NEW SRN TINEL WITH BE THE-CAB "FLAT" ENGINE
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THE.details that we are about to give of the new Sentinel V-tonner may be looked upon as a curtain-raiser of what we may expect from our leading makers in the way of post-war vehicle design. It is not new in the sense that it is an untried proposition, because, in point of fact, the machine has been well tested under the most exacting road conditions for a mileage of well over 200,000.
As, however, permission has now been given by the M.O.S. for the maker to produce a very limited number for sale to civilian operators, against a permit, of course, we are now able to give our readers the first technical description of its salient features.
Although following normal Sentinel practice, the horizontal disposition of the engine beneath the chassis frame, on the off side and behind the cab, is an unusual feature in I.C.-engined -vehicles.
Such a design at once clears up the whole of the forward end of the chassis, and thus the driver's cab can be made roomy and free Of all obstructions.
The engine is a four-cylindered unit having a bore of 41 ins, and a stroke of 5f ins.; it gives 85 b.h.p. at 2,000 r.p.M. The bearings throughout are of generous area, a force-feed pump providing pressure lubrication to all frictional surfaces, includinig the valve gear, which is of the overhead type. In view of the comparatively exposed position of the engine, special provision has been made in the design to exclude dust and other foreign matter. The unit is three-point suspended on rubber mountings so that any sugg,estion of vibration is reduced to a minimum,
Being so amply powered for a 3-ton unladen-weight vehicle, it is reasonable to suppose that the engine will always have its load well in hand; nevertheless, a radiator of generous area has been provided. It is of the tubular-element type, and cooling is assisted by a four'bladed fan.
The gearbox is unit-mounted with the -engine, the drive being through a heavy-duty. 12-in, single-plate clutch. In view of the ample power available, the gear
box ratios have been worked out to make the utmost use of this feature, and are as folltiw; top, direct; second, 1.73; third, 3.31; bottom, 6.35 and reverse 5.51. The back-axle ratio is 6 to 1.
The drive to the rear axle, which is a fully floating, overhead-worm-driven unit, is by a short tubular propeller shaft having rubber-cushioned universal joints. A one-piece alloy-steel axle casing is used, and the wheels are mounted on taper-roller bearings.
With a high-performance vehicle of this type nc chances have been taken with the braking system, which is hydraulically operated with a servo device for the foot brake, The drums housing the Girling shoes are 16 ins. in diameter, with a shoe width of 4 ins, at the rear and 21 ins, for the front wheels.
It will be noted from one of the illustrations that ihe• frame is built up of deep-sectioned material, well crossbraced to give a strong and rigid structure. Semi-elliptic springs are used front and rear, those at the front being 3 ft. 4 ins, long by 2-i ins, wide, and those at the rear, which are of the progressive type, being 4 ft 6 ins, long by 3 ins. wide.
Carried to•the rear of the engine, midway in the chassis frame, is the fuel tank, which has a capacity of 30 gallons. The electrical equipment, which is a 12-volt set, includes a voltage-control dynamo, starter, horn, two windscreen wipers and a fully furnished illuminated instrument panel.
With the engine positioned as it is, full advantage has been taken to provide a really comfortable driver's cab giving the maximum degree of visibility from the seat. It is coachbuilt with hardwood framing, and has full
height coach-type doors and sliding windows. The• safety-glass windscreens are hinged at the top and can, of course, be opened or closed individually.
Regarding the general dimensions of this new Sentinel product. these are as follow:—Overall length Of the chassis, 19 R. 4 ins.; width, 6 ft. 8 ins.; height (to roof of cab), 7 ft. 5 ins.; overall length of body, 14 ft. 6 ins.; inside dimension, 14 ft. 2 ins.; width of body, 6 ft. 9 ins. ; wheelbase, II ft, 0 ins. ; wheel track, front, 5 ft. 8 ins., rear, .5 ft. 3 ins. ; turning circle, 44 ft. ; ground clearance under the rear axle, ll ins.
A steering wheel of large diameter in conjunction with cam and lever steering mechanism, with a correct choice of ratio, makes for ease of control. Incidentally, the steering joints are self-adjusting. The front axle is of deep section, and has its steering pivots mounted in plain bearings with taper roller bearings to take thrust -loads. The hubs are also mounted on taper roller bearings.
The disc-type wheels are equipped with heavy-duty tyres, the spare wheel and tyre being accommodated on a carrier at the rear of the chassis frame.
• It may be of interest to mention that, whilst the electric starter is of a heavy-duty type, provision has been made for hand-croaking the engine from the front of the vehicle. This particular point is mentioned in view of the unorthodox position in which the unit is located.
So far as chassis lubrication is concerned, this is carried out by aid of a Tecatemit gun.
In this vehicle the extent to which the cab imposes upon the available body space is almost at the irreducible minimum. . The under-the-bonnet engine design with forward control is, of course, as good in this respect, but the unusual layout adopted in the Sentinel has the distinct advantage of freeing the cab of any form of obstruction.
Arrangements have' been made for carrying out our usual road test of this new Sentinel machine, and we shall shortly be in a position to give our readers our own impressions of its performance on the road under fully laden conditions. The maker is the Sentinel Waggon Works (1936) , . Ltd., Shrewsbury.