Scammell's Latest Fire-fighter Embodies New Features
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FOLLOWING the successful operation of the first Scammell fire-engine delivered to the Watford Borough Council early in 1933, the council decided to purchase a second Scammell machine; and this was delivereet_last week to the fire brigade. A demonstration was given before the Mayor and Mayoress of Watford, and members of the council, and the engine was named " Silver Jubilee."
The new machine embodies certain features of design that have proved successful on other Scammell models. and notable amongst these is the provision of a six-speed constant-mesh gearbox. The gears are engaged by means of internal sliding-dog clutches, and those wheels that are not fast on the shafts run on needle-roller bearings. A power-take-off is provided, and lubrication is by means of a submerged
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gear-type pump. Further details of this interesting gearbox were contained in a road-test report of a Scammell vehicle in our issue dated October 19 last.
A second feature of special interest is the rear axle, which embodies a double-reduction gear. The first reduction is obtained in a normal manner, through the medium of a bevel pinion and crown wheel, the bevel-type differential being accommodated within the crown wheel in the usual way, The second reduction is, however, obtained by means of two epicyclic trains, which have their sun-wheels on the ends of short shafts from the differential wheels. The planets are carried on a spider on each end of the axle shaft, and mesh with internally toothed rings formed on the inner periphery of the axle casing.
By this means the second reduction is obtained in a simple manner, and it is possible to keep the axle weight low, the design being compact and the mechanical efficiency of a. high order.
In order to obtain a low loading line a new dropped frame is employed, the side-members being parallel throughout their length, but dropped behind the engine and upswept over the rear axle. It is well braced by tubular cross-members, which are bolted in position, no rivets being used for either these members or the frame brackets.
The engine is a standard Scammell product and has a bore and stroke of 5 ins. and 5i ins. respectively. It is rated at 40 h.p., and develops a maximum of 85 b.h.p. The unit is threepoint suspended on rubber buffers, so as to minimize stress due to chassis distortion when operating on uneven ground.
Dewandre compressed-air-operated brakes are used, the pedal applying brakes on all four wheels. Air pressure is maintained by a Scammell twocylindered water-cooled air compressor.
The two-stage turbine pump, of 400750 g.p.m. capacity, is mounted at the rear of the frame, and is provided with two 5-in, suction points. The machine has two deliveries, and a range of 200 g.p.m., at 200 lb. per sq. in., to 830 g.p.m., at 50 lb. per sq. in., may be obtained.
Four 8-ft. 6-in, lengths of internally and externally armoured flexible suction hose are provided and are carried on top of the body in specially constructed racks. The first-aid hose is mounted on a reel on top of the body.
The machine is completely equipped, and carries a 40-gallon first-aid apparatus, Pyrene extinguishers, a searchlight and a gantry for an escape. Ample locker space is provided for, firefighting equipment and the 2,000 ft. of hose normally carried. Side seats are provided for the crew.