Britain's Largest Municipal Trolleybus Operator
Page 52
If you've noticed an error in this article please click here to report it so we can fix it.
Bradford Adds 15 Karrier Machines to a Fleet which is the Largest of Its Kind in the Country
AMONG the earliest operators of trolleybuses, Bradford Corporation, will, wheri its most recent order is completed, become the largest municipal operator of this type of vehicle in the country, with a fleet of 153. Several of its 15 new Karrier doubledeckers are already in commission. These vehicles have special distinction, inasmuch as they are fitted with series dynamic control, a feature of particular value to this prominent West Riding municipality, the trolleybus routes of which encounter very steep ascents. The chief characteristic of this system of control is that it provides a safe and easily operated electric brake, which is devoid of complicated mechanism and does not, under any operating condition, return a heavy regenerative current to the overhead wires.
The chassis are of the E4 fourwheeled type. This model has a wellbraced deep-section frame inswept at the front end to reduce the turning circle and dropped at the rear to provide a low-loading entrance and exit step. A special subframe amidships carries the 80 h.p. main motor, flexibly mounted on anti-vibration rubber bushes, which, additionally, afford secondary electrical insulation.
The generator, for charging the battery which supplies the low-voltage lighting is integral with the main motor, this being fitted with an extended armature shaft to provide the necessary drive. Another point of interest concerning the electrical equipment is the unit construction of the cab-mounted contactor panel, master controller, and brake switch, whilst a further feature of importance is the fitting of electro-magnetic contactors, foot-operated by a controller of the drum-type with self-aligning contact fingers.
Four-wheel air brakes are served by a Westinghouse 5 cubic ft. compressor with motor unit mounted an an insulated base on the off side of the main A34 frame, an air-pressure governor being fitted automatically to control the compressor motor and prevent pressure in the reservoir exceeding a predetermined amount. A chassismounted anti-freezing device is also included: The brakes are of the internal-expanding type, housed in 17-in, iron-alloy drums. The hand brake is of the pull-on type and works the same set of shoes as the foot brake, the total area available for either method of application being 550 sq. ins. All wheels are provided with large-section low-pressure tyres.
The bodies, each seating 56 passen
gers, have been built by Metropolitan Cammell-Weymann Motor Bodies, Ltd., and are of patented lightweight all-metal construction. On both decks the seats are of the tubular type with chromium top rails.
Adequate ventilation is provided by Ashanco ventilators and 12 halfdrop windows in anodized aluminium frames. For lighting, 24-volt spherical opal lamps with Bakelite-moulded reflectors are fitted, there being 12 in the lower saloon and 16 in the upper saloon.
Outwardly, these new Karrier vehicles, with their blue and white livery, possess a smartness which will make them prominent in Bradford's fleet, and there is no doubt that their comfort and silent operation will greatly enhance the popularity already gained by trolleybuses in this progressive Yorkshire city.