How hitch height affects towball mass and trailer stability - it's not obvious
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- Опубліковано 19 чер 2024
- #towing #hitchheight
You have a towing hitch, and you have a trailer. What happens if the trailer isn't level when it's towed - either nose up or nose down? What effect does that have on trailer stability, the towball mass, and the towcar? Is it different for single-axle vs tandem-axle trailers?
00:00 introduction & measuring scales
01:01 single-axle trailers
03:42 load-share vs non-load-share suspension
05:25 tandem-axle trailers
07:41 combined hitch height/towball mass results
08:08 hitch options
09:09 why you need to tow level explained for single and tandem trailers
12:28 reasons why you might be 'towing low'
14:33 summary of hitch heights vs TBM & trailer stability
Post questions as comments!
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Support blog post for this video which addresses common questions including "but that's a load-share system and you said it wasn't".
l2sfbc.com/my-error-on-the-hitch-height-video/
Robert the suspension at 4.10 is load sharing . It's called a roller rocker set. Former trailer builder
Another effect related to leaf springs which is almost never addressed. Leaf springs have a roll steer effect. They act as a trialing arm suspension in that regard. If the front mounting point for the spring is higher than the axle mounting point you have an unstable condition. When the vehicle (car, trailer, whatever) rolls to one side the front portion of the spring on that side become effectively longer as it flattens and the other side becomes shorter. This steers the axle toward the side of the roll (outside on a curve causing the roll), a unstable condition (learned this from the Chrysler guru for ride and handling in the 1960s. "When all else fails to make the car stable, just lower the front spring eye (rear axle) one inch. Done, problem solved.") Raising the tongue also raises the front mount of the spring relative to the axle. Many small trailer springs have too much arch which already raises the front mount above the axle. Raising the tongue aggravates the problem. Here in the SE U.S. we often see trailers hitched to tall pick ups without a drop hitch. Tongue very high. "Well that's how you're supposed to hitch it. That makes it easier to load my lawn mower on the trailer because the ramp is lower." And then they wonder why their trailer is weaving all over the road. "Must be a bad trailer. I need to get a better trailer."
Related stability issue: Tongue length. Increased distance from hitch ball to axle both smooths the ride of the trailer (reduced pitch over bumps) and reduces the trailer load effect on the hitch both side to side and vertical. Longer tongue also makes backing easier. How many times have I heard from people who now nothing about towing, "I can't handle a long trailer, it would be to hard for me to back it up." Precisely the opposite of reality. Semis (short truck, long trailer) are very easy to back. Crew cab pickup with 8' trailer nearly impossible to back because the trailer steers much more quickly than the truck.
This wisdom coming to you from someone who at the age of 14 could back a four wheel trailer hitched behind a forage harvester hitched behind a John Deere with a hand clutch. Not easy, but it can be done. And at 77 I have a class E (non commercial class A) and still tow frequently up to 40,000 GCW using a 1T truck.
Thank you, very good points! Trailer dynamics is a sadly ignored field for trailer makers.
A few days ago I saw a lifted box trailer. Both axles had been installed below the leafs which seemed to have too much curve.
Not sure what he was trying to accomplish because with those axles it wasn't more ground clearance 😢
My boat trailers tounge is too short and is a PIA to back up 😢
that would have to be the most entertaining AD ive seen in a long time , keep her ,luv your products
Great video, this is the info I really needed. I have been towing unlevel and had three tire blow outs. Now I know why. Thanks very much.
Bloody excellent old mate, well presented and very concise. Thank you.
Great explanation and examples Rob 👍🏼👍🏼👍🏼
I’ve watched 4 or 5 of your towing videos now and they’re all extremely good. Thank you for making these!
You're welcome
I went through this same process with our tandem trailer with non-load sharing suspension. I had the springs altered by the trailer manufacturer to suit our use (they often install 3.5T leaf packs which we did not need), then worked on getting the load distribution right, change the standard trailer hitch to an Ark XO 2T over-ride for articulation, then installed a Hayman Reese adjustable tow mount 3.5T (we tow 1.7T gross) on the ute, positioned it to tow level on flat concrete with the ute loaded. Also, the ute has had suspension upgrade for the higher constant load and towing. Before doing all this the tow rig and trailer handled like a bag of wet laundry and it was a rough ride. It wasn't fun. Now, it's so much better, though I still have four shocks to get installed on the trailer. Well worth doing.
I guess this highlights that caravans have quite a lot of mass high above the axle line. The effect would be less pronounced for a trailer loaded with dirt.
Great information that everyone towinga caravan or boat or other should be aware of for the sake of safety as a priority and other reasons such as the effect on the comfort of the towingvehicle..
