After dragging my new-ish Bailey round Europe and Ireland for a couple of months, it occurred to me that I’m pulling twenty grand of caravan with a fifteen quid ALKO type towball and a couple of two quid bolts. Stupidly I mentioned it to the boss (who also tows, having passed the test) and she has told me to go find a tow ball that is worthy!
I’ve read up and towballs do seem to get gradually weakened due to the continuous push/pull/twist of an ALKO stabiliser head. So now I understand about S-values and D-values. I also know about fitting new bolts and washers every time. I know about using the correct torque to tighten the nuts.
So, I’ve been looking. The ALKO shop sells a cast towball with an S-value (max noseweight) of 200 and a D-value of 17 kilo newtons. And they want £30 for it. Yet Maypole sell a cast towball with an S-value of 350 and a D-value of 17.5kn for twelve quid. Towsure’s towball is listed as S-value of 120 for the same cost.
How often should you replace a towball? How important, really, are the S & D values? Is the Maypole one stronger? Are all ALKO tow balls made of cast steel? I’ve read scathing reports of Chinese-made cast tow balls. Does no-one make a fully machined tow ball? Has anyone ever found a truly heavy duty ALKO towball? I double-nut the towbar bolts, but do I need to? Am I being a caravan nerd?!
Whatever else you might have to worry about it's not the towball which will last the life of the car. If you are worried it might be worth checking the bolts holding it on are tight & also rest of towbar fittings but usually the bolts remain tight for life of car.
Steel towballs are not cast (from a mould), they are forged. The reason being is that a percentage of cast metals will contain porosity (air bubbles) which means that 100% of manufactured towballs would have to be X-ray'd to ensure no porosity was evident which in turn would not be cost effective either.
A towball starts off as a lump of steel that is heated till it is red hot then half is hammered into shape by constant pound of a press over a die (forming tool) to form the shape. The towball is reversed and the opposite side is formed in the same manner till the contour of the towball is achieved. It is manufactured this way because the grain in the material will follow the contour which will never snap but only bend in extreme circumstances. This means that the towball will never weaken so should never need replacing which should effectively answer your question.
Sorry for lengthy reply but it needs to be understood first why the facts outweigh the theory.
Cast iron is brittle as it has a high carbon content and has low tensile strength. Towballs tend to wear rather than snap. At least I have not heard of one snapping. The stabiliser has a wear indicator.
These days I would worry more about the car failing with more and more lighter materials being used. As for cost if you need an Alko ball then you buy one not a cheap ball that will fail in an Alko stabiliser hitch.
Quote: Originally posted by Taylor56 on 06/7/2016
These days I would worry more about the car failing with more and more lighter materials being used. As for cost if you need an Alko ball then you buy one not a cheap ball that will fail in an Alko stabiliser hitch.
The point is that the £12 ALKO-type towballs from Maypole have a much higher s & d value than the £30 branded product from ALKO. The Towsure towball is, however, significantly less strong than even the ALKO branded ball.
Nevertheless, I am reassured, particularly from tango55. Very helpful, thanks and I'll be sticking with my existing tow ball which is stronger than the ALKO branded product.
In a few decades of towing I have never heard of a towball failure nor towbar bolts failing for that matter, so if it is fitted and torqued correctly in the first place it should last forever in my opinion. How many miles does it take for friction pads to wear down a towball I would not like to guess. D and S values? Never heard of them and feel I have not missed out on anything, I think you are reading far too much into a problem that probably does not exist, but if is worrying you .........
Quote: Originally posted by Taylor56 on 06/7/2016
These days I would worry more about the car failing with more and more lighter materials being used. As for cost if you need an Alko ball then you buy one not a cheap ball that will fail in an Alko stabiliser hitch.
The point is that the £12 ALKO-type towballs from Maypole have a much higher s & d value than the £30 branded product from ALKO. The Towsure towball is, however, significantly less strong than even the ALKO branded ball.
Nevertheless, I am reassured, particularly from tango55. Very helpful, thanks and I'll be sticking with my existing tow ball which is stronger than the ALKO branded product.
But do you have an Alko stabiliser hitch ? Because if you have you should be using an Alko ball. If not a normal one is fine
Quote: Originally posted by Taylor56 on 07/7/2016
But do you have an Alko stabiliser hitch ? Because if you have you should be using an Alko ball. If not a normal one is fine
Correction.
You have to use an Alko pattern tow ball, with the extended neck, not an actual ball made by Alko.
For quite a few years I towed a large trailer with a 2 tonne carrying capacity. I had an ordinary tow-ball on my truck, nothing special or "heavy duty", and I never had any problems whatsoever. To be honest, I never even knew such a thing as a heavy duty tow-ball existed.
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Topic: Heavy Duty Towball?
