Three Makers Co-operate in Building
Page 43
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New Silent Gully Emptier
THE diminution in the noise of operation of gully-cleansing machines has, of. late, received much attention, and this -problem has assumed special importance in those areas where it is necessary to carry out specific municipal tasks at night time. Until recently, gullies in the City of Westminster have been cleansed at night by manual labour owing to the disturbance caused by the operation of petrol-driven machines.
The fact that manual cleansing of gullies was unhygienic and inefficient was, however, fully recognized by the Westminster cleansing authorities, and to overcome the difficulties created by noisy operation, a specification for an electrically operated machine was framed; the outfit has been built with the co-operation of the Electricar, Scammell and Dennis concerns.
The outcome of this experiment is a battery-operated mechanical-horse tractor unit, drawing an articulated gully emptier. The pump is electrically driven from a separate battery and is quite silent in operation.
Starting first with the tractor unit, this has been designed to employ, so far as possible, standard Scammell 6-ton mechanical-horse parts. The drive is transmitted to the rear axle by a propeller shaft to which an electric motor is directly coupled. The motor is situated amidships in the centre of the frame and current is supplied by a 44-cell battery of 364-amp. -hours capacity.
The battery is divided into two sections, each part being carried in panniers on each side of the frame, whilst the necessary cables are plugged into conveniently situated holders to facilitate a quick change-over. The bat
tery boxes are held in position by clips, and with the use of an elevating truck it is possible to change over the main batteries and the battery for the gully pump in 15 minutes.
A neat hand controller is situated on the left-hand side of the driver, and five contact points ensure smooth acceleration with a full load. The speed of the outfit is about 10 m.p.h.
The gully-emptying unit, designed by Dennis Bros., Ltd., Guildford, is mounted on a semi-trailer chassis equipped with a Scammell retractable undercarriage for connection to the tractor. It has a capacity of 800 gallons of clean water and 400 gallons of sludge; a separate compartment is provided for draining off dirty water for return to the gullies.
The vacuum pump is mounted in a compartment at the front end of the unit and it is coupled to an electric motor which is automatically controlled to cut-in when the suction valve is opened. The battery for the suction-pump motor is carried in a quickly detachable container mounted beneath the frame; it has a capacity of 168 amp.-hours.
The rear wheels are shod with Dunlop 13.50-16 pneumatic tyres and Smith's hydraulic jacks are a permanent fixture. Tipping is effected by hand-operated hydraulic gear.
After some six months in service the outfit has proved highly satisfactory. It operates over two shifts, making a total of 16 hours a day, and, although certain gullies may be cleansed during the day time, the bulk of the work is carried out at night.
In an average working day (16 hours) the machine has proved capable of cleaning 46 gullies and 16 pits, the weight of the gully contents being 5 tons. The amount of water used is 2,400 gallons and the mileage is almost 20. Current consumption works out at 300 amp.-hours for the motive unit and 122 amp.-hours for the gullycleansing apparatus. This consumption is equal to 66 units, which, at the rate available in Westminster, gives a cost of is, 10d.
Since the capacity of the batteries is adequate for operation over a full working day, a second set of batteries is used and this is Charged at a time when " off-peak" rates are available.
At a demonstration of the outfit held last week we noted that the machine was commendably quiet in operation, and the results so far obtained show efficiency and economy.
The concerns responsible for the production of this interesting outfit are Scammell Lorries, Ltd., High Holborn House, London, W.C.1, which built the tractor unit and coupling gear, Electricars, Ltd., Lawley Street, Birmingham, which was responsible for the electrical equipment, and the development work, and Dennis Bros., Ltd., Guildford, which produced the gully-emptying unit. The batteries were supplied by the D.P. Battery Co., Ltd., Bakewell, and the Chloride Electrical Storage Co., Ltd., Clifton Junction, Manchester