Another trip - another breakage

[Sam Vimes]

I think I've posted a similar thread before about the worry about whats going to break on the next trip out. Mostly driven by the poor design and poor assembly techniques and lack of QA.

Came back from our last trip three days ago. On the outbound journey at a coffee stop and quick check of van I noticed that one of the kitchen draws had come out fully. On inspection the cross rail that should hold the catch in had come adrift. I managed to get it wedged back in but it still came out again later.

So this weekend I take the draws out to do a proper fix. The cross rails that hold the mating half of the catch, are made of the light weight wood that only caravan makers can seem to get hold of. Look too quickly at it and it will break. The cross rails are fitted to the cabinet carcass using only a couple of corrugated fasteners - one each side. Like that shown below. The corrugated fasteners had sheared of on one side and were just hanging in on the other. Obvious solution was to put proper angle brackets on them - job done.

I'd also noticed that when the draws were opened and closed there was a knocking noise. Not too much of a problem but annoying. Now was the time to look at why.

The drawer sliders that are fixed inside the cabinet are screwed to the sides. The front screw was a pan head screw. The other part of the runner that attaches to the actual drawer is secured with a screw that's too long. So as you push the draw in our pull it out this screw hits the other one. Solution - use a countersunk screw on the cabinet rail. How difficult was that?

What's next I wonder!

 

[Buckman]

Surely a better repair would be using balsa wood as that is tougher than any wood a caravan manufacturer uses?

 

[GaryB]

One of our previous caravans (2007 Elddis Avante 540) used to jettison it's kitchen drawers on every trip, even fitting strong magnet catches failed to stop it happening so in the end I ran a rubber cord bungee through the handles, fixed above to a shelf and somewhere else lower down (cannot remember to what exactly now), there's only so many times you can pick up every item of cutlery from the floor when arriving on site/back home before your sense of humour starts to wear thin..........

 

[ProfJohnL]

Back in the 1980s we ran a series of towing tests to measure the vibrations and forces that affect the interior and appliances inside a caravan. We used the Motor Industries Research Associations (MIRA) facilities at Nuneaton. A caravan was set up with accelerometers to record the motion, and it was towed at varying speeds around MIRAs sample roadway surfaces. Even on what is considered a smooth surface, we saw accelerations in the order of 3G but on the rougher surfaces there was a background level of 3 to 5G with peaks exceeding 8G.

What this means is if a tray contains 2kg of cutlery, under even good conditions the accelerations the caravan experiences the impact load created by the mass of the cutlery would be up to 6Kg force, and under poor conditions it could produce a 16Kg impact force load on the draw runners.

 

[Mel]

Back in the 1980s we ran a series of towing tests to measure the vibrations and forces that affect the interior and appliances inside a caravan. We used the Motor Industries Research Associations (MIRA) facilities at Nuneaton. A caravan was set up with accelerometers to record the motion, and it was towed at varying speeds around MIRAs sample roadway surfaces. Even on what is considered a smooth surface, we saw accelerations in the order of 3G but on the rougher surfaces there was a background level of 3 to 5G with peaks exceeding 8G.

What this means is if a tray contains 2kg of cutlery, under even good conditions the accelerations the caravan experiences the impact load created by the mass of the cutlery would be up to 6Kg force, and under poor conditions it could produce a 16Kg impact force load on the draw runners.

So with solid research findings like this, the caravan industry decides the best way to build a drawer was with the weakest wood and most inappropriate fixings available!
Yes, I know it is all to do with cost, profit and what have you. However, does sort of mean that the research was somehow a waste of time ☹️
Mel

 

[Sam Vimes]

Surely a better repair would be using balsa wood as that is tougher than any wood a caravan manufacturer uses?

Agreed..

Most of my model airplanes survived many uncontrolled landings.

I'd be interested to know what type of would it is.

 

[GaryB]

What this means is if a tray contains 2kg of cutlery, under even good conditions the accelerations the caravan experiences the impact load created by the mass of the cutlery would be up to 6Kg force, and under poor conditions it could produce a 16Kg impact force load on the draw runners.

That's interesting, thanks John and certainly explains why caravans seem to want to self-destruct internally.

 

[Sam Vimes]

When we were considering purchasing our van one of the reviews went into raptures about the fact that the drawers were made using dove tail joints. It's bits of cheap ply wacked together and the edges are covered in splinters.

Perhaps IKEA should consider making caravans.

 

[Mr Plodd]

Ah the joys of caravan ownership, constantly utilising DIY skills.

 

[Buckman]

Ah the joys of caravan ownership, constantly utilising DIY skills.

We have been lucky with our current caravan as the only DIY we have had to do is modifications like fitting hooks. LOL!

 

[Dustydog]

Back in the 1980s we ran a series of towing tests to measure the vibrations and forces that affect the interior and appliances inside a caravan. We used the Motor Industries Research Associations (MIRA) facilities at Nuneaton. A caravan was set up with accelerometers to record the motion, and it was towed at varying speeds around MIRAs sample roadway surfaces. Even on what is considered a smooth surface, we saw accelerations in the order of 3G but on the rougher surfaces there was a background level of 3 to 5G with peaks exceeding 8G.

What this means is if a tray contains 2kg of cutlery, under even good conditions the accelerations the caravan experiences the impact load created by the mass of the cutlery would be up to 6Kg force, and under poor conditions it could produce a 16Kg impact force load on the draw runners.

This may explain why some axles have failed prematurely .

 

[GaryB]

Part of the problem is that (I suspect) a fair few caravan owners are competent DIY people and if something falls off/comes loose/breaks then it gets fixed there & then and eventually the problem gets forgotten/lost in the midst's of time, hence after five years or so, the caravan gets viewed as "faultless" rather than one that falls to bits in one go within a month or so of ownership. We had our previous caravan for 4 1/2 years and my first thoughts are "faultless", however, after a good think, the ones I remember/remember fixing were:

• End panel of settee coming away (wrong screw used in production).
• Aerial in lounge not working (cable unplugged behind a cupboard).
• Sink waste pipe coming off (one free with every Swift).
• Shower waste pipe falling off (underneath the caravan thankfully!).
• Microwave cupboard pulling away from the ceiling (so is the one in the Swift we have now! I fix them by using slightly larger diameter screws and a polyurethane adhesive).
• Seat back boards/vents coming away from the walls (thank goodness for 3M number plate adhesive strips).
• Cooker/hob glass lid working loose.
• Step grip-pads on the A-frame fairing cracking/peeling.
• Door fly-screen coming off.
• Seat foam losing it's shape.
• Roof light blinds being so stiff they felt like they'd break every time used.

 

[Dustydog]

Thankyou Gary. Spot on. After our last two weeks away , apart from the crunch, I have 7 items on my snagging list.
The Heki skylight blind above the bed failed last week.
Thanks to You tube I fixed it this morning. Note I used two spoon handles to prize the unit away from the roof frame. All because of a tiny piece of plastic. Probably saved my £150 ish.

 

[ProfJohnL]

So with solid research findings like this, the caravan industry decides the best way to build a drawer was with the weakest wood and most inappropriate fixings available!
Yes, I know it is all to do with cost, profit and what have you. However, does sort of mean that the research was somehow a waste of time ☹️
Mel

The research was not done for any caravan maker, it was for the company I worked for who produced various appliances for caravans, and it informed on how we designed various products.

I'm sure the manufacturers did get to hear some of the results.

 

[Hutch]

The research was not done for any caravan maker, it was for the company I worked for who produced various appliances for caravans, and it informed on how we designed various products.

I'm sure the manufacturers did get to hear some of the results.

Just out of interest Prof, can you remember if the tests were done with the caravan wheels balanced, probably not something that was done in the 80's.
I know after I had my caravan wheels balanced I noticed that not so many panels or cupboard doors came loose.

 

[Mr Plodd]

Un balanced wheels are not going to influence the G forces experienced by the caravan over a rough road surface, it will however cause vibration through the caravan on a smooth surface.

 

[Dustydog]

I’ve had shock absorbers fitted last 20 years. I’m certain they have reduced the various destructive forces.

 

[Mr Plodd]

They are not shock absorbers! They are dampers, they control the road springs rebound.
See here

 

[Dustydog]

They are not shock absorbers! They are dampers, they control the road springs rebound.
See here

I know that but please let’s not be too pedantic. Al-ko sell them in a box labelled “Shock absorber”. Fact is I guess we both believe they are a pre requisite for the caravan.
Maybe the Aussies description is different from Europe?

 

[Mr Plodd]

I have never subscribed to the "Caravans need shock absorbers (!)" argument
My reasoning being that the "springs" on a caravan are basically rubber bands within the axle that compress. The amount of movement is very minimal so there is precious little rebound to need damping.
Others hold a different view, and that's fine, its wrong, but still fine

 

[Beachball]

Ah the joys of caravan ownership, constantly utilising DIY skills.

Our caravan needed some new curtains my wife made some more and fitted them

 

[Buckman]

I’ve had shock absorbers fitted last 20 years. I’m certain they have reduced the various destructive forces.

We first fitted shock absorbers on our Lunar in 2005 and also had the wheels balanced and it made a massive difference. We have had that done ever since although our last and current caravan had them as standard.

Just to add the proper name for shock absorbers is “damper” as it serves to dampen motion so basically no difference. While shock is absorbed by the spring, the damper functions to modulate the oscillations

 

[otherclive]

A report by University of Bath stated the dampers fitted to caravans aren’t as effective as those fitted to cars due to the limited movement allowed by the rubber bush “springs”. But they did have some effect in reducing the impact of road perturbations. After having an Alko axle bush fail I had to have a completely new axle. So I decided to fit Alko dampers if only to reduce the effect of loadings on the rubber bush springs. The wheels were always balanced too. I did not notice any discernible differences whilst towing but it was a well matched outfit at about 70% ratio.

 

[Gafferbill]

......true caravan rubber block suspension doesn't have as much movement as most forms of vehicle suspension but it moves 15 cms or so.
I take the load off the suspension rubbers and tyres all the time I'm not actually using my caravan, so I get to see this movement on a regular basis.
IMO Alko dampers don't do much damping of the caravan's suspension but they do help absorb the shocks of for example uneven road surfaces.
This has to be beneficial to the relatively fragile fittings and bodywork of the caravan.
.....I agree with otherclive.

 

[Mr Plodd]

There may well be 13cm between fully relaxed and fully compressed, but most of the time it's 75% compressed so only 5cm of compression left to use.