Skid Wheels

[trevskoda]

But I would rather use wheels if possible...
Ridiculous prices (low) here...in Thailand..available as well in local "B&Q".
Plan is to buy 2 here and bring to uk in April.

I have a shed full of those,handy for all sorts of things,bought a tea chest full at auction for about £10

 

[jagmanx]

Yes. ... But they will

I have a shed full of those,handy for all sorts of things,bought a tea chest full at auction for about £10

Use linux. I need windows

 

[Dowel]

Many of the castors etc found in hardware stores or the modern equivalents, Screwfix, Toolstation etc, have small load capacity 200kg or less. There are stronger options on line:

Heavy Duty Stainless Steel Nylon Wheel HSS Series

80mm Ultra Heavy Duty Castors With Cast Nylon Wheel Up To 2000Kg

If this were my problem I would avoid castors, fixed or swivelling, that hang down below the chassis mounting points. The greater the distance between the point of impact and the mounting point the greater the load on the fixings.

I would favour strong skid plates with rounded off edges, to minimise the possibility of digging in, or a wide roller(s).

The air suspension option sounds better if available for your Renault chassis and would save structural works behind the axle to adequately support skids or rollers. I suspect structural work to support skids or rollers would cost you more.

I used to run a Marlin kit car in long distance trials and had to strengthen the front suspension fixing points to resist the loads of driving over rough ground. IIRC I had two goes before it was strong enough.

 

[ricc]

with any sort of wheel or skid at the back youll end up with the vehicle supported on front wheels and one rear corner.... not only is the chassis not designed to be supported at the extreem rear it and the bodywork wont like the twist.

nobody has mentioned loss of drive if its rear wheel drive and no weight on rear wheels.


raising the body by improved suspension has to be the right way to go. ... dont forget stowing heavy stuff as far forward as possible...

 

[jagmanx]

Front wheel drive

with any sort of wheel or skid at the back youll end up with the vehicle supported on front wheels and one rear corner.... not only is the chassis not designed to be supported at the extreem rear it and the bodywork wont like the twist.

nobody has mentioned loss of drive if its rear wheel drive and no weight on rear wheels.


raising the body by improved suspension has to be the right way to go. ... dont forget stowing heavy stuff as far forward as possible...

Also not looking to put at the very rear
But I appreciate both points the twisting effect
Any such imbalance would only last seconds

 

[trevskoda]

Use linux. I need windows

Windows are for looking through not at.:lol-053::lol-053::lol-053:

 

[Wully]

I’d go with the air suspension if you think you’re gonna keep you’re van a few years. My vans got a large overhang and found it difficult with the smaller ferries around Scotland now I manage fine you’ll also benefit from being able to lift the back when you’re carrying a bit of weight and there’s the ride quality as well I don’t like the idea of the weight of the van on two wee casters probably at you’re chassis weakest point especially if you’re chassis got an extension all that weight is transferred to the bolts holding extension on to the body.

 

[jagmanx]

Thanks Terry

Posted these pics while back, try to get some today of underneath setup.

How much might it cost to get this sort of thing Retro Fitted ?


Air suspension looks to be about £250
plus Fitting maybe £100 but could do it myself ?

 

[jagmanx]

Aha

Windows are for looking through not at.:lol-053::lol-053::lol-053:

That is where I am going wrong !

 

[jagmanx]

My Thanks Terry and all others

Hard to say, Phil. Our one is a be-spoke job for sure. Google MH towbars, some are fairly cheap, you could *******ise one, plus no need to wire up or add tow ball. Having such certainly protects rear of van.

Air suspension ticks a few boxes, too.

So I have a few months to ponder..
At this stage

1 Towbar a bit pricey but offers other protection
2 Air suspension probably better for us and should mean NO GROUNDING and minor levelling bonus
Use half inflated most of the time raise as appropriate..We prefer the van level but raising the rear at night after food would also suit
3 Roadpro do the Skidwheels I can do better and stronger here but then they need fitting

So I will bide my time and checkout the items here noting all the advice given

 

[jagmanx]

These look interesting

Shock Absorbing Rigid Casters - DASHICASTER

 

[jagmanx]

Forces and angles

Wheel Skids Angles and Forces
Still considering this (but keeping the other options fully open)
Casters
80mm Ultra Heavy Duty Castors With Cast Nylon Wheel Up To 2000Kg shows castors but as with the roadpro item I reject them but note their weight capacity is OK ....But the Fixing ? But my previous post may change this
Castors are not good as the swivelling simply complicates and weakens the solution. So back considering wheels
BUT....http://www.dashicaster.com/product/...g-polyurethane-cast-iron-rigid-caster-wheels/
More of a wheel than a castor PLUS shock absorbing !

Roadpro sell skidwheels here Skid Wheels: Set Of Two - RoadPro
A high price for the quality and small (only 12.5 cm diameter, Plastic wheels, lowgradw metal) Thus I will probably not be getting those.
It does however confirm for me that wheels are a possible solution.

