replacing a single acting cylinder with double acting

[thendrix]

I need to replace the single acting lift cylinder on my JD 1219 moco and I think I would like a double acting instead. What do I need other then a cylinder with the same bore, stroke, ends, and a return line?

The way it works now is you raise the mower to remove a pin from the transport position and put it in the operating position then when you turn off the hydraulics a spring and the weight of the mower compress the cylinder. The issue I have with this is there's no adjustability other then drilling more holes in the bar that the pin goes in and I would like to be able to set the hight with my hydraulics rather then either being up or down.

 

[Tx Jim]

May I ask what is your reasoning is to desire a double acting cylinder?? You can set the cutting height just the same with SA as DA cyl. If you change to DA cylinder you will eliminate the headers(cutter bar) ability to float over uneven terrain unless you perform some serious modification to lifting mechanism. Only advantage I can envision for a DA cylinder is one can operate with a smaller hyd reservoir with a DA cyl compared to a SA cyl. To answer your question just find a DA cyl the correct size route the hoses from cyl to tractor,plug hoses into tractor and use Mo-Co

 

[thendrix]

This brings up another question. I was under the impression that once pressure is released from the single acting, the spring and mower weight would cause it to compress until it either his the pin or the bottom of the stroke? How do you set cutting height with a single acting?

 

[Soundguy]

Ditto what TXjim said. by adding a DA cyl you introduce problems, namely flaot.. plus.. you need that return, and then your valve has to be able to handle DA hyds.

For setting the height ( drop.. whatever ), you get clamp on donuts to go on the cyl rod so that it's can't compress fully. they make them in different thickness's also called cylinder limiters.

http://www.catford.com.au/images/B6436wm.JPG

http://www.depthstop.com/imgs/block_set_a.jpg

 

[Soundguy]

extend cyl, clamp a few on.. drop cyl.. see if it's too low or high a height, then lift cyl again and swap in more or less donuts of different sizes till you get it to ride where you want it.

once you have your set picked out, leave em on... you can still lift and pin to transport height.

if you later decide to go lower.. just pull one/few while in transport and see what you got.. etc.

they are cheap.. sold in sets at farm stores... lots of implements with lift wheels and folding decks or wings etc use them.

 

[thendrix]

Hmm. That's almost to simple. Thanks everybody

 

[Tx Jim]

Actually if SA cyl. rod seal,hose or male coupling isn't leaking you should be able to lower cutter bar to desired height put control valve lever in neural then cutter bar should stay at set height. This depends on if control isn't leaking internally. Soundguy's depth stop clamps will insure cutter bar stays at set height or you could set depth shoes that came on your Mo-Co.

 

[thendrix]

The cylinder is leaking and the rod is scored pretty bad. That's why I'm replacing it. I figure seals would be a waste because as rough as the rod is they wouldn't be there long

 

[Tx Jim]

After viewing JDparts.com it appears cyl rod is NLA but I would think a used salvage Mo-Co cyl. could be located. One might get a machine shop to make a rod.

 

[J_J]

Why can he not use a DA cyl like he wanted to do..

You simply add a breather screen to the rod end port and it becomes an SA cyl.

 

[Tx Jim]

You're correct BUT once one adds a breather and uses ONLY one hose then it's not a DA cylinder any longer is it????? OP didn't ask if he could convert a DA cyl to a SA cyl. application. I think a regular DA cyl converted to SA will be difficult to locate with the correct dimensions for this application but I've never attempted that feat.

 

[J_J]

This brings up another question. I was under the impression that once pressure is released from the single acting, the spring and mower weight would cause it to compress until it either his the pin or the bottom of the stroke? How do you set cutting height with a single acting?

If you have a perfect valve with no spool leakage, then the cyl will stop and hold at the last position you left it in.

As you know, most valves spools leak, so a needle valve is a positive shut off to hold the cyl in place.

Using a SA cyl and valve in neutral, the only pressure is the load.

If you want to lower the load, you release the fluid back to tank.

 

[Soundguy]

Why can he not use a DA cyl like he wanted to do..

You simply add a breather screen to the rod end port and it becomes an SA cyl.

He can... just not as a DA cyl like he mentioned originally ( return line etc. )


For the price, he can find a red lion cheaply on a shelf and be working in a few minutes. right next to those at TSC and rural king are those clamp on donuts I mentioned. 2 birds, one stone ( trip )..

Probably took longer to read all the posts in this thread than it would to swap the cyl out.

 

[J_J]

What he said was , I would like to use a DA cyl.

You have to think he has the knowledge to use it anyway possible.

Donuts would work as would a block of wood or steel bracket.

Question is, is that a SA valve he is using.

 

[Soundguy]

yup, i asked in post #4, and he has chosen to not answer...

 

[thendrix]

yup, i asked in post #4, and he has chosen to not answer...

Uh....I didn't see a question anywhere in post 4 and since there was no question I see no reason to answer a statement in any other way then what I did 2 posts later with "simple enough. Thanks everybody"

 

[Tx Jim]

What he said was , I would like to use a DA cyl.


Question is, is that a SA valve he is using.

I operate a SA cylinder on a DA valve every time I operate my Krone or Vermeer disc mower so why the need for SA valve? Here's a parts photo of how the DA cyl if OP elected to substitute for SA must be mounted and it doesn't allow for much room for substitution.

 

[J_J]

There you go again. You seem to misunderstand just about everything I say.

I never said he had an SA valve, even if the same valve can contains both DA spools and SA spools.

He said he had a SA cyl and I wanted to know if the valve was an SA valve and if it was not I would tell him how to use the SA cyl on a DA valve, of which there are two ways.

I know very well how to use a DA valve on a SA cyl.

 

[Soundguy]

Uh....I didn't see a question anywhere in post 4 and since there was no question I see no reason to answer a statement in any other way then what I did 2 posts later with "simple enough. Thanks everybody"

In post 4 I said that your valve would need to be able to handle DA hyds. ( if you were wanting to use da, and the 2nd line as you also mention in your first post. )

you never specified if it would or wouldn't.

However with the tone of your reply here, I'll be sticking you on ignore now.

 

[thendrix]

The tone of my reply represents the tone I got from your reply that I quoted