaft, the rear spring blocks are mounted on trunnion bearings on the axle casing, to allow for the necessary relative movement.
The power unit has a capacity of just over 2ilitres, and is rated at 15.9 h.p. only, despite the fact that all production engines develop over 35 b.h.p. before being passed under test conditions, and many, after short service, afillreaeh the 40 b.h.p. mark. The power is developed at a comparatively low rate of revolution speed—around 2,500 r.p.m.— but this, of course, does not represent the maximum speed at which the engine will turn over. The four cylinders each have a bore of 80 nun. (the piston stroke is 125 mm.), and are cast monobloc with the upper half of the crank case. This particular casting is a very rigid structure, deeply ribbed internally to carry the three main beuxings for the crankshaft. The last-mentioned component, too, is sturdy and, combined with the stiff nature of the crankcase, undoubtedly accounts very largely for the smooth running which characterizes the unit when installed in a chassis.
A full-pressure lubrication system is used, a double-acting plunger-pump driven from an eccentric on the camshaft forcing oil to the crankshaft mains and, by internal passages in the walls of the shaft, to the big-end bearings of the connecting rod ; a supply is also by-passed to the two outer bearings (of four) for the camshaft. -Side-by-Side valves are enclosed by a cover which, by the way, is easily detachable, so that tappet adjustment can be effected on the road if necessary, but all moving Darts are well supplied with oil from the inside of the crankcase. A detachable cylinder head is, of course, a feature.
The inlet and exhaust manifolds are formed in one castz_ ing, which is attached to the valve side of the cylinder block. The carburetter, however, is on the opposite side, the mixture being fed through passages cast between Nos. 2 and 3 cylinders. This layout doubtlessly accounts for the splendid manner in which the engine will pull shortly after being started up. The mixture is first given a slight heat ing during its passage through the block, and then vaporization is further assisted by a hot-spot formed at the junction of the two systems—the inlet and the exhaust. A small item, but nevertheless one that is important, is the fact that the flanges of the single casting are split between the inlet and exhaust branches, so that •the unequal expansion which inevitably takes place (caused by the hot exhaust gases and the cold inlet gases) does not cause the stress in the manifold to be transmitted to the cylinder block and, contrariwise, prevents the manifold from cranking if the cylinder casting is very rigid. The dynamo and magneto are driven in tandem by spiral spur gearing, a Maxwell tyre pump being installed at the forward and of the auxiliary line. Cooling is assisted by an impeller pump and a large-diameter air fan, which is driven by belt from a pulley on the forward end of the crankshaft, a jockey pulley maintaining the correct tension automatically.
A single-plate clutch and three-forward-speed gearbox are mounted unitwise with the engine, the whole being sup ported in the frame at three points. The single-point attachment at the front is of more than passing interest, for the mounting is so arranged that the engine can plunge in and out, rotate laterally, or rock longitudinally. Actually, the stub-end of the crankcase assembly, i.e., the timing cover, fits into a yolk which, in turn, is held in a double trunnion support. Chassis distortion, therefore, is not passed on to the engine.
This covers the main features of the chassis design. We will now turn our attention to the behaviour of the vehicle on the road.
Mention has already been made of the general roominess of the cab. Actually there is acecommodation for two pas sengers besides the driver. Comfort has 'Obviously been studied, for the seat and back rests are suitabfy upholstered and each door has a winding window.
Engine starting throughout our test was practically instantaneous, a dash-operated strangler to the carburetter facilitating matters when the engine was cold. The vehicle we tested was brand new when we started nut, consequently some of the controls Inotably the gear lever) were a little stiff, hut doubtlessly after travelling a further thousand miles or so this initial stiffness will wear off.
The clutch takes up the drive very smoothly indeed, no matter whether the vehicle is standing on the level or on a severe incline. Actually; we made Several restarts on a gradient of approximately 1 in 51, with a load of 30 cwt., exclusive. of the driver and his mate. The first test to make was With the speedometer, which proved to , read only .4 per cent. fast ., We set off from the Morris-Commercial works at Smethwick on a cross-country route to the Watling Street, which seived to take us to our ohjectiVe=the Wellington Wtekin, neat Slaretsbury. Without taking any tisk in. driving, 26 miles were covered in the first hour.
The behaviour of this new Morris-Commercial truck on both main and secondary roads can only be likened to that of an ordinary touting ear, for the top-gear 'perftirmance is really comprehensive (all main road hills being takea he the engine's stride, as it were which, combined with light steering and a supple but non-roiling suspension System; -made travelling very comfortable and speedy. The 'engine seems to settle down to its work at about 30 tra..p.h„ and at that speed it appears to be capable of propelling the vehicle all day long if required, withont fatigue, and without any anPleasant vibration becoming apparent.
We turned off the main road at Wellington and took. the secondary road around The Wrokin, when Willow-Moor hill with its long gradient of about 1 in 6 had to be negotiated. This particular hill lies on the road between The Wrelsin and Little Wenlocic, . and With its narrow, leafy' and partially broken surface, proved an excellent test, Bottom .gear was, of,course, required, but the speedometer never dropped below the 7 m.p.h. mark, despite -Fhb fact that we had to ease up onseveral occasions to negotiate sharp corners.
Continuing. through Little Wenlock, another hill, even steeper than the first, was encountered. This particular incline—known as Malthouse Bank—was used for the purpose of taking photographs, so that a certain amount of manceuvring on the steepest part of the hill was required. Taking a general survey, the maximum grade was found to be about 1 in 5-A., yet, despite the full load carried 'by the new Morris-Commercial truck, there was never any doubt whatever in our minds but that the engine as well as the transmission was fully up to its work.
The brakes would hold the truck with equal satisfaction whether travelling forwards or backwards, at the steepest part of the hill, the hand system or the pedal system being independently capable of bringing the vehicle to rest. Tint road surface was distinctly greasy, but no matter how fiercely the brakes were applied a skid could not be provoked.
After a few more miles of secondary roads, we joined the main arterial road through Shifnal and Wolverhampton to the works at Birmingham. To our consternation, when we arrived there, the speedometer mileage recorder was found to have failed after 40 miles of running. Careful note, however, was kept of the course, so that by spending an hour or so with an Ordnance Survey map we 'were ale to obtain a fair approximation of the mileage covered.
As nearly as can be computed, •a total distance of 804 miles was covered, and as the amount of fuel consumed was 5 gallons 1 quart, the consumption works out at 15.2 m.p.g. —a highly creditable figure considering the nature of the work to which the engine was submitted. The oil consumption was not 'proportionately so good, but we were
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assured that future production chassis will show a great improvement, because the matter has already received attention in the works. -Taking the useful load as 30 cwt., the net ton-miles per gallon figure is very nearly 23, whilst the gross figure amounts to no less than 46; both are extraordinarily good.
Priced at £228 for th,e Home model chassis, and £270 and £288 for the truck and van respectively, this new Morris. Commercial vehicle thoroughly deserves the success which it must, so it 88£111s, inevitably receive.