DEVELOPING AN EIGHT-WHEELED BUS CHASSIS.
Page 13
Page 14
If you've noticed an error in this article please click here to report it so we can fix it.
The Latest Details of the Versare Petrol-electric Multi-wheeler Which Incorporates Several Noteworthy Features in its Design.
TN our issue dated June 2nd we pub'fished a short article dealing with an experimental eight-wheeled bus chassis' built by the Versare Corporation, of Albany, New York, and now that the company have formulated plans for the manufacture of the new vehicle we feel justified in amplifying our previous description by referring to the latest features in its design, many of which are the outcome of experimental work extending over a period of years.
it will be remembered that in the Versare multi-wheeler the petrol-electric system of drive is employed, and, in some respects, the general construction follows railway practice in that the vehicle has two separate four-wheeled bogies, with the body serving as the structural connection between them.
As our American contemporary, "Bus Transportation" (to which we must aelindwledge our indebtedness for the details we now publish), observes, the bogies are in effect small chassis in themselves. That at the rear has a Sheldon axle in front with a modified form of Ackerman steering. An electric motor is slung by trunnions on a sub-frame, and is connected hy a Spicer universal/ joint to the Eaton doublereduction rear axle.
The springs for the ,rear axle are underslung, those at the front being mounted above the axle, but instead of their inner ends being attached separately to the frame channels they are arranged to operate on each side in series, so that a double4ength spring is virtually available for absorbing vibration and road shocks. To effect this end the springs are connected through the medium of links to an equalizing quadrant whichturns on an 8.K:iv. bearing.
So far as the disposition of its main. units are concerned the design of the front bogie is a duplicate of that at the rear, but in addition it has the engine and generator mounted above it. • The type of Versare bus which we illustrate is designed to seat 44 passengers, whilst ample space is available to permit a further 52 persons to stand, It is obvious that to accommodate this nnmber of passengers in a single saloon a 'body of considerable length must be employed, and for this reason the manufacturers have given much attention to the question of steering control, so that
the vehicle can be operated in congested traffic areas with comparative ease and speed. When it is mentioned that the overall length of the bus is 88 ft. and the wheelbase (measured from centre to centre of bogies) 29 ft., it will be acknowledged that the problem is one which had to be satisfactorily solved to render the vehicle, as a type, a practicable proposition.
The manner in which this difficulty has bees met is one of the outstanding features 'of the design. In the first place each bogie is connected to the body through a king-pin, and is thus free to be steered independently. When the steering wheel is turned, the motion is transmitted through a worm-gear reduction and through a patented form of linkage to a three-armed lever on the front axle. Two of these arms are connected to the steering-knuckle levers through rods that result in a true Ackerman action. Any movement of the front wheels of each bogie (the limit is 33 degrees) determines the movement of the rear wheels, which follow the course of those ahead. • In the case of the rear bogie, the front wheels are turned through the medium of a linkage connected to the body, and this enables the movement of one bogie in relation to the other to be synchronized. Suitable stops are fitted so that the movement of t b e bogies from the centre line of the body is limited to 45 degrees. This articulated form of steering enables the bus to be turned in a circle of 43 ft. diameter, i.e., very little more than its own length.
The Westinghouse motors which drive the rear wheels of each bogie derive their power from a six-cylinder Waukesha engine which develops 110 h.p. at .1,700 r.p.m., and is directly coupled to a 40 kw. Westinghouse generator with a special shunt-wound field.
Control is ordinarily by the engine throttle up to the rated speed of the power unit, at which 30 m.p.h. can be reached, the two motors then being connected in parallel. A series position is also provided so that sufficient power is available when climbing steep gradients. During normal operation the generator voltage falls off above a certain speed, and this characteristic avoids overloading of the engine. The generator is provided with a special field winding to permit of a small amount of separate excitation from the battery of the starting and lighting system.
The braking system is worthy of special mention. A controller is connected with the driver's brake pedal for use when braking is performed electric ally. As developed on the Versare chassis, the first movement of the brake pedal cuts off the generator from the electrical system, and later positions graduate the resistance into the rotor circuits and connect the armature of one motor with the field of the other, and vice versa. Three frames, each with 25 grids in series, are mounted under the body and furnish ample resistance for braking work.
"Bus Transportation" states that, on a 10 per cent, gradient, the speed of the vehicle can be reduced to about 3 m.p.h. by electric braking, and to bring it to a halt Westinghouse air brakes are used, a two-cylinder compressor driven by the engine being fitted. For this system chambers are mounted on all eight wheels, the pistons actuating internal brakes inside the drums. The rear wheels on each bogie are fitted with side-by-side internal brakes, both of which are connected to the air system.
We have now dealt with the major features of importance in the design of the chassis and, before closing, we would refer to one or two points of interest in the body. Firstly, it is apparent that as the body takes the place of the ordinary frame members, and takes the weight of the passengers, it must be of very strong, construction, and this end is attained by building up the floor of two sheets of steel, 0.025 in. thick, these being separated by V-shaped sections laid across the body throughout its entire length. The pillars for the doors (there are two, as one of our illustrations shows) and the windows are of wood which is braced by longitudinal members of steel, additional strength being given by angle-iron members disposed diagonally.
The body supports on the bogies consist of heavy rollers turning on Hyatt bearings on which the steel floor rests, or slides, when the vehicle is negotiating corners.
Certain dimensions have already been given, others are as follow :—Weight, complete, about 16,500 lb.' wheelbase of each bogie, 4 ft. 6 ins. ; track, 5 ft. 9 ins.; width over rubbing rails, 8 ft.; overall height, 8 ft. 8 ins. ; body interior height, 6 ft. 4 ins. When the bus is carrying a full load of seated passengers the weight is equally distributed over the to bogies.
• We shall watch with interest the progress of the Versare multi-wheeled bus, and will keep our readers duly advised of any developments which are made in its design and eonstruction.