How to determine towball weight

Submitted: Sunday, Sep 22, 2013 at 09:09
ThreadID: 104428 Views:4413 Replies:10 FollowUps:11
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I've been reading a recent thread which in part discusses towball weights.
http://www.exploroz.com/Forum/Topic/104409/Ford_Ranger_as_possible_replacement_Tourer_for_a_young_family.aspx?ky=&sn=&p=%2fForum%2fdefault.aspx%3fpn%3d1

My question is:

How do you measure the weight of a trailer with regard to the mass which will be put on to the towing vehicle?

I am reluctant to use my bathroom scales as they are a glass topped unit & the potential of cracking the glass is quite high.

My trailer weighs approx 1.4 t loaded (from a weighbridge) so I'm expecting 10% as a towball weight. Dunno if my bathroom scales will like either that weight or it spread over a ting footprint such as a jockey wheel.

Suggestions (polite) welcome.

Thanks
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Reply By: landseka - Sunday, Sep 22, 2013 at 09:51

Sunday, Sep 22, 2013 at 09:51
You can safely use the bathroom scales with the method shown here from caravaners forum . You could place a folded towel on your scales then a light board or something to protect the scales then zero the scales.

Keep in mind that this method only places 1/3rd of the ball weight onto the scales, in your case probably less than 50kg.

Cheers Neil
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Follow Up By: landseka - Sunday, Sep 22, 2013 at 09:53

Sunday, Sep 22, 2013 at 09:53
Darn link didn't work & no edit on here.....Try this link. http://caravanersforum.com/viewtopic.php?f=60&t=6557

Copy & paste if necessary, it appears the Insert Link function is not working.
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Reply By: Member - John and Val - Sunday, Sep 22, 2013 at 10:17

Sunday, Sep 22, 2013 at 10:17
Rick,

One option using your bathroom scales is to use a length of timber as a lever. Use one end of the timber as a pivot point, the other end resting on the scales (with something to spread the weight on the scales in you case). After an initial unloaded measurement to find the weight of the lever system, position it so that the jockey wheel rests on the lever towards the pivot end and take your loaded measurement. Subtract the unloaded measurement to get a corrected measure. Measure the distances from pivot to scales and from pivot to jockey wheel. The magnification provided by the lever is given by pivot-to-scales divided by pivot-to-jockey. Multiply your corrected weight measurement by this factor to get a pretty accurate measure of weight at the jockey wheel. Note that the measurements should be taken with the towbar at about it's correct towing height, and with the lever roughly horizontal. Suggest initially use with the jockey wheel close to the pivot point until you get the hang of it, then move out to get better accuracy.

It's not as complicated to do as it is to describe in words!

Hope that helps
Cheers

John

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AnswerID: 518574

Follow Up By: wizzer73 - Sunday, Sep 22, 2013 at 10:22

Sunday, Sep 22, 2013 at 10:22
haymanreese

have a look at the haymanreese method

wizzer
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Follow Up By: Member - John and Val - Sunday, Sep 22, 2013 at 10:48

Sunday, Sep 22, 2013 at 10:48
Good one wizzer! Saves a lot of words!

Cheers

John
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Follow Up By: landseka - Sunday, Sep 22, 2013 at 21:29

Sunday, Sep 22, 2013 at 21:29
Pretty much the same method as what I posted above.
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Follow Up By: Member - John and Val - Sunday, Sep 22, 2013 at 21:50

Sunday, Sep 22, 2013 at 21:50
Hi landseka - think we were both typing at the same time so I didn't see your response till I'd posted mine. Then couldn't get into the site you suggested without going through the registration process!

