Road Weigh Bridges

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purple5ive
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Road Weigh Bridges

Post by purple5ive » Thu Mar 21, 2019 10:18 am

So,
while on the way back from coota we went past a Weigh bridge on the side of the road, ive always been curious as to how much my BTM weighs as its not braked and hence should be under 750kgs to be legal.

i went in an drove over the weighbridge but the bridge wasnt long enough for me to unhook the trailer and plonk it on, so i just parked the trailer wheels on the weighbridge and took the reading. Just Under 700Kg is what i got. which was pretty close to what my esitimate was so was happy with that.

Question is, is this the right way to do it though??

Bugatti

Re: Road Weigh Bridges

Post by Bugatti » Thu Mar 21, 2019 12:20 pm

Hey P5, yeah it is close with a but.

Those Weigh bridges (operators) add up all the weight from all sets of wheels for the total gross weight.

Your trailer would be transferring weight to the road via the wheels and via the downward load on your tow-bar and then subsequently through your vehicle to the road.

So your trailer's total weight would be the weight at the wheels AND the weight (downward load) at the tow hitch. You can measure the tow hitch weight quite easily with some Bathroom Scales (my advice is take the Bathroom Scales to the trailer and not your trailer to the Bathroom lol). Just place the tow hitch of the trailer (not attached to the vehicle) on the bathroom Scale, obviously, and preferably at the same height that it is when it is being towed to be more accurate. This can be done quite easily with a milk crate.

Cheers, Bugatti

skronkman
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Re: Road Weigh Bridges

Post by skronkman » Thu Mar 21, 2019 12:51 pm

You can weigh your car (all four wheels) with the boat on, then the boat off. Subtract one from the other and you get ball weight. Add this to your boat weight at the trailer wheels. That's the actual weight. I had to do this as my bathroom scales
didn't go to 300kg!

Bugatti

Re: Road Weigh Bridges

Post by Bugatti » Thu Mar 21, 2019 1:14 pm

skronkman wrote:
Thu Mar 21, 2019 12:51 pm
You can weigh your car (all four wheels) with the boat on, then the boat off. Subtract one from the other and you get ball weight. Add this to your boat weight at the trailer wheels. That's the actual weight. I had to do this as my bathroom scales
didn't go to 300kg!
Yes, you are right skronkman. I was making an assumption that the ball weight (or should I say, all ball weights) are within the range of Bathroom Scales, which wouldn't be the case for all boat/trailer combinations. I used the Bathroom Scales method with my boat, some years back when the over 750 kg needs brakes rule came in. My ball weight came in at 90 kgs.

Mind you, glad that your Bathroom Scales don't go to 300 kgs, as anyone who has Bathroom Scales that when to 300 kgs, would have bigger problems than just tow ball weight. Puts a whole new spin to "I went out, and all I got was donuts"

doughnuts.jpg

Cheers, Bugatti

purple5ive
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Re: Road Weigh Bridges

Post by purple5ive » Thu Mar 21, 2019 7:59 pm

Thanks guys,
so next time weigh the whole car and then the trailer, then minus trailer from whole car to get ball weight, and then add ball weight to trailer to get the actual trailer weight.
Cheers

frozenpod
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Re: Road Weigh Bridges

Post by frozenpod » Thu Mar 21, 2019 10:41 pm

Park the trailer so the car wheels are just off the bridge but the jockey wheel is over the bridge.

Weight the trailer connected to the car.

Lift the tow ball off the car with the jockey wheel making sure the jocking wheel is on the bridge and weight the trailer free of the car.

The difference is the downball weight.

purple5ive
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Re: Road Weigh Bridges

Post by purple5ive » Fri Mar 22, 2019 8:47 am

will give it a go next time. cheers lads

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