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.