Cheers

John
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Reply By: Member - mike g2 - Sunday, Sep 22, 2013 at 10:32

Sunday, Sep 22, 2013 at 10:32
Hi Rick, try a search of exploroz for term towball weight. you will find your 10% is agreed average . also look at vehicle recommended weight for towball and towing capacity etc..

assuming 10% .... "home made" methods to try? : load up trailer with usual gear, weigh some heavy items 10-20k or more ( weights from home gym, large bags of rice, potatoes, etc..), or on the bathroom scale. chock the wheels to keep trailer still. set up a simple see saw balance by putting known heavy articles ( I'm a big fat fella at 110 kg!) on a 10' plank , one end to trailer, items at other end . trailer should lift/balance off ground to level ( check height off ground of towing vehicle ball to get correct level) . I reckon that should do the trick . checking ball loaded weight of a loaded trailer is thus achieved with see-saw set up of counter-balancing weights . can do this with jockey on: put trailer front end on see-saw or attach to pulley set up as a weight balance system , wind down jockey and let weight be taken up by the arrangement.
As said in other articles, without jockey wheel, trailer ball end should touch ground. some 4 wheel HD trailers don't touch ground.
also try industrial scales or any other known large weights ( 4x 25 k bags of sand or cement = 100k) . pulley balance can be attached to a garage rafter/beam or tree branch (solid one!), use similar weight balancing method.
MG
AnswerID: 518577

Reply By: Sand Man (SA) - Sunday, Sep 22, 2013 at 11:19

Sunday, Sep 22, 2013 at 11:19
Rick,

I had a similar problem to you with the bathroom scales.
Not only are they glass, but you need to tap on them to turn them on.

My solution was to purchase a new hydraulic bottle jack (my old one was cactus anyway) with one that includes a pressure gauge.
Cost was about $150 but works extremely well. Bought it from Maytow Caravans on Brien's Road Northfield.
Bill


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Reply By: The Bantam - Sunday, Sep 22, 2013 at 11:28

Sunday, Sep 22, 2013 at 11:28
If ya worried about ya good bathroom scales, go buy a cheap set for the purpose...you realy need to be able to check this from time to time....like every time you load up to go away.

If you need some sort of lever arrangement.....maybe its best to make up a jig out of timber or steel so ya don't have to reinvent the wheel every time.

AND you realy need a mechanical scale because the, step on step off, fiddle with some of the electronic scales is just not workable

remember too that you realy want to be measuring the ball weight directly under the hitch, many trailers the jockey wheel is over a meter back from the ball.

Best to use a jack stand or other contrivance ( that purpose made jig perhaps) directly under the ball.....then you can use the jocky wheel to raise and lower the drawbar on and off the scale.


As for the mythical 10%.....it is far from agreed....most of the modern trailers and all of the modern vehicles will have a specified maximum drawbar weight....and let me tell you it is often way less than 10%......more like 5% in many cases.

Some of these vans are running so close to the wind on the specified & permissable weights you realy do need to check them...and accurately.

Remember most council dumps & transfer stations have weigh bridges....my local does to charge unless you need a certificate.....just dont turn up at a bussy time and expect to piss around weighing ya rig.

When things are quiet and their eyes are glassing over the wiegh bridge attendants will be happy for you to drive over.

cheers
AnswerID: 518579

Reply By: Dennis Ellery - Sunday, Sep 22, 2013 at 11:36

Sunday, Sep 22, 2013 at 11:36
The company that services my caravan, in Perth, has a scale that clips into the jockey wheel clamp - they let their clients use it for free.
I park in front of their workshop and shift gear in my van, if I need to balance its towbar weight.
Talk to a similar company in your home town – they may have one.
AnswerID: 518580

Follow Up By: Dennis Ellery - Sunday, Sep 22, 2013 at 12:08

Sunday, Sep 22, 2013 at 12:08
By the way - my jockey wheel is 400mm from the ball, which is 5 metres from the centre of the wheels. The ratio isn’t had to calculate - subtracting 25kgs from the scales weight is a reasonable adjustment in my case.
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Reply By: Member - Frank P (NSW) - Sunday, Sep 22, 2013 at 12:00

Sunday, Sep 22, 2013 at 12:00
I use a public weighbridge at the local tip. Reads to two decimal places of a tonne, so that's about +/- 10kg accuracy, isn't it?