Thanks mate. Your vids are really helping us get things sorted. Good onya 👍
Glad to help
Great info Robert.. nice to educate all of us. I dont usually to a trailer but its good to know this info regardless cause it may save your "rear" end literally.
Thanks 👍
Another excellent and informative video Robert. Well done and thanks.
Very welcome please share
Great video! Very clear and concise! Thank
Another smashing video thanks.👍
Thanks for another informative video
Great video. I appreciate the through yet succinct explanation and the visual aids. 👍
Thank you
Excellent video! You should see some of the things I have with people in the U.S. and how they tow their trailers! The hitch is only 16-18 cm above the ground because it is so overloaded!
Important matter. Thank you!
Once again a very informative video. Further to the points explained everyone pretty much, only adjust the tow ball height on their car well what if the van / trailer has a hitch height that is outside of the ADR limits of 360mm to 460mm "not sure if this is measured hitched to a vehicle or not". People have sometimes on leaf sprung vans flipped the axle for more clearance so that is a near 100mm height adjustment. Also I have seen off road vans where the hitch height is way more than the 460mm.
I understand this is a point not in the focus of this video but it did raise some questions and i have not have any definitive answer on the subject.
Awesome videos… very informative. Thank you
Glad you like them!
Excellent video. One thing i will point out is when using the spring tow ball scale on a DO35 hitch use extreme care. With the rotational ability of these hitches I have seen a bloke get a fractured eye socket when the hitch rotated & was shot by the scale itself. Tyre chocks while excellent won't prevent the tow hitch rotating.
Great video, just confirmed a whole lot of things for me.
Glad to hear it!
That was a really informative video. Thanks a lot.
You're welcome please share 😊
Love your work Rob. Very thorough as always. I've towed with inverted hitches and never knew some aren't supposed to be inverted. Perhaps do a clip on that topic alone as I'm sure people don't know about it.
So much to do...
Same here. 😕
Thanks Robert
Good video Robert.
Just to add another factor to the discussion, because of the height of the centre of gravity, which may change with load, the centre of gravity moves forward, closer to the towball, when the towball is lowered, and rearward when the towball is raised, thus changing the distribution of load between the trailer axle group and the towball.
Indeed, I didn't want to make it too complex. I have another video using a model where I demonstrate the effect of height on stability - in fact two videos. Low CoG is good!
great explanation
It appears in the single axle, by raising the hitch, the high center of gravity shifts the weight backwards, which reduces the weight on the hitch. On the unloaded tandem axle (with low center of gravity), raising the hitch shifts only a negligible amount of weight backwards. The dominant effect here is that the rear axle becomes the primary pivot point, which means the hitch has to take more weight. To visualize this, think about the rear axles as the wheelbarrow tire and the hitch where you pick it up. In the case where the front axle is the primary pivot point, think a teeter-totter with the load in the center. Less force is needed to balance the teeter-totter than the wheelbarrow.
Another great piece of towing information that's not well known and a great reason to require towing license restrictions.
Yes. Even a semi-licensed driver like myself is not aware of Robert's knowledge. Thank goodness for his videos
I didn’t know most of this but did know to get it as close to level as possible.
Very informative, thanks.
You're welcome!
John, I am going to have to apologise. You have made me think further, and I have learnt something. I was thinking in terms of simple levers. The effect you have identified comes from the height of the van. As it leans down at the front the centre of mass moves forward minutely, putting more load on the ball, and when the ball height is increased the centre of mass moves rearward. But these are very small amounts. If the centre of mass is below the ball height (unlikely) the effect will be reversed. The closer the centre of mass is to the ball height the less the effect will be. But if you are that close to the limit of your towball capacity I think you need to review your rig.
I don't know aboout you but that hitch flex is crazy!
Thanks this has helped me.
Glad it helped please share!
At least you guys have parking brakes. Here in the US, we've got nothing and it would be fantastic to have such a feature.
Thanks for an informative vid.
What! Didn't know that! Not that'd I'd rely on ours anyway...
Very informative!
Glad it was helpful!
That truck your towing with is pretty sweet.
Thank you so much!
You're welcome!
Another good bit of info. I've always tried to keep a trailer level but hadn't thought much about why. Interestingly, I saw an ad today for a curt rockerball. Would love to see an analysis of that. It looks like a gimmick to me but I've been wrong before.
I have one and they do work very well. Takes a lot of the jerkiness out of the towball connection.
Rocker ball, or air shock hitches or GenY torsion hitch assembles, all are designed to take the shock out of trailer hitch connections. A must for longer and heavier trucks and US puckups. Isuzu advise it is a must, kedron will not warrant their vans without an air shocker hitch, stops the porpoising of trucks and vans.
