Posts Tagged ‘HGV Trailers’

March 29, 2008










See also 


Paragraph 33 


Air Speed Indicators


Peter W Jones MInstP


.In drawing attention to the need for the above I am suggesting a change that has not, as far as I know, been proposed elsewhere.The Caravan Industry and the Caravan Clubs have regrettably resisted the use of safer technology for some years and have left the EU/UK very much in a technological backwater, whilst the air craft industry (Air Bus) are now amongst the world leaders.As Standen’s 1999 Bath University Phd thesis (Towed Vehicle Aerodynamics) still only resides in the British Library on microfiche, few people are aware of the fact that he proved in wind tunnel tests (with scale models) that an HGV could destabilise a car/caravan combination and aerofoils improved the stability of a caravan.In 2003 when I was using the Road Traffic Accident Investigators private Yahoo e mail system and circulated the above and other details of the Bath University research I discovered that the aerodynamic research mentioned above was quite unique far beyond the EU, and the fact that it must also at least apply to some HGV trailers ( the need for aerofoils) was also not known.

However, it may well be that research has been done that has not been published.
Even with aerofoils and electronic brakes there will still be an upper speed limit for all vehicles, particularly trailers, which must be decided on the basis of the Laws of Physics and then enshrined in Government regulations as is already done in a similar manner for the air craft industry.
I do not think it will ever be necessary to take as many precautions for solo vehicles as if you cannot sense yourself the effect of the wind on the vehicle you are driving, you should not be in charge on the road. When towing a trailer there is another vehicle to be considered with very different characteristics, and an electronic system is needed to give information about the forces on the trailer as well as an air speed indicator.
Designing a suitable air speed indicator for use by road and rail vehicles will be comparatively easy once the need for same has been accepted. All that is required is a “weather vane” (to sense direction) and rotating parts ( to sense speed)   


The direction that the “weather vane” would point is determined by the wind produced by the forward motion of the vehicle and the wind ( if any) resulting from natural weather fluctuations. The software would then convert this into a “Head wind” component (in mph) and a “side wind” component. The two speeds would be displayed for the driver to read.
The maximum safe air speed ( road speed plus head wind component) must be established for each vehicle, but this as with aircraft will vary depending on the load being carried.
Similarly the side wind component will vary, but for the driver (as with the pilot) this only has to be looked up once in a set of tables for each journey. There would have to be anemometers in exposed places at the side of major roads to send out details of side wind speeds by radio ( information is currently transmitted by the RAC that determines “congestion points” by measuring traffic speed at many points on all major roads in the UK).
For minor roads drivers would still have to depend on the wind speed forecasts given by the met office, as we shall still have to do for some time in all cases.
Even if there are no fatalities or serious injuries every time an HGV trailer over turns or otherwise gets out of control we have a major problem as it takes some hours to get a crane to the site which is capable of lifting up the wreckage. A caravan is easily pushed out of the way by a Police Land Rover.
When considering the costs of my proposals the lost productive hours of the many thousands of people caught up in resulting traffic jams should be taken into account.
Currently I do not think the DfT have any records concerning HGV or caravan accidents resulting from the effects of the wind, as this in the past has not been properly recognised as a serious problem.  



Addendum 5-11-08.

It seems that I was seeking information concerning currently available anemometers for road and rail vehicles in the wrong place. I should have used Google !

There are suitable appliances on the market that will only need a comparatively minor modification ( to the software only in some cases) to meet the requirements of locomotives and road trailers.

It is most probable that suitable hardware already exists and the only remaining task is to programme same so that the “air speed” and “side wind component” can be displayed.

I have also recently realised that I have failed to draw attention to another aspect of this matter. Formula 1 racing cars and HGV’s with trailers frequently travel at about 100mph air speed, but only the former have the benefit of aerofoils to help keep them in good contact with the road and more able to resist any side forces from the wind. Racing cars are viewed by thousands of spectators and officials are prompt in their control of the situation when extreme weather conditions apply. On the motorways little can currently be done by traffic police in the same situation as critical air speeds and side wind components need to be known for each type of vehicle, as is the case for air craft.

However as I feel certain that the anemometers/air speed indicators that I have outlined above could be produced at a reasonable price and even if they were only half as popular as GPS navigation ( and I feel certain they would cost much less), a considerable contribution could be made towards reducing accidents because drivers would use their own judgement. Governments would then eventually legislate to ensure that ( as with the air craft industry) the critical speeds for each type of vehicle were stated in the manufacturers’ manuals for drivers.


