BUS BODY DESIGN AND CONSTRUCTION.
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The Various Kinds of Entrance and Their Disposition Discussed.
/TIRE bus which has a near-side back entrance is a 1 development of what may be regarded as the original pattern—that is, one having. a doorway in the middle of the back of the body. At first a hind platform was added, so that the steps could be placed at the near side, allowing the passenger to mount from the kerb, and a small circulating area was formed, adding to the convenience of access and providing room for the conductor *hen not collecting fares. The open hind platform panelled to the waist is a type seldom built nowadays, but the leading features of this form of construction are retained for double-deck bodies, as, by this means, a foundation is made for the staircase. The open hind platform is favoured abroad. In France it is used for passengers standing and often has the steps mounted at the middle in the rear. The open platform is also specified for buses to be run in warm climates.
The Enclosed Hind Platform.
The practice now is to enclose the hind platform so that seats can be placed here, which are as well protected as those in the saloon if there be a door at the steps. But if every available inch of space be utilized on the hind platform in this way any special circulating area—that is, space in excess of an actual gangway— tends to disappear. It is customary to retain the hind bulkhead with its entrance way, since it is valuable as a means of strengthening the body at a vital part.
The front bulkhead, or partition behind the driving seat, ties the two sides of the body together effectively at this point. If it be not pierced with any doorway, it can be made rigid without undue weight by the use of cross-bracing below the windows. Sometimes this partition is reinforced by screwing on a well-fitting inside panel of sheet steel.
If the near-side back entrance be right at the end of the body, then the back edge of the steps may be exposed, giving more freedom of entry and, incidentally, giving an opportunity (not to be encouraged officially) to those passengers who desire to mount or get off while the vehicle is in motion.
This aspect, however, must not be emphasized, because the back-entrance bus is regarded as safer than the -front-entrance type, owing to the fact that the passenger does not have to approach or leave the vehicle at any point between the wheels. On the other hand, the back-entrance bus must be vestibuled at the rear if protection from the weather and dust is to be afforded should exposed areas have to be traversed.
If a single door be pro c36 vided at the top of the steps, it may be hinged on the right-hand or hind corner pillar, and open inwards, lying against the inside of the back of the body. A. radius of at least 2 ft, 3 ins, must be left clear for the door in which to swing; hence, no seats can be provided in this part of the hind platform.
Side Panelling Beyond the Entrance.
It is usual, however, to plot out the steps so that there is at least a rounded corner, representing a radius of from 8 ins, to 12 ins., between the steps and the rear limit of the body. If the body by a long one, having an overhang in proportion, there may be room for a seat right across the back with a window beyond the steps. The usual rounded corner is chiefly employed as an item to enhance the general appearance; it also gives scope for the continuous off-side-and-back-seating arrangement, but on the near side it is seldom of much use except as a space for the conductor's locker. The design of the hind platform varies between these two extremes, the seating capacity behind the rear bulkhead depending on the seating plan adopted here and the type of door mounted.
A Single Door Opening Outwards.
A single door is occasionally hinged on the left-hand side and hung on the near-side standing pillar of the bulkhead entrance. When closed, the door reaches from this pillar to the right-hand side of the steps. The door stands, therefore, at an acute angle with the back of the body. The door opens outwards, so that the distance from the entrance in the bulkhead to the side of the body must correspond with the width of the door. The advantage of this method of hinging the door is that very little space is taken up which is likely to be required for seats. aoci, Of+ve-Y
The door at the steps may be dispensed with and a sliding door hung behind the bulkhead, or, as in the L.G.O.C. type of single-decker, there is no door at all. With double doors at the top of the steps each door usually opens outwards, where it lies fiat against the contracting panels. The disadvantages of this arrangement is that not only does the thickness of the doors decrease the effective width of the entrance, but any commode handles provided must be fastened to the inside of the doors.
The doors may also be of the double-folding type, being hinged to gether in .the centre and opening' inwards and towards the rear, or they may reach to the bottom of the step, as !n a front-entrance bus. Another method, not often seen, is to have a door at the top of the steps which slides to the right, a rail being framed into the roof to act as a guide.
The landing, or top of the hind platform, may be on a level . with the main flooring, or a further step has to be negotiated in order to reach the saloon. It is better to arrange the final step in this latter way than to concentrate all a them at the side of the platform, as the exertion of mounting is reduced when it is divided into two stages by the few paces required across the platform. The low hind platform is quite, a modern feature of the single-decker, although it has always been adopted for the double-decker. As the roof line is practically maintained throughout the length of the body, a lower platform increases the headroom here and facilitates access.
The Driving Compartment.
The conventional type of driving compartment of the back-entrance bus has the seat carried across the full width of the body, with a half-door on the near side, and panelling to the waist or a door on the off side. There is usually a .fixed window at the ends of the seat, with further protection on the off side in the shape of another window between it and the windscreen, with fa:Hhlies for signalling as already described. An interesting variation from the usual seating plan is that adopted by the Aldershot and District Traction Co., Ltd. In this instance, the driving seat is enclosed by a partition parallel with the central axis of the body, so that a longitudinal seat can be placed in front on the near side, which is included in the main saloon. With the forward-control type of steering the driver's cabin is entered by a special door on the off side. With a bus of this type the interior would be better lighted if the roof were cut back to follow the plan shape of the body, with its driver's cabin jutting out in front.
