Tractor Repair: Hydraulic cylinders, hydraulics system, double acting cylinder

Question
Hi Arnie:

First off let me thank you for volunteering its sincerely appreciated.

Heres my problem. I have a JD 2350. There are two hydraulic ports on the back to hook equipment to.

I have a woods 15 foot batwing brush hog.  ONe of the cylinders went on the batwing.

Its a welded cylinder and there was only one hose going into it ( I was assuming this is a one way cylinder that uses a spring to move the cylinder one way?? )

Heres a link - its page 68

http://www.woodsequipment.com/WorkArea/showcontent.aspx?id=10561

It says though that it is a double acting cylinder (??). I am unclear how it can be double acting with only one hose going to it ??  

OK so I go to farm and tractor and buy a tie rod double acting 3 x 12 cylinder  

WE go to hook it up and it has hose hook ups in each end - so we plug one end and put the hose in the other.

However it was moving opposite the other bat wing. So I move the hose to the other side thinking that would switch it and ...nothing - no movement   

I guess I am confused - if it were a double acting cylinder wouldn't you need a hose on each end  - one to take in the fluid and one to take the fluid out?

ANd if that's the case  how would that fluid return to the tractor? There are two hoses going into the tractor hookups but it seems they are both pushing out fluid at the same time?

Also why did the new cylinder move when the hose was on one end but not the other ?

Well as you can tell I am a bit confused on this whole hydraulics system so any help you can give to a struggling wannabee farmer would be greatly appreciated!

God Bless

MIke  

Answer
Hello,

  The cylinders can be used as double acting cylinders so they are called double acting, but in this application they are being used as single acting cylinders as you said.  The hose attaches to the rod end of the cylinder and the other end should have a vent plug.  A solid plug would trap air inside the cylinder and affect operation.  The oil coming into the cylinder causes the rod to pull the wings up, and the weight of the wings pushes the oil back out the same hose when the wings are lowered, so only one hose is needed.  The plumbing diagram in the link you sent shows the cylinders connected to a 3 spool control valve with 2 hoses going to the tractor.  If you have this control valve, each cylinder is connected to a separate valve section and you only need one remote valve on the tractor.  If you do not have this 3 spool control valve, you don't have enough outlets on your tractor to plug in all the hoses from the cylinders to make it work.  If there are only 2 outlