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Gas Struts On Beds

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mike
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Re: Gas Struts On Beds

Post by mike on Thu 16 Feb 2012, 1:38 pm

John wrote:rover struts are 600long 220 stroke, I cannot see a gas strut failing if it is fitted correctly, they do not buckle and bend on cars because the hinge controls it, this is where the answer lies, make sure the hinge is free and secure and the problem will not arise.
gas strut number is 6714DA 0360N 341/98A22
BHE45001


Pleased you have said that John i have always maintained that a damaged strut normally happens because some thing else gives way then the assumption is made the strut failed first causing other damage.
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Helen
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Re: Gas Struts On Beds

Post by Helen on Thu 16 Feb 2012, 2:15 pm

I remember the strut failing on the boot of the 307, it must have been running on one strut because when the working one went I couldn't lift the boot lid without help. New struts and hey presto working fine and no damage to the boot lid, hinges or anywhere else. It didn't bend or anything but didn't help with the lifting at all and wouldn't hold the boot lid up.

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Caz1960

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Re: Gas Struts On Beds

Post by Caz1960 on Sun 19 Feb 2012, 11:39 pm

so it sounds like my side struts are naff because lifting is hard with two people and when lowering that's a feat as well to stop them slamming down ha A JOB TO DO BEFORE FRANCE bounce bounce
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Caz1960

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Re: Gas Struts On Beds

Post by Caz1960 on Sun 19 Feb 2012, 11:58 pm

Just had a nosey as you do on the official Dandy site and noticed " Gas struts fitted to your bed sections to make the erection of your camper even easier.
Please note these gas struts can be fitted to existing campers after manufacture
GREAT NEWS
WE CAN NOW FIT GAS STRUTS TO THE OLDER DESTINY MODELS
£440.00 FITTED
John you save us loads of monies keep inventing
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Tow Itch
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Re: Gas Struts On Beds

Post by Tow Itch on Fri 24 Feb 2012, 6:59 pm

. Elsewhere Helen asked if I'd fitted the struts yet.

Helen wrote:
So have you got your gas struts on the designer now Kevin, we may consider doing ours eventually.


No. I'm still looking for information, or I was until this afternoon.
The information has been like pulling teeth. See next installment of gas struts saga.
Just needing a little more info then negotiating price.
What I want is an idiot proof kit. All brackets and spacers included, no self made bracketry.
I want to price up looking at normal and stainless struts because the units are outside.
Then I want to test fit, because I presume if I can get a large enough bulk buy discount lots of members might be interested.
Hence I want to test fit because I want to fault find first.

I'm going to re post this on the gas strut thread because I think it helps explain my thoughts.



Gas Struts. What I think I now know

Why we look to mount the struts at lesser angle than 450
N.B. I'm trying to say this with a minimum of maths but it is the nature of the beast.
The strut is not there to open the bed up from folded and unfolded. Indeed we want the bed inert at rest when folded or unfolded.
Otherwise we have to lock the bed down during transit and onto the bed support when extended.
If you think of a car you often have to start the "hatch" off to open or close. The strut assists through the rest of the arc of movement.
The strut pushes open in the direction in which it is aligned.
If you draw an imaginary circle about the hinge. Then think of the bed describing (Travelling) its arc of motion.
At any point through the beds semi circle of travel the most effective force is one applied at a tangent to the circle at that point.
If the strut is mounted at 45% i.e the spacing of the mountings are equidistant from the hinge then the force upwards is
Rover 25 strut=350Newton(N)=35Kg(force)2(No of struts) X 0.71 (Tan450= 49.7Kg so that is an almost 50Kg upward force.
The angle derived from the drawing on the Dandy Owners Yahoo Group is about 260but it's unclear as the measurements are the distances stepped off on the trailer and bed frame. Not from strut pivot centre to centre.
I have been told we might look down to as little as 150

Upward force on open or closed bed at 450 50Kg 260 31Kg 150 18Kg
It can be seen that the sharper the angle the less need we have to tie down the beds.

As we open or close the bed lots of factors start to vary.
The force is quoted as 350N but at is only at its instant of opening as it opens the pressure decreases in the strut.
So the moment the strut starts to open the pressure reduces reducing the force. At the same time the strut points increasingly vertical thus increasing the force pushing upwards.
Also as the bed rises the point of the centre of mass of the bed moves towards the hinge. This reduces. the effective mass of the bed.
The bed doesn't feel as heavy at vertical as when open or closed.

By raising the mounting point of the strut on the body the force from the strut outwards (In the horizontal plane) is always greater but the force upwards is always less.

To allow for this it was suggested to use a variable pressure 650N strut. Starting off at 650N and reducing the pressure gradually.

