The live wires of bus electries
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Electronics gets more sophisticated almost by e minute. but technologists are also active in finding ways of making maintenance and repair easier
A GREAT deal of thought has been put in to designing efficient, accessible and easy to repair electrical systems on modern buses and coaches. However, some small operators still have a lot of trouble.
Modular electrics is becoming popular in new bus bodies and Greater Manchester Transport, with its relatively vast resources uses a centralised electrical control system in the layout of its double-deckers. From this the Brighton Corporation Transport chief engineer, David Toy, gained ideas that have been incorporated in the standard specification of its new buses.
Time used to be wasted in identifying and locating electrical faults. But on Brighton's latest buses, all electrical controls are grouped in the rear wall of the cab and the area immediately under the stairs. The main electrical control centre for the bus is located immediately behind the driver under an easily detachable panel.
The control panel contains relays and circuit breakers — in place of fuses — for the main bus body electrical circuits, lights, bells and heaters.
The control panel can be unplugged from its sockets to colour-coded cables at the bottom and top that connect with the bus body's wiring looms. The complete panel is removeable and a spare one put in its place. That takes care of any fault in the panel itself.
Brighton Corporation's daily bus services operate Leyland Atlantean double-deckers with fully automatically controlled pneumocyclic gearboxes. The gear controls are electrical and are incorporated on a small circuit board which governs the speed at which the bus changes gear. This board is fitted in a compartment under the stairs.
The gear board can be removed by taking out four bolts and like the main body control panel, it is connected to the chassis wiring and the gear selector control by plugs and sockets.
All Brighton's buses have radio apparatus located directly under the gear control board and maximum use is made of electrical devices to protect and check other major mechanical units.
The driver's instrument panel includes a bank of warning lights to check air, fuel and water levels and electrical functions. A separate switch allows the driver to ensure that these lights function correctly. Faults in the earthing of the body wiring can also be checked and if the fault is due to a badly earthed circuit this will show up immediately.
Besides replacing fluorescent tubes in the case of interior lamp failures, the only routine job that maintenance crew do from inside the bus is to check the battery. This is in an underfloor compartment and can be reached by removing seat swabs and a floor trap. David Toy wants to incorporate a slide-out tray arrangement on all new buses to allow the battery to be checked from outside the vehicle.
Minor accident damage to panels is common in towns, so in order to avoid excessive downtime, the front and rear lights and indicators and -pay as you enter" signs can be disconnected quickly by removing a plug from a socket.
To replace panels the bodybuilder plugs the lights on the repaired or replaced panel directly into the bus wiring circuits.
Brighton Corporation found that a common cause of electrical breakdowns is alternator faults. On the Atlantean, the alternator is badly sited and so unnecessarily difficult to remove.
When an alternator appears to fail,the first job is to check that it is in fact at fault and there is no malfunction in another electrical component. The offending unit is replaced with either a new or rebuilt one from the stores. If it is cheaper in terms of vehicle downtime and man hours to repair rather than replace units, then this is what is done in Brighton. In the case of alternators and starter motors, it has been proved that repair is more economic and an Octopus electrical test bed is provided. But it is cheaper to use outside specialists to repair fuel pumps.
The Corporation also looks after the borough enginee refuse vehicles and the cour council's and Area Heal Authority vehicles. So a wi variety of electrical componer is stocked. The borough eng eer's electricians can find the selves working on vehicl varying from the sophistical double-deck bus to the relativi simple Sherpa van.
All electrical jobs are cost and details entered in individt vehicle records, now being r on computer. Recurring fau therefore come to light quickl
Bigger loads are put on coa wiring systems, but mc thought is now being given relay and fuse location. ACCE to them can normally be gain from outside the vehicle. ( some bodies thermal int( rupters or circuit breakers ha been used to replace fuses.
Despite increased deman from those operators w' sometimes expect new coa bodies to incorporate su luxuries as microwave ove and colour television, t vehicle electrician's job is eas than it was. continued overt(