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96 Per Cent.
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Page 141
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Availability in Tipper Fleet
By P. A. C. Brockington, A.M.I.Mech.E. THE diversity of factors in the economical operation of a tipper fleet can be aptly illustrated by quoting from notes made during a visit to Henry Joyner. Ltd., Short • Heath Road, Birmingham, 23. According to Mr. R. Rogers, the manager, who supervises all maintenance and operations of the 50-vehicle fleet, lack of tyre maintenance can ruin a concern financially in a year. In the Joyner workshops, a mechanic has a full-time job of inspecting and repairing the tyres. Engines are changed in a day, and if a vehicle is docked for the most serious of all repairs—reinforcing the chassis
the job is completed in two days, use being made of a stock of sheath-fit plates for bolting in position. In a general qualification of all maintenance requirements, Mr. Rogers emphasizes that "the driver is everything."
B.R.S. Rejects Provide Spares The fleet is based on 38 Dodge vehicles, and at least 12 spare engines are available for replacement purposes and for reconditioning vehicles of other concerns. A number of British Road Services Dodge rejects was purchased at
low cost to provide spares. In some instances the vehicles were found to be in good condition except for a cracked frame, and these were ready for the road in 48 hours. The two-speed axle of the Dodge machines is found particularly useful when the vehicles are engaged on sand-and-gravel haulage. Replacing the petrol engines of some of the Austin three-axled 10-tonners by Perkins P6 oil engines has improved the fuel consumption rate on long hauls from 7i m.p.g. to 13i m.p.g.
The 50 vehicles average more than 800 miles a week each, 60 per cent. of the running being on the transport of coal and the remainder on sand-andgravel work and general haulage work. Overall running costs vary between Is. and Is. 6d. per mile according to the size of the vehicle, and tyre costs are about 2d. per vehicle-mile. Dodge tippers with a 7-ton load average 9 m.p.g. and Bedford 5-tanners, loaded with more than 6 tons, 81 m.p.g.
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The cost of supplying and fitting, Perkins engines to the Austin threeaxled tippers is fully compensated by the saving on fuel costs in 12 to 14 months. Four of the six Austins have so far been converted.
The Dodge chassis comprise ex-W.D. Canadian-built vehicles and a number of similar types built in this country. After a tipper has run 50.000 miles. new Wellworthy piston rings are fitted, and, as a precautionary measure, the connecting-rod bearing shells are renewed. Pistons are sometimes replaced to ensure the maximum mileage before complete stripping becomes necessary, but both pistons and bearings would normally operate for a much greater
distance. The cylinder bores 0.003 in. maximum wear of the at this stage is about
The Dodge tippers cover up to 100,000 miles before. a major overhaul is required. the low-rate of cylinderbore and-bearing wear being attributed, in part, to side-valve construction. The engine and gearbox are removed from the chassis as a unit Lnd all reconditioning, with the exception of crankshaft grinding, is carried out by the operator's mechanics. Particular attention is said to the cylinder block, the water tube and plugs being renewed after thorough cleansing of the water passages. It is of related interest that thermostats are maintained in good working condition
to reduce warming-up times to re minimum, and that Pram full,fkiW5Iters 'are_ fitted to all engines. . '• The aVeragi ra 01 fleet availability is 96 Der cent Lubricant for all the vehicles is supplied by the Regent company, the Dodge and Austin lorries rtinning'on S.A.E. 30, and the Bedfords on S.A.E. 20 'oil. If an engine is using an abnormal amount of oil and must be retained in service temporarily. it is filled with lubricant of S.A.E. 40 viscosity. The Oil is changed at 2.000-mile intervals, and is then sold for 3d. a gallon Reclamation is not considered economic.
Chassis are stripped to the frame every two years. which represents approximately 100.000. miles running, and, in addition to the overhaul ref major components. small parts such as pipes, clips and brackets are renewed where recessary The reinforcing plates for the Dodge chassis are pre-drilled for attachment by the existing bolts.
The maximum number of vehicles normally off the road at one time, including those undergoing intermediate repairs, is two.. Combining fleet maintenance with work for other hauliers enables a staff ' of seven mechanics to be kept fully employed and provides a large labour force to cope with emergencies.
Care of Tyres
Tyre pressures are checked nightly and all covers are examined on Sunday mornings by the tyre mechanic, who visits the concern's premises at this time solely for the purpose. The overtime paid to the mechanic for this work is fully justified by the resultant reduction in tyre troubles. Firestone tyres now form standard equipment, and no blow-out has been experienced by the drivers during the 12 months they ha; e been used. Cuts are filled with soluti n by a pressure gun. Sound covers that have worn smocith are returned to the makers for remoulding. It is estimated that in most instances the tyres could be used for a further 2,000 miles. but leaving an ample tread margin is considered to be more economical. Amongst the factors which contribute to long tyre life are accurate front-whcel alignment and cortiect wheel-stud maintenance. Studs of larger section than the standard type are fitted to thewheels of the Austin threeaxled vehicles.
The tyres on the twin rear wheels of the two-axled tippers' are paired as accurately as possible and are all inflated to the. se e pressure The rear tyres of the three-axled vehicles run at a lower temperature than twin tyres and given that tread wear is equal all round or that the wear of diagonalllt opposite tyres is equal, have a reasonable long life. With unevenly worn tyres. the " wind-up " between the axles greatly increases the wear.
The Canadian-built Dodge tippers were originally fitted with single wheels at the rear and with 10.50 by 16-in. tyres on all wheels. These vehicles were rebuilt with twin rear wheels of 6-in. base, carrying 35 by 71-tn. tyres, having a 1J-in, air gap; the capacity of the vehicles is now 8 tons. The capacity of the home-built Dodge 6-tonners in the fleet has been raised to 7 tons by replacing the 34 by 7-in, rear tyres with 35 by 7i-in. equipment.
The 7-tonners are now rated as 8-tonners having 35 by 7i-in. tyres all round, in place of 34 by 7-in. tyres at the front, and 36 by 8-in, tyres at the rear. The original 900 by 20-in. tyres of the Austin tippers have been replaced by 11.00 by 20-in. tyres.
Operating on sand-and-gravel work, which -necessitates a great deal of reversing, the 34 by 7-in. tyres are worn smooth in 12,000-14,000 miles, and the 35 by 71-in. tyres fitted to vehicles on sand-and-gravel and coal-haulage work cover 22,000-25,000 miles before renewal or remoulding becomes necessary. The tyre mileage of the Dodge 8-ton tippers on long-distance work is about 30,000 miles and of the Austins approximately 26,000 miles.
tteintorced Bodies
All the tipper bodies are built in the workshops and are reinforced to withstand arduous conditions of service. A noteworthy feature of their construction is the use of corner irons, side plates and a steel rear member fabricated in one piece.
The drivers do not undertake any mechanical work, but they clean their vehicles with the assistance of a Laycock power washer; no spare parts or tyres are carried on the vehicles. Tippers are driven only by their allotted drivers, to whom every encouragement is given to take care of their vehicles. An accidentfree bonus of £2 10s. is paid for the first six months, £3 10s. for the following six months (0 in a year), with an additional £20 for each period of five years.