ADDENDUM  22-11-08

I have now written to several manufacturers of anemometers and had one positive reply.    of Portishead, Bristol, UK  sell a suitable anemometer which only needs extra software to be written to convert to my above mentioned specifications.

edit 30-09-09

I received a quote from of around 1500 pounds sterling (UK) for the above during the Summer.

This type of cost will be considered reasonable when more people become aware of the reduction in accidents that would result. However, Governments would have to legislate before the HGV industry would install these devices.

For recreational trailer towers like myself  the cost would be unacceptable at present and I shall continue pestering our Met Office to make more widely available their internet wind speed forecasts. I can always use the internet beore I leave home, but this Summer found myself having to restrict my speed considerably on one journey because I failed to get to an internet cafe before setting out. In another instance I made a detour to avoid the M5 bridge over the river Avon when it may not have been necessary. However, I have lived to start my 34th year of receational towing if the cancer clinic eventually discharge me tomorrow after 5 years of “monitoring.”


Para 36 Stabilisers; Bath University

March 22, 2008




Para 36

Peter W Jones MInstP

The above graph and the photograph below have been copied from the Bath University Report (see further below).

The electronically produced graph above shows the effect of an ALKO stabiliser on a snaking caravan (blue graph).  The red part of the graph shows the oscillations without the stabiliser in place. This graph should have appeared in the space in the account below.

The photograph below shows the ALKO stabiliser tested by Bath University.


March 9, 2008


Information Concerning Stabilisers for those reading this blog

with no experience of caravanning or trailer towing. 

This stabiliser is several years old, but it still meets the specifications prescribed for a new item.

Similar items of the same type are still on sale in large caravan dealer’s show rooms, but under a different brand name.

The rather grubby spherical item of maroon colour is the cover over the tow ball. I keep the latter well greased.

The approximately circular item to the right of the tow ball contains the friction pads held between plates of metal.

The nut in the centre of the circular item can be tightened or slackened in order to obtain the prescribed amount of friction.

To measure the friction  place a set of accurate bathroom scales against the right hand end of the lever and apply pressure. The reading should be taken just as the stabiliser arm begins to move.

The amount of frictional force is laid down by the manufacturers, but according to the caravan club’s advice section for members it is almost exactly the same for all types. In my view the limiting factor is the amount of torque the towing bracket of the tow car will stand.

The caravan club did not give the specified torque for the ALKO stabiliser, presumably because it can not be adjusted

In use on the road the right hand end of the  stabiliser arm ( as shown in the photograph above) fits into a plastic mounting on the front of the caravan chassis, so that if the caravan oscillates from side to side  ( snakes) when being towed the friction between the sections of the circular part of the stabiliser should dampen down the oscillations.

For details of how to test whether the stabiliser is likely to be of any use on the road go to  section  18a by scrolling to the end of this blog and then clicking on “Older Entries,”  and scrolling further.

To read the 1994 Bath University result on Stabilisers

 go to section 2e

The 2003 Bath University report on stabilisers supports the 1994 result.

I shall add further comments on this within the next few days.

Para 40 The IVRA conversion for O/R Brakes

February 28, 2008


Peter W Jones AMInstP

I would like to draw attention to the efforts of Charles Irving of Preston Lancs who has for  over 30 years endeavoured to improve caravan stability, but in the past has  mainly been  side lined by the Caravan Industry.

The IVRA system depicted in this brochure was tested and approved by the Caravan Club’s experts whose account was published on page 80 of the July 2000 Caravan Club Magaazine. It can just be seen that Charles Irving is named at the end of the brochure and the IVRA system had been developed from Charles Irving’s original design.

In spite of this approval the Managing Director of a  Caravan Group told a large meeting of Caravan Club members (Thistle Hotel, East Midlands Air Port) in February 2004 that he had never been so frightened in his life as when he was given one of these systems to test on the motor way.

However, he failed to tell the meeting whether the person who fitted the system had been trained for this new type of work and whether he himself had been advised by an expert of the different nature of the response compared with over run brakes. The CC, CCC, and the NCC control the quality of the work in a large number of the Caravan Workshops in the UK and training in electrical/electronic braking systems will only be given when the former give approval.

Further on is a Short History of the New ALKO braking system; this short item is an introducton.