Slide-out problem

I would be surprised that the ram would not come out. Is it welded to the frame somehow?? I know, hard to tell from 5000 miles over the pond!!

It might not be easy, space-wise...

It just occurred to me to look at the table of contents for Bob Livingston's RV Repair and Maintenance Manual (available from amazon.com), and there's a section devoted to troubleshooting 'The HWH room extension system'. I can't find my copy of the book here at home (it might be in the coach), but I suspect mine was published before they were putting slideouts in RVs. The 'new' price will give you sticker shock, but (they) also sell used copies, assuming they're not too old.

Thanks again Tom.  Thinking about it, I know several farmers & their assorted workers, some of whom I know have a good working knowledge of hydraulics.  I'll call them when we get home, but of course am grateful for your lad's perspectives.  I do have a load of manuals in the coach including HWH stuff - and in fact the repairer himself has been faxed several drawings from HWH engineers during the process.

Dougie.

Dougie, glad you mentioned farmers; They would definitely be a good source of knowledge for fixing hydraulic stuff. FWIW we're in the middle of farming country here, and there are lots of tractor dealers and tractor repair shops around. I've used some of them to make up custom hydraulic hoses and fittings.

Aye, the lad has learned a few things in his 45 years, and is a useful source when I need help in that area.

Dougie, just ran across your post and have some suggestions. First they do have such a thing as throw away (welded) cylinders but I cannot believe HWH uses them. Your seals should be replaceable which means they have a removable end cap. I can look closer at mine tomorrow if needed.
Using two cylinders on the slide could very well have the effect you are describing but usually a bypassing seal will also not allow the cylinder to extend with a load, not just stop it from retracting. If I understood you said it would extend ok but not retract.
The important thing is getting the slide to close. Whether this is from a bad seal or not just remove the hyd hoses from the opposite side of both cylinders (use plugs in the hoses) and try and retract the slide again. As the ram retracts and the slide starts moving in, the cylinder pistons will push oil out of the open ports on both cylinders. This will not come out under high pressure but be ready to clean up a little oil. By removing the opposite ends of the cylinder hoses this stops the bypassing oil from travelling to the opposite end of the other cylinder and locking the system up. If one cyl seals are bypasing so bad the system cannot build enough pressure to move the slide then you will have to retract the slide manually as described below. In this case the bad cyl will be shooting out much more oil than the other one.
Keep in mind I am assuming a lot here because I cannot see what you are describing and don?t know what system you have. This is also pretty basic stuff for a hydraulic guy so anyone that can look at your schematic or plumbing should be able to do this. If you know what model system you have maybe we can look at a schematic on the HWH website to see exactly what is going on.
If all else fails remove both lines from each cylinder (leave the cyl ports open) and retract the slide manually using a ratchet strap etc. If it will not move it is possible you have a bent cylinder rod and it is locked up in the barrel or a mechanical bind in the track that the hydraulic system cannot overcome.
Hope this helps.

I appreciate the detailed input - thank you.  I'll paste this to the repairer in the UK so he can add it to the mix - he's waiting for HWH to come back to him after the holiday weekend for more guidance.  Hopefully, this will add some more clarity.  I'll also ask him for the system model & will get back to you on that.

Thanks again,

Dougie.

Further update from the RV repair guy in the UK:-

As far as i know all hwh cylinders have welded ends, if they were conventional ones it would be easy to repair, both cylinders extend ok but about but not simultaneously and one locks up about a foot from the end of its travel (this is the cylinder that does not have the failed seals) and the one that has the failed seals extends all the way.

The reason that this happens s that when the fluid is bypassing the main ram seal it then goes down the pipe that goes to the other ram increasing the pressure on the wrong side of the piston in the other ram thus stopping it extending fully. Both cylinders retract ok but again not simultaneously, the one with the failed seals bounces back out when you let go of the retract button(this is the one with the failed seals) this is caused by pressure going past the main seals into the wrong side of the ram and pressuring the pipes which are expanding under pressure and when then pump stops the pipes contract forcing the piston to bounce back.

Joe at hwh told me how to test this by disconnecting the extend pipe from the ram and then retracting the ram, once the ram ran out of travel there should be no fluid coming from the extend port on the ram, but on this one if you keep your finger on the retract the fluid is bypassing the seals and piston and is coming out of the extend port.

The numbers on the existing ram are AP15224 the replacement according to HWH is RAP90488 . the system number is difficult to identify, however if you put AP15224 into google it comes up with this:
http://www.hwh-europe.com/download/mr400625.pdf.  The system is one of the ones with the sync cylinder.

I can certainly speak to Pearsons who are in lincoln about the possibility of repairing the existing ram, the only possible way to do this is to cut the weld on the end of the existing ram.

Pearsons are professional hydraulic specialists so in view of previous advice here, I am sure that's the way to go for now.  Any thoughts on what he's saying though?

Dougie.

