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THE VENTILATION OF ENCLOSED VEHICLES.
Page 92
Page 93
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Brief Details of Some of the Most Important Devices Which are Available for Securing Proper Ventilation on Saloon Buses and Coaches.
OF the various factors which contribute in a large measure to the comfort and convenience of passenrs in motorbuses and saloon coaches that which can he covered by the wide term "
ventilation" is as important as any. The extraction of foul air from the interior of an enclosed vehicle and the provision of a continuous supply of fresh air is absolutely imperative if a road journey over long distance is to prove a source of enjoyment and relaxation and not to be provocative of undue physical and mental fatigue. Many are the ways in which these objects are achieved, and one has not only to consider the different fittings built for fixing in the roof, but also the various forms of side ventilators, as well as drop windows.
So far as the main lights are concerned, the different types of window which are available and the methods by which they are raised and lowered will be reviewed in a later issue, and it is our intention here to deal solely with devices which are ventilators or extractors pure and simple.
To secure really thorough ventilation
on an enclosed-type vehicle up to 30 changes of air are necessary per hour, the actual number being determined by the cubic capacity of the vehicle and the number of people which it seats. Moreover, these changes must be effected whether the vehicle be travelling slowly or maintaining a good. average speed. Thus it will be seen that what is really required is proportionate ventilation, and a device which is claimed to meet this requirement is the Airvac, which is manufactured by Messrs. Airvac Ventilators, Honeypot
Works, Darlington. This fitting. has been on the market for some years and has given adequate proof of its efficiency on buses and coaches.
In the Airvac ventilator two distinct cycles of operation are employed, both of them being automatic. The lowspeed cycle enables the ventilator to produce the maximum ejector action at extremely low speeds (extraction actually commences at + m.p.h.), whilst the other becomes operative under higher speed conditions. The device is completely weatherproof and functions automatically and continuously whatever thee weather conditions. It is constructed of sheet steel, tinned or leadcoated according to type, and brags is used for all 'the interior fittings, the standard finishes for which are in nickel-plate.
The fittings which are available for use with the Airvac are distinctly neat and artistic, and the useful combine
D30 tion of an electric roof light, a shutter or grille and a ventilator increases the value of the device and renders it particularly suitable for saloon vehicles in which a high-class decorative finish is employed.
To overcome the retarding influence exercised by a grille or shutter when fitted below an Airvac the makers have patented a special mounting block which contains a series of specially shaped apertures communicating with the main
aperture. We illustrate the type MI Airvac, which. is specially suitable for buses and coaches, and the mounting block whichis .built for use with it. . Another patent type of air extractor and ventilator is the Ashanco, which is marketed by Geo. Johnston, Ltd., 173177, Shaftesbury Avenue, London, W.C.2. After many important anemometer tests this device has been found to give achange of air every, three minutes in buses and other enclosed vehicles. The Ashaneo is made in five models, four of them being roof models and the fifth, which is made in a number of sizes, to take the place of the front narrow swinging-out glass vents that. are usually fitted above the Main windows at the sides. Certain of the roof ventilators are plaeed sideways and fitted above the seats, in which position advantage is taken of the camber of the roof, with the result that the fittings do not increase the overall height In another model the deepest part of the extractor faces the forward direction of travel.
The Ashanco roof fitting is supplied with a rid having a central mesh, or with combined under-grid and lamp unit. The device is made of sine and the standard pattern for use in buses weighs 3+ lb.
Another company which has successfully tackled the problem of bus ventilation is Messrs. James Muirhead and Sons, 1,276, Maryhill lload, Glasgow, N.W., and in their device the difficulty of avoiding down-draught has been overcome. The ventilator depends for air extraction upon directing a wind current caused by the movement of the vehicle across the outer end of the up: take or outlet, the inner end of which opens directly into the body of the vehicle. A cowl, which is protected by an outer covering, is provided over the uptake. The Muirhead ventilator is made in four models, which vary only in height, the base fitting being the same
size in each case. One of them is shown in an accompanying illustration and it can be used with two different types of inner grid ; they are both nickelplated and therefore in every way suitable for use in high-class saloon buses and coaches.