If the link between the front and rear leaf springs can pivot, which it looks like yours can, then the axles are load sharing. Load on one axle will push up on the link, forcing the other axle down with an equal force.
True, but you can see that the TBM changes according to a non-load-share, the rear wheel comes off the ground, and load changes from front to rear axles on the trailer. So the load-share effect is tiny, and a nice contrast to the single axle which behaves in the opposite manner.
I was confused by this as well. A rocker roller suspension type as shown in your video is a load sharing suspension.
@@L2SFBC The load sharing is not working because there is no weight on the trailer.
Tandem axles with slipper springs is non-load sharing suspension. Rocker suspension as in this tandem trailer is load sharing. The difference is probably due partly to the geometry relative to the suspension but more likely due to component friction which diminishes perfect load sharing.
@@wanajday l2sfbc.com/my-error-on-the-hitch-height-video/
Great vid Robert! Really educational for those that don’t understand. Have you done a vid on breakaway cables on trailers and where they attach on to the vehicle ? This is always a debatable topic on social media and forums and I reckon would be great content for your channel! Cheers Adam
Maybe in future
Great to see more of your always-excellent content, Robert! I wished to comment on (at least in the USA) the recommended TBM of 10-15% trailer weight... When towing recreationally (retired, now), I deliberately tow smaller and lighter trailers than what my tow vehicle is rated for. This has it's obvious benefits. I also use less than 10% TBM ("trailer tongue weight", here) because I work hard to load my trailer with it's heaviest cargo as centered over the trailer axle as is possible, with an eye for keeping weight away from aft of the axle. Your earlier vids on this topic (trailer loading for stability) are spot on. I suspect one reason for the recommended as high as 15% TBM could be due to the tow vehicle being a pickup truck or ute with an empty bed... we would want a heavier TBM to add weight to the lightly-loaded rear axle of the empty-bed tow vehicle. I think you get what I'm trying to say...
I use an F150 but keep tools and equipment in the bed 24/7/365 and already have, before I add any trailer TBM nearly 50/50 F/R weight distribution. I therefore strive to achieve 5-7% TBM using my F150 as it is already loaded. My little combination tows like a dream.
Thanks again as always for your great content.
Thank you for the educational comment, really adds to the video, appreciated!
This makes so much common sense - thank you. I was so fixed on that 10-15%, but on a single axle trailer (what I have) it makes more sense to me to just focus on leveling the car and trailer.
Are there any concerns going over bumps/inclines/declines/turns etc with it being only 5-7%?
@@midnight121190 Only if your tow vehicle's rear axle is lightly loaded. See the second half of my original reply? I use less than 10% tongue weight/tow ball mass because my tow vehicle's rear axle is already sufficiently loaded even before I hang a trailer on it.
Look for Robert's videos on the topic of trailer weight distribution. Safe travels!
@@applesbighatranch6906 I did see that part just wanted to double check 👍 thanks for replying!
Hi Robert, excellent info, thanks. Have you considered doing a similar investigation into tow ball extensions and their benefit vs weights changes?
Maybe in future yes
Great video
Glad you enjoyed it
I wonder if the change is consistent as a percentage the more pitch is raised or lowered. Great video Dr Pepper.
Non-linear
Interesting video thank you. Your tandem looked like it had walking gear or rocker arm type suspension, it if it does, it would be doing a little load sharing, but still a significant change.
Yes, it was doing a little load sharing, but not much!
Your camp trailer has parking brakes? That’s cool. I wish my camper had them like my army trailer
Very informative, thanks Rob. I know aftermarket airbag suspension does nothing to share load on the tow car's axles but I presume (and I know I shouldn't!) by using airbags to level the rig it would provide optimum towing and, in the case of my single axle trailer, relieve some weight on the towball and hence the rear axle? Great work, cheers
Absolutely right Mark, if the towcar can go level chances are the trailer will be level and life will be good!
At 4:09 the photo appears to be of a compensated link suspension. If the rear wheel rises it puts pressure on the left hand end of the spring. Forcing the lever up. Which forces the font part of the lever down increasing the spring tension on the front wheel. A standard method used on railway engines for at least 150 years. Note that because the attachment points for the springs are above the pivot point of the lever this has the equivalent effect of an anti-rollbar. As the suspension moves away from the level one side increases its leverage and the other reduces its leverage. This creates a controlled amount of self levelling function. ( controlled by the design of the link but not adjustable).
l2sfbc.com/my-error-on-the-hitch-height-video/
Nice job on the demonstration with the two trailers, I didn't see that reverse effect coming on the tandem. But I'm left wondering if the tandem results would be different with a significant load (500-1000kg) on the trailer vs empty.
The suspension would load-share a little better, but even at max load the effect would still be there.
