Sometimes I wish I still had my father's mid '70s V8 Statesman! You could do a lot worse for towing a horse float.
Roger
Roger
Towing with 2019 Koleos
- Thread starter boleropilot
- Start date
i remember reading an article by a lady in the Herald Sun years ago, she was complaining about other drivers on the road getting in her way when towing her double horse float with two horses in it with her ford bronco at 100kph, she commented also that people don't realise how long it takes to pull up all of two tons going at 100kph,i laughed as she would have not been half way there with her weight estimate.... jim
got a, brother in law who years ago got 10speeding fines in n. t. towing van at 120to130kph with Prado. had a discussion with him about when things go wrong what happens, still wasn,t fazed just pissed off he got caught. same bloke got pinged by speed camera three times in one day in 60k,zone only 1to2 km from his home. just waiting for the news that he, s killed some other poor driver..... jim
spose he had to get home fast before he ran out of petrol ,the van would have been a bonus ,extra traction to get all those ponies down !,dont get me started on towing things, iv got away with some crazy things ,
I can vouch for a BX carrying half a tonne of tiles....
That speeding up to get home before the fuel ran out was common practice in Kenya. We lived there for two years....
The equivalent of 5 x 75 kg people, a full tank and a boot full of luggage!
Except that the driver has to sit in the front!
Roger
Roger
Re towball weights - 2019 Koleos.
Just as a possible guide to towball weight, I took the opportunity to make a few measurements yesterday when I picked up some concrete landscape blocks in the Koleos. 12 blocks at 14kgs each - approx 170kgs spread evenly with the C of G approx 300mm behind rear axle.
My rough calcualtion (50 years since I did moment calculations - so anyone is welcome to disagree) is that it would have been approx equivalent to a 137kg load on the towball. At this load the wheel arch heights were 760 rear, 810 front. After removing the load the measurements were 791 rear, 801 front.
So the rear wheel arch dropped 31mm under this load, and the front raised about 9mm. I reckon this would be about the same as a reasonably loaded trailer would apply to the car. I think it may need air boosters if it was doing a fair bit of towing at say 1500/150kg towing weights.
01 - 170 kg load
02 - Loaded condition.
03 - Unloaded condition.
04 - Rough calculation - am I on the right track?
Cheers.
Just as a possible guide to towball weight, I took the opportunity to make a few measurements yesterday when I picked up some concrete landscape blocks in the Koleos. 12 blocks at 14kgs each - approx 170kgs spread evenly with the C of G approx 300mm behind rear axle.
My rough calcualtion (50 years since I did moment calculations - so anyone is welcome to disagree) is that it would have been approx equivalent to a 137kg load on the towball. At this load the wheel arch heights were 760 rear, 810 front. After removing the load the measurements were 791 rear, 801 front.
So the rear wheel arch dropped 31mm under this load, and the front raised about 9mm. I reckon this would be about the same as a reasonably loaded trailer would apply to the car. I think it may need air boosters if it was doing a fair bit of towing at say 1500/150kg towing weights.
01 - 170 kg load
02 - Loaded condition.
03 - Unloaded condition.
04 - Rough calculation - am I on the right track?
Cheers.
Sounds plausible to me.
Roger
Roger
Interesting thanks. Moments.... Takes me back! I think that's right - I was thrown at first thinking about springs and compression but that's a consequence of the forces not a control over them.
I not convinced firmer rear suspension is the way to go. Some weight distribution bars if sensibly applied (so you don't overstress anything) makes more sense to me. If you put heavier rear suspension in, the rear axle is still carrying all the extra weight. Weight disbribution bars will spread some of that weight back onto the front axle that does all of the steering and most of the braking
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Fordman, I think you can expand the experiment and measure everything with a driver in the seat. Or driver plus front passenger.
Your calculations are however slightly wrong because you can see the front lifts and the back drops. That would suggest that the fulcrum point is somewhere inbetween the axles, not at the front axle. Which means the levers are all a bit shorter, hence the load at the ball is more than what you worked out.
To work out where exactly the fulcrum point is, you can try loading another two known loads at the exact same point and do all the measurements again. This is so you can have one extra equation to express the front mass (which you don't know) as a function of the two unknown levers. Use one of these three equations to do that and plug the expression in the other two equations and now you have two equations with two unknowns (lever to front and lever to load). That will give you the fulcrum point and then, with the correct lever to load you can work out the load on the tow ball.
You could also try to measure along the car to find where the height does not change.
Your calculations are however slightly wrong because you can see the front lifts and the back drops. That would suggest that the fulcrum point is somewhere inbetween the axles, not at the front axle. Which means the levers are all a bit shorter, hence the load at the ball is more than what you worked out.
To work out where exactly the fulcrum point is, you can try loading another two known loads at the exact same point and do all the measurements again. This is so you can have one extra equation to express the front mass (which you don't know) as a function of the two unknown levers. Use one of these three equations to do that and plug the expression in the other two equations and now you have two equations with two unknowns (lever to front and lever to load). That will give you the fulcrum point and then, with the correct lever to load you can work out the load on the tow ball.
You could also try to measure along the car to find where the height does not change.