The Seating Plan.
The seating plan of the back-entrance bus has as its chief characteristic pairs of cross-wise seats facing forward, with a gangway between them. Occasionally a seat the full width of the body, facing the rear, is to be found at the back of the front bulkhead. it has the advantage that an extra seat in the middle is gained, but unless ample knee room be provided the passengers sitting at the ends of this seat experience some difficulty in reaching the gangway. Owing to the
presence of the high wheel-arch of the low-loading chassis, long seats towards the rear of the saloon are now a common feature. The problem of a moderately high wheel-arch may also be surmounted by placing a pair of seats, back to back if the centre of the arch be about midway between these seats.
The seats on the bind platform often take the form of a large corner seat running round the off-side corner. There is seldom accommodation for more than seven passengers on this type of continuous seat, as, for this capacity, the platform should be about 5 ft. long. This seat often has to be cut short as it approaches the nearside back corner, in order that the feet of sitting passengers shall not impede the gangway or door.
The body which has both a front and back entrance on the near side is very popular for the larger type of bus for service work in busy towns. It is ideal from the operating point of view, since no time is lost at the terminus in emptying the vehicle at the front entrance while the other passengers are entering at the rear for the return journey. It can also be arranged that the passengers mount and alight in the same way at any intermediate point if the front entrance be provided with a mechanically operated door. If both entrances be kept clear—that is, no gangway or flap seats are used— then there is usually a loss of a couple of seats if the capacity of a similar size of body be compared with one which has only a single entrance.
The two-entrance bus can be adapted for one-man or two-men operation. In the former category the rear doors are locked and the bus is used as a front-entrance vehicle, the driver collecting the fares. This alternative may be taken advantage of during slack periods. At the busy times of the day the passengers may enter at the front and leave at the rear, or vice versa. The use of the rear as an exit gives the conductor a better chance of collecting all the fares. With the forwardcontrol type of steering the forward door will not be in the same relation to the driver's seat; consequently, mechanical control is more difficult to arrange, capedaily if the driver's seat be isolated. A double-entrance bus is also unsurpassed from the safety point of view, because it has an extra door, which can be used in emergencies and which forms a more convenient exit than a door specially provided in the middle of the body.
When the front-entrance body is motinted on the forward-control type of chassis, the steps are placed farther back than opposite the end of the driving seat, but their position, relative to the dash or back of the bonnet, is much the same as with the conventional pattern of chassis. But if the steps be close to the hind wheel, or nearer to it than the front one, and, say, at least one-third of the passenger seats are in front of the doorway, then the body may be described as having a central or mid-way entrance.
The Necessity for an Emergency Exit.
If the type just described be not considered a frontentrance bus, then it will probably be decided that an emergency exit is not required. The conditions which render an emergency exit necessary are not always clear. When the fuel tank is mounted under the driving seat, or close behind it, there is an element of danger if the main entrance be adjacent to it, so that an exit at the other end of the vehicle is a reasonable precaution. But if the tank be suspended under the chassis just below the rear exit this door will not be of any use. If the tank be slung underneath more or less in the middle there is little difference in the value of either door should a fire occur, although two exits are always batter than one on such an occasion. A back-entrance bus is never regarded as one requiring an extra door, hut, after all, this is a condition which presumes a forward tank position. It is seen, therefore, that, with the central-entrance type of body the necessity for an emergency exit must depend entirely on the location of the tank. Happily, it is the common experience that this exit is seldom or never used. It has been suggested that, by adding convenient steps and a handrail, this door could be used as an additional rather than an emergency exit, or as a means whereby a front-entrance bus could be converted into a back-entrance one.
The central-entrance bus is not a common variety. It is most suitable to a large body, as then the seats are approximately equal in number on each side of the entrance. The stresses incidental to the mounting and dismounting of the passengers are well placed, but if the usual front entrance be supposed to have a somewhat dangerous step position, then the central-entrance btis has this feature more pronounced.
The True Back-entrance Body.
As already mentioned, the body which has an entrance in the middle of the back is the original type from which the so-called back-entrance body of to-day has been evolved. Its chief uses are as an hotel, railway or private bus holding from six to fourteen passengers on longitudinal seats. This variety of seat is hest suited to this style of doorway, because both it and the gangway are in the middle, unless cross-wise seats, each holding two, be adopted. The true back entrance has its uses as a country bus, but it is being rapidly superseded by the front entrance for this class of work. Its disadvantage is that the passenger must mount and alight in the roadway, although this is not so inportant a matter in the country as in a crowded city thoroughfare. From the constructional point of view, no space is wasted on the chassis, but the bus has no proper accommodation for a conductor, should it be considered desirable to carry one.
Having reviewed the chief characteristics of each type of entrance of the single-decker, it would appear that the front entrance has many advantages, and they are not affected by the size of the body. The best pattern, no doubt, is the combined front and back entrance, but if seating capacity is not to be sacrificed unduly, then it is most suitable for the larger type of vehicle.