Great video... where do I find a link for the NZ company that has the adjustable trailer hitch; seen at 09:03. Thanks. Also, are there tow ball scales starting at 50 kg? They all seem to start at 100 kg.
glad my Touareg has air suspension, any load and it's level automatically.
btw pretty sure that car trailer with the bell crank between the leaf springs has a form of load sharing? unlike vans with fully independent suspension.
I thought those roller rocker tandem setups were load sharing. From the Alko webpage:
"Rocker Roller springs are used in a multi axle configuration. Linking the springs through a “rocker” assembly, a transfer of load is achieved when one axle is carrying a large percentage of the weight (crossing kerbs etc.) so that the loads are more evenly spread throughout the system."
Sort-of load sharing. Have a look at the Bruder video for true load sharing. You see the rear wheel of the trailer lift off the ground, and the hitch weight changed in accordance with non-load-share. ua-cam.com/video/hwU5D5vwRqc/v-deo.html
I have to agree with Nicholas ..The rocker in between the leaf springs makes this suspension "true" load sharing within the limits where the rocker is able to rotate, usually the tow ball height has a height range of some 250mm(depending on distance from wheel centerline and tow ball) where both axles have the same weight.
@@PJ-rf4uw I came to say this but you beat me to it. Thanks for saving me some typing
@@PJ-rf4uw Also agree. When the front axle is pushed up the rocker arm pushes down on the rear transfering load.
It is a load sharing suspension set up. The reason it lifts an axle is due to limited wheel travel with that suspension. The other video he refers to is for an off road set up so it has more wheel travel and keeps the tyres in contact with the ground.
You might like to edit your segment on the tandem box trailer. The arrangement is full load sharing. A non load sharing tandem comprises two totally independent axles.
True, it's designed as a load share but doesn't really load share.
The tandem axle trailer you used has roller/rocker suspension which is load sharing according to every thing I have read. Not that this changes any of your findings, in fact may suggest that roller/rocker only partially load shares. Thanks for an interesting and informative article.
Correct it is designed for load sharing, but doesn't really otherwise I wouldn't have got the results I did.
@@L2SFBC Perhaps more aptly named partial load sharing?
If the tandem trailer had a significant load on it, ie. a car, that put the suspension into its working load region then the results would be negligible as the roller rocker suspension would do more load sharing than it does when not loaded enough as in this demonstration. Still a good demo of how non load sharing suspension works though.
One additional reason for having trailer level is carrying livestock, horses in our case. This is because they travel standing and if trailer is nose high or nose low the animals will compensate by carrying more weight on their front or back legs as required making the whole trailering experience more uncomfortable for them. Perhaps not as large a concern on short trips but it can become an issue when hauling several hours +.
Good points regarding the effects of trailer being out of level. Many of our North American horse trailers use rubber torsion axles which are non load-sharing similar to the tandem trailer from your demonstration.
Interesting, I want to do something on horse towing. I've never done it and didn't realise until recently how much care had to be taken with horses.
@@L2SFBC I think much of what you have already covered regarding proper set up, safe driving etc. is equally relevant. Equipment specifics and applicable regulations would likely be the major differences, and of course these would also vary depending on country.
Don't know about other countries but here in North America there is very little in the way of required driver education for trailering.
@@brsnorthernhorsejourney3579 Thirty years ago I asked the same question of Vic Roads as I was planning on towing a mobile billboard. No extra lessons required and the only time things started to get tricky was to do with P Platers and Learners. I was understandably flabbergasted.
I’ve noticed that only smaller horse trailers are bumper tow. Anything more than 4 or so becomes 5th wheel/gooseneck. My guess is that the load is dynamic and if a larger livestock trailer were bumper towed, the truck’s squat would be all over the place
@@andrewahern3730 You're correct for the typical pickups commonly used as tow vehicles here in North America and their GVWR/GAWR ratings, I personally wouldn't go any larger than 2 horse on a 1500 ("1/2 ton") pickup for that reason.
The "bumper tow" (a misleading term with today's vehicles, it has been a long time since you could tow anything of substance with a hitch ball mounted directly to bumper!) configuration can be used on trailers with fairly high GVWR's providing tow vehicle is of sufficient size and weight, an example being dump trucks that pull triaxle trailers carrying backhoes, rollers etc. In this application a gooseneck or fifth wheel hitch is not feasible due to dump box, and these trailers get pretty heavy loaded with equipment.
If possible with a tandem car hauler like you used I will have the hitch a little high when empty so when I load the car it levels out
Great explanation and demonstration.
My single axle camper hitch point is low by around 20-30mm, even after
I've installed an high rise 50mm rated towball and that is at the limit of being able to open the barn door on the 4x4, and that result in less, but still substantial tilting of the trailer tow hitch downwards.
