Built In Stabiliser (Alko / Winterhoff) and Stabiliser Bar (Used together?)

[Lutz]

Sorry if I got your cars confused, but that doesn't in any way affect the substance of my statements. It is still the owner's responsibility if he fits an item for which his vehicle was never designed.
I don't share your opinion suggesting that the car maker would be at fault if a towbar that meets EU regulations has failed. The EU regulations only cover the towbar assembly itself and do not require the towbar manufacturer to test in a vehicle environment. However, if he ignores the vehicle structure then he may still be fulfilling legal requirements, but he still hasn't done enough to ensure that the component is fit for the job. He has stopped halfway through doing his homework. At the start of development of a new vehicle, the car manfacturer makes it quite clear to all of his suppliers that he expects a fully developed component. It cannot be the job of the car maker to complete someone else's unfinished work unless this is specifically agreed to in a separate development contract.
There is nothing wrong with breaking convention so long as one doesn't complain to the manufacturer later if problems arise. Without serious consideration of all parameters which could affect performance this can be very risky. But if a towbar manufacturer, who one would presume to possess adequate engineering competence, makes a mistake like the one I described, then just stop to think how much more likely such a mistake is for a layman without a professional engineering background.

 

[colin-yorkshire1]

Sorry if I got your cars confused, but that doesn't in any way affect the substance of my statements. It is still the owner's responsibility if he fits an item for which his vehicle was never designed.

Lutz I never suggested that it wasn't mearly pointing out that the manufacturer "note any manufacurer" builds into his products a very large safety marging to make his product idiot proof,
when changing a component or uprating some aspect of the vehicle one is mearly shaving off some of this safety margin, the whole of the motor tuning and car accessory industry is built on this princible, indeed even some manufacurers do it by offering higher spec models based on the same basic design.
if one fits wide 20in alloy wheels to a car designed to have 14in 5J steel rims and a wheel bearing fails of course it's the fault of the person who changed the wheels from the original spec HOWEVER what I am saying is just because the wheels were changed does not automatically mean that the wheel bearings WILL fail. (this is a different arguement alltogether)
colin

 

[Lutz]

I fully agree with you, Colin. The thing is, however, that it is difficult, if not impossible, for the average owner to be able to judge the degree of risk of fitting 20in alloy wheels to a car designed to have 14in wheels, and for this reason, one would be well advised not to fit bigger wheels without an OK from a third party authoratative source.
In the case in question, it would mean that one could write to the car manufacturer and ask for his assessment, if two stabilisers acting in parallel is feasible without a potential problem. I somehow doubt whether he will commit himself if he hasn't tested such a combination, but that's a different issue.
On the bottom line one would probably be better off to fit an electronic stabiliser if one has doubts about the performance of a single frictional stabiliser. At least that involves no additional risk and, in fact, it would offer unbeatable protection anyway.

 

[Steve L]

Lutz. When copy paste the comments try to copy all relatvive info.
Yes I am suggesting that it would be possible to use both types of sabiliser. BUT I also stated that if the trailer or caravan is loaded correctly then a stabiliser would not be needed. Point being that in the first place one should load correctly to get the best stability they can of the caravan. Then and only then use a stabiliser as a secondary assistance tool and not the cure for all.

The aalco hitch stabiliser does a good job of damping any sway momentum, but as for yawing (up and down of hitch), it doesn't do so well. I found that the leaf spring (blade) type stabiliser helped more with that.

I also agree with colin. Tow bar manufacturers over engineer the tow bars for all the right reasons, as you wouldn't want your caravan overtaking you!
On my Abbey, there is a fitting centralised under the A frame below the hitch, to enable a blade stabiliser to be fitted as well as using the aalco hitch stabiliser. Our van because it is definately loaded to the max. you do get yawing. I have considered using a blade to damp that momentum, should we go back to touring. I don't want to mess about with the suspension of the rover as not only will that be expensive and as it would constitute a "modification" I would have to tell the insurance Co who would then load my premium.

 

[Lutz]

I also agree with colin. Tow bar manufacturers over engineer the tow bars for all the right reasons, as you wouldn't want your caravan overtaking you!

I can't comment on whether towbar manufacturers over-engineer their product other than if they did, why did we have a failure?
Don't forget that the car manufacturers do not include any specific provisions for the fitment of towbars in the design of their cars. They leave the responsibility of providing any additional structural measures that may be necessary to ensure a durable solution to the towbar manufacturer. This is so because it would otherwise increase the product cost of the car for the majority of customers who do not fit a towbar. The car manufacturer will conduct tests to determine safe towloads based on engine cooling, braking and vehicle handling requirements, etc., but structural limitations are something that they have little control over, for the reason mentioned. Therefore, it would be a bit pretentious to describe towbars as being over-engineered. One must avoid considering the towbar on its own, but rather as part of a system.

 

[Gafferbill]

Lutz……you have eloquently written why I have a ladder frame 4x4 as a tow car.
Most other types of private vehicles are not engineered for towing in the first place and are a compromise.
(I have a 1.4 diesel hatchback for non towing duties)
I also think that caravan chassis makers are in the dark ages and the only up to date component they use are electronic stability controls, a far better stability solution as you say.
I note with amusement, that the horse drawn carriages that ply the tourist trade in Bruges are all fitted with disc brakes!

 

[Steve L]

Having been heavily involved in chassis manufacture for Lotus and Aston Martin cars, I have a good insight of how the modern car chassis has evolved. And yes we had to include strategic attatchment points not only for tow eyes to tow the car front and back, but also a rear tow bar mounting option, just incase some horay henry wanted to tow his gin palace to Monaco.

Modern cars are designed to crumple and absorb the crash impact leaving the passenger compartment relatively intact. Now that doesn't mean they are weak at the extremities it just means there are designed load capability's for the chassis design. Most tow bars fit at designed strong points between the crash cans (bumper shock impact absorbers for sub 20 Mph impact) and the chassis arms.
On my Rover for instance the aluminium cross beam attatched to the rear chassis legs is removed and a bespoke steel tow bar cross beam is fitted instead and the carsh cans and original bumper fit to that. Now there is one point for car buyers to watchout for, because if the towbar is removed and the aluminium original equipment beam has not been put back, the car is then seriously weakened at the rear. The whole towbar has been very carefully designed by the towbar manufacturer who has worked very closely with the car manufacturer, to tow the maximum defined load and also to withstand accident damage to a pre-determined amount of impact before detatching from the car to enable passenger protection to still be facilitated.

The old style ladder frame chassis predominately used in 4X4's doesn't have specific crumple zone passenger protection as such and this does result in more serious personal injury from impact deceleration in an accident. That is why until recent years 4X4's were at best Ncap 2 rated. Also they were forced to remove bull bars made of steel and replace them with pedestrian friendly plastic ones.

Now relating this to the use of stabilisers. The function of the stabiliser is to counteract the sway forces placed upon the tow bar by the unbalanced trailer. But again the stabiliser manufacturer these days has worked closely with the car manufacturer and the tow bar manufacturer and the caravan industry, to design and build a product that doesn't adversely react with either car or tow bar.

I've been in meetings with car manufacturers, caravan chassis manufacturers and tow bar manufacturers and the top brand stabiliser designers, where we all brought our design specifications and thrashed out what was acceptable or not. There is an awful lot of thought and testing put into all towing accessories today as should there be a bad accident and the cause put down to a tow bar design for instance. That comany could face a very heafty court case and fines, damages claims etc etc that could criple any business.
That basically is why we say towbars are over engineered. They are, because the manufacturers don't want any compo claims for failure.