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Schlitz, I agree and disagree. I am struggling to get my head around it, as I said it's a long while since I did this more professionally (for example, calculating 5th wheel turntable distance behind (edit: in front of) truck rear axle centre line to produce correct front axle loading with fully laden semi-trailer).
I believe from the measurements I have that one can work out the equivalent weight at the towball to give the same downforce on the rear springs. Given that the car body/chassis is a rigid beam, I think there can only be 2 fulcrum points, the centre line of the front or rear axles. Think about jacking the rear of a car, it pivots around the front axle, and vice versa. In my above calculations I have used the front axle as the fulcrum, but I suppose once the rear axle is supporting the mass, I guess it becomes the fulcrum. Or you could be right, the effective fulcrum lies between the two axles.
However, it's all just guesswork for fun at the moment. When I get a towbar fitted in a couple of weeks, I'll just hang some weight on the towball and see what the suspension travel really is.
Chris M.
I believe from the measurements I have that one can work out the equivalent weight at the towball to give the same downforce on the rear springs. Given that the car body/chassis is a rigid beam, I think there can only be 2 fulcrum points, the centre line of the front or rear axles. Think about jacking the rear of a car, it pivots around the front axle, and vice versa. In my above calculations I have used the front axle as the fulcrum, but I suppose once the rear axle is supporting the mass, I guess it becomes the fulcrum. Or you could be right, the effective fulcrum lies between the two axles.
However, it's all just guesswork for fun at the moment. When I get a towbar fitted in a couple of weeks, I'll just hang some weight on the towball and see what the suspension travel really is.
Chris M.
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Hello Chris,
Once you have the towbar installed you can measure its height loaded and unloaded. This third height difference ought to allow you to determine the fulcrum point.
Roger
Once you have the towbar installed you can measure its height loaded and unloaded. This third height difference ought to allow you to determine the fulcrum point.
Roger
Hi schlitzaugen. I disagree with your logic. Fordman is correct in his extrapolated towbar downforce based on his load of pavers. In his calculation the rear axle centerline is the correct fulcrum point to use. You are confusing the net effect of the movement of a rigid beam as a consequence of the applied load.
Based on the above data the net reduction in downforce on the front axle is 300/2700 x 170kg = 18.9kg.
Fordman, Whippet, I don't think so.
For a very simple reason.
You can not isolate a physical system from the outside as long as there are interactions with said outside. At least not unless you replace said interactions with equivalent forces/momenta/etc.
If the car didn't move at the front I might be inclined to agree with you, but the fact that it moves proves there is some interaction between the front mass hanging over the front axle and the rear mass (sure, everything else too, but we're looking at these two). So if you want to balance moments, you need to find the correct fulcrum point about which all these weights give some moment according to their leverage.
Sure, you can use any arbitrarily chosen point but if you eventually want the weight at the towball you will need to apply a correction, which is to say, you will need to "normalise" (or correct) all the momenta to account for the distance between your chosen fulcrum point and the real fulcrum point. In other words, you need to calculate the moment about the real fulcrum point as I said.
You guys would be correct if the car didn't have any suspension. Like a slab of rock resting on two jackstands (one at the front, one at the back). Then, yes, the rear axle would be the fulcrum point.
For a very simple reason.
You can not isolate a physical system from the outside as long as there are interactions with said outside. At least not unless you replace said interactions with equivalent forces/momenta/etc.
If the car didn't move at the front I might be inclined to agree with you, but the fact that it moves proves there is some interaction between the front mass hanging over the front axle and the rear mass (sure, everything else too, but we're looking at these two). So if you want to balance moments, you need to find the correct fulcrum point about which all these weights give some moment according to their leverage.
Sure, you can use any arbitrarily chosen point but if you eventually want the weight at the towball you will need to apply a correction, which is to say, you will need to "normalise" (or correct) all the momenta to account for the distance between your chosen fulcrum point and the real fulcrum point. In other words, you need to calculate the moment about the real fulcrum point as I said.
You guys would be correct if the car didn't have any suspension. Like a slab of rock resting on two jackstands (one at the front, one at the back). Then, yes, the rear axle would be the fulcrum point.
problem is with reduced load on the front wheels ,traction and steer ability ,are reduced! ,particularly when you are going into a dip which has a turn just after it ,the dip forces the rear down lifting the front ,and the car just dousnt go where you point it ,scarry,i have experienced this on a rear wheel drive, with front wheel drive ,could be real interesting ,
Hi schlitzaugen.
If the rear and front axles were rigid and not sprung, would you still pursue your argument?
If you had the vehicle front and rear axles as rigid (unspring) and sitting on individual scales, the load figures calculated by Fordman still hold and would be reflected on the scales.
You are confusing that the rear (and front) axle is a pivot point and suspension concurrently. It reacts in response to changes in load.
Not sure what you either of you are getting at here but I do know that heavy vehicles are weighed on weighbridges which don't give a toss about suspension arrangements. Each axle is apportioned a weight from the combined total registered, and there can be up to eleven or more. Their combined weight has to be below what is legally permitted as does the weight of each axle and axle group. Cars have maximum manufacturer stipulated axle loads as well, not only GVM's and GCM's.
P.S: For all the scientists out there I have used the term "Weight", whereas I should have used the term "Mass". I don't want to confuse anyone!
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