Long Wheelbases Best for COAL TRANSPORT
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Midlands Haulage Company, with Definite Ideas About Design Suitability for Practical Considerations, Favour Big Bodies
By
P. A. C. Brockington,
A .M.I.Mech.E.
IN the interests of stability and control on the road, the use of longwheelbase vehicles for coal haulage is advocated by Mr. John Took, of John Toole, Ltd., Regent Wharf, Bilston. He considers that some form of tilt test for goods vehicles should be introduced into the regulations to prevent the use of high-sided shortwheelbase tippers with a dangerously high centre of gravity.
He also emphasizes that stability when tipping is essential to safe working and to obviate tipping-gear and chassis damage. A twin front-of-body gear is, therefore, preferred for longer bodies to other conventional types because it provides rigid support when the vehicle is moved forward on rough ground to discharge the load.
Minimum Costs The small difference between the cost of coal at the pithead and the regulated retail price necessitates using the most suitable type of vehicle and keeping running costs to a minimum but, in Mr. Toole's opinion, the optimum overall economy cannot be achieved by overloading vehicles or even, in many eases, of loading them to the maximum legal limit.
Before they were nationalized, an associated company, Queen Street Motor Garage, Ltd., Bilston. operated a fleet of some 12 vehicles on long distance, about half of which comprised White Indiana trucks equipped with a Boys third axle that increased the payload from 51tons to 10 tons. The first converted vehicle was introduced in 1937, and some of the original Indianas had been running satisfactorily
c20 for 10 or more years when the fleet was acquired.
When, therefore, the decision was made late last year to operate a number of B.M.C. 7-tanners equipped with the Boys third axle, Mr. Toole had had ample evidence of the value of the conversion,
The first vehicle of this type has been running for several months, and has provided satisfactory traction on treacherous colliery sites in the worst of the winter weather. The useful tractive effort available is superior to that of both a twin-steer six-wheeler and of a dual-drive six-wheeler with one of the differential units removed.
A second B.M.C. vehicle with a Boys axle will be delivered in the near future, and it is probable that, in the interests of standardization, the other six-wheelers in the fleet of 24 lorries will be replaced by similar vehicles in due course.
The full-length sub-frame with which the vehicles are fitted is regarded as a good feature because of the stability it provides for tipping. The lifting gear is of Ed bra-B. and E 4LNX twin-ram
triple-telescopic type mounted at the front of the body on a special subframe, stiffened by cross-members to provide extra rigidity. Features of the system include a neutral control valve in the cab with " raise," hold" and " lower " positions.
The White Indianas were amongst the first vehicles to be fitted with Tufnol shackle bushes, which were used as replacements for the bearings of the rocker-beam ends and gave reliable service. The Boys axles now in production are equipped with Tufnol bearings of improved quality, and can be satisfactorily lubricated with water. In some cases, mileages up to 90,000 have been recorded between replacements.
The rated payload capacity of the B.M.C. 7-tanner has been increased, by the addition of the third axle, to 10 tons, and can be used for carrying 12 tons. Although this is only some 21 tons more than various coal hauliers are carrying legally on four-wheeled lorries, Mr. Toole considers that the vehicle represents the most economical solution to carrying a maximum load, compatible with low maintenance and
running costs. The average fuel consumption rate is 151 m.p.g.
A special articulated trailer combination with a side-tipping body is being built in the workshops of the concern. This will be used for deliveries to appropriate sites, and will be hauled by a four-wheeled tractor converted from an E.R.F. twin-steer six-wheeler' with a Gardner 5LW engine and David Brown five-speed gearbox. It is envisaged that the rigidity of the trailer body provided by the well-spaced twin rams, which will give a tipping angle of 45° with a movement of 3 ft. 6 in., will be an advantage. If the vehicle proves successful its load-carrying capacity may he later increased by adding a trailing axle to the tractor.
Fluid Flywheel Another interesting conversion has been performed in the workshops on a vehicle which was originally an Austin ex-W.D. petrol-engined six-wheeler; it has been changed to a four-wheeler, powered by a Gardner 4LW oil engine. and has a Daimler fluid flywheel and preselector five-speed gearbox to overcome repeated clutch trouble which it at lint experienced on certain types of job. The vehicle runs economically-the consumption being at the rate of about 16 m.p.g.—and no further clutch trouble has been experienced.
Based on an Albion CX1 chassis, a coke-carrying vehicle is claimed to have a greater bulk capacity than any other four-wheeler in the Midlands, the wooden body being 18 ft. long, 7 ft. 6 in. wide and 5 ft. high. The payload is 8} tons.
Other vehicles in the fleet include E.R.F. twinsteer 10-tonners equipped with Gardner 41W or 5LW units, and a number of Albion fourand six-wheelers powered by' the Maker's engine. The remainder comprise Austin and Bedford 5-6tonners, most of them with Perkins P6 engines, and Morris-Commercials with Saurer units. Only two vehicles have petrol engines.
The average distance covered by the vehicles before the engine is reconditioned or replaced is about 75,000 miles, which is considered satisfactory. The mileages covered are relatively small, and the engines are running below the normal running temperature for much of the time; otherwise a longer life would be expected.
The yardstick of 'engine condition which determines the need for an overhaul represents a higher standard than is set by most operators, being based on an oil consumption which is considered excessive if topping-up is more than occasionally required between oil changes at 3,000mite intervals.
Gardner and Albion engines are completely overhauled in the workshops, whilst the Perkins engines are replaced by factory-reconditioned units. Injection pumps are returned to the makers for recalibration after 50,000 miles.
In addition to greasing their vehicles, the drivers are responsible for changing the filter every Saturday morning_ Mr. Toole would welcome a type of filter with a low-cost destructible element which could be easily replaced without danger of letting air into the system. The drivers are often loath to change the elements because of this problem, which could be overcome by the provision of an adequate seal.
Shell Rotella lubricating oil is employed for all the oil engines. Although detergent oil has been found unsatisfactory if used for the first time in a worn engine, results have been good in new or reconditioned units.
The sites visited include iron and steel works, where tyres are liable to be cut by sharp pieces of metal, and an average tyre mileage of 20,000 is regarded as good. Michelin Metallic covers are fitted to vehicles with higher axle loadings and Goodyear covers to the lighter trucks. Factory remoulds or Tyresoles are mainly employed on the short-distance vehicles.
Operating in conjunction with the haulage fleet, six Priestman grab cranes of up to 3-4 cu. yd. capacity are used for internal distribution, dispersal and so on. Of these, three are mounted on six-wheeled chassis, and the mobility of the cranes adds greatly to their earning capacity.