Friday, 29 August 2014

Axle weighing is easy, right?

Installing an axle weighbridge is easy isn’t it? Just fit four load cells under a piece of steel, sink it into a hole in the ground, mount a weight display somewhere and start parking axles on it. Easy right?

If only it was that simple.

If it was that simple, we wouldn’t go to the trouble of doing levels surveys at every site, making a complex frame design to an extremely high tolerance, invest in expensive on site testing equipment or using some of the most expensive construction materials on the market.

Getting it right takes a lot more effort and knowledge than it seems.

And getting it wrong can sometimes prove costly to correct.

A major high street retailer installed an axle weighbridge at a large distribution centre. Unfortunately for them, the contractor who built the warehouse chose the cheapest system he could find and then installed it himself.
The client was only weighing 2-axle rigid vehicles, normally the simplest vehicles to weigh but despite the best efforts of the axle weighbridge supplier, they came and replaced all the electronics and load cells not once but twice, it still wouldn’t weigh these simple vehicles accurately.

So we were call in to give a second opinion. And we spotted the problem within about 15 minutes of arriving on site, ten of which consisted of signing in and waiting for our contact to arrive!

The client was using shunting vehicles to weigh drop-bodies before parking them up ready for the distribution fleet to take them away in the morning. These off-road shunters had a very soft suspension which meant it reacted to every bump and hollow in the yard.

The axle weighbridge had been installed about 5mm proud of the approach concrete which, combined with the soft suspension caused the axles to bounce as they crossed the platform. Any weighing machine will only record the weight applied to it and if the axle is bouncing as it crossed the platform, the wrong weight will be applied and the wrong weight recorded.
A correctly installed axle weighbridge - unlike some we see!

There was nothing wrong with the load cells or weight indicator at all just a lack of knowledge of what is needed to weigh axles accurately.

Having to dig the system up and install it correctly is never a cheap option but there was no alternative.
This is a common issue and a trap that many companies have fallen into over the years.

It’s not the only one example. We’ve seen many installations using perfectly good load cells and mountings which simply do not weigh axles correctly. The only trouble is these load cells are perfectly good for many applications but are simply not designed for the job they’re being asked to do.

All we have to do is fit four load cells under a piece of steel, sink it into a hole in the ground and start parking axles on it isn’t it? Not true and demonstrably so in many of the sub-standard installations we see.

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