I think my only choices are to a/ increase the tyre size of the 4x4 from (245x70 R16) 70's to 75's or b/ decrease the tyre size on the trailer from (265x75 R16) 75's to 70's or c/ both increase the 4x4 tyre size and decrease the trailer tyre size. Unfortunately the offsets and weight range of the wheels on the trailer are incompatible with the 4x4, so I can't just swap them.
There's the more extreme option D of having the attachment point of the trailer frame modified to sit lower. An adjustable height coupler would be a good choice if you decided to go that route.
@@jeffwuzhere Thanks Ziduli. I have a adjustable tow hitch and could under mount the tow hitch on the trailer, but both options stop the vehicles barn door opening.
@@BenMitro Ah right. I realize now you'd have to modify and lower the trailer tongue a good ways back to gain the needed clearance through the full swing of a door. Didn't quite consider all the details I guess.
@@jeffwuzhere I even considered cutting the bottom of the barn door off by 100mm to get the clearance, but oh, so much panel work! Nonetheless, thanks for the suggestion!
Does your suspension droop much when the van is attached?
If yes, perhaps airbags, or a wdh would help?
Thanks for this well thought out video. In either this video or another I couldn't help noticing that you have removed one of your spare tires from the van. Is this to save weight?
I have a very similar van (a Mars Saturn 12.6) and I was considering doing just this for 'local trips', my concern was that there may be a balance issue.
Yes, just don't need the weight. No balance problems.
Maybe an extention to this subject to cover load distribution adjustment methods, eg load inside the van, load adjuster / sway bars and agjustable suspension. Great video thanks.
Some of that on the way 👍
AWESOME.
FANTASTIC.
THANK YOU Rob.
A LOT of work/research/knowledge/experience has gone in making this video. THANK YOU.
Off topic, I have been trying to work out the, 'L2S-FBC' for 'years'.
I assume, Love to ?????????? something something something.
May I ask please, what does, L2SFBC mean? (I can't sleep!!! hahahahaha)
Regards.
Life's too short for boring cars :-)
@@L2SFBC
Hahahahahahahahahahahahahahahahahahahaha.
THANK YOU Rob.
WHAT a Classic!!!
You made my day!
Thanks again.
Love these videos. Probably too late for a reply but what to do if van is level but weight distribution between van front/rear axles is about 60/40? Hard to get around this with front toolboxes, etc.
Never too late. Continue to centralise best as you can!
brilliant video, very professional and informative. i believe that with more novices towing larger caravans that we should have a licence endorsement where this valuable information could be included.
Glad you enjoyed it!
Here in the UK the hitch weight is set to about 75kg for most vehicles but up to 200kg or there abouts for 4x4's, Land Rover has a max 150kg towball weight. Tow ball weight is less critical than a lot of people think, correct weighting of the trailer is much more important as well as all single axle trailers should be nose down as that is a stability factor, nose up is inherently unstable as it forces weight back past the axle.
I don't know if you can do a video on dynamic hitch heights and the effects on the trailer, but it would be interesting .
Yes, in Australia we have European vehicles with what to us are very low towball weights (which we call masses, wrongly). I prefer to European approach and agree with your comments thank you, Land Rovers over here go to 350kg TBM.
Single axles trailers a very easy to correct load, you can simply check the towball weight by lifting it up by hand to see if you are ok
Hi Robert i have a yellow hammerlock with no 2202 on it is this legal for 1 ton trailer in nsw
I am interested in the open trailer if you had a load on it, like my car trailer which is exactly like this trailer. Depending where the load is on the trailer, makes a huge difference on your hitch weight.
Yes, that's different though - this is same load placement, varying hitch height.
I like to, and was always told, set my trailer at about 20mm down at the front from level, or 0.5 degree.
What is the reasoning? Tandem or single axle?
Very good video Robert, but 4:05 That looks like a load share setup to me. Am I wrong? How common are load share suspensions on caravans?
It's meant to load share but doesn't work effectively.
Can a do35 actually run at 600mm like many vans are designing the off road vans to be when level.
Excellent! I know your videos aren't intended to be a public service exclusively and rightly so. Have you ever explored the possibility of having specificly chosen videos recommended by trailer/caravan manufacturers to their customers? Raising awareness can be an uphill battle and encouraging people to care even harder. Seems so many, if they have the money available, will purchase equipment with no understanding of how to use it properly or how it benefits their safety and longevity of their trucks and trailers/caravans. Just a thought... Love your work.
Seeing a caravan smashed to pieces on the highway is a good way to learn to care about your tow vehicle and trailer/caravan set up.
@@markfryer9880 True but Mr. Pepper's content could educate people before that happens. At the same time his exposure would increase directly to his target market, which would help him continue to provide these first-rate videos.
