Help in sourcing ram cylinder housing for my passerelle

[vas]

evening,
yet another question from me!

this time it's the passerelle ram which was removed and serviced last year as it was leaking (slightly).
Mechanic said that the cylinder housing is scored inside and the seals wont last long.

True, it is pissing oil now, so removed reopened and we are trying to find a tube to rebuilt it.
You can feel and under the right circumstances even see a slight score going halfway along the cylinder. From fully closed to half open (guess that's where most of the forces are put...

Not particularly good with the terminology, so bear with me, the inside solid rod with the piston and seals is fine, just need a new cylinder housing for it to slide into

Now, throughout Greece there's noone stocking such a size tube and the mechanic suggested I should look at Italy or UK. He recons mine is Italian. He even mentioned Radice although I'd expect that they'd be more into solid axles and not hollow tubing, but who am I to argue?

So anyone got any idea where I can get hold of a stainless steel tube with the proper treatment to be used in as a cylinder housing for a high pressure piston with the following dimensions:

OUTSIDE DIA: 50.92mm (give or take should err to the larger sizes else the solid bar and head wont fit, that's too close to 2inch)
INSIDE DIA: 45.75mm (again give or take a bit)
LENGTH 500mm

Should be around a kilo of steel to ship over.

He can find black cylinder housing (for elevators and other uses that don't need ss) but we cannot use it. Not to mention that the black cylinder has too thick walls as the material properties are much lower than the SS one.
Could go slightly larger and redo the rod and piston (and loose a bit in speed and gain in lifting power), cannot go smaller as it's not going to be strong enough for the job.

Since I don't actually know how you call this thing in engineering english, I'm having problems even searching the web for it. Tried http://smt.sandvik.com/en/products/tube-pipe-fittings-and-flanges/tubular-products/ who have 50 different types of SS tubes and got totally lost...

Any ideas welcomed!

cheers

V.

 

[colhel]

when we (OYS) manufacture hydraulic assemblies w use a company in Andover called Perfect Bore to do the cylinder bores. If you have to get one made specially this would be a good place to start, they may even make one complete for you http://www.pbm-ltd.com/

 

[vas]

when we (OYS) manufacture hydraulic assemblies w use a company in Andover called Perfect Bore to do the cylinder bores. If you have to get one made specially this would be a good place to start, they may even make one complete for you http://www.pbm-ltd.com/

thanks,

however these guys seem to be doing jobs way over what I need.
I'm told that the cylinder housing I'm after should come straight and honed, ready for use.
I'll sent them an email just in case, not sure if they stock material that they can sell on untreated by them.

The rest of the ram is split in the workshop so no point in them doing the whole work as I'll have to ship bits up there and then them ship the whole lot down here, gets complicated

cheers

V.

 

[colhel]

I'm just a machinist not a hydraulics engineer which may account for why I'm not sure what exactly you need. Do you just need a piece of tube honed to size?

 

[vas]

Do you just need a piece of tube honed to size?

that's EXACTLY what I want!!!

you don't happen to have any at the right size do you?


cheers

V.

 

[colhel]

the issue for me would be getting a good enough finish over that length. Gun drilling and then turning the OD would be the way I'd have to do it. I can dig deeper if you're stuck for alternatives......

 

[rogerthebodger]

As a retired mechanical engineer you have 3 options.

1) go back to the original manufacturer of the cylinder for the passerelle to get a direct replacement for the cylinder casing.

2) have one manufactured to the spec of the original.

3) find a complete standard hydraulic cylinder from a local manufacturer with the same bore/ stroke/ rod size and end fittings

If you can post a pic and details sizes etc I may help with internet searches.

try these

http://gr.kompass.com/a/oil-hydraulic-equipment/32620/

http://www.hellotrade.com/psearch?p=hydraulic+cylinder+in+greece

 

[vas]

As a retired mechanical engineer you have 3 options.

1) go back to the original manufacturer of the cylinder for the passerelle to get a direct replacement for the cylinder casing.

2) have one manufactured to the spec of the original.

3) find a complete standard hydraulic cylinder from a local manufacturer with the same bore/ stroke/ rod size and end fittings

If you can post a pic and details sizes etc I may help with internet searches.

try these

http://gr.kompass.com/a/oil-hydraulic-equipment/32620/

http://www.hellotrade.com/psearch?p=hydraulic+cylinder+in+greece

Roger,

1 is out of the Q, wanted to charge me 250euro for a bleeding remote, I wont dare think how much the ram will be (and tbh I doubt they'll sell spares, just full cylinder with rod and piston)
2 that's where I'm heading atm as 3 is already searched and nothing found...

FWIW, I can go up a bit in dimensions but don't want to go down. The machinist will have to fabricate another piston if we go up in size, no big deal.

So effectively I want some SS cylinder, honed and with internal diametre of 45.75mm or greater and half a metre long. If you could help in sourcing that online I'd be greatful (but preferably not one in Jo'burg...)

cheers

V.

 

[Portofino]

What's the aetiology of the "scoring "
I would want to understand that 1st ,then find a solution .Otherwise if you just manage to replace the tube alone ,how do you know that will not end up scored sooner or later .

Piston -via worn seals --metal -metal contact ?
Carp in the hydraulic fluid -- faulty filtering ?

