COMMER INTRODUCES F1\ ENTIRELY NEW MODELS
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the imaginative mind numerous desirable characteristics are called up by the word "Superpoise." It suggests, for example, mechanical correctness, graceful proportions, balance and efficiency. It has been coined by Commer Cars, Ltd., Luton, to designate a new range, and having closely examined some of the chassis included we have formed the opinion that a good name is well deserved.
The Superpoise range consists of five models of 1, 2, 3, 4-5 and 6 tons capacity, respectively. These replace the existing chassis of corresponding ratings, but the 8-cwt., 15-cwt. and 20-25-cwt, models are being continued. With standard lorry bodies, all thenew machines, except the 6-tonner, come within the 30 m.p.h. limit, whilst in certain forms this also weighs under 2i tons. Every model, except the 13-tonner, is offered in two wheelbase lengths.
Basically, all five new vehicles closely resemble one another, and they incorporate many novel and interesting features. Perhaps pride of place should be given to the relative positioning of axles, engine and driver's compartment, 816
because in this lies the significance of the name. The layout appears to constitute a happy compromise, and affords ample body space, correct weight distribution, only moderate overhang, reasonably short wheelbase and good comfort for the driver.
At first glance the machines appear to be of the normal-control type, but in point of fact the power unit does just protrude into the cab. Nevertheless, as some of our pictures show, there is no encroachment upon useful space, and a
feature is that seating accommodation is afforded for three persons with reasonable comfort.
For the first time, the Commer concern is employing an all-steel cab. Before embarking on this course, bowever, it evolved a method of definitely ensuring against distortion, which ultimately leads to cracked panels and like troubles, The whole arrangement is most interesting and, we believe, unique.
Cab, scuttle, bonnet, radiator and
wings form a unit, which is built up on What is virtually a subsidiary frame. This is mounted on the chassis frame at four points, but these are so arranged that chassis wrack or weaving sets up no stresses in the cab assembly. Another name—" Diafiex —has been originated and applied to this mounting system.
The four points of support mark the angles of a diamond (hence the first part of the name), one being in the centre of the front cross-member, the next two being just outside the frame side members, in the plane of the dashboard and in line with the rear engine mountings, and the fourth being on the middle of the first cross-member behind the gearbox.
A moment's thought reveals that when tile frame is warped to the extent of any one cross-member being displaced angularly about the frame longitudinal centre line in relation to the next cross-member, there is no relative movement between cross-member centre s. Therefore, when excessive upward or downward displacement of one wheel occurs, although the transverse line through the side cab mountings is moved out of parallel with the first and third cross-members, there is no force tending to stress any part of the cab assembly, including its sub-frame, because this can rock on its front and rear mountings, nor is there any relative movement between the last-named points.
Whilst the foregoing constitutes an apparently incontrovertible theoretical explanation of the functioning of the system, a practical demonstration is even more convincing. In our presence a vehicle was driven up an 18-in, ramp placed under one front wheel. A photograph taken at the time is reproduced. This caused material twisting of the frame, but no indication of cab distortion could be detected. Both doors opened and closed .freely and all controls functioned normally.
By way of contrast, an earlier model, with coachbuilt cab conventionally mounted, was similarly treated, but in this case the wheel was raised only 12 ins_ Under the stress thus imposed, both doors jammed and the clutch control would not operate.
In connection with this matter of control functioning, the placing 'on a common plane of the cab side and engine rear mountings is noteworthy. Obviously, the power-unit displace ment, under frame distortion, will follow that of the cab and radiator. Accordingly, no trouble is likely to be experienced with control rods, piping, cables, etc., interconnecting these three units.
Accompanying drawings show details of the actual mountings. Rubber insulation is used for both engine and cab; in the latter case Metalla.stic bushes form the elastic elements and are housed in neat alloy die castings. • Again, for the first time, the company is standardizing hydraulic brakes, Lockheed equipment being employed on all the Superpoise range, except the 6-tonner. On the four models ranging from 11 tons to 4-5 tons, Cowdrey shoe gear is used, whilst the biggest chassis has Bendix brakes.
Outstanding among other new features are a considerably improved power unit, designed for greater economy and durability than its predecessor; new steering gear—of Commer manufacture—another feature calculated to lessen the driver's labours; stronger and lighter frames; a heavyduty gearbox, with constant-mesh third gear and provision for two power take-offs; Layrub universal joints; sturdier back axles, with straddle pinion bearings and overload crownwheel pads; improved progressive springing, and wider spacing of the twin rear tyres.
Before going into the details of these components, the main dimensions and prices of the new range must be given.
Costing respectively £214 and £220, the 11 and 2-tonners have 70 b.h.p. (rated at 20.92 h.p.), 75 mm. by 120 mm. six-cylindered petrol engines. The wheelbase of the former is 10 ft., whilst the larger chassis is available with a wheelbase of 10 ft. or 12 ft. 9 ins. For these two dimensions, the overall lengths, respectively, are 16 ft. 11 ins. and 19 ft. 101 ins., whilst the body spaces are 10 ft. 41 ins. and 14 ft. 51 ins.
The 2-tanner has 6-20 tyres, with twins at the rear, whilst the rear equipment of the 11-tonner is 32 by 6 single truck tyres. Chassis weights for the smaller and larger of these two models are, respectively, 281 cwt. and
B I Et
30 cwt., whilst the maximum gross laden weights (for plating purposes) are 4 tons and 51 tons. For these figures, however, R.H.S. tyres are stipulated on the rear of the 11-tanner and 32 by 6 all round on the 2-tanner.
• The 3-tonner particulars are as follow :—Price, £237; engine, as above; wheelbase, 10 ft. or 12 ft. 9 ins.; overall and body lengths, as above; tyres, 6.5-20, twin rear (32 by 6 R.H.S. twin rear for maximum loading): chassis weight, 302 cwt.; gross weight limit, 61 tons.
4-5-tonner: Price, £275; engine, 80 b.h.p., 27 h.p., 85 mm. by 120 mm.; wheelbase, 10 ft. or 13 ft. 9 ins.; overall length, 16 ft. 2 ins. or 21 ft. 102 ins.; body length, 10 ft. 41 ins. or 15 ft. 111 ins.; tyr6s, 32 by 6, twin rear (34 by 7 for maximum loading); chassis weight, 351 cwt.; gross weight limit, 8/ tons.
6-tonner: Price, k333; engine, wheelbase, overall and; body lengths as 4-5tonner; tyres, 34 by 7, H.D. twin rear; chassis weight, 41 cwt.; gross weight limit, 91 tons.
These prices represent a small reduction. on the range superseded.
All models are also available with Perkins six-cylindered oil engines, of
85b.h.p.Having
a sturdy one-piece cylinder and crankcase casting of nickel-chrome iron, the engine possesses many attractive and up-to-date features. A well. designed head promotes efficient combustion; adequate water-jacketing ensures uniform cooling, and a robust, counterweighted crankshaft mounted in four bearings minimizes vibration.
For the inlet valves silicon-chrome steel, and for the exhausts austenitic steel is used. The pistons are of castiron and the full pressure lubrication system includes drilled connecting rods to supply the gudgeon pins, and jetfeed from holes in the big-ends to flood the cylinder Walls.
A duplex chain, with hydraulic