I my experience most problems are caused by the cars rear suspension being too soft however a possible argument towing drawbar down is it push's the cars rear axle down when you hit the cars brakes which naturally causes the cars nose down and the rear up. I don't have any experience towing a braked trailer which would probably help prevent this hinging effect if towing level.
The effect of load transfer under braking from rear to front is true, but you ALSO get the same effect on the trailer which has the effect of increasing TBM when you're braking. Often the trailer effect cancels the car effect.
Good vid thanks Robert. One thing though, at 1:50 you state that the van is level due to it having 70mm blocks under the tyres and 70mm blocks under the tow ball scale. Did you actually level the van using a spirit level because unless that scale is, coincidentally, exactly the right length when loaded, you can't assume 70mm under all three ground contact points results in the van being level? Or have I missed something?
Yes checked level I have a spirit in the caravan and I have used that area before. However what's important is that the change is consistent and it was at 70mm.
As you mentioned anout using a WDH.
There are others out there who say if you have to use a WDH then either you havnt packed the van correctly or you shouldnt be towing anyway .
Thats because those the say this dont use a WDH and belive no one else shoud be using one
I am always curious why there are not 4 wheel caravan trailers with front steering wheels. Trucks all use that kind of trailers with super heavy load and no trailer sway issue at all. There's no towball weight either since the trailer is free standing. The only downside I can think of is reversing, which is not a big deal.
Cost and weight. Might do something on this later.
Is this correct?
Load single axle van & towing vehicle fully as if you are going on a trip, including fuel, water and all the stuff your wife puts in at the last minute.😃
Nick off and go to the weighbridge.
Van weight is 2500kg, tow ball weight 200kg. (Vehicle is say 3400 or whatever.)
All your GVM's & GCM's are ok.
Nick off to some flat ground.
Unhitch van.
Set up van level using spirit level on the A frame or perhaps a few degrees lower at the front.
Set/adjust vehicle towball height the same as the van hitch.
Hookup van to vehicle.
If the vehicle sags in the rear, head off and spend some money on helper springs, air bags etc..(don't even think about asking her to remove anything from the van)
and then start all over again.
Basically yes, welcome to the life of towing, and could you remove anything from the van, not her?
@@L2SFBC Actually her indoors weights 60kg, about the same as 3 jerry's full of diesel. Now that could be a swap. 🤣
Great video thank you for that. My question is I have a long caravan 25 footer. I have an adjustable Hayman Reese towbar hitch when I connect to the car. How does one make the caravan level and the car level with the weight on it? Do you raise the hitch before you connect And keep going backwards and forwards. I have 350 kg 10% on my toe ball mess and my problem is I have airbags and new suspension. Caravan is at its weight max. Car is at its weight max at the rear of the car is sitting squad headlights up in the air.
Don't fixate on 10%, there's no science behind it. With 350kg TBM you're probably 500kg+ on the rear axle so stiffer suspension is your first job, and I'd also look to reduce the TBM a bit. Hard to say more without details.
Be careful when using drop- or extended hitches. The towball position directly influences the results of the certification testing that all towbars must meet (in Australia anyway). That is why the hitch part number must be shown on the towbar compliance plate, if the hitch is removable.
By using a different hitch to the one specified on the towbar compliance plate, you invalidate the certification testing making the towbar non-compliant.
So would that mean that i moving from a HR hitch to a E2 hitch would mean non compliance?
Please show us where in the adr, legislation or traffic rules that this is so. What you are saying is we can never use a hitch other than factory, and the part number is most definitely not displayed on any plate attached to the car.
@@AU_4591 Not sure what a HR hitch is (Hayman Reese...?) but yes, unless the towbar is certified for the E2 hitch, you will be non-compliant. Most manufacturers in Australia do not recommend using Weight Distribution Hitches anyway.
@@rossatkinson3160 Not sure a UA-cam comment is the best way to discuss this but I'll try my best.
ADR 62/02 says "For vehicles with a maximum rated towing capacity of up to 3.5 tonnes ‘ATM’, the ‘Towbar’ towing bracket, towbar attachment and vehicle structure must comply with the requirements of AS 4177.1 - 2004 Towbars and towing brackets."
AS4177.1 describe the static and dynamic test requirements for towbars, as well as the labeling requirements. (You can purchase a copy from SAI Global's website)
It says: "Towbars shall be legibly and permanently marked or shall carry a permanently attached identification plate, made from a durable material, in a conspicuous location with at least the following information in characters in English not less than 2.5 mm high:
(a) Factory mark, trade name or manufacturer’s name (if appropriate).
(b) The vehicle make and model or Towbar Part Number.
(c) The rated towball down load, in kilograms.
