BogMonster Posted November 28, 2007 Share Posted November 28, 2007 Is there a maximum permitted noseweight for 50mm towballs? I figure that while something like a NATO hook is pretty robust, the "neck" of a 50mm towball, being fairly skinny, must have a safe working limit and I wondered what it was - can't find anything on Google though. The maximum permitted noseweight quoted for a Defender is 150kg but I assume that is more to do with on road stability at speed, than what the chassis or the towing fittings can actually cope with. Anybody know the answer please? I'm not unduly concerned about stability at speed (because it will only be travelling slowly) but I'd hate the ball to snap off... Quote Link to comment Share on other sites More sharing options...
sgnas Posted November 28, 2007 Share Posted November 28, 2007 I would have thought that noseweight would be a test of your fixings rather than the towball. As the ball would be in compression and pretty unlikely to fail. Wait for a grownup to do the proper calcs but in tension (pulling the ball up) assuming the grade of steel and the forging is good, I reckon it is good for a 40tonne pull. I cannot think how to translate that to shear though! Quote Link to comment Share on other sites More sharing options...
BogMonster Posted November 28, 2007 Author Share Posted November 28, 2007 Depends on the shape of the towing ball - if it is any sort of a swan-neck type then it will have a twisting force on the assembly. I just ask because I am sure I have read reports of the balls shearing off when used for towing with a shackle around them, which suggests they aren't all that strong... Quote Link to comment Share on other sites More sharing options...
Discovan300tdi Posted November 28, 2007 Share Posted November 28, 2007 I would like to know the forces involved especially as last week my gaffer used the 50mm towball on his 2005 defender 110 along with a steel towing rope to drag our caterpiller 6x6 dump truck out of the mud after getting bogged down and as it was fully loaded must of been the best part of 65 tonnes eeek what a shame that my wheeled loader was on downtime with a blown hose on the steering ram and couldnt be used to do the towing Quote Link to comment Share on other sites More sharing options...
ozzie1989 Posted November 28, 2007 Share Posted November 28, 2007 That must be one strong and powerful 110 I've seen many things being towed with a 50mm ball, they do seem to be very strong, especially if you get a decent one like Dixon Bate etc. Quote Link to comment Share on other sites More sharing options...
lrfarmer Posted November 28, 2007 Share Posted November 28, 2007 the max nose weight is written on the plate of the trailer tow hitch. but i think the max weight on a 50mm ball is 175kg ish (not 100% shore tho) but when you've got over 100kg the handling go's out the window if you haven't got anti roll bars Quote Link to comment Share on other sites More sharing options...
Paul Posted November 29, 2007 Share Posted November 29, 2007 I think you'll find it to be a great deal more than 150kg. Most Toyota Landcruisers in Australia have a maximum noseweight on the ball of 350kg, and they can do that legally with a 50 mm ball. Paul Quote Link to comment Share on other sites More sharing options...
BogMonster Posted November 29, 2007 Author Share Posted November 29, 2007 I think you'll find it to be a great deal more than 150kg. Most Toyota Landcruisers in Australia have a maximum noseweight on the ball of 350kg, and they can do that legally with a 50 mm ball.Paul Yeah I have seen Cruisers here with 350kg stickers on the back end, didn't realise they also used 50mm balls over there though, I thought maybe it was just a European thing and Aussies used something different (like US trucks do). Ta. Quote Link to comment Share on other sites More sharing options...
white90 Posted November 29, 2007 Share Posted November 29, 2007 http://www.autow.co.uk/smmt/trailer_coupli...pling_ball.aspx no law but 75kg nose weight is the highest I've seen Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted November 29, 2007 Share Posted November 29, 2007 IIRC there is a note on the swan neck ball on my D3 with reference to the max nose weight of the fitting. When SWMBO is back I will go and have a look. Quote Link to comment Share on other sites More sharing options...
tacr2man Posted November 29, 2007 Share Posted November 29, 2007 Yes the l/crusr in OZ had that nosewieght limit, but they also have a 2.5 ton tow limit as well, thats why I used a 130DC HCPU to tow a recovery trailer ,as you cant trailer tow a l/crusr or nissan patrol on a trailer with another nissan or l/crusr Quote Link to comment Share on other sites More sharing options...