As I'm given to believe the original option of 350N worked then I might not bother with a variable pressure strut and just use the original strut.

So I've now found out the nature of the compromises or at least some of them. I'm not sure about reducing the angle further and increasing the pressure. To quote John:

Having given more thought to this, what is needed is a new approach. A cam action that holds the bed down when closed and down when opened, at the moment the bed tends to lift from the thrust of the strut, a simple cam action would solve this similar to what a car uses , there is a point in travel that holds the boot shut and a little lift from the user and it lifts open, that is the answer. It may prove a can of worms owning to the hinge not being engineered to suit the force that will be placed on it, or indeed the weld on the bed frames, but hey why not give it a go, mine works at the moment do I need to progress this to a higher level, in theory at least I will have a go, but I do not think a dandy in it present state could handle the forces generated without costly changes to the hinge and re-enforced welds to the bed sections, it may prove a bridge too far

To top it all I've just found a gas strut supplier about 5 miles down the road
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Nick
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Re: Gas Struts On Beds

Post by Nick on Fri 24 Feb 2012, 7:59 pm

this whole strut thread confusing,i am glad ours had struts already fitted.I can get the info off out struts if any use these are obviously rated for the Designer model.
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Tow Itch
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Re: Gas Struts On Beds

Post by Tow Itch on Fri 24 Feb 2012, 8:29 pm

It's me I'd have turned the Green Cross Code into a 12 page pamphlet.
If you have the numbers on the side of the struts that would be good.
Also the measurements from the end of the struts to the point where the bed touches the tub when unfolded.
I should have all these measurements already but it would be nice to check.
Please see the drawing of the gas struts in the files on the Dandy Owners Yahoo Group. So you can see the dimensions I have.
I always like to double check so that would be a massive help.

Finally your fully happy with the struts you have?
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John

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Re: Gas Struts On Beds

Post by John on Sat 25 Feb 2012, 9:06 am

Yes, cheap and replaceable at 13 quid a corner should one fail
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Krist0n

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Re: Gas Struts On Beds

Post by Krist0n on Sun 26 Feb 2012, 7:02 am

The struts on my 2006 destiny are rusty and useless. I don't think the wall struts inside work either. It certainly isn't a light task putting the Dandy up, but I have youth (Ish) on my side, and will manage for now. Does anyone know how much the origional struts are, or wher I can get them though. Would be good to just see the difference on one side. Then maybe both sides!!
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mike
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Re: Gas Struts On Beds

Post by mike on Sun 26 Feb 2012, 8:25 am

Krist0n wrote:The struts on my 2006 destiny are rusty and useless. I don't think the wall struts inside work either. It certainly isn't a light task putting the Dandy up, but I have youth (Ish) on my side, and will manage for now. Does anyone know how much the origional struts are, or wher I can get them though. Would be good to just see the difference on one side. Then maybe both sides!!

Can you read any details off them,not had a lot to do with mine i took one of at trentfield as i thought it was faulty but refitted it when i found it wasnt,didnt look at any of the details.
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Tow Itch
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Re: Gas Struts On Beds

Post by Tow Itch on Sun 26 Feb 2012, 9:23 am

John wrote:Yes, cheap and replaceable at 13 quid a corner should one fail

Blast another time where I thought I'd posted and I must have exited after preview.

John the £13 pound per replacement is just for the strut?
I realise everything is price sensitive but your stuff came from SGS(?) Who at this point having phoned twice and then sent an email as requested I can't get to say jack to me. A total lack of communication from them.
If you can quote the package price for the strut, the strut end pieces and then hardware for mounting it would be a start point for price negotiations.
I was going to ask you "Having Had Your Struts For A while How Do You Feel About Stainless Steel Struts And Or Hardware?"
KirstOn's post has furthered that thought.
Unsurprisingly I now realise that the gas strut supplier five miles down the road was Riva's OE supplier.

John and anyone else with a technical bent.

Please read my mutterings earlier where I'm trying to justify the placement of the struts. I thought it was important not just to understand the placement myself but to explain to everyone how that point was derived. Then add the drivel bellow and see if you can turn it into something that reads in English.

Where I'm viewing mounting the struts at 450 through to mounting at 150 and trying to balance the benefit that less upward force is placed on the bed at rest with a more acute angle but that to do this successfully, increasingly large pressures are required in the strut. These forces possibly then exceed those that the hinge or the frame could handle.
I don't personally have the time, patience or resources that would allow me to go to increasingly acute angles and greater strut pressures, destroy a few Dandys then "back off a bit". So I'm more than willing to accept the given 260 or so as the working compromise.
450 would work, possibly with the advantage of lower pressure struts. However we'd need to design a catch for the bed to stop uplift when extended or folded (John partially negates this because his struts don't close completely. It can be argued if this works do we need to fix this?)
The one other thing about fixing in the position given in the Yahoo Group is that the struts have to be compressed by about 4" to assemble. The good point is that this avoids the feeling of "backlash" as the beds are always under force even while vertical. The bad point is compressing struts to fit. This is a possible point of danger I'll get advice on compressing.

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John

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Re: Gas Struts On Beds

Post by John on Sun 26 Feb 2012, 1:30 pm

Here is the list,
four brkt @£3.95
four brkt @£3.75

four struts @£13.00
fifty two stainless steel rivets [four per brkt six per hinge] about £10]
eight 5 mm bolts £1.0

TOTAL=£93.80/ using used parts take off £26.0 =£67.8 about..
so for about £70 you can have gas struts using used parts or if you are feeling flush £94 using new
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Nick
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Re: Gas Struts On Beds

Post by Nick on Sun 26 Feb 2012, 2:19 pm

Steve McVicar who lives near us in co Durham,who we bought our winter cover off did all the drawings and calculations for adding struts to a designer.He posted the information and drawings on the Yahoo dandyowners group.
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John

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Re: Gas Struts On Beds

Post by John on Sun 26 Feb 2012, 4:32 pm

There was also some bad information on there about compressing the strut to fit,I think the drgs reflect riva installation, and the photos of his unit are for what he used, Rover struts
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John

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Re: Gas Struts On Beds

Post by John on Sun 26 Feb 2012, 4:52 pm

Just to confuse everybody, you can use adjustable gas struts to get the balance you require but the price goes up to £26 each
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Tow Itch
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Re: Gas Struts On Beds

Post by Tow Itch on Sun 26 Feb 2012, 7:01 pm

NickB wrote:Steve McVicar who lives near us in co Durham,who we bought our winter cover off did all the drawings and calculations for adding struts to a designer.He posted the information and drawings on the Yahoo dandyowners group.

Nick I did ask steve. He was one of the first people I thought of speaking to. Hopefully I always credit the "owners" Yahoo group. I think it's a great resource. However the owners group didn't explain the reasons for the placement. Then when I looked at Steve's photos I couldn't reconcile his placement against the measurements he gave. Indeed his photos illistrate the difference between the Dandy set up and his.
Thus when I got this email back I was befuddled.
hi, thanks for the post.

All I can say is that the struts I fitted were done in 2007. They were still working when the camper was sold in 2011. I shamelessly copied the idea from the factory fitted units done at Riva. If you can do any better, get on with it & good luck with them.

Steve
Nick look at the photos on file at the Yahoo group. Steve's strut fix and the original strut set up are not the same.
I feel dumb that it has taken me weeks to realise things about the strut actuating that I could have reconciled within half an hour and with a bit of paper when I was 17.
I am at least happier that I know a bit more and that I'll have the confidence to encourage others to follow the same method.

Nick: I was uncertain about viewing the Riva struts. Do they have covers over the strut that extends? I've not seen them in the extended position.
John: As asked earlier your opinions on stainless? I've noticed you writing about Rover 25 struts as what others have used. Your choice was of Rover 25 type struts wasn't it?
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Nick
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Re: Gas Struts On Beds

Post by Nick on Sun 26 Feb 2012, 7:38 pm

Kevin,due to having no wheels on the dandy and it being in a tight space i cannot open wings but the Struts are just like regular Struts there are no covers on them,they are just like what i have on my Car.
I had a bent strut and started looking into replacement pair and became so confused by stroke lengths push/pull actions etc,i just beat the rod straight with a lump hammer and some wood,been good ever since.
The rep from the company that manufactured the original struts quoted me about £90 a pair Shocked

Hopefully Rover struts are better made than the cars they were attached to Smile
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Tow Itch
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Re: Gas Struts On Beds

Post by Tow Itch on Sun 26 Feb 2012, 7:55 pm


Nick

Ace Controls, who manufactured the original struts quoted you £90 a pair?
I was going to contact them this week. Ouch!
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Nick
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Re: Gas Struts On Beds

Post by Nick on Sun 26 Feb 2012, 8:14 pm

Kevin,
I am sure it was about £45ea i was pretty surprised when i was quoted hence trying my DIY approach to repairing the strut and it bloody worked.
I couldn't find the model no for our 2005 struts in the current Ace catalogue i assume it's been replaced or they have changed their product coding.
Maybe the wind caught our bed section once and bent the strut its strange as the strut looks as robust as the strut on my Estate car boot although i doubt a Dandy strut installation is as precise as a car tailgate.
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John

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Re: Gas Struts On Beds

Post by John on Sun 26 Feb 2012, 8:24 pm

I used second hand,I did not consider stainless on cost, but I might go for the adjustable in the future should one fail, the ones off the rover work very well indeed,
p.s. tell Nick mine came off an MG, MG sounds a lot better than a Rover 25, oh and I will colour code when the weather improves Very Happy
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Nick
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Re: Gas Struts On Beds

Post by Nick on Sun 26 Feb 2012, 9:19 pm

John wrote: I used second hand,I did not consider stainless on cost, but I might go for the adjustable in the future should one fail, the ones off the rover work very well indeed,
p.s. tell Nick mine came off an MG, MG sounds a lot better than a Rover 25, oh and I will colour code when the weather improves Very Happy

haha well thats fine then if they came off a MG,least using MG(rover)struts replacements will be very easy to come by and a lot cheaper than the ACE ones.
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vessey44

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Re: Gas Struts On Beds

Post by vessey44 on Sun 26 Feb 2012, 11:54 pm

Nick you also forgot to mention the quality of them because they are MG Rover
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Tow Itch
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Re: Gas Struts On Beds

Post by Tow Itch on Mon 27 Feb 2012, 3:50 pm

Nick

One obvious question I never asked you is about the struts mounting. One photo I have suggests Riva mounted the strut reservoir at the base and the rod at the top. Is yours like this? If so that is why they fail. The strut and seal should be lubricated by the small amount of oil in the reservoir. Opposite way round and the seal dries out.

How a strut works. the entire body is pressurised i.e. both sides of the internal piston. The force is the difference between the pressure acting over the entire area of the piston on one side and the area of the piston minus the diameter of the strut. The resistance coming from the changing pressure and a small port allowing gas between the two chambers.
[You must be registered and logged in to see this link.]

From the above it will be seen that while it's better to mount the strut with the rod down, if we are mounting the strut at 26deg that is not ideal to the longevity of the strut. A specialist strut would be better but the price makes it more economic to replace rather than up spec.
This would support the idea of mounting closer to 45deg and placing catches on the bed at it's closed and open positions.
Allowing that the diagram on the Yahoo doesn't actually show the distance between centres. The length at maximum extension will be about 540mm 550mm apparently the struts are best not going to full extension and remaining compressed by about 20mm. Apparently 50mm will be perfectly functional.
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John

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Re: Gas Struts On Beds

Post by John on Mon 27 Feb 2012, 4:22 pm

you are then placing force to hinge rivets at there weakest position which is a straight pull vertical, for my part I cannot see any reason to change from 45deg the bed lift about 12mm when open, but not a chance when closed due to weight of the roof on top, as I said earlier I might change to adjustable if they stop giving the umph and I have to renew but at the moment they are fine, When I first put them on I did use the 170 dimension from the hinge but found I did not get enough lift and also less movement on strut so I went for max lift and max stroke and that is at 45 deg I am more than happy with set up so far Very Happy
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Tow Itch
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Re: Gas Struts On Beds

Post by Tow Itch on Mon 27 Feb 2012, 6:19 pm

John wrote:you are then placing force to hinge rivets at there weakest position which is a straight pull vertical, for my part I cannot see any reason to change from 45deg the bed lift about 12mm when open, but not a chance when closed due to weight of the roof on top, as I said earlier I might change to adjustable if they stop giving the umph and I have to renew but at the moment they are fine, When I first put them on I did use the 170 dimension from the hinge but found I did not get enough lift and also less movement on strut so I went for max lift and max stroke and that is at 45 deg I am more than happy with set up so far Very Happy

I thought that it was a given that the dimensions given in the Yahoo group would work.If it's the same dimensions as the Riva (that I was concerned about) I was more concerned in the whys and wherefores.
You said you did use the 170mm dimension from the hinge
I have always that the dimensions in the Yahoo drawing only give the distance measured down from the base of the bed and the distance out from the side of the tub.
The 330mm dimension is more like 345mm horizontally between centres (of the strut ball joints)The ball is mounted 15mm or so inboard of the tub.
The 170mm is more like 205-210mm as the ball is half the thickness of the bed frame up from the base.
I would guess the distance from the hinge to the strut mount on the tub to be in the region of 240-270mm. 170mm + the thickness of the bed.

you are then placing force to hinge rivets at there weakest position which is a straight pull vertical,

I missed this bit completely.


Ah think I need to look at the hinges and rivets. Then ask again if it doesn't jump out at me.

Thanks for the time John, this is getting to be a bit of a three act play.

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