Welded VS Bolted hydraulic cylinder?

[unioncreek]

I'm looking at a hydraulic cylinder for the tilt on my loader and have noticed that the price varies between the welded and bolted one's. Is there a difference in performance and quality of the two and can the welded ones be repaired as easily as the bolted together one's.

Thanks,
Bobg

 

[Renze]

Bolted hydraulic cylinders is an American thing. Here in Europe they dont make them that way at all, and the odd one to be seen here, is the same Chinese stuff that you guys get retailed by Harbour Freight.
You can allways unscrew the caps of welded cylinders because they arent fully welded: only the end cap is welded on, the front part (from which the piston sticks out) is screwed into the tube.

Off course it depends on how its built, but as a rule of thumb i think cylinders with welded or screwed caps are more sturdy than those that hang together with some threaded rods: Especially on long rods, they need a lot of pre-tension because the full length can stretch out, and lead to leakage if stretched further than the seals can make up for.

It might be cheaper to manufacture, because the DOM tube only has to be chopped to length and deburred, not requiring the extra welding and thread machining, which are extra steps in the manufacturing process.
In high end applications, i dont think you'll see any cylinders held together with threaded rods.

 

[Wayne County Hose]

Bolted hydraulic cylinders is an American thing. Here in Europe they dont make them that way at all, and the odd one to be seen here, is the same Chinese stuff that you guys get retailed by Harbour Freight.
You can allways unscrew the caps of welded cylinders because they arent fully welded: only the end cap is welded on, the front part (from which the piston sticks out) is screwed into the tube.

Off course it depends on how its built, but as a rule of thumb i think cylinders with welded or screwed caps are more sturdy than those that hang together with some threaded rods: Especially on long rods, they need a lot of pre-tension because the full length can stretch out, and lead to leakage if stretched further than the seals can make up for.

It might be cheaper to manufacture, because the DOM tube only has to be chopped to length and deburred, not requiring the extra welding and thread machining, which are extra steps in the manufacturing process.
In high end applications, i dont think you'll see any cylinders held together with threaded rods.

Very well said from a different perspective than we on this side of the pond have.

The tie rod cylinders are a little easier to rebuild.

 

[Renze]

Very well said from a different perspective than we on this side of the pond have.

It seems acceptable in the USA... but over here, if the company i work, showed a payloader with tie rod cylinders on a fair, that would be a total embarrassment...

 

[Wayne County Hose]

It seems acceptable in the USA... but over here, if the company i work, showed a payloader with tie rod cylinders on a fair, that would be a total embarrassment...

Over here as long as it's cheap it's okay. And if it doesn't work, it's not an embarrassment, it's an experiment.

BTW, I don't agree with it, but it's what the American public has asked for. Now, they got it.

 

[RickB]

Over here as long as it's cheap it's okay. And if it doesn't work, it's not an embarrassment, it's an experiment.

BTW, I don't agree with it, but it's what the American public has asked for. Now, they got it.

How very, very true.

 

[EV59]

In the USA machinery needs to look HD and be functional. In Europe machinery needs to have Beauty-Smooth lines-and be functional.

Buy the cheaper cylinder...90% are made in China.

EV59

 

[Renze]

In the USA machinery needs to look HD and be functional. In Europe machinery needs to have Beauty-Smooth lines-and be functional.

Even though the American culture has strong roots in several European cultures, there is, and allways will be, a difference in many little things...

And: I'd rather put it the way that the European market requires the looks/appearance of sophisticated engineering, rather than just the looks of smooth design lines.... Lets put it this way: no two dogs are alike (read my signature)

 

[Wayne County Hose]

I'm looking at a hydraulic cylinder for the tilt on my loader and have noticed that the price varies between the welded and bolted one's. Is there a difference in performance and quality of the two and can the welded ones be repaired as easily as the bolted together one's.

Thanks,
Bobg

Bob,

If you get the tie-rod cylinder, you will probably never notice a difference on performance. The welded one is definately higher quality and will stand up to more abuse and last longer. However, for your application, the tie-rod will work just fine.

Andy

 

[Renze]

The welded one is definately higher quality and will stand up to more abuse and last longer. However, for your application, the tie-rod will work just fine.

I agree with that..
compact tractors would probably not go over 150 bar... construction applications go over 300 bar.. If i had to build something for a customer, i'd use "welded" cylinders because it looks better... if it was for myself, in this application i'd probably use whatever is cheapest..

 

[joes_427_vette]

Renze;
I bought a used Kubota plow and frame to mount on my John Deere. To rebuild the cylinders I had to cut them with a bandsaw and reweld them. The local hydraulic shop said I wouldn't be able mto get them apart for seals. When I brought the pieces back for seal comparisons he laughed and said, " I see you found the secret to getting them apart. " I normally wouldn't have done this but without seals they leaked and would have been junk anyway. This must have been some Japanese engineering.

 

[Renze]

When I brought the pieces back for seal comparisons he laughed and said, " I see you found the secret to getting them apart. "

A hydraulics shop where i once been on behalf of my former boss, had a special bench to clamp and unscrew cylinder caps. They have a little notch in them, comparable as how you mount tapered bearings with a nut and special wrench.

When i rebuilt the cylinders of my loader (63mm, 2.5") my pipe wrench wasnt big enough, so i notched it with an angle grinder and tapped the head loose with a chisel.

On some cylinders, like the assister rams on a tractor 3pt hitch, have a small nut which you can unscrew. then when you shake it, there are a load of securing balls rolling out of this hole, after which you can easily take the plunger out of the cylinder.

I think the hydraulics guy was either pulling your leg, or just uninformed. He probably said that because he wanted to discourage you to generate some work for his shop, or he just wanted to sell you a set of new cylinders...

The 300 bar, 100mm diameter cylinders we build into the loaders at my daytime job, have the pistons screwed onto the rod with a tightening torque of 2200 N/m which is 220 kg/meter. I have no idea how much foot/pound this is, but its HUGE. The average 80kg person would require a wrench length of allmost 3 meter to generate this torque by his/her own weight...

We dont sell spare piston rod seals for them because there is no way a local shop could get the piston off the rod to take it out of the cylinder cap. We have piston rebuild kits, but when the rod seal leaks, you're going to need an exchange cylinder. The customer gets a rebuilt one and trades his old cylinder, for the cost of labour and seals. Once rebuilt (in the hydraulics shop we deal with) the cylinder goes back in stock for the next exchange customer.

 

[Wayne County Hose]

Renze;
I bought a used Kubota plow and frame to mount on my John Deere. To rebuild the cylinders I had to cut them with a bandsaw and reweld them. The local hydraulic shop said I wouldn't be able mto get them apart for seals. When I brought the pieces back for seal comparisons he laughed and said, " I see you found the secret to getting them apart. " I normally wouldn't have done this but without seals they leaked and would have been junk anyway. This must have been some Japanese engineering.

Can you take pictures of this cylinder and post? I have never met a cylinder I couldn't take apart without cutting it. Well, no, sorry. There was this one Yanmar loader cylinder one time. It was supposed to unscrew, but even heating the tube cherry red wouldn't loosen it, but that's another story. n