Paul Posted November 30, 2007 Share Posted November 30, 2007 Yes the l/crusr in OZ had that nosewieght limit, but they also have a 2.5 ton tow limit as well, thats why I used a 130DC HCPU to tow a recovery trailer ,as you cant trailer tow a l/crusr or nissan patrol on a trailer with another nissan or l/crusr Yes, it's an interesting one. The standard trailer setup in Australia puts about 10% of the trailer weight on the towbar (generally accepted over here as the requirement for stability), so with a Landrover limited to 150kg (all pre TD5 Defenders), then the towing limit is only 1500kg, which is not enough for a decent boat really, let alone anything large. Paul Quote Link to comment Share on other sites More sharing options...
ThreeSheds Posted November 30, 2007 Share Posted November 30, 2007 <Ramblings of aconfused old man alert> I never thought of this as a percentage thing, I just thought that I needed a roughly balanced trailer for stability, but with a little (I generally go for what I can fairly easily lift) nose-weight to make the cup spend most of it's time pushing down on the ball rather than pulling up. This (as my assumption goes) is probably to increase the contact area and reduce wear... Thinking on though, I know from un-streamlined projectile aerodynamics (and feel that the principle applies to the trailer too) that for stability you need the centre of gravity in front of the centre of pressure (or drag, or point at which the restorative force is applied - the wheels in this case) - ie the CoG in front of the wheels. To make a significantly stable un-streamlined projectile a rule of thumb is that the GoG must be at the 1/3rd maker (near the front) and the CoP at the 2/3 marker - or further apart than that. Of course into this 'free-flight' scenario we must also throw the fact the the towing vehicle is applying the towing force, which will also act as a restorative force should the trailer be out of line. The effectiveness of this force depends on the trailer's dynamics AND on the tug's dynamics (tyre flexing, bush flexing, distance from CoG to towball, ditance from rear axle to tow-ball, wheelbase, blah, blah, blah) and so it too complex to be taken into account by my limited brain, but this probably accounts for why some vehicles make excellent tugs and others not. My RRC is the best I have known, you really can't tell from the handling the I have the trailer on there.... From my unproven thoughts and ramblings above, I think that if you put a lot of weight on the nose of the trailer it will be more stable, however this will obviously upset the towing vehicle. the degree to which the towing vehicle is unbalanced by excessive weight is probably easiest found by experimentation and may account for different vehicles having different advised to-ball weight limits. For simplicity, I will stick to about 50Kg, but not worry too much about small variations from this. As to the original question WRT towball strength - I have seen, and heard of them pulling off the mountings when being used for recovery, but not heard of the actual ball or neck breaking... I do, however, reckon a good make is worth paying for (although with D-B ones costing four or five times cheapo ones, it hurts to stick to that principle ) Just a final thought - do we need to consider aerodynamics too? Hmmm...Probably not since the trailer is usually smaller than the towing vehicle and anyway is traveling in a very turbulent wake anyway. Well - made myself late for work now and I still have to walk the dog in the Blair-Witch forest - hope I make it back... TwoSheds Quote Link to comment Share on other sites More sharing options...
lrfarmer Posted December 1, 2007 Share Posted December 1, 2007 I think you'll find it to be a great deal more than 150kg. Most Toyota Landcruisers in Australia have a maximum noseweight on the ball of 350kg, and they can do that legally with a 50 mm ball. i didn't say i was right that it was 175kg. i've towed many thing some of them not trailers one thing was 3.5ton unbraked with the wheels at the very back, so the nose weight was well over 175kg just been out to have a look at my trailers my cattle trailer max noseweight is 150kg, 3500kg max gross my car transporter max noseweight is 100kg, 2700kg max gross. saying that i put discos on this trailer was shore it had a 3.5tom max gross??????? are you able to tow trailers in Ausralia with over run brakes or do thay have to be cuppled brakes as that would make a big diffrence. Tim Quote Link to comment Share on other sites More sharing options...
paintman Posted December 1, 2007 Share Posted December 1, 2007 Noseweight is the measure of down force exerted by a trailer on the towball/hook of the vehicle it is fitted to. Too much or too little will affect the handling of the towing vehicle. The vehicle manufacturer will usually specify the appropriate amount for the vehicle. The vehicle manufacturer will usually also specify the max weight that the vehicle can tow - which may be well below the various maximum legal weights as regards braked/unbraked trailers. This has nothing to do with what the towball assembly is actually capable of pulling before something bends or breaks - as borne out by some of the examples given above! Quote Link to comment Share on other sites More sharing options...
