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

[EmmaM]

Hello again,
Hubby reckons towing with built in stabiliser and his trusty bulldog bar is much better than just built in stabiliser.
However, I have been told not to use both, and typically being a man he wont listen

Can both be used at same time ?

Thanks Em

 

[Damian]

The simple answer (without going into all the tech stuff) is no.
The hitch head stabilisers are not designed to be used with another stabiliser, and the hitch head type are far superior to the blade type.

 

[EmmaM]

Is it possible to have the detail......I just took him breakfast in bed and said "oh by the way.......stabilisers" oh I'm terrible

He maintains its definately better with both...........will it cause any damage?

Thanks Em

 

[Damian]

Just a couple of things to start with:
1. Its big, heavy and needs to be stored when not in use.
2. It affects the braking of the van as it has pressure on the A frame and slows the reaction of the drawbar, which slows the application of the brakes.
3. It is putting an extra load on the towball, above the noseweight.
4. The blade can ,and does, easily slip out of its cup on uneven roads.

Just ask if he does not think the ball acting built in stabiliser is up to the job, is he happy with just a diagonal seat belt, or will he now fit a full harness seat restraint system?

.................................. perhaps you had better not ask

 

[Lutz]

Because two frictional stabilisers double the resistance forces acting on the towball and the car manufacturers do all their testing according to ISO11555-1 which specifies torques that would be exceeded using two systems in parallel, you could even lose warranty coverage by fitting a blade-type stabiliser, as well.
If you really feel unhappy with the degree of protection that one system offers, then the only alternative is to fit an electronic stabiliser (AlKo ATC, BPW iDC, or LEAS) as this does not place any additional loads on the towball except on the rare occasion when it deploys.

 

[colin-yorkshire1]

TIN HAT READY??
yes you can and no it wont cause any damage it's not to everyones taste but neither is "marmite" been doing the same thing for the last 4 years since bringing the van home from the dealers and thinking how crap the alko hitch was (aks 1300 model) first job before using the van again "fit the scott brackets" we have just got back today from a 3week jaunt around the south west and midlands covering 1700miles in total with probably the most stable outfit I have towed with in over 40years, nothing bothers it it never moves off line even in the gale force winds we had first week away, some say it will damage the car?/ B*.S*. had the tow bar off last year for rear end repairs everything perfect replaced bar with new bolts nuts ect,
to answer some of Damians points."
1. Its big, heavy and needs to be stored when not in use.
A. so does a wheel clamp but we all carry one, as for storage thats what the big box on the front of the van is for!!
2. It affects the braking of the van as it has pressure on the A frame and slows the reaction of the drawbar, which slows the application of the brakes.
A. yes it does and it also resists the damper return stopping the thump in the back of car giving a smoother transfer of energy rather like a brandnew damper would do so what is so bad about that? abolute braking ie downhill is not affected

3. It is putting an extra load on the towball, above the noseweight.
A, it lowers the noseweight not increases it, yes it's true there is some extra load but not on the ball just the "bracket" considering all the forces applied to the towbar during use the extra bit made by the blade is miniscule
4. The blade can ,and does, easily slip out of its cup on uneven roads.
A, not so if it is fitted and adjusted correctly I have never had one disengage in 30 years of using one

Just ask if he does not think the ball acting built in stabiliser is up to the job, is he happy with just a diagonal seat belt, or will he now fit a full harness seat restraint system?

Can't answer that one exept I have allways believed that belt AND braces was perferable to losing ones trousers

 

[colin-yorkshire1]

P.S. note for Lutz where exactly does the regulations specificaly say what stabilisation systems can or cannot be used or what figure is quoted I have not been able to find any documentation to say the practice could be illegal or unsafe. as for warranty with a 5year old van and a 8year old car not a issue.

 

[Lutz]

Colin, we are not talking about regulations here, but industry standards. ISO11555-1 specifies the following maximum values:
350Nm max in articulation, i.e. side-to-side
300Nm max in pitch, i.e. up-down
300Nm max in roll
These values are the ones that are used by the manufacturers to check the durability of components. As this is a standard, not a regulation, it is not illegal to exceed them, but as they don't test to higher values, no-one would be able to accept any responsibility should a failure occur. The onus is therefore 100% on the owner.
That said, in case of failure, it is highly likely that this would go unnoticed for a very long time. Probably the weakest link in the whole system is the car's underbody structure. Few people have a look under their car regularly for possible cracks in the sheet metal, so it may take quite a while before any failure is identified.