(d) The rated towbar capacity, in kilograms.
(e) Towing lug part number (if different from Towbar Part Number).
(f) The words ‘FOR TRAILER TOWING ONLY’."
Under the old Motor Vehicle Standards Act (MVSA), towbar manufacturers had to apply for a Component Register Number (CRN). The CRN has been replaced by a Component Type Approval (CTA) under the new Road Vehicles Standards Act (RVSA) that came into affect on 1 July 2021.
To be able to receive either a CRN or CTA, you have to prove compliance with ADR 62/02, which means you had to meet all the requirements of AS4177.1, including submitting your test results.
The reason why the "towing lug" (hitch) part number is required on the identification plate, is so that (amongst other things) the towball position used during the testing is defined. Some manufacturers would have more than one towing lug part number listed, or different orientations for the same lug (e.g. flipping the hitch upside down). All of these different positions if applicable would have been tested and results submitted as part of their CRN/CTA application.
If you were to use a hitch that places the towball in a different position to what has been tested and certified, the test results are no longer valid, which means the CRN/CTA is invalid and the towbar manufacturer can no longer guarantee that their towbar would perform as per their design intent.
I don't think you can post photos in a UA-cam comment, else I would've posted some of the towbar labels on my Nissan Patrol. Have a look on your towbar itself. There must be a plate/label with the information required as per AS4177.1 on there. If not, your towbar is non-compliant.
For those outside Australia, UNECE R55 have a similar requirement for Europe. So does SAE J684 for the US.
Thanks @@andriekruger . That was much appreciated. And, it worked just fine as a UA-cam comment :)
Does using a wdh reduce towball weight?
That tandem trailer suspension looks like it has some load sharing with that pivot bolt on the link bracket between the two springs, or is it limited physically somehow?
It has some but it doesn't really work.
Robert, how is an air suspension describes, load sharing or not? thanks
It can be load sharing or not.
Did that Triton have ropes holding down the Landcruser,
How much does a say 12" drop hitch induce a leverage arm on the receiver it self? and how does it effect the capacity of the receiver?
A lot...don't recover off them, use with caution for towing
the axle you showed at 4.07 min is for sure a load share suspension as the middle boogie acts as the load share device.
see pinned post
@@L2SFBC thank you very much! The trailer with Elise loaded is actually the same system as your trailer only loaded.
it would help if you know what you are doing the first trailer is a load share .a non share load trailer has the ax les that do not have a pivot between them and leaf spring have axle steer that can have all sorts problems
See pinned comment
I am sure that you should be aware by now - at 4:07 (and onwards) the photo is of a load sharing suspension on the car trailer... (stated to be non load sharing) -that cast link is a load sharing equaliser link (between leaf springs) - "pretty sure" - a quick google shows your exact setup, those geometries simply don't have mich "sharing travel...
Yes, it is meant to load share but it doesn't really. I should have been clearer on that sorry.
What effect does the wind load at say 80 kph on the front have on the tow ball weight?
Can you elaborate?
I guess you are talking about a caravan that is higher than the towcar. If so there will be a force at the top of the caravan that is trying to rotate the caravan about its axle, and this will inevitably reduce the towball mass to some degree.
We see plenty of vans 'dragging their ass' whereby people with lifted 4WD's or 4WD's towing on road style vans. Obviously if the trailer / van is running on non load share suspension, then providing the rear suspension, wheel bearings and tyres have sufficient capacity it may well tow ok providing the load distribution is on point. If not .......... Rest assured that losing a rear tyre and or wheel due to overloaded tyre / wheel bearing / wheel studs on a tandem can go from 0 to code brown super quick!!
Robert, a hitch at the wrong height would it also compromise stability by swaying?
Yes
Hi Robert, I appreciate all your good advise on towing etc, but in this video where you measure the tow hitch weights of your big tandem trailer, you state that it is a non load sharing suspension. I can clearly see that it has a load sharing Rocker/Roller leaf spring system which means that the tow hitch weights will be wrong.
Sorry Robert, regards, Ted.
Yes thanks see pinned post
I have single axle trailer....is it better to tow with trailer pointed up or pointed down.
Level
No matter how hard you push down on a towball it mass will not change. You are confusing Mass, Force, and Wight, as well as the unit of measurement to describe them. Good job using the concept of lode.
I agree with you. However, the parlance is TBM, Towball Mass. That is what people understand. The people who know the difference between mass, load and weight, and force being in newton as opposed to kilograms generally understand the simplication I'm making and why.
What does L2SFBC stand for? 🤔
My husband has done over 100K with "bumper hitch" trailers attached, he carries 4 different ball mounts, and an adjustable WD hitch, just to make sure both the pickup and trailer are each level at all times. When not hitched, his pickups always ride tail high as the manufacturers intended. Leveling kits are one of the things he will rant about for hours.
