How to weigh axles (1 Viewer)

[Lanerboy]

How does a weigh bridge work

I know if you drive on fully it gives you the gross weight of the vehicle but how do you get the correct weight of each axle

Do you drive on enough so only the front axle is on the bridge to get get front axle weight then drive off leaving just rear axle on the bridge to get rear axle weight or does it matter how far either axle is positioned on the bridge to get an accurate figure

 

[tacr2man]

Just put one axle on and then other , as long as the other axle is on level ground . Weight distribution is not affected by one end being on a weighbridge

 

[Detnor]

If you are passing junction 15 of M40, Warwick, the trading standards weighbridge is only a few minutes from the junction. Normally they will give you a total weight without charge, but if you want certificates, they have 2 weighing plates, so just put the front wheels on the front plate and the rear will be on the other plate. Easy access and exit.

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[Lanerboy]

Cheers that's what I thought just want to weigh it when fully loaded before we head off to Germany

 

[mike mcglynn]

I speak from experience ,provided that you are on a flat approach and exit weighbridge as many are ramped these days ,and tell the weighbridge keeper exactly what you want to do he/she will advise .It is surprisingly accurate if done properly ,most modern weighbridges weigh in 20 kilos steps ,the ones I used to work were in 7lbs steps progress eh!

 

[Lanerboy]

If you are passing junction 15 of M40, Warwick, the trading standards weighbridge is only a few minutes from the junction. Normally they will give you a total weight without charge, but if you want certificates, they have 2 weighing plates, so just put the front wheels on the front plate and the rear will be on the other plate. Easy access and exit.

That's good will be passing there so will pop in it cost £10 but would rather have piece of mind

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[Zigisla]

If they charge by the axle, you only need to weigh the front axle, then drive fully on to weigh both and then subtract the front from the total to get the rear.

 

[nicholsong]

I speak from experience ,provided that you are on a flat approach and exit weighbridge as many are ramped these days ,and tell the weighbridge keeper exactly what you want to do he/she will advise .It is surprisingly accurate if done properly ,most modern weighbridges weigh in 20 kilos steps ,the ones I used to work were in 7lbs steps progress eh!

Yes that is a problem since there will be some weight transfer to the 'downhill' axle when weighing the front and rear axles.

What is the solution?

Is there a mathematical calculation to correct any discrepancy if the two axle weights do not match the total weight?

Geoff

 

[Deneb]

Yes that is a problem since there will be some weight transfer to the 'downhill' axle when weighing the front and rear axles.

What is the solution?

Is there a mathematical calculation to correct any discrepancy if the two axle weights do not match the total weight?

Geoff

The frame that surrounds the plate should be as flat as the plate itself. When I used to carry out enforcement weighing, if we were in any doubt as to the level of approach, we would position the tyres of the axle not being weighed on the frame, as close as possible to, but making sure that they weren't actually touching the plate obviously.

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[mpdcymru]

Agree with Zigisla above. However if you want to make the best job of it your should drive the vehicle onto the bridge stopping with the rear axle directly on the frame of the bridge - take the weight measurement. Drive the vehicle off the bridge and allow it to zero first and the drive the vehicle over the bridge again stopping with the front axle on the frame of the bridge.

By getting the "non-weighed" axle eon the frame, it guarantees (as much as this is possible) that the vehicle is level.

 

[mike mcglynn]

Yes that is a problem since there will be some weight transfer to the 'downhill' axle when weighing the front and rear axles.

What is the solution?

Is there a mathematical calculation to correct any discrepancy if the two axle weights do not match the total weight?

Geoff

 

[nicholsong]

The frame that surrounds the plate should be as flat as the plate itself. When I used to carry out enforcement weighing, if we were in any doubt as to the level of approach, we would position the tyres of the axle not being weighed on the frame, as close as possible to, but making sure that they weren't actually touching the plate obviously.

Thank you

Of course that makes sense.

Most advice on forums in the past has been to drive one axle onto the edge, but I can understand that there is no reason why it cannot be anywhere as long as it is the only axle on the weighbridge.

The method you describe gets rid of the weight transfer problem even on a 'ramped' approach/exit.

Geoff

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[mike mcglynn]

Not as far as I am aware Geoff but if you are using a full w/bridge rather than an axle scale you should get it to the nearest 20 Kilos .

 

[Deneb]

The method you describe gets rid of the weight transfer problem even on a 'ramped' approach/exit.

I was taught to always position the axle(s) not being weighed as close as possible to the plate irrespective of the level of the approach or run off. It won't make any practicable difference if the bridge and approaches are certified level for enforcement purposes, but it is one of those things that circumvents any doubt being introduced by the defence when practised and documented in evidence.

Split weighing (assuming the weight of an unweighed axle by subtraction of the other axle from the gross weight) was also frowned on where it was possible to physically weigh the axle in question. One issue being that the bridges normally record weight in defined increments, often 20kg, so it is possible to multiply errors by relying on two incremented readings to calculate a third. Obviously with certain vehicle configurations it is impossible to not split weigh.

This all assumes weighing on a bridge plate, not dynamic axle weighbridges, which are a different fish entirely.

 

[Box Boy]

If you use the unstaffed one at Lancing on the A27 it instructs you to drive slowly over the weighbridge without stopping and gives a visual of first the front and then the rear and finally the gross weight!
Brian

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[mpdcymru]

If you use the unstaffed one at Lancing on the A27 it instructs you to drive slowly over the weighbridge without stopping and gives a visual of first the front and then the rear and finally the gross weight!
Brian

Then that is a dynamic bridge and it is not as accurate as the weights found on a plate or "static" bridge for vehicles of around 3,500 kgs. There are several of these throughout the country- most of which are maintained by the Department for Transport. I used to use the ones at Risby A14 and Felixstowe dock (though the latter is not available to the general public as it is inside the dock compound.