New Vehicles for the Trials.
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The Straker-Squire 1-ton Van with Worm Drive and "Concentric" Back-A_-1-1c.
The latest production of Sidney Straker and Squire, I.tcl., is the one-ton van or lorry chassis; two of these are entered for the forthcoming R.A.C. Trials. This chassis has been designed and constructed to meet the growing demand for reliable vehicles capable of dealing with such a load. The particular machine under notice could not, by any chance, be mistaken for a converted pleasure car : it is soundly built, and most business-like in appearance.
The space available for the body, which may be of any description, is sufficient to allow the vehicle to deal efficiently with the bulkiest of articles. The 'overall dimensions of the chassis are : length, 14 feet 3 inches; width, 5 feet 6 inches ; wheel-gauge, 4 feet 6 inches; wheel-base, so feet ; length available for the body, measured from the front of the driver's seat to the extreme back cross-member of the frame, 8 feet 6 inches.
The frame is of pressed channel-steel, and the underframe is formed out of stiff, steel plate, which also does service as an undershield. This method of construction provides a very rigid support for the engine and gear-box, and affords them the greatest protection from the mud and grit that is thrown up from the roadway. The underframe and shield may partly be seen in our illustration of the clutch-gear (page 585).
The engine presents quite a clean and simple tout ensemble. It is of the vertical type, with all its four cylinders cast in one piece. The cylinder diameter is 3:1 inches, and the pistons have a stroke of 4,1 inches. All the valves are mechanically operated, and are interchangeable; the exhaust valves are situated within pockets on the near-side, and the inlet valves are in similar pockets on the off-side of the engine. The cooling of the walls should be very effective, as the water-jacket is continued down to the foot of the cylinders, and the water-space is of such an area as to offer the least resistance to the flow of the water. Circulation is
dependant on the thermo-syphon principle, and, in order the better to promote the flow of the water, the upper portion of the radiator is provided with a large water-space, as will be seen in our illustration of those parts which are forward of the dashboard—the left-hand one, above.
The location of the low-tension magneto, and of the eover which encloses the make-and-break gear, are also clearly seen in these two views.
The make-and-break gear-cover may easily be removed, by the unscrewing of two wing-nuts; one illustration of the engine shows this cover removed, and from this it will be seen that a horizontal, longitudinal shaft is driven by spiral gearing from a vertical shaft, which latter receives its motion through similar gearing from the inlet camshaft. On the horizontal shaft are fixed four face-cams, for the purpose of operating the trip-levers of each make-and-break plug. The trip-levers are drawn towards each other, and kept up to the cam faces, by means of helical tension-springs:
It is the practice of most motor manufacturers of the present day to fix the timing of the low-tension ignition. On the engine at present under consideration, however, provision is made for a slight variation of the timing of the spark. This is effected from a small hand lever, which is mounted on the dashboard; by this means, the spiral wheel -on the horizontal shaft is caused to slide along the shaft, and thus to alter the angle of advance, each face-cam being thereby advanced or retarded an equal amount. The whole arrangement of the ignition gear is, at the same time, original, neat, and accessible, whilst the aluminium cover ensures perfect cleanliness and protection for all the component parts.
The nickel-chrome, steel crankshaft rotates in phosphorbronze bearings that are lined with an anti-friction metal. The lubrication of the engine is automatic, by the splash method, but the design of the crank-case is such that the oil therein is at a constant level. This is effected by making the case, into which a small gear-pump delivers a large quantity of oil, as shallow as tx)ssible : the overflow from the shallow crank-case runs back to a large sump, which contains the oil-pump. The exact position of the oil-pump is at the foot of the vertical shaft which actuates the ignition gear. Both our views of the engine show the perforated, ball-headed plugs, and these fit into sockets that are cast on the crank-ease covers. The oil supply may be replenished through either of these plug-holes, and the perforations permit of easy " breathing " for the crank-case.
The carburetter is of the automatic type, and above it is situated a simple throttle-valve, which is operated by a small hand lever that is placed on the steering pillar, just below the steering wheel. This lever may be set for any desired engine speed, and the subsequent control of the engine may be effected by means of an accelerator pedal. This Arrangement provides for easy -control, and the avoi LAnce of gover nor complications. The details of the inter-co, of the hand control and the foot accelerator are cleal.y shown in the illustration of the clutch gear.
The clutch is of the leather-faced, coned type. The thrust of the clutch-spring is entirely self-contained within the clutch, so that there is no end-thrust, except at the moment of gear-changing. The clutch-adjustment is perfectly simple ; it consists of a short compression-rod and two nuts, the screwed end of the rod passing through a trunnion between the upper ends of the clutch-bridle links. The flywheel is of ample proportions, and the space between the clutch-cone and the rim of the wheel is bridged by six vanes, with the object of drawing a strong current of air through the tubular radiator.
