An Unusual Use for a Sprinkler
Page 77
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TVIE motor vehicle which is built for sprinkling duties is usually employed by municipal authorities for work upon the highways, but in the case of an appliance of this kind which has recently been completed in the works of Dennis Brothers, Ltd., of Guildford, the use to which the machine will be put is most unusual.
The appliance, which consists of a Dennis 2i-ton 12-ft-wheelbase chassis carrying a 500-gal1on tank body, has been supplied to the municipality of Jammu (Kashmir) for employment upon the local polo ground. It incorporates in its design several features of outstanding interest.
Those who have had experience of street-sprinkling operations, when the water is delivered under pressure, will be well aware of the difficulties entailed in maintaining a constant width of
spray. This is due to the fact that most of the machines have the pump driven by the engine of the vehicle and running at a constant speed relative thereto. The natural consequence is that, when the machine is speeded up in the lower gears while accelerating from rest, a far wider spread is obtained with a given setting of the spray opening than if the engine be ticking over as the machine proceeds in top gear.
In order to ensure that the polo ground is evenly watered, this difficulty had to be overcome and, for this reason, it was found desirable to use a separate petrol engine for driving the pump. This unit is placed amidships on the chassis frame, between the water tank and the driver's cab, into which the controls project.
The power unit consists of a singlecylindered engine, water-cooled by the provision of a by-pass from the pump. The drive, which is arranged transversely, is taken direct to a small edition of the Dennis patent multi-stage turbine pump, so popular in fire-fighting circles.
As hydrants for filling the tank are available in the area in which the machine will operate, it has not been necessary to provide for the pump to fill the tank.
another advantage of the independent power unit is that, when a wide spread is required, there is no need for the machine to remain in a low gear in order that a high engine (and pump) speed May be maintained ; such a procedure would obviously adversely affect petrol consumption. The amount of
petrol consumed by the independent unit is very small, whilst the amount of fuel used by the engine of the vehicle_ is comparable with the figure obtained under ordinary transport conditions.
Another point of interest is that the sprinkler heads are not mounted at the front, where the spray is in view of the driver, as is customary with streetsprinkling machines, but they are located on each side at the rear end of the frame. By adopting this method the machine always travels on dry ground, whereas if the sprinkler heads were at the front the surface would be made wet prior to the passage of the vehicle, and the tyres would be liable to leave their imprint in the turf. As the machine is not for use on the roads and no traffic will, therefore, be encountered, it is not necessary that the driver should have the spray under constant supervision.
The machine is equipped with 38-in. by 7-in pneumatic tyres in order to provide a maximum ground clearance.