 

[colin-yorkshire1]

hi Lutz, I did not think there were any regulations in force so it really is up to the owner, well that suits me just fine as the Sinatra song goes "I do it my way",
not being any sort of engineer although my brother was so picked up a few things over time I was wondering !!! if the industry does not test higher values than the ones specified and does not do destruction tests how tough are they!!
any idea's!! I have one try this :- car has towbar fitted and has rear end contact with immovable object how much force is required to damage the underframe. answer quite a lot far more than being rammed up the rear by a 4x4 whilest parked !!!
now given the astronomical forces resisted by the underframe in such an event can one be absolutely positive that any damage will be caused by increasing the torque force by a few kg's, obviously the industry doesn't as it doesn't test it!!!

 

[Lutz]

The tests may well be to destruction. It's not a matter of one single application of the specified load, as in the case of an accident where much higher forces are encountered. Unless someone has made a really big mistake the loads that I have quoted above would not cause a failure. However, the tests that I refer to are conducted on a shaker, where loads are applied several million times. The regulations covering towbars, for example, specify 2 million cycles. Such a large number of cycles could well cause fatigue failure.

 

[Gafferbill]

If the OP does not mind I have a question.........

I have never used a modern alko hitch; I still have an older simple hitch and use a blade stabiliser.
How are these modern hitches supposed to work since the frictional area of the pads is so small and the leverage of the caravan on the hitch so great?

From an engineering point of view I genuinely do not understand them or how they are supposed to be effective!

 

[ProfJohnL]

Hello Bill,

You have correctly identified the difference in the loading of the two systems, but in essence the lever mechanism on the Alko hitch is capable of applying some quite astounding thrust to the friction pads against the ball and so the device can be just as effective as the blade and disk systems.

In addition the side to side motion the Alko system also provide resistive motion in the vertical axis and torsional twisting, neither of which the blade type achieves. Consequently the ALko system damps all trailer motions that react through the hitch.

 

[Lutz]

As the manufacturers only test using the loads that I have mentioned, should a blade type stabiliser be used which is capable of providing more resistance that an integrated frictional stabiliser like the AlKo or Winterhoff, then the manufacturer will also absolve himself of any responsibility in case of failure. Therefore, a blade type stabiliser cannot be more effective without increasing the risk.

 

[Gafferbill]

A blade stabiliser should be far more effective than any hitch head device due to its larger frictional area.
In use, the performance of a blade stabiliser is effectively tested and inspected every time it is fitted, whereas the user cannot know how his hitch head device is working.
For me they are fitted on modern caravans to make attachment simpler not because they are a superior device.
By the way Prof, they do dampen pitch movement.....the blade is made of spring steel and thus has a resistance.
Speaking personally, I tow with a 4x4 with a massive ladder frame chassis, fitted with an equally robust towbar.
The risk of structural damage to my towing vehicle is not a concern.

 

[Lutz]

It's the coefficient of friction between the surfaces moving relative to one another and the clamping force that determines the efficiency of a frictional stabiliser, not the frictional area.
A spring has absolutely no damping properties. Only frictional or viscous forces can act as a damper. A spring can only provide a stiffer joint.
If the vehicle structure is as massive as you describe, then obviously structural problems are unlikely, but blade type stabilisers are used on average family saloons, too. It is for these that one should point out the potential risk of increasing the performance of such stabilisers beyond the limits specified in the industry standard.
But no matter how high the damping effect of a frictional system is, there will always be a threshold limit above which it will no longer be able to cope in an extreme case of instability. This is an inherent disadvantage of any passive system. Only an active system can provide absolute protection without reservation.

 

[ProfJohnL]

Thank you Lutz.
You answered for me on the blade spring.

But to answer some of Gaffers other points,

Most cars rely on disk brakes on the front wheels, compared to the drum brakes that used to be fitted most disk pads have a smaller surface area, yet they are considered by most to offer superior stopping ability. This is fundamentally due to the thrust the system uses to push the pads against the rotating disk. So this is another well proven example of where its the force rather than the surface area that does the job.
The effectivness of a blade type stabaliser is not 'tested' as I seriously doubt you have the equiepment to check its resistance, other than to guage its resistnce by hand or foot.
I do concure though there is equally no way you can guage the effectivness of the ALKO head until you ae on the move.

 

[colin-yorkshire1]

Hi Lutz, in most cases I would have to agree with most of what you say, however in this case I have to differ not on technical expertiees but in terms of practice and experience, also I think you are simplifying the facts just to get a point across.
for a start "It's the coefficient of friction between the surfaces moving relative to one another and the clamping force that determines the efficiency of a frictional stabiliser, not the frictional area." not entirely the whole story otherwise why would sporty type cars have great big brakes instead of small ones, plus the small friction area of the alko pads (the size of a 5pence piece) must be more prone to give way earlier than the 3in dia double pads of the blade given the total area of pressure over the whole clamped surface.