The gear-box is of compact design, with short shafts, and provides for three speeds forward, and one speed reverse. The gear-changes are effected by a single handlever and gate-quadrant, thus differing from all the previous commercial motors which have been built by this company. The top, or third gear, is a direct-through drive. The transmission from the change-speed gear-box to the live back-axle is by a cardan shaft, and worm and worm-wheel gear. The " concentric " back-axle is of ample strength tor the designed load : it comprises a central, cast-steel casing, in which is contained the worm and differential gearing, and two, mild-steel, tubular sleeves or arms on which the road-wheels rotate. The drive to the road-wheels is transmitted through two enclosed shafts, which are relieved of all but torsional strains by the tubes: no bending strains, due to the load, are set up in them. The axle-casing is anchored by the long, tubular sleeve which encloses the cardan shaft. Both the change-speed gear-box and the axlecasing are fitted with ball-bearings.
Our illustration of the complete chassis will convey a good idea of the proportions and the general arrangement of the machine. The road-wheels are of the artillery type, and are fitted with solid rubber tires, the sizes of which are : .87o by 75nun., for the leaders; and 870 by toomm., for the drivers, Two brakes are fitted : a foot-controlled band-brake, which operates on to a drum at the after-end of the gearbox (this isnot seen in the illustration of the chassis, as it is below the petrol tank), and a hand-operated brake, of the expanding type, which acts within a brake drum on each driving-wheel.
The leading-axle is constructed according to Butler's patent, with stamped-steel ends, which are securely riveted to the axle-body of two pieces of steel of channel section, back to back. The steering gear is of the screw-and-nut type, and is quite irreversible.
The petrol tank is mounted on the chassis, in such a position that it is enclosed by the driver's seat, and the feed to the carburetter is by gravity. By making the tank as a part of the chassis, it is not necessary to loosen any unions, or to break a single joint, in order to remove the body : interchangeable bodies may thus be used without trouble.
The smooth and silent running of the engine on the van which we illustrate, was one of the points noted by us when we recently inspected this new model at the company's London depot, Nelson Square, Blackfriars, S.E. The photographs, from which the accompanying illustrations are reproduced, were speci_J ally taken on that occasion for "THE COMMERCIAL MOTOR," and they are the first-published illustrations of this most promising vehicle.
The 2-ton Straker-Squire Model.
The illustration of the van bearing the legend " Stop this van if you have goods to send "is of another entry of Sidney Straker and Squire, Limited. It is at present employed in demonstration runs between London and Maidstone, a daily trip of some 72 miles. The van leaves Nelson Square about noon for Spitalfields Market, where it takes a full load of empties ; it leaves there in time to arrive at the fruit farms at Maidstone about five o'clock. Loaded up fully at this point with three tons of fruit, it leaves about six o'clock, to arrive at Covent Garden some 3j hours later. The van started running on this trip on the 1st August, and has done extremely satisfactory work. The object of the demonstration is to show to those engaged in the fruit-growing industry the capabilities of the petrol-propelled van for the rapid transit of fruit, and a considerable advantage is gained by the use of such a speedy vehicle, as the fruit may be picked later, owing to the time saved compared with that occupied when horse traction, or haulage by steam tractor or lorry, is employed. The van, we understand, negotiates Wrotham Hill, which is some two miles long, and is reputed to have a gradient, in parts, of i in 6, with a load of three tons on second speed. It is geared to run at speeds from 14 miles per hour downwards. An excellent report on the condition of the fruit delivered by this van to a leading firm of jam manufacturers has been received by the makers.
The engine is a four-cylinder one, and develops 22b.h.p. at about 900 revolutions per minute, The diameter of the cylinders is tosionn, and the piston-stroke is 33omm. All the valves are mechanically operated. The engine is of special construction, the main features of which are as follow :— The camshaft is placed on the top of the cylinders, so that the inlet and exhaust valves may he placed at opposite sides of the cylinders and may still be opera. Led by the same camshaft. It is claimed that this arrangement has many advantages, amongst which is, that all the valve-operating mechanism is thus removed far from dust and grit, and where it is more easily accessible. It also leaves the crank-case entirely free for the introduction of large and unobstructed inspection doors, and through these the big-ends of the connecting rods, and the main hearings, may be adjusted,.
The speed of the engine is regulated by a governor acting direct on the throttle ;. it may also be controlled by a foot
lever, and it gives a range of speeds of from 200 to 900 revolutions per minute. This pedal and the governor constitute the only means of control. The lubrication is on the splash principle, and low-tension magneto ignition is employed. The change-speed gear-box gives four forward speeds and one reverse. The changes of gear are effected by three hand levers (one for 1st and 2nd; one for 3rd and 4th ; and one for the reverse), placed in a central position on the chassis ; they are operated by the driver's left hand. The final drive from the countershaft is through side chains to
the back wheels. The petrol tank is placed under the driver's seat, and contains sufficient petrol for a continuous run of to hours' duration, with full load.