A welded end on the cylinder was mentioned as a possibility in the phone call yesterday, although this would be a little unusual. It certainly makes the replacement of the seals more difficult. Glad to see Mavarick's comments, and his observation of his own coach helps shed some light. Also glad to hear that professional help is nearby.

Good luck, and be sure to let us know the outcome; We might all learn something from this.

Looked at my HWH manual today but the parts breakdown does not show my cyl. construction so I can?t verify the cyl assy. Usually a welded cyl is cheaper to replace than to repair, and not a common practice in the hyd. industry. This is because of having to use a lathe to cut off the old weld, repairing the seals and then re-welding the base. The base would usually be indexed but there has to be enough steel to weld it without distorting the bore from the weld. I wouldn?t think this would be the practice at HWH but you can?t dispute what they said on the phone. If this is the case I would check replacement from HWH cost vs repair cost.
I also agree with what Pearsons and HWH Joe is saying regarding the actions of the cyl. If the seals are bypassing oil will come out the end (open port) of the bad cyl even though the ram has stopped moving. This stops the room from closing fully and is why I suggested removing the oil lines and retracting manually. Sounds like Pearsons is the place to use in your case.

That's pretty much what we've concluded too.  The problem with it being in the UK is that obtaining a replacement is a lengthy and expensive business, due to HWH locking their business into one European supplier (in some eastern country, I think Hungary?).  They in turn do not hold stock and have to order from HWH in the US, so it takes weeks for it to arrive and is marked up by around 150%.  I got around this by getting the equalizer valve easily here in the States and shipping it to the UK myself (something HWH would not approve of).

I called a second hydraulic repair specialist in our home town this morning, who immediately understood the issue and said, "Yep, we can fix it".  This confirms Mavarick's and Tom's helpful input, for which obviously I'm grateful.

The RV guy is therefore dropping off the ram tomorrow to the firm, who will give him a costing & timescale there & then.  I didn't realise he'd removed both rams off the RV.  He's had them working and connected with the rams facing outwards to see exactly what is happening  (i.e. turned 180 degrees with cylinders supported on axle stands).  This feels like progress, finally.

Dougie.

I didn't realize the mark up was as high as 150% to get something there. In that case a local machine shop or a large well staffed hyd shop would have the lathe and capability to rebuild that cyl. The next issue will be getting seals and any other parts. Most of these welded cyls do not use "standard" seal kits, just a heads up. While they are out I would at least pressure test all the cyls. Remember you are using a sync cyl with this circuit. That means if you have to make cyl mods on the bad cyl and it affects the stroke, you have to make the same change to the other cyl. in order for the sync cyl to keep the slide coming in even. Good luck and let us know what you find.

I took the ram to the hydraulic engineers last week and collected it again yesterday.  They stripped it (without cutting the end off - it unscrews....) and found the brass piston (looks like a collar) to have a hole punched through it by a small rogue piece of steel which was also in the chamber.  That looks as if it's a piece off the end of the screw-in connector nozzle which has obviously been removed at some stage in the past.  In the brass -v- steel competition, brass always loses.  The seals were also fractured, so it was definite internal damage.

They manufactured a new brass piston & seals, and it's all reassembled with new connectors - all for ?180 which in real US terms is a couple of hundred bucks - and returned to the RV mechanic who intends to refit the ram tomorrow.  So there were two issues - the equalizer valve and the damaged ram.

D'ya reckon it'll work by the weekend? 

D'ya reckon it'll work by the weekend

Click to expand...

It should be good until the next thing breaks...

Good to hear it is resolved.  And that the fault matched the guesswork as to the cause, i.e. fluid bypassing the piston in the ram. It's always rewarding to prove that the diagnosis was generally correct, even though the actual cause, the hole in the piston, was unguessable.

Thanks for the follow-up Dougie, glad you got it fixed. Welded ends on the cylinders made little sense to anyone I've talked with. Getting the hydraulic experts involved was obviously the right move.

Glad to hear you were able to repair it also. Hate to say it but it's probably a good idea to install fresh oil in the reservoir etc. and start out as clean as possible. Good luck with it.

Fresh oil is going in, for sure. It's already depleted through the many failed bleeding attempts.

Thanks.

Tom, thanks for taking the time to call yours son & explore the hydraulic specialist route. It was spot-on advice.

Dougie.

Not a problem Dougie, glad to help in some small way. Others I talked with were of the same opinion, but by then you'd already decided to get the experts involved.

Dougie, thought you might get a kick out of this. ...

While talking with my son yesterday, I mentioned your positive outcome with the hydraulic guys. Out of curiosity, he asked what diameter the rams are, and I could only guess somewhere between 35-50mm, and suggested these might be small compared with the stuff he works on. But, the ram on the smallest system he works on is about the size of a finger, while at the other extreme, he'd recently replaced a cylinder on a system with 36" diameter rams/pistons.

That's impressive. My ram is probably 3" in diameter. Wouldn't like to have a problem with a 36" one!!