My background is as a Maths teacher and so I am able to work with angles and forces etc
Whilst it is a 3D problem the sideways forces/considerations are so minimal that I ignore
The main sideways forces on a MoHo are when turning at speed. These forces are essentially on the front wheels/tyres and the rear wheels simply track so minimal effect.
Thus we have a simple "Body on an inclined plane" situation which is classic Newtonian mechanics. We can simplify this further by considering one (rear) wheel only which can be modelled as a 1000kg mass thus effecting a vertical downforce of 1000kg weight.
Many will be familiar with the "3, 4, 5" pythagoras triangle this gives rise to a substantial angle of about 35 plus degrees but another such triple is 24 , 7, 25 or lets say 96 28. 100. OR 960 280 1000 to match with KG Weight of my vehicle
With 16 degrees being the angle this corresponds to a 1 in 3 Hill and maybe similar to the fundamental profile of a levelling block. Thus I will base my forces on an inclined plane which is at 16 degrees which I suggest is adequate.I am probably being over cautious and an 8 degree slope would simply halve the front back force and have minimal effect of the vertical force.
IF the vehicle is at rest on such a slope the vertical downforce of 1000kg is kept in equilibrium by an upward force of 960kg at at angle of 16degrees from the vertical and a horizontal force of only 280kg at angle of 16 degrees above the horizontal.
Similar the the support forces provided by a yellow leveller (16 degrees) AND the brakes.
A wheel in its housing will transmit those forces directly to the point at which it is attached to the motorhome chassis. I suggest the most demanding of the above is the forward force of 280kg but 16 deg is very steep.
This force is the most concerning is impact .....There will also be an instantaneous impact force as you "Bottom out" on the wheel. For this reason and others I believe a metal based wheel with a rubber tyre to be best. This impact is directly proportional to the speed of the vehicle so less than 5mph !!! No swivelling needed For me the challenge is to find the correct size wheel/tyre and to get it properly fixed to a suitable structural point about half-way (or more) between the rear wheels and the rear end
I will be interested to receive thoughts on the above analysis !
As stated still considering all 3 options !

Thanks again

:juggle: :idea-007:

 

[jagmanx]

Thanks

My van has nylon wheels at either end of the towbar. Living in a hilly area, I find they do get used a fair bit. Sadly years ago their bearings seized, so for the last few years the have been nylon feet. They work well enough though they are wearing away.
The load on them is hard to calculate. When the tail strikes, normally the rear wheels are still carrying most of the weight. My guess is they they rarely take more than a ton each, though sometimes one or the other will take much more, particularly at a tight sloping junction.
I'd love to find suitable replacements, but the ones I've seen seem far too weak.

Look at the links I have posted Most of them bear a very good weight

 

[colinm]

My background is as a Maths teacher and so I am able to work with angles and forces etc
Whilst it is a 3D problem the sideways forces/considerations are so minimal that I ignore
The main sideways forces on a MoHo are when turning at speed. These forces are essentially on the front wheels/tyres and the rear wheels simply track so minimal effect.
Thus we have a simple "Body on an inclined plane" situation which is classic Newtonian mechanics.

I will be interested to receive thoughts on the above analysis !

If you are cornering, even slowly, and the fixed wheel comes into contact with the ground the sideways forces can be quite high as the rear axle and the fixed wheels don't follow the same track, this is why 'tag' axle vehicles wear out rear tyres.

 

[colinm]

No swivelling needed For me the challenge is to find the correct size wheel/tyre and to get it properly fixed to a suitable structural point about half-way (or more) between the rear wheels and the rear end

Mounting the wheel too far forward can mean that you have situations which it contacts the ground when not needed or doesn't contact the ground when needed, I'm guessing that right on the rear point will provide the best protection.

 

[jagmanx]

Yes

Mounting the wheel too far forward can mean that you have situations which it contacts the ground when not needed or doesn't contact the ground when needed, I'm guessing that right on the rear point will provide the best protection.

Thanks for both posts
I aim for about 1 ft (30cm) from the rearmost point but maybe less dependent on motorhome chassis

 

[jagmanx]

Thanks Terry

Phil,

I honestly think the use of castors is not a good idea, after a few impacts, there is a high possibility they will break up, due to not designed for what you want them to do?

With issues such as bottoming out, you would think manufactures would design in rear overhang protection, instead of leaving it to aftermarket manufacturers.

However, I could be wrong, just my thoughts.

I therefore think Air suspension is the solution.
The basic kits are cheap enough but IMO I need the on board compressor to be able to raise the rear without visiting a garage with air..
This puts the price up but HeyHo
Ideally I would like 3 levels Low Medium and high but may well have to do with None medium and high but that would do provided I can raise simply by activating the compressor...from inside the vehicle .

I have contacted a "welder" to estimate the cost of a solution such as you have but I suspect nearly £1000

 

[jagmanx]

It is just the odd car park or campsite

I already have air suspension (not just air assist), but having that can't prevent tail strikes, it just makes it possible to reduce the number of them.

That causes a problem once a year say
Air Assist or Full Air would IMO do 4Us

 

[Papillon]

These work

Top marks for no jokes !!
But seriously Our Motorhome (see avatar) has a longish overhand and on a few occasions minor damage has occurred.
The latest being the demolition of the waste water drain pipes and tap.
I have sourced suitable items here in Thailand to bring back to UK (for the drainage items)
But I am also looking to prevent similar damage by fitting said "Skidwheels" to a suitable cross member (NOT A WC Cross member).
The cross member being behind the rear wheels and suitably strong

View attachment 68654 View attachment 68655​

I attach photos and ask
a) which ones would you recommend
b) what size
c) how to fix

Any ideas from such as Runnach (Terry), Trev(skoda)or and others with suitable experience knowledge

Thanks in advance
Phil

These have been on our van for almost two years and are used on every trip. I bolted them under the tow bar. 50mm Heavy Duty Swivels Castors Solid Nylon Wheel 200kg

 

[wildebus]

i do find this an interesting thread as my overhang is relatively long for a PVC (I think!?) and wondering if I should mount a roller under the towbar Mount as a precaution.

It is fairly obvious how to check the departure angle, but this is a video from "The Fit RV" which shows how. I imagine the biggest risk of exceeding the departure angle is getting winched onto a low loader or at a ferry terminal (I got the number plate ripped off getting pulled onto a recovery truck in my Triumph Spitfire )