Novelty in Motor Sprinkler Design
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THE municipality of Khartoum has
• . two principal types of roadway under its supervision—the entirely unmetalled by-ways and the main roads, which consist of an asphalted surface, some 15ft. wide; with sandy margins at each side.' . The task of watering the unmade parts, as distinct from the prepared surface, calls' for a streetsprinkler with unusual characteristics. Not only must it be possible to cut out the central,flow as required, in order to conserve water when dealing with the highway system, but it is also important that the water pressure (one of the factors governing the width of spread) should remain constant irrespective of the speed of the machine.
It may be recalled that in a recent
article, describing the Dennis watering machine supplied to the municipality of Iammu for use on the local polo ground, we stressed the ability of this .type nf machine to conform with this specific requirement, a small independent power unit for driving the water pump being incorporated to meet this need.
A Dennis 3-ton pneumatic-tyred chassis carrying a 675-gallon cylindrical tank and an independent pumping set, has accordingly been commissioned by the Khartoum authorities. Constructed of gunmetal, the two sprinkler heads are fitted at the forward end of the frame, their controls being operated by levers alongside the steering wheel, so that the whole appliance can be conveniently operated by one man.
Normally, the two sprinkler beads give a 'total spread of 45 ft., but for operation on the main roads rotatable sleeves fitted to the heads are turned-so as to. restrict the water flow to the areas at each side of the metalled surface.
Water 'reaches "the -sprinkler. '‘ heads from the pump, which -in ), turn draws it from the tank. The pump is of the two-stage fire7engine. type, being driven by a singlecylindered water-cooled engine to which it is coupled direct, the whole assembly being situated Close behind the driver s cab and in front of the tank. For use When the driver is starting up a step is provided at the off side of the chassis, after which the pinuping engine is controlled from the interior of the cab.
A system of p*s and cocks and an auxiliary suction inlet enable the pump c37
to be used for filling the tank from open water, the tanks beside irrigation canals being the usual source of supply. Tests have shown that with the customary lift of 5-6 ft. filling is carried out at the rate of 125 gallons per minute, whilst the rate is 50 gallons per minute when the lift is increased to 20 ft.
An interesting and unusal detail of this machine is the air pump for the
inflation of the pneumatic tyres. In view of the exceptionally hot climate in which the machine operates, this pump is water-cooled by means of a by-pass from the main engine-cooling system.
The tasks which face municipal authorities in some parts of the world are without a counterpart in this country, but nevertheless British makers are able to supply types of machine for meeting unusual requirements, and the Dennis appliance provides another instance of the adaptability of the commercial motor for such duties.