Paul Posted December 1, 2007 Share Posted December 1, 2007 are you able to tow trailers in Ausralia with over run brakes or do thay have to be cuppled brakesas that would make a big diffrence. Tim A couple of snips from the guide to towing regulations put out by the various Road Traffic Authorities in Australia: The minimum braking system required for a trailer or caravan depends on its type and weight, as well as the weight of the tow vehicle: Up to 750kgs GTM: No brakes are required. 751-2,000kgs GTM: There must be a braking system on the wheels of at least one axle and over-ride brakes are permitted. However, for caravans exceeding 1000kgs, independent brakes (electric brakes are the most common form) are strongly recommended. Over 2,000kgs GTM: A brake system operating on all wheels is required. The system must be capable of automatically activating should the trailer become detached from the tow vehicle. Under these circumstances the brakes must remain applied for at least 15 minutes. These 'break away' systems are compulsory on all trailers over 2,000kgs GTM. and another: the ball mass (the mass towards the front of the trailer carried by the tow ball of the towing vehicle) should be about 10 % of the total laden trailer weight. The ball mass can be measured either at a weighbridge by resting only the jockey wheel on the scale, or by placing a ball mass scale under the coupling then taking the weight off the jockey wheel. Notice it says "about 10%", so by interpretation I wonder if about 10% can be a bit over 5%, thus getting the towing weight on a Landrover up to something reasonable. I suspect the insurance companies might pounce on you if you had an accident though. Paul Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted December 3, 2007 Share Posted December 3, 2007 Have had a look at the tow bracket on the D3. It has a "D" value of 16.5kN what ever that is, and an "S" value of 150kg, which I take to mean the nose weight. HTH Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted December 3, 2007 Share Posted December 3, 2007 Done a bit more digging and came up with this site http://www.maypole.ltd.uk/27.pdf Quote Link to comment Share on other sites More sharing options...
nas90 Posted December 3, 2007 Share Posted December 3, 2007 Have had a look at the tow bracket on the D3.It has a "D" value of 16.5kN what ever that is, and an "S" value of 150kg, which I take to mean the nose weight. HTH I would guess D = Dynamic; S = Static kN = kilo (1000) Newtons, which is a dynamic force since 1 Newton = 1 kg m/s^2 Therefore 16.5 kN (16500 Newtons) = 1682kg x 9.81m/s^2; where 1g (unit of gravity) = 9.81m/s^2 So you can dynamically shake 1682kg at 1g around the back of your Disco 3 and statically place 150kg on the hitch. This 10% of trailer weight is nonsense, for a single axle trailer you need about 25kg to 50kg nose weight and for a twin axle possibly slightly more nose weight. With a caravan you put your tins of baked beans over the axle low down and any lightweight bedding over the hitch. With any trailer you do not put heavy items behind the trailer axle with negative nose weight. All common sense really. Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted December 4, 2007 Share Posted December 4, 2007 Found a really good website for trailer regs in the UK http://www.ntta.co.uk http://www.ntta.co.uk/law/towbars/type_approval.htm is the page from which I got the following info <quote> This information is included in the Vehicle's Handbook. From this data the towbar manufacturer constructs a test load, called D Value, which will be used to test the towbar. As well as providing the test load, the towbar manufacturer is obliged to include a D value in kn on the towbar identification plate. "D" Value The "D" value is calculated as follows: (GVW x GTW ) / (GVW + GTW) x 9.81/1000 (gravity)= kn Where GVW is Gross Vehicle Weight, and GTW Gross Trailer Weight. The maximum D value for an M1 vehicle is 17.7kn that represents a GVW of 3500 kgs towing GTW of 3500kgs. </quote> Quote Link to comment Share on other sites More sharing options...
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