Is it possible to re-bore the exsisting tube and maybe (depending on how much bigger the new Dia)
Wider -different seals
Oversized new piston + standard seals .

Or as suggested ring around and buy a new whole new ram ,if it's bigger -it may have a bigger lift capacity or an easier life last longer ?

 

[Portofino]

These do SS cylinders-- new unit 50 mm ?

https://www.phoenixhydraulics.co.uk/ProductGrp/50-Bore-Hydraulic-Rams

 

[vas]

What's the aetiology of the "scoring "
I would want to understand that 1st ,then find a solution .Otherwise if you just manage to replace the tube alone ,how do you know that will not end up scored sooner or later .

Piston -via worn seals --metal -metal contact ?
Carp in the hydraulic fluid -- faulty filtering ?

Is it possible to re-bore the exsisting tube and maybe (depending on how much bigger the new Dia)
Wider -different seals
Oversized new piston + standard seals .

Or as suggested ring around and buy a new whole new ram ,if it's bigger -it may have a bigger lift capacity or an easier life last longer ?

that was my first Q to the machinist.
Considering the load they're under and the slope at which they operate minute flexing or rather sloping of the rod when the piston pushes it up is enough for the piston edge to score the cylinder on the lower vertical axis. There's a straight line score approx half way the length of the cylinder that you can feel (and that subsequently has scored the two rubber seals of the piston) Hence oil is leaking only on certain extensions of the ram (low to mid) if you lift it all the way up, it's fine, but lowering it to enter means I loose 10-20cc each time

So yes, it's piston metal to metal, even on new seals. But was there with the old seals when I had a first go at repairing.

Solution is as I said a new cylinder that the machinist will weld the cap with the hole for the rod on the one side and then weld the flat cap with the eye for the passerelle fitting on the other.

If I could get a new overall cylinder I wouldn't mind too much, but I doubt I can get one at the right dimensions and right price. Bear in mind that the machinist is probably only going to charge me 100euro for all the work.

Failing all that, he suggests to try and hone it (he's got tools) and postpone the repair for next season, but I'd rather finish and tick off jobs rather than shift them back in time

cheers

V.

 

[vas]

These do SS cylinders-- new unit 50 mm ?

https://www.phoenixhydraulics.co.uk/ProductGrp/50-Bore-Hydraulic-Rams

thanks but I'll probably skip that 590+VAT for a 50mm X500mm full cylinder is half as much I paid for the passerelle altogether

cheers

V.

 

[rogerthebodger]

Solution is as I said a new cylinder that the machinist will weld the cap with the hole for the rod on the one side and then weld the flat cap with the eye for the passerelle fitting on the other.

.

Do not do any welding on the cylinder after honing as it will distort the honed bore.

I have just converted a hydraulic shock absorber from an outboard to a single acting hydraulic cylinder. The rod end is screwed into the end of the cylinder tube the other end was welded before honing.

Dont forget you need a seal between the end cap and the cylinder and the end cap and the rod.

Post a pic of the dismantled cylinder and we can get a better view of its method of construction.

This is the same type of construction as the one I converted

you may be able to hone out the scratch in the bore and make a net piston using the existing rod and endcap. An engine reconditioner will be able to do the honing or you could use a break cylinder honing tool

 

[colhel]

t

If I could get a new overall cylinder I wouldn't mind too much, but I doubt I can get one at the right dimensions and right price. Bear in mind that the machinist is probably only going to charge me 100euro for all the work.

Failing all that, he suggests to try and hone it (he's got tools) and postpone the repair for next season, but I'd rather finish and tick off jobs rather than shift them back in time

cheers

V.

It does sound as though your machinist is capable but I agree with Roger regarding welding after honing. If I were in your shoes I'd just give him the whole job. As he can do the honing which is a very crucial part of the work, why does he need a tube supplied?

 

[vas]

from what he said, the score is deep enough that wont be cleared with honing. He has to cut through material which will end with a larger size of seal which is not available (I gather that there are more or less standard sizes for them, dunno!)

hence the request for a new tube...

cheers

V.

 

[vas]

quick update,

Following my unsuccessful attempts to source the right ss cylinder for my ram (thanks for the pointers!) I searched around all the machinists in Piraeus last Friday to no avail.
I went to one of the best chandlers in town and asked for ideas. Apparently he's also managing fabrications of all sorts of things for large yachts and showed me drawings for a large passerelle that folds down and becomes a bathing ladder dunno around 4m long and massive! He explained that he has a fabricator that's cheap and does ss work for him and full rams as well.
Sent him the dismantled ram yesterday and today came back with a price, 200euro + VAT!
They'll reuse the ss rod, obviously change the piston end to fit the right size seals. The ss cylinder will be slightly larger than mine which is fine by me, slightly slower but stronger.

That's a reasonable price for me to pay, although sounds silly cheap compared to what I've heard. Gave him the go ahead and looking forward to receiving the thing next week!

More news once it's fitted and tested. Cannot wait to do a load testing (using 5 50kg sacks of cement ) and confirm that my passerelle will be happy lifting a 250kg rib (before I go to Athens and buy one!)
Assuming it's up to the job and works fine, needless to say if someone wants any custom ram work on a budget, I can point you to these guys or explain in Greek what you want and get them going.

cheers

V.