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FORWARD-CONTROL CAB Has Become Popular
A Discourse U pon the Merits and Disadvantages of th e Driver's Forward Compartment, Together with a Few Suggestions for Improving It
THE chassis that has its steering control mounted on the off side of the engine is now adopted for most double-deckers and for the larger sizes of single-deciter. For some time after its introduction this design of
chassis was not favoured to any great extent by the coach owner, because it was considered that the lack of symmetry of the front portion spoilt the appearance of a vehicle, which was intended to have as elegant an exterior as possible.
This prejudice is, however, fast dying away, owing to the fact that the off-side cab is now of better design and has become so common that it excites no comment. Consequently, if the maximum amount of body space be required within a certain overall length, there will be little hesitation in selecting the forward-control type of chassis, even for the most luxurious type of longdistance coach.
Forward control not only saves valuable space, but the driver is seated in a better position, with regard to his view of the road, and, although the general loading line of the chassis is low, the driver's seat is usually about 6 ins, higher than those of the passengers.
Furthermore, when there is a half cabin the view from the near-side front portion of the main saloon is unobstructed. Full advantage may be taken of this relationship of cabin and saloon if the near-side front window be undivided, the roof cut back at this point to the bulkhead and no route or destination indicator situated in this position.
Nowadays the driver's cab usually has a sloping screen and the seat is more comfortable than the pattern often provided with the conventional form of steering. The semi-bucket type of chair is much in favour and the back is generally high, so as to give the driver sufficient support.
A drawback to the advanced-cab position is that the doorway has to be cut over the front wing and, in order to obtain a few inches of horizontal landing, the bottom of the door has to be almost level with the top B12 of the wheel, making necessary an intermediate step.
This step has to be recessed into the body side if there ls to be a sufficient width of tread, otherwise it will project beyond the legal limit of width. This, however, is not so great a disadvantage as it may at first appear, seeing that the driver uses the door only at the beginning and end of the journey, or on those rare occasions when some mechanical adjustment is necessary.
The difficulty may, however, be surmounted by providing an off-side door behind the bulkhead. This door May be of the coach or private-car type, opening outward like the driver's usual door. In this position it becomes also an emergency. exit for the passengers.
If this method of entry be adopted the Cab Odor is omitted .and the driver gains his seat through an opening in the bulkhead. This entrance may be left permanently open,
• or be provided with a sliding door. The former arrangement simplifies communication.
between driver and conductor. Furthermore, if the front off-side seat faces the rear there will be little temptation for the passengers to converse with the driver, who will not be sitting in the bulkhead opening, but immediately to the left of it.
When the forward cab is used for the pleasure coach the slope of the screen may be repeated for the front of the main saloon.
Now that there is but little demand for a totally disappearing top, the forward cab becomes suitable for the all-weather coach, because there is seldom any need for the cab roof to open and the top cover may slide from any desired position behind the dash.
If the owner cannot be reconciled to the appearance of the off-side cab he may still have the forward type of steering and a fully balanced front to the vehicle, by adopting the full-width compartment.
The Full-width Cab of the Trolley-bus.
A near-side seat in line with that of the driver then becomes available. Although many an agile passenger would like this seat, with its excellent observational facilities, it is more suitable for a courier.
The trolley-bus usually has •a full-width cab, and when the petrol engine is finally disposed under the floor this pattern of front will probably become a common feature of all types of service bus. With the engine as now mounted and its partial and complete enclosure by half and full-width cabs respectively, it would appear to be but a logical step to redesign the engine so that it encroached less above the top of the chassis, the whole being available for arranging seats.
Although few persons would object to the suppression of the bonnet, there are many who regard the radiator shell as a decorative as well as an essential item of the chassis. The radiator, however, would, for any new type of under-floor engine, still be retained in its old position. The trolley-bus, with its dash devoid of radiator, looks somewhat plain, although its austerity may be relieved by recessing the headlights on each side of it.
Necessity of Efficient Ventilation.
The cab, whether of .half or full-width design, should not only be provided with means for permitting fresh air to enter, but it is also important that the vitiated air should escape readily, owing to the proximity of the engine. A stream of air entering through the screen is driven against the front of the bulkhead and, if it cannot at once escape, is driven downward and causes an objectionable draught.
There should be, therefore, an open ventilator at the top of the bulkhead, whilst, as an additional outlet, there may be a glass louvre at the top of the driver's door and a corresponding one on the other side of the cab. A ventilator may, if the vehicle be a single decker, be disposed in the roof of the cab. This arrangement may also be employed in a double-decker if the top saloon does not extend beyond the front bulkhead of the lower main saloon.