"A spring has absolutely no damping properties. Only frictional or viscous forces can act as a damper. A spring can only provide a stiffer joint." in part this is true however what a spring does do that a damper does not is try to return to it's rest position, therefore it is constantly trying to push the the joint "ie the coupling head" back to level this has the effect of a dampening the joint, also there IS frictional damping with the blade because the spring blade has to slide over the plastic shoe on the A frame when deflected in an up and down movement.
"but blade type stabilisers are used on average family saloons, too. It is for these that one should point out the potential risk of increasing the performance of such stabilisers beyond the limits specified in the industry standard." now come lutz you know as well as I do that industry standards are set far lower than ever envisaged in the life of the product that it is made for its called safety margin, increasing this does not mean certain failure "only possible failure after prolonged use" while it is not wrong to point this out it is not the whole story and could be the case that NO damage will occur EVER by increasing the threshold somewhat.
"Only an active system can provide absolute protection without reservation." with this I assume you refer to electronic systems like leas you may be right upto a point however electronics are notoriously tempremental fine when they work pity it's not all the time,

Plus if one just had to make a comparison of blade to Alko hitch the blade would come out on top because it's cheaper by a big margin does not require a special ball or the immaculate cleaning to keep the pads free from contamination can be maually adjusted and is less hassle for the ones that tow other trailers with the towcar.
colin.

 

[colin-yorkshire1]

Most cars rely on disk brakes on the front wheels, compared to the drum brakes that used to be fitted most disk pads have a smaller surface area, yet they are considered by most to offer superior stopping ability. This is fundamentally due to the thrust the system uses to push the pads against the rotating disk. So this is another well proven example of where its the force rather than the surface area that does the job.
The effectivness of a blade type stabaliser is not 'tested' as I seriously doubt you have the equiepment to check its resistance, other than to guage its resistnce by hand or foot.
I do concure though there is equally no way you can guage the effectivness of the ALKO head until you ae on the move.

Hi john you too are simplyfing the facts to get a point across drum brakes for the most part did not have servos but did work fine drum brakes with servos are as effective as discs AND far superior to discs WITHOUT a servo as I wrote to Lutz why do sporty cars have have bigger brakes instead of smaller more effecient ones!!! cos it's got something to do with surface area and temperature management,
P.S. I dont know about Gaffer but I can tell you exactly what the measurement of my blade is 30kg's whats the mesurement of the Alko hitch considering there no way to test it??

 

[ProfJohnL]

Hello Colin,
I disagree, neither Lutz or I has over simplified the situation.
Fact - to make a given area of brake (whether pad or shoe) to work harder you need to thrust the friction surfaces together harder. Of course there is a point where too much thrust and the material will fail, but we are not exploring such extremess in this discussion, just normal opperating conditions.
The natural consequence of this, is that to make a smaller contact area work as well as a larger area, the closing thust has to be increased.
The point of comparing drum vs disk brakeing sysems in cars was to show that small contact areas do work. The choice of disk over drum in cars is not restricted by the reduction in contact area. Yes alternative methods of activation such as servo's may be necessary, but there must be good reasons for car manufactures to choose more expensive disk systems over drums.
The size of the braking system used in vehicels is almost certainly dictated by thermal considerations. Brakes convert mechanical energy of movement into heat , and the bigger or faster a vehicle is, the more kinetic energy that has to be converted to heat. However in stabalisers, the relative movement between the car and trailer under normal towing conditions is very small and not very frequent so the amount of energy needed to be disipated is vastly smaller than that of the brakes. Consequently the difference in size of the two types of stabaliser is not driven by that factor.
Alko achives the greater contact thrust by using a cam action in the hitch head, so ther is no reason to suspect the Alko sytems has less potential than the balde type. But the fact that the Aklo system is not restricted to a single axis of operation, means it has the potential to offer greater benefits.
Either type can increase the safety margin before the onset of instability which has to be a good thing, but for the reasons alredy indicated that it is difficult to guage the working effectivness of a stabaliser they should not be relied on to correct an inherrently unstable outfit.

