Weighbridge - rear axle estimate based on 2 wheels on 2 wheels off?

[VXman]

Just put the MH on a weighbridge fully laden. Electric Motorscooter, Electric bike and normal lightweight bike plus chairs, table, BBW etc etc in garage.

Total weight was 3700kg so well within my 4250kg.

I did a measurement with the rear wheels only on the scales`. This came to 2240 out of a permissible 2500.

Question is - I know this is not accurate but in what way is it likely to be inaccurate? Is it likely to be more than 2240 or less?

 

[Langtoftlad]

Just put the MH on a weighbridge fully laden. Electric Motorscooter, Electric bike and normal lightweight bike plus chairs, table, BBW etc etc in garage.

Total weight was 3700kg so well within my 4250kg.

I did a measurement with the rear wheels only on the scales`. This came to 2240 out of a permissible 2500.

Question is - I know this is not accurate but in what way is it likely to be inaccurate? Is it likely to be more than 2240 or less?

Yes.
Depends on the weighbridge
But like speedometer, they tend to veer to the cautious.

I know you're trying to stay legal but you're well within plated limits.

Only advice is re-weigh at a different weighbridge (when passing).

 

[VXman]

Yes.
Depends on the weighbridge
But like speedometer, they tend to veer to the cautious.

I know you're trying to stay legal but you're well within plated limits.

Only advice is re-weigh at a different weighbridge (when passing).

It's more about the rear weight. Not concerned about legalities. I'm thinking of locating the bikes to a cycle rack on the back which will move a fair bit of weight rearwards on what is already a sizeable overhang. I'm wondering what 'spare' I have to play with at the rear. So really wondering how accurate the 2240 is likley to be based on the fact that the front wheels are off the scale.

 

[2x2camper]

Just put the MH on a weighbridge fully laden. Electric Motorscooter, Electric bike and normal lightweight bike plus chairs, table, BBW etc etc in garage.

Total weight was 3700kg so well within my 4250kg.

I did a measurement with the rear wheels only on the scales`. This came to 2240 out of a permissible 2500.

Question is - I know this is not accurate but in what way is it likely to be inaccurate? Is it likely to be more than 2240 or less?

Why did you not do the front?

 

[TheBig1]

The fulcrum effect will mean that the combined weight of rack and bikes, taking account of the rear overhang will be slightly higher as a down force on the rear axle, but only likely a few extra kg. There is always an inaccuracy with 2 wheels on 2 off weighing, usually reading slightly higher. Hence sometimes you see front and back axle weights added together weighing more than the overall 4 wheels on weight

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[Barti Ddu]

You've better to have the unweighed axle only just off the weighbridge plate, particularly so if the weighbridge has ramps on the approach rather than being flat and flush mounted into the ground.

 

[TheBig1]

forgot to mention, a lead up or off ramp throws the figures out as well

 

[tonyidle]

The ONLY error is caused the front and rear wheels being at different levels. I f they're at the same level there will be no inaccuracy.

 

[Daffy64]

There are set tolerances, if it’s a big weigh-bridge capable of weighing trucks then it’s within 20kg unless there is a significant difference in height between the front and rear axles, it it sits fairly level on and half off the weigh-bridge then chill out and accept the figures as good enough.

 

[VXman]

Why did you not do the front?

Error

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[2x2camper]

Error

Shit happens

 

[Revolvor]

It's more about the rear weight. Not concerned about legalities. I'm thinking of locating the bikes to a cycle rack on the back which will move a fair bit of weight rearwards on what is already a sizeable overhang. I'm wondering what 'spare' I have to play with at the rear. So really wondering how accurate the 2240 is likely to be based on the fact that the front wheels are off the scale.

Now you know the actual axle weights, you can use THIS spreadsheet in Resources to calculate the effect of moving your bikes.

 

[stevewagner]

There are set tolerances, if it’s a big weigh-bridge capable of weighing trucks then it’s within 20kg unless there is a significant difference in height between the front and rear axles, it it sits fairly level on and half off the weigh-bridge then chill out and accept the figures as good enough.

Within 20kg? I very much doubt it.

 

[Daffy64]

Within 20kg? I very much doubt it.

Why do you doubt it?

We’ve a 50t weigh-bridge at a quarry near us and it’s calibrated, I was talking to the guy doing it and he said at 50t it won’t be more than 40kg out and that could be scaled back so 20kg @25t etc.

They might look rough but are very sophisticated pieces of equipment.

 

[VXman]

Why do you doubt it?

We’ve a 50t weigh-bridge at a quarry near us and it’s calibrated, I was talking to the guy doing it and he said at 50t it won’t be more than 40kg out and that could be scaled back so 20kg @25t etc.

They might look rough but are very sophisticated pieces of equipment.

I wasn't doubting the accuracy of the weight bridge. While I was there there were a dozen commercial skip trucks etc going in/out getting official tickets so clearly it is calibrated for legal use.

However, I'm just questioning how accurate the measuring of one axle would be as I am aware this is not the official way to weight specific axles.

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[funflair]

I wasn't doubting the accuracy of the weight bridge. While I was there there were a dozen commercial skip trucks etc going in/out getting official tickets so clearly it is calibrated for legal use.

However, I'm just questioning how accurate the measuring of one axle would be as I am aware this is not the official way to weight specific axles.

If the axle is on the bridge it gets weighed and as others have said unless there is a massive difference in levels between the two axles it will be as good as it gets.

 

[Daffy64]

I wasn't doubting the accuracy of the weight bridge. While I was there there were a dozen commercial skip trucks etc going in/out getting official tickets so clearly it is calibrated for legal use.

However, I'm just questioning how accurate the measuring of one axle would be as I am aware this is not the official way to weight specific axles.

As long as the vehicle is level or at the same sort of level both on and part on the weigh bridge then it’s going to be good enough.

It’s never going to be perfect because even if you had 4 individual weight pads then the tolerance in calibration between the different pads will build in some inaccuracy and anything off level still has the effect of transferring weight to the lower axle.

 

[Boldly]

Think the weight will be a lot less if you ditch the bbw

 

[georgio]

Weighbridges are tested periodically by trading standards, formerly called weights and measures department. They are extremely accurate so as to be evidence in court .These are the ones where you get a weighbridge ticket which is your evidence of not cheating your customers.