Park with the rear wheels of the tug just off the platform. Indicator then shows weight of van while hitched up.

Lower the jockey wheel and lift the coupling off the tug's hitch. Indicator shows increased weight because the tug is not supporting any of it.

Difference is the towball weight.

My tip will let me do that FOC if they're not busy providing I don't ask for a printed copy. That costs $30.00!!!

If you do that don't forget to step off the platform while doing this, otherwise you're adding your own weight :-)

Cheers
FrankP

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Follow Up By: Robin Miller - Friday, Sep 27, 2013 at 07:34

Friday, Sep 27, 2013 at 07:34
I like and do that one also Frank - and same as you, its free in dandenong south victoria as long as you don't want a printout.

I also measure front/rear wheel weights (which are nearly always the same) so I can put air into tyres proportionaly.
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Reply By: Lakers - Sunday, Sep 22, 2013 at 15:00

Sunday, Sep 22, 2013 at 15:00
The bathroom weight method (x3) has worked OK for me for the last couple of years, but I managed to pick up one of these recently...

http://www.ebay.com.au/itm/CARAVAN-AND-TRAILER-BALL-WEIGHT-SCALES-ACCESSORIES-/350879802350?pt=Caravan_Parts_Accessories&hash=item51b210e3ee

You can get these from MALZ and a number of caravan and/or camping outlets for around the $80 mark. Makes checking ball weight a breeze. Out of interest, I checked my van using the bathroom scales method and then with this new scale, and there was only 1 or 2 kg in it.

Cheers
Greg
AnswerID: 518589

Follow Up By: bluefella - Sunday, Sep 22, 2013 at 17:21

Sunday, Sep 22, 2013 at 17:21
Thanks for the info Greg.
I have just ordered one.
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Follow Up By: Member - Phil 'n Jill (WA) - Tuesday, Sep 24, 2013 at 14:12

Tuesday, Sep 24, 2013 at 14:12
These work for me - simplicity & accurate enough - The units slips in the tow ball position, so no recalculations for varying jockey wheel positions. No mucking about with bathroom scales & scraps of timber anymore. Best investment yet.

Cheers - Phil
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Reply By: Rick (S.A.) - Sunday, Sep 22, 2013 at 16:15

Sunday, Sep 22, 2013 at 16:15
Problem solved, with thanks to all.

Solution:

Place large piece of ply onto carport pavers.
Place electronic/digital scales upon that ply.
Place 9 ply on top of scales.
Place axle jack on the 9 ply. Note weight.
Lower Treg Poly block on to Axle stand.
Subtract 9 ply + axle stand from total weight = trailer drawbar weight, which is

108 kg.

The trailer weighs as mentioned, 1.4 t, but it is currently not fully loaded, so in my situation the 108 kg is close to the 10 % figure. Next time I'll weigh when the trailer is fully loaded. No doubt 3 x jerries on the drawbar will add a bit!!

Replace stuff into shed & scales into bathroom.
Job done.

Cheers


AnswerID: 518595

Reply By: member - mazcan - Monday, Sep 23, 2013 at 21:59

Monday, Sep 23, 2013 at 21:59
hi
towsafe tow ball weight scales 100kg-350kg on ebay for $85 p&h free
cheers
AnswerID: 518665

Follow Up By: member - mazcan - Monday, Sep 23, 2013 at 22:00

Monday, Sep 23, 2013 at 22:00
www.ebay.com.au
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Follow Up By: member - mazcan - Monday, Sep 23, 2013 at 22:05

Monday, Sep 23, 2013 at 22:05
hi and I have used my glass top bathroom scales several times by placing a 20ml thick x 150wide pine board across the top of them and haven't broken them yetby jacking the a/frame and sitting the jockey wheel in the middle of the pine board and then lowing the hydraulic jack slowly down until the scales take the weight read and jack up
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