 

[Lutz]

Colin, brakes on sports cars can be designed for the highest possible performance because the engineers have to freedom to match the parameters accordingly. For example, if the braking forces are so high that stress failure were to occur in an adjacent component such as the suspension system, then it would be reinforced accordingly, but this is not so easily possible in the case of the average family saloon as it would unnecessarily increase the costs for the majority who will never use the car to tow a caravan.
The degree of reinforcement that is necessary would be established or at least confirmed by carrying out appropriate tests. However, in the case of stabilisers, the tests that the industry carries out are based on the the loads that I have quoted out of their own standards. These loads were determined for integrated stabilisers only. Nobody has tested higher levels of performance so nobody will know whether other parameters, such as structural durability, are adequate to meet higher levels. Whilst there is undoubtedly a safety margin in the figures that the industry uses, the manufacturers will protect themselves from possible warranty claims by only guaranteeing their product up to the limits that they have tested to. Everything over and above that is the owner's responsibility. I do know for a fact from my active days in the car industry that structural failure did occur on at least one occasion, even within the existing limits, so it would be wrong to think that the standards set are unrealistically low.

 

[Steve L]

First off. John please refrain from typing in such small print. if you have a comment put it loud and proud. I for one don't bother to read coments that are not in paragraph format. Cos I don't want eye strain.

I quite agree with colin, you can use both types of stabiliser. I have used the snakemaster leaf spring type for many years and find it equally as good as the aalco hitch type I now have. In fact the leaf spring type does damp the pitching and yawing better IMO.

I would however have to say that a well loaded caravan driven properly doesn't need either type of stabiliser.

For many years I have towed a 3500Kg Ifor Williams trailer fully loaded without any stabiliser fitted and had no issues at all.

Now running to my anderson shelter with gas mask & tin hat in hand.

 

[Lutz]

I quite agree with colin, you can use both types of stabiliser. I have used the snakemaster leaf spring type for many years and find it equally as good as the aalco hitch type I now have. In fact the leaf spring type does damp the pitching and yawing better IMO.

That's dangerous advice you're giving out there. While it may be in order to use both stabilisers in parallel on your car or on Colin's beefy 4x4 it would be risky to generalise that it would be OK for all applications. Like I said, we had at least one structural failure when conducting our own tests within the parameters specified in the regulations and industry standards. Admittedly the failure was only on one model and only in conjunction with the towbar from one particular prospective supplier, but it just goes to show that anything beyond what the car manufacturer intended will be sole responsibility of the owner. (Needless to say, that company was not awarded the contract to supply towbars, even though their own tests documented that they met the requirements of EU regulations).

 

[Gafferbill]

…..wow that set every one off!

Remember tow bar integrity is now part of the UK annual MOT test for private towing vehicles......... so that helps with safety issues.

 

[ProfJohnL]

Sorry Steve,

It wasn't intentional, and it is actually in paragraph format - incidentally what you ran to wasn't the anderson shelter but the pig sty, though I would have thought your nose should have told you the differnce. Obviously you should have gone to that well known opticians

 

[colin-yorkshire1]

I quite agree with colin, you can use both types of stabiliser. I have used the snakemaster leaf spring type for many years and find it equally as good as the aalco hitch type I now have. In fact the leaf spring type does damp the pitching and yawing better IMO.

That's dangerous advice you're giving out there. While it may be in order to use both stabilisers in parallel on your car or on Colin's beefy 4x4 it would be risky to generalise that it would be OK for all applications. Like I said, we had at least one structural failure when conducting our own tests within the parameters specified in the regulations and industry standards. Admittedly the failure was only on one model and only in conjunction with the towbar from one particular prospective supplier, but it just goes to show that anything beyond what the car manufacturer intended will be sole responsibility of the owner. (Needless to say, that company was not awarded the contract to supply towbars, even though their own tests documented that they met the requirements of EU regulations).

LUTZ, LUTZ. LUTZ. LUTZ, LUTZ, LUTZ. PLEASE, pay attention before you lose the plot completely.....
COLIN does not have a beefy 4x4 he/I have a mk1 renault megane 1.9DTI and uses a blade stabiliser togetther with a Alko aks1300 hitch, without problems??
GAFFERBILL has the BEEFY 4x4 and uses "A" blade stabiliser on it's own WITHOUT a Alko hitch,
STEVE IN LEO has a 2.0cdti Rover 75 with a Alko hitch BUT used to use a blade stabiliser before.this.

All clear now good"" regarding your last point "so what" all the illustration proves it that car manufacturers will do what is nessassary to protect THEIR name and product market , so a failure in one car of one model failed a test and the towbar maker was at fault even though their bar was indeed up to standard that says more about the car maker than anything else don't you think??
could not have been a faulty design or fitted poorly ""no of Course not"
I will make one more observation if I may before leaving it" it's fine to continually stick up for convention as the only right way to do things and new is better than old and all that but sometimes thinking and doing outside the box and ignoring convention acctually "works".
colin