Please record a rant and send it to me :-)
Well even with your husband’s 100k of experience, he’s obviously unaware that air bags and the proper drop hitch solve the simple issue involved with a leveling kit.
The rocker box suspension is actually considered a load sharing suspension !
See pinned comment
The design of the rocker box equaliser is actually to prevent excessive weight transfer forward to hitch unlike the single point style suspension system, as a Heavy Vehicle body builder it's important to understand the application to utilise the appropriate suspension system
I watched this, and other videos as I'm trying to determine if I can use our 4 ft x 6 ft utility trailer, with 3.5 ft tongue to carry our 16 ft tandem kayak. If I can carry it with the kayak overhanging the front of the trailer bed 3 feet, the rear overhang would be 7 feet (if that's even legal). The center of balance of the kayak is at 8 ft, which puts the fulcrum at 2 ft aft of the axle. The kayak weighs 92 lbs. I'm trying to determine if this would be ok with a little extra weight in the center and/or front of the trailer. Or spend $1700 on a kayak trailer.
It depends on what you tow it with. A 6x4 trailer is tiny, the kayak is tiny and so if your towcar is at least as heavy as the trailer...I wouldn't worry about it, just tow.
@@L2SFBC My tow vehicle is a RAV4 with a towing capacity of 800lbs. Thank you for your reply and your excellent videos.
You can just put some balast like sandbags on the trailer to compensate for it, but in your case with that little weigh it probably doesnt matter
Robert: when I saw this pop up in my feed and saw it was you, I had to watch it because you do such good videos on trailer towing. But I will have to disagree with you on one thing. The shot you showed of a non-load sharing suspension is actually a load sharing suspension, but is just not really a good design for a load sharing suspension. If you look, the ends of the springs where they meet between the axles are connected to a part that pivots. This part is actually called the equalizer. It is supposed to equalize the load on the two axles. But if you look carefully in your footage where you pull the tandem axle trailer up on the boards, you will notice that the tires on the rear axle lose contact with the ground for a little bit. That is because this "equalizer" is only able to equalize the load between the axles for maybe 2 cm of suspension travel. That is not much . . . hence why I say it is not a good design. A good example of a non-load sharing suspension for a tandem axle trailer would be the use of torsion axles (I know there are some designs where there are bars connected between the axles, the axles themselves can rotate and the bars force them to rotate in opposite directions -- I am not talking about these designs). Some trailers in the US use torsion axles on tandem trailers and it is considered an upgrade. These axles ride best at half their rated load, and some manufacturers set up their trailers so that a typical load will utilize half of the capacity of the axles. These setups work OK, but if not towed level, the wear on the components between the front and rear axles will not be even. If the axles aren't oversized in this manner, towing out of level results in nightmares for the owner -- and most will never figure out what the problem is.
Thanks David please refer to pinned comment
I have an 8x5 gal trailer with the rocker type duel axles, mechanical front brakes.
One problem I've had a couple of times, is that the spring shackles on one axle have become inverted. This causes the axles to become out of alignment and a wheel picks up of the ground and it applies the brakes.
I am at a loss as to why this happens!
It did it ones when I drove over speed bumps after unloading at the tip, the other was when a mate borrowed the trailer.
To reset the suspension, I had to remove the shackles and springs ant start from scratch.
Have you ever had or heard of this happening before and what can I do to stop it happening again?
“ duel axles “, sounds like they’re fighting each other . 😁
I have had this problem as well, in my case correct assembly was not the way it look like it should be, and changing it solved the problem . Cant say in your case with out knowing the set up, there are quite a number of variations.
Your mounts have not been installed at the correct positions. No suspension if installed correctly should invert. Poor build quality for sure.
Any idea where the 10% TBM 'rule' comes from? I can't for the life of me figure out the rationale for it aside from being an easy number to calculate based on the ATM of the trailer 🤷🏻♂
It is based on an American study but has become a bit of a “rule” in Australia. Personally I don’t subscribe to this “rule”. How you load is more important.
The problem with this scale is that the height should be adjustable to match the tow ball height.
Yes - you need to use blocks as I did.
Yes, that's exactly what I concluded. I've decided to measure the height of my 'nose weight' gauge when it's measuring my target nose weight of 90Kg and then comparing that height to the top of my tow ball (with my tow vehicle loaded with all my regular camping equiment). If the tow ball is the higher measurement then I'll make a standing block for that difference in height for my nose weight gauge to stand on.
I thought that tandem slipper was non load sharing what you used was rocker which is load sharing.
l2sfbc.com/my-error-on-the-hitch-height-video/