Sidney Straker and Squire, Limited.
Page 21
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Exhibit :—New Traction-Type Wagon for 5-ton Loads.
The newest and simplest design in the steam-wagon line will be found on the stand of Sidney Straker and Squire, Limited, of Nelson Square, Blackfriars, London, S.E. In the design of this vehicle, well-known and successful principles, as proved on the numerous traction engines which are in daily use, have been carefully followed. There is, however, one point which is foreign to the design of either traction engines or steam wagons, We refer to the sloping back wall of the fire box. Although novel as far as road locomotives are concerned, this idea is not by any means a new one ; it was used with successful results by Sir John Tharnycroft, some years ago, for marine work, and it is net unlikely that the sloping back wall is actually more effective, from a steam-raising point of view, than the vertical wall.
As applied to the new Straker steam wagon, the sloping back allows the second-motion shaft to be placed directly underneath the crankshaft, and in this way the vehicle may he short ened without sacrificing any of the effective heating surface of the boiler. This boiler has about 30 per cent, more heating surface than the older model of this company, and it has three sq-uare feet of grate area. It is constructed
to meet the requirements of the Manchester Steam Users' Association, and is intended to work at a pressure of 200 lb. per square inch.
The engine is mounted over the barrel of the boiler, and is of the com pound type : it has a high-pressure cylinder four inches in diameter; the low-pressure cylinder is seven inches in diameter ; and the piston stoke is seven inches. The general design of the engine does not differ very much from the type which has previously been made by this company. The crankshaft bear ings have, however, been made much longer, and they are carried in large horn plates, which extend upwards and backwards from the boiler shell ; the flywheel is situated within these horn plates, and is at the driver's left hand, so that, when it is necessary to pull the crankshaft round a little for the purpose of facilitating the meshing of the gears, the flywheel offers a handy leverage for the purpose.
The second-motion shaft, as mentioned earlier, is .situated immediately -Wow the crankshaft, and it is mounted on two long bearings which register in holes that are bored in the horn plates. This is, undoubtedly, a much better mounting than the plain " stud shaft " which is so frequently found on steam tractors.
The forwardends of the channel-section side members of the main frame
are securely riveted to the horn plates, 'which extend backwards for this purpose. The manner in which this atlachment is effected is clearly shown in the illustration. It is more than probable that the horn plates may be called upon to play a much more prominent part in the construction of future vehicles that may be built by this maker, but on this matter we are not yet in a position to give further information to our readers.
A heavy roller chain transmits the drive from the second-motion shaft to the back axle, and this important detail is about as simple as it can be made. The axle itself consists of a plain steel bar, Which rotates in two plain axle boxes; the latter are situated directly below the rear bearing springs, and the differential gear is mounted outside the off-side axle box : a long differential sleeve is, therefore, unnecessary. This is simply the type of back axle which has for many years been employed by our old traction-engine builders.
The arrangement of the various parts of this wagon is such that the vehicle may be handled with ease by one man, although the foot plate is arranged to take one man at each side of the boiler,
which has an injector and a firing door at each side. Another advantage of the arrangement of gearing as carried out in the design of this wagon is the possibility of shortening the wheel base. The wheel base of this wagon is to feet 6 inches, whereas that of the older model of the same make was 12 feet 8 inches. This means a decreased overall length (i8 feet), without reduction of the platform capacity. The front axle is made from a solid forging and Has a central pivot which iscarried in a cast-steel jaw that permits of the requisite amount of rise and fall which is due to the movement of the transverse, laminated spring. A stout stay extends from the bottom of the cast-steel jaw to the firebox, and the steering of the wagon is of the usual traction engine type which oonsists of a couple of chains and a worm-driven, drum. This company has taken the. precaution to enclose the worm and worm-wheel of the steering gear on all its steam vehicles, and is to be commended for thus ensuring good lubrication of these parts, and perfectly easy steering. The body on this vehicle has a superficial area of 77 square feet ; its totat length is it feet ; its total width is seven feet ; and the height of the platform from the ground line is four feet, one inch. The boarded sides are ig inches high and the whole of the woodwork is strengthened, where necessary, by the addition of plates and angles. A canopy over the driver's head is also. fitted to this wagon.