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Ventilating and Heating
Page 83
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A Brief Summary of Devices for Coaches and Buses and How They Operate
IN addition to adjustable windows, a bus or coach should have other devices for maintaining ventilation when the windows are closed, such as in bad weather, as well as to assist the displacement of the vitiated atmosphere on a hot day. A ventilator on the roof, or at the cant-rail position, is placed to advantage for extracting the heated air, because this always tends to rise to the highest level.
The Airvac, made by Airvac Ventilators, of Honeypot Works, Darlington, is an air extractor which is fitted in the roof. It has two openings, both at the front and rear of the cowl. These ports are guarded by means of slotted vanes. When the vehicle is travelling fast the air currents passing over the roof are deflected by the vanes, behind which the air pressure is reduced. This causes the air inside the vehicle to be drawn out of the front ports.
How the Airvac Works.
At low speeds the reduction of pressure is compensated by the slots in the vanes. The air passes through the slots in the front vanes and is then deflected towards the rear air ports, so that an additional extractive effort is set up. The ports communicate with the interior of the vehicle through the apertures in the base plate.
The Ashanco system, as supplied by George Johnston, Ltd., 173-177, Shaftesbury Avenue, London, W.C.2, includes an air intake as well as extractors. The former is fitted in the front bulkhead and the latter are placed at the side immediately under the cant-rail.
The extractor is compactly designed and consists of a curved baffle plate behind which is the open ing of the main body of the extractor, communicating with the interior of the vehicle. This system is suitable either for the single or double-decker.
It is claimed that the air in each saloon is completely changed in three or four minutes and that an ample volume of air enters at the bulkhead, irrespective of speed.
Glass louvres above windows may be regarded as standard fittings on coaches, although they are also to be found on many service buses. Cox and Co., of 135, Lowee,Richmond Road, London, •S.W.15, the well-known manufacturer of windscreens, is also a maker of glass louvres. For the convenience of the bodybuilder the top channel is supplied so that it may be cut to length.
The louvre ventilators of, Joseph Gibson and Co., Tjnity Works, West Bromwich, Staffordshire, are made in various patterns. The ends of the louvres are designed to fit between the pillars with or without a top flange to screw on to the face of the cant-rail. The ventilator is made also with a channel along the bottom edge of the glass. A fourth variety has outside fixings both on the pillars and cant-rail.
Beckett, Laycock and Watkinson, Ltd., of Acton Lane, London, N.W.10, is the maker of the Beclawat Ventilouvre, which is built up from standardized parts to suit any size of window. An improved appearance is_obtained by an unbroken line Of 1 louvres and guttering along the whole side of the vehicle.
The Ventilouvre is easy to fit, because the side glass supports are permanently fixed to the body and the glass is held in position by side cover plates, which, being separately removable, simplify the replacement of a broken glass. These cover plates are held by screws locked by a device which prevents vibration.
The corners of the glass are easily kept clean, because the rubber channels into which the glass is bedded have rounded corners. Plain glasses may, therefore, be used and no special notching is required. The end supports are made as "rights" and "lefts," and double ones.
For the doors the supports are shorter, so that the bottom line of the glass is maintained throughout The Ventilouvre is supplied in a variety of finishes.
An Exhaust Heater.
The equipment of a long-distance coach is incomplete without a heating system. This is also of value in a service bus if it runs in a locality where the weather conditions in winter are severe. The Thermorad exhaust heater, made by A. W. Chapman, Ltd., Ranelagh Gardens, Hurlinghain, London, S.W.6, is operated by a control which can be fitted in any convenient position, enabling the temperature to be graduated at will. John Kay and Graham, of 260, Main Street, Bridgeton, Glasgow, William Truswell and Sons, Cossey Road, Sheffield, and the Buda Co., Cecil Chambers, Strand, London, W.C.2, can also supply heaters.