Messrs. Muirhead and Sons also market several types of extractor which are designed purely for the removal of the smoke and foul air in an enclosed vehicle. Both the ventilators and extractors .001.111nenCe to function at extremely low vehicle speeds, and their
efficiency rises without a break as the rate of travel increases.
Messrs. Rovac Extractors also claim that there is an entire absence of downdraught with their patented form of ex ' tractor which acts whether the vehicle to which the device is fitted be travelling in the forward or reverse direction. Moreover, if in wet weather the vehicle be stationary, there is no chance of rain finding its way into the interior. The constructional features of the Rovac are clearly discernible from the complete and sectional views which we publish. As with other devices of this kind, the Rovac can he supplied with an ornamental roof grid..
Light weight is a feature of the Brown roof ventilator, which is the product of E. G. Brown and Co., Ltd., West Road, Tottenham, London, N.17. This type is constructed of light steel pressings and has a form of hinged top which prevents the open section from. falling owing to the effect of vibration. The ventilator can be obtained with a plain or a covvled top, the latter, permitting a constant flow of fresh air to enter the vehicle without any sugges
tion of direct draughts. With the Brown fittings a circular ring is provided for securing a neat internal roof finish.
Of the more orthodox forms of roof ventilator one can mention the type made by G. Beaton and Son, Ltd., Victoria Road, London, N.W.10, and R. Disturnal and Co., Bridge Works, Wednesbury. In the I3eaton devices, models with solid tops and those with
a glass panel are available The Dish tnrnal roof fitting is marketed in two sizes, one being Si ins. by 6i ins, and the other 11 ins. by 8 ins.
Having now dealt with some of the most important ventilating devices for roof use, we can briefly refer to those types which are used at he sides of buses and coaches. The old form of rectangular light is still largely employed for regularservice buses ;in ' some cases it is hinged at the bottom, and in others it opens from the side. The latter arrangement is, perhaps, the better, since it enables those in the forward part of the vehicle to be fitted so that they open at the front and those In the rear section to be opened in the reverse direction, thus ensuring a constant current of air ip tie interior. This method has certain objections, we know, but whatever its distalvantag,es it certainly does prevent the interior from becoming unnecessarily stufty. For saloon buses and well-appointed coaches considerable use is now being made of louvre ventilators! which are unquestionably neater than the ordinary fitting and, so we are told, every bit as efficient. One of the outstanding patterns in this class is the Beelawat, inade by Beckett, Laycock and Watkinsou, Ltd., liarlesden, .Lorid n, N.W.10. This the company calls the swivel type, and to appreciate its men i one must deal with each of the side windows as a whole. Strips of glass no arranged above the main light, and hese have a spring swivel action.. One or more strips can be used, and in the drawing which we reproduce it will be seen that three louvres are employed Each has an independent movement. Brass cups —in channel form—lined with rubber
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are arranged to grip the glass sections at each end. The cups are attached to a brass channel box, which is fitted in the side pillars, the spring pivot arrangement being contained in this special form of box.
Joseph Gibson and Co. also supplies louvre ventilators ; they are made of polished plate glass and are 81 ins. deep. One pattern is made to fit between the side pillars, a slight modifi cation of this having a flange along the top, which is screwed on to the face of the cant rail. In another model a i-in..flange extends .around the sides and the top, being screwed to both pillars and cant rail. If reqnired a metal channel can be used on the bottom edge of the glass. The louvre ventilator made by Cooper, Webb-Jones and Co, Stockwell Works, Walsall, for fitting on the outside of the top of drop windows, is now being supplied to many bodybuilders. It is an overlapping ventilator and enables a window to be lowered 2 ins. or 8 ins, without fear of rain entering. Its standard depth is 8/ ins., and it is provided with a channel at the top or along the bottom edge.