Author Topic: Do Weighbridges Usually Have Tow Ball Scales?  (Read 1101 times)

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Offline baz1

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Do Weighbridges Usually Have Tow Ball Scales?
« on: September 16, 2019, 09:47:22 AM »
Hi All,

We want to use the Caboolture Public Weighbridge in Qld, i've never used one before, and am trying to find out if they have a tow ball scale. The only number listed with the weighbridge is a mobile number which goes to anwserphone. Does anyone know if weigh bridges usually keep tow ball scales you can use? I know you can buy them, but i'd rather not shell out $70 for something i would only use once.

Cheers!

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #1 on: September 16, 2019, 09:49:34 AM »
Hi All,

We want to use the Caboolture Public Weighbridge in Qld, i've never used one before, and am trying to find out if they have a tow ball scale. The only number listed with the weighbridge is a mobile number which goes to anwserphone. Does anyone know if weigh bridges usually keep tow ball scales you can use? I know you can buy them, but i'd rather not shell out $70 for something i would only use once.

Cheers!
no I woudlnt think theres much call for semi's using a towball scale :)

Buy one, use it and then return it ;) you bought it as a gift, and they didnt want it
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Offline RebsWA

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #2 on: September 16, 2019, 10:33:08 AM »
Buy one and keep it if you are concerned with ball weight.
It can change from trip to trip depending what and how you load.
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Offline Beachman

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #3 on: September 16, 2019, 10:56:01 AM »
I've used the Caboolture Public Weighbridge to weigh the Car/Camper Trailer once and they were fantastic. They don't have a Tow Ball Scale as such, but they weigh the car/ trailer together and I then drove forward so the car is no longer on the scales to unhitch but keeping the trailer/Jockey wheel is on the scales. Then they work out your Tow Ball weight and total trailer weight. 

Offline Champin

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #4 on: September 16, 2019, 11:22:19 AM »
I checked mine at a caravan sales.

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Offline rags

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #5 on: September 16, 2019, 06:39:34 PM »
I've used the Caboolture Public Weighbridge to weigh the Car/Camper Trailer once and they were fantastic. They don't have a Tow Ball Scale as such, but they weigh the car/ trailer together and I then drove forward so the car is no longer on the scales to unhitch but keeping the trailer/Jockey wheel is on the scales. Then they work out your Tow Ball weight and total trailer weight.

Same for me

Offline DandyD

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #6 on: September 16, 2019, 07:26:55 PM »
I know you can buy them, but i'd rather not shell out $70 for something i would only use once.

I've got one and I use pretty much every time I tow.

Offline weeds

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #7 on: September 16, 2019, 08:25:27 PM »
I've used the Caboolture Public Weighbridge to weigh the Car/Camper Trailer once and they were fantastic. They don't have a Tow Ball Scale as such, but they weigh the car/ trailer together and I then drove forward so the car is no longer on the scales to unhitch but keeping the trailer/Jockey wheel is on the scales. Then they work out your Tow Ball weight and total trailer weight.

Yep if there is no line up do this


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Offline #jonesy

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #8 on: September 18, 2019, 12:57:14 PM »
As a side issue. Some Victorian weighbridges on the freeways, which are used by Vic Road and Police have displays that are on all the time. (At least on the Hume and Western) You can do all your own measurements for free. 
« Last Edit: September 18, 2019, 01:03:23 PM by #jonesy »
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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #9 on: September 18, 2019, 01:56:37 PM »
Yep they do and a lot of weekends when I have gone to weigh the car I have found a police car sitting at the Seymour one, not sure what they are doing but not game to weigh the car while their sitting beside the scales.
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Offline baz1

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #10 on: September 18, 2019, 02:14:29 PM »
Thanks for all the replies!

Offline baz1

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #11 on: September 18, 2019, 04:43:24 PM »
Out of interest, I’m aware of another guy who took his camper to Go Weigh in Geelong, Vic, he did all the things described here to identify the tow ball weight (weighed car on bridge, then weighed car on bridge hooked up to trailer, with only car on bridge, and subtracted the two). The towball weight came in at 260kg. He then went home, and used a tow ball weigh scale from somewhere like BCF, no change to the load, it comes in at 110kg. How would you account for a 50kg difference, and which one would you trust?

His unladen towball weight is 150kg, he had two full 9kg gas bottles, so about 20kg total, two full 20ltr fuel jerry cans, so about 30kg total, a full fridge, so about 40kg, and a front and rear 80ltr water tanks full, the front water tank is about 2 feet further away from the axle than the rear, so it must have some bearing on the ball weight. Then he had all the other usual stuff. So in light of this, what would you estimate his ball weight to be, and therefore which of the two weighing methods would you say is more accurate?

The difficulty is, presumably it’s not as simple as saying 20kg in front of the axle equates to an additional 20kg of ball weight, as it depends on the distance of the 20kg from the axle. 20kg directly on the hitch is going to add 20kg to the ball weight, 20kg just in front of the axle is not.

Offline DandyD

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #12 on: September 18, 2019, 04:53:18 PM »
The difficulty is, presumably it’s not as simple as saying 20kg in front of the axle equates to an additional 20kg of ball weight, as it depends on the distance of the 20kg from the axle. 20kg directly on the hitch is going to add 20kg to the ball weight, 20kg just in front of the axle is not.

You would need to draw a free body diagram.


