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Municipal Maintenance Methods and Equipment
Page 96
Page 97
Page 98
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SINCE Mr. Vane Morland became Leeds, many advances have been municipal transport manager for
made, particularly in respect of the modern fleet of buses, which now numbers some 180, 98 being equipped with oil engines.
The maintenance works, not only for these buses, but for miscellaneous vehicles, amounting to an additional 90, is at Donisthorpe Street. At present this is both a depot and a works, but the rapid growth of road transport has resulted in considerable congestion, and a new depot for 100 buses is being built in Torre Road, following the opening of which the Donisthorpe Street *premises will become mainly a maintenance and servicing centre. The need for this can be realized when we mention that 30 more buses are on order.
A Remarkable Breakdown Vehicle.
Perhaps one of the most remarkable items in the equipment is the breakdown crane, which we illustrate. One of the primary reasons for the construction of this vehicle was that a steam roller broke down on the tram track, resulting in considerable delay of the tramway services, whilst even if an ordinary vehicle obstructed the lines there were frequently arguments as to who should remove it. Such delays in the services might mean a loss of hundreds of pounds to the city transport department.
The breakdown unit is based on an old Liberty chassis, for the reason that this is robust and has particularly low
gear ratios. The crane can deal with maximum loads of 81 tons, and by the employment of outriggers on the chassis it can exercise a 4-ton lift at the side of the vehicle. Two sets of twin trailing wheels come into action if the load at the rear exceeds 4 tons, with the result that the vehicle can sling and tow weights of 8 to 10 tons. A useful part of the equipment is a 100-yd, cable winch. This has been employed in extracting a bus which had driven right into a building.
When the works receive news of a salvage job, a siren is blown, and the average turn-out time for the machine is three minutes.
Oil-fuel Cleanliness Vital..
In the maintenance of the oil-engined vehicles, in particular, cleanliness is a matter of vital importance. The oil fuel is delivered to a reception tank and is centrifuged before entering the delivery tank, this being effected at 250 gallons per hour in equipment supplied by British Separators, Ltd.; de livery for both oil and petrol is through Hammond or Avery pumps. ' All used lubricating oil is passed through a Stream-Line niter plant of the 037 type, and an entire depot of 40 oil-engined buses is run on this reclaimed oil. A Hopkinson centrifuger is also employed for ordinary lubricating oil, paraffin, etc.
In the oil, fuel and carburetter section, the C.A.V.-Bosch filters are cleaned every fortnight. Brushing of the filters is not permitted. They are mounted on a frame provided with eight nozzles, which blow air through , the filters from the inside while they are immersed in paraffin, after which they are drained for 10 to 15 minutes, each of the clean filters then being kept in a dirt-proof container until it is fitted. The condition of the material is determined by its discoloration, and every 10,000 miles new cloth is fitted.
The nozzles are cleaned and tested, and if faulty, are sent to the C.A.V.Bosch concern. The deliveries from the injectors are all calibrated, using a hand-operated pump, but a power plant with an electric motor and variable-speed gearbox is being obtained for this work.
The balancing of the sprays exercises
a marked effect on the condition of the engine, and all injection pumps are checked, even if they.come 'direct from' the manufacturers, over three ranges of 'speed, idling, intermediate and maximum. For the petrol vehicles the jets are calibrated in an Amal instrument at every 10,000 miles.
The tank of every vehicle as it comes in for attention is emptied, which helps to get rid of any dirt. This operation is effected by a semi-rotary hand pump discharging into portable metal barrels.
Colours to Indicate Fuels.
To ensure that there is no mixing of fuels, everything to do with oil fuel is painted red, and with petrol, green; the tank caps are coloured to correspond.
Exhausters for braking, etc., are run off the shafting. They are coupled to an exhauster tank to register the suction. The standard employed is 15 ins. of vacuum in one minute at oil-engine idling speed. After an exhauster is overhauled it has to be run in for some three" to four hours before it will register this figure.
Accumuliitot • Charging is done by a Timgar liakilowatt panel rectifier supplied by the Edison Swan Electric Co., Ltd. The modern oil-engined bus with 24-volt starting has to carry 4 cwt. of batteries consisting of four six-volt groups. These want a lot of handling, and on the Leeds buses the batteries are slung on the side of the chassis, hinged panels giving access. Simple platforms, each having at one side a single rod carried on three ball races, facilitate the work, as the bat; .tery siniply slides on the rod, which acts as a roller bearing.
All metal parts are cleaned in a washing machine supplied by Dawson Bros., of Leeds, and a-25-ft, machine with a roller conveyer is being installed. Metso fluid and boiling-water sprays are utilized. This has halved the cleansing troubles previously ex
perienced. .
For testing dynamos, starters, magnetos, etc., an apparatus by Crypton Equipment, Ltd., is employed. Heater plugs are tried out ori an Oldham tester. Previously it was necessary to pull all heater plugs to see if the filaments were broken; now they can be tried in position. Despite criticisms by some sparking-plug makers, it has been found that sandblasting, the Plugs in a B.E.N. device every 1,500 miles keeps them in good condition and prevents straining the magnetos. Striping the plugs at each short intervals would not be feasible.
FOr, the supply of compressed air for tyres; etc., a Luchard.airlhottle
working at 2,000 available:
An interesting point is that the additional • vibration " caused " by -oil engines at certain speeds results in trouble with leakage.of radiator tubes. To avoid this experiments are being carried out with rubber ferrules.
All the work is sectionized. There is an engine line, on which one bench deals solely with cylinder heads, magnetos, pistons and valve inserts, and here there is a Black and Decker plant for valve and seat refacing. The inserts are usually the Sheepbridge Centrilok. In the latest A.E.C. units the inserts are screwed in. Where there has been trouble with inserts,"it is' more in connection with side valves than with the overhead type.
Care in Engine Maintenance.
On the bearing bench the fitters now partly machine their own brasses, using Newton boring bars for both connecting-rod and main bearings. These have proved quite Satisfactory for both white metal and lead bronze. Connecting-rod alignment is checked on a Buma jig, and the rods are tested with the gudgeon pins in position. The chief engineer coesiders that connecting-rod alignment prevents many troubles. The boring bars are always hung up; for a long bar may distort by its own weight. Crankshafts are carried in rows in an angle-iron frame on angle-iron brackets, and rest on pads made from old leather-seat material.
Much work is saved by the employment of stripping trays for engines. These are trolleys with angle-iron posts and expanded-metal trays on angleiron slides. It has been found that .the simpler the engine stands the better. The latest consists of two uprights of channel-steel placed back to back and sunk in concrete with a bearing and cap for horizontal bars carrying spiders and end plates for bolting to the crankcase.
To support gearboxes, steel templates are belted to the ends of the benches, which are' zinc-Covered for .c45 cleanliness. A Manley 60-ton press • deals with bushes, gears, etc. COnsiderable use is made of expandedmetal partitions, which give air, light and, in some cases, safety where this is required, as in the case of the enginetest department.
For washing purposes there are in the yard three B.E.N. pumps in tandem, the whole being enclosed, together with banks of hot-water radiators, to avoid freezing.
Every part replaced during docking or Overhaul is passed through a salvage department. Even ball races are reconditioned by the makers.
All body repairs are carried out at the works, but, to avoid removing a bus from service until the next docking, where a panel is bumped in, fabric patches are stretched over the hollow and ,painted to match.
A close watch on maintenance is kept by a variety of simple but effective records. The docking and unit-replacement chart consists of vertical red lines rising from the base according to the mileage figures at the left of the chart A dock overhaul is represented by a stamped green star, " E" at the side of -the line represents an engine overhaul, which is further modified by which is a first overhaul from new; and "A" a similar overhaul to " 13," plus crankshaft grinding and new bearings. Each chart runs up to 96,000 miles, or two and a half years' work.
Each vehicle also has its own card, on which are recorded fuel and oil consumptions. There are also cards for magnetos, cylinder-bore dimensions,