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by Ron Cater. AMInstBE NUMEROUS ATTEMPTS have been made to

13th March 1970, Page 52
13th March 1970
Page 52
Page 53
Page 52, 13th March 1970 — by Ron Cater. AMInstBE NUMEROUS ATTEMPTS have been made to
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produce an acceptably accurate and reasonably priced weighing device to be carried on a vehicle for the purpose of checking its weight in all states of load. One of the many devices is the Ax-Way, made by Bowran Design and Technical Developments Ltd and news of which was first published in CM May 2 1969.

When I was first introduced to the Ax-Way early in 1969 it was still in the very early stages of development; it then comprised a strain-gauge stuck on to the main leaf spring of a vehicle suspension beneath a strip of a coarse canvas. I was convinced even then, however, that of all the built-in weighing devices I had seen, this was the only one that would fulfil the needs of operators wishing to establish just how much load was imposed on a vehicle rather than tell when it was overloaded.

Overloading fines The possibility of huge fines being levied on persons convicted of overloading is but one of the problems facing hauliers, for as vehicles get heavier and larger the number of weighbridges which they can satisfactory use dwindles.

Even on the most accurate and well cared-for weighbridge there can be discrepancies of the odd hundredweight and where the care of equipment is perhaps not all that might be desired, the discrepancy can be quite substantial. So if a device were produced which would check axle weights to an accuracy of 0.2 per cent and could be fitted for about £100, I considered it would be interesting to the haulage industry in general.

So far as axle weights are concerned, only the most sophisticated weighbridge will weigh individual axles with a great degree of accuracy, so the 0.2 per cent tolerance aimed at by the inventor of the Ax-Way, Jack Bowran, is I feel entirely reasonable.

When I first saw the Ax-Way in use I had no chance to check that what it registered was correct. Also, as it was still being developed I asked the manufacturer to get some units into service and let me have another look at it when they were satisfied that everything was all right. Subsequently, units were placed in service on some tippers belonging to R. Hanson and Sons on a job which entailed loading and tipping eight times daily.

Checks made over a long period showed that the spring-mounted strain gauges were unsuccessful owing to frequent renewal of springs, necessitating new strain gauges being fitted. So a spring-steel sensing arm was arranged to bear on the axle being sensed and this had the strain gauge mounted on it. In this way Bowran was able to predetermine how much deflection of the strip was required to produce given readings to the sensing unit. This being the case it was now possible to use gauge blocks when fitting the sensing arms to a vehicle, so simplifying and considerably cutting down the installation time.

It also permitted very much closer control over the waterproofing of the strain gauges, an important factor from• a reliability point of view. The present sensing arms are now protected with a nylon sleeve which is heat-shrunk over the strain gauge and the wiring connections. The system has been further improved to take account of vehicles with balanced axles where two sensing arms feed a common electronic circuit. As the balance beam tips up and the position of the axles changes, one arm suffers a greater deflection while that on the other is reduced. The signal therefore remains constant.

The test vehicle which I was able to observe was an eight-wheel Atkinson tipper. It was carrying coal between two pits near Barnsley, Yorks--Riddings Drift and South Kierby Colliery. The roads over which it was running can only be described as bad third-class and at each end of the route the vehicle had to negotiate deep slurry and severely uneven ground. At the loading point (Riddings Drift) a weighbridge is installed over which the vehicle must pass on every trip, so there has been ample opportunity for the maker of the unit to rectify any faults that have shown up. In my opinion the road conditions have imposed the most stringent conditions on the equipment and its performance has justified the maker's claims for its reliability.

I was able to watch the loading and tipping of three loads during which time the equipment was used to prevent the driver having to return either to make the load up to the maximum permitted gross weight of 24 tons or take some off to bring the gross down to that figure. Here I must stress the importance of educating the driver of the vehicle as to the purpose of the Ax-Way unit and the correct method of using it. Without this being done the unit is virtually useless and it does, I feel, take a deal of common sense on the driver's part to make the best use of it.

On the three loads that I witnessed; the gross weight of the vehicle when put on the weighbridge was within lcwt per axle accurate. The readings were, for the first load on which the unit was calibrated, 24 tons 4cwt, on the second, 24 tons lcwt, and on the third, 23 tons 18cwt. On each load the driver had instructed the driver of the digger as to how much load he must add or take off the vehicle, based on the information he got from the Ax-Way, so proving that the claims of accuracy made by the manufacturer were justified. The driver's aim had been to get a gross weight of exactly 24 tons when laden.

Any number of axles The Ax-Way unit can he supplied to serve any number of axles. Each unit has a zero calibrating device which can be used for setting in conjunction with a recognized weighbridge. Once the unit is zero'd, each time the driver wants to check the gross or axle weights it is necessary for him to set the pointer on the 0 reading on the dial, then by pressing the READ button situated on the bottom of the control he can read off the load imposed on the particular axle.. By adding up the weights shown for each axle he can ascertain the gross imposed load on the vehicle. The system will show how much weight is imposed in increments of 4cwt and is presently being evaluated by the Ministry of Transport.

The Ax-Way is available from stock and for a two-axle vehicle costs approximately £70. A full set of fitting instructions is available enabling purchasers to do their own fitting. Installation takes approximately four hours, and the makers will put in units at a rate of £2 per hour plus expenses if required.


Organisations: Ministry of Transport
People: Jack Bowran

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