The trouble with cheapo nose weight scales is that they are not calibrated. Even the calibrated ones will lose their calibration with age. The weighbridge will be calibrated regularly, although they are usually intended for weighing heavy weights and perhaps not so accurate with lighter loads?

Offline #jonesy

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #13 on: September 18, 2019, 05:16:22 PM »
Yep they do and a lot of weekends when I have gone to weigh the car I have found a police car sitting at the Seymour one, not sure what they are doing but not game to weigh the car while their sitting beside the scales.
If they are angled facing the wrong direction, they will most likely be doing speed checks.
Doubt very much they will worry if you go in and weigh yourself.
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Offline edz

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #14 on: September 18, 2019, 05:32:04 PM »
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Offline GBC

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #15 on: September 18, 2019, 07:42:57 PM »
Out of interest, I’m aware of another guy who took his camper to Go Weigh in Geelong, Vic, he did all the things described here to identify the tow ball weight (weighed car on bridge, then weighed car on bridge hooked up to trailer, with only car on bridge, and subtracted the two). The towball weight came in at 260kg. He then went home, and used a tow ball weigh scale from somewhere like BCF, no change to the load, it comes in at 110kg. How would you account for a 50kg difference, and which one would you trust?

His unladen towball weight is 150kg, he had two full 9kg gas bottles, so about 20kg total, two full 20ltr fuel jerry cans, so about 30kg total, a full fridge, so about 40kg, and a front and rear 80ltr water tanks full, the front water tank is about 2 feet further away from the axle than the rear, so it must have some bearing on the ball weight. Then he had all the other usual stuff. So in light of this, what would you estimate his ball weight to be, and therefore which of the two weighing methods would you say is more accurate?

The difficulty is, presumably it’s not as simple as saying 20kg in front of the axle equates to an additional 20kg of ball weight, as it depends on the distance of the 20kg from the axle. 20kg directly on the hitch is going to add 20kg to the ball weight, 20kg just in front of the axle is not.
The distance from the tow hitch to the centre of the tow vehicle’s axle is another lever and the mass increases from the towball to the rear axle (people with long tow hitchs take note). This is the only real weight the scalies are interested in. They weigh axles. I’ve never seen them unhitch a trailer ever. Weigh your rear axles while hooked up and compare against what manufacturer max is for that axle.

Offline baz1

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #16 on: September 18, 2019, 07:48:11 PM »
Thanks, how would you go about weighing your rear axle on the bridge?

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #17 on: September 18, 2019, 10:33:35 PM »
Thanks, how would you go about weighing your rear axle on the bridge?
drive the front wheels off the bridge.. but again how far off you move them will change the reading.
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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #18 on: September 18, 2019, 10:55:01 PM »
Yep they do and a lot of weekends when I have gone to weigh the car I have found a police car sitting at the Seymour one, not sure what they are doing but not game to weigh the car while their sitting beside the scales.

Police,  dont worry. Road traffic authority in charge of weigh stations. Just a good spot for speed checks...
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Offline #jonesy

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #19 on: September 19, 2019, 06:11:33 AM »
drive the front wheels off the bridge.. but again how far off you move them will change the reading.
Approach and departure on the weigh plates are the same level so the distance off ddoesn't effect the reading.
This allows B doubles to be weighed by axle groups.
 
Also need to be mindful of the increments the scales show.  Eg.   10 kg, possibly 20kg.
Not much when you are weighing 20 tonne trucks, but more when calculating ball weights. 
Also make sure YOU are standing on the plates, as you are also part of the load.
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Offline GBC

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #20 on: September 19, 2019, 06:25:36 AM »
Thanks, how would you go about weighing your rear axle on the bridge?

Drive the front axle off the bridge and get a weight of the rear and trailer, then drive the rear axle off and weigh trailer only, then subtract the trailer weight.

Offline Rodt

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #21 on: September 19, 2019, 06:54:17 AM »
I more than likely don't understand but why would you want to weigh your tug rear axle with the van hooked up? This won't give you a ball weight as the weight of the vehicle will be in the mix wouldn't it?

The way I weigh mine is drive forward enough so that the tow vehicle rear axle is off the bridge which gives me my van gtm and I then put the jockey wheel down (on the platform) to take the weight off the tug which then gives me my atm. I then take the gtm weight off the atm which gives me a rough ball weight. There is more included in the atm (ie: drawbar weight etc) but it serves as a rough indication if I don't wish to buy a towball scale.

Cheers

Rod

Offline baz1

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #22 on: September 19, 2019, 07:33:51 AM »
Thanks Rod, so are you saying if you use a weighbridge to identify the ball weight, using the various methods described here (thanks everyone), that ball weight will include the draw bar between the ball and the trailer, which ordinarily would not form part of the ball weight?

This being the case, would this explain this other persons discrepancy between the ball weight identified at the weighbridge and the tow ball scale?

Offline baz1

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #23 on: September 19, 2019, 07:57:35 AM »
I think I’m just going to bite the bullet and buy a tow ball scale. All the ones at BCF etc look like they are not for polybpock couplings, but the ball couplings. Can anyone recommend one for s polyblock coupling?

Offline #jonesy

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Re: Do Weighbridges Usually Have Tow Ball Scales?
« Reply #24 on: September 19, 2019, 08:11:35 AM »
I use the one for a ball coupling, at the front of the drawbar there is a plate the poly black is connected to. I just put it under here. It is only about 10-15cm back from the poly block so makes minimal difference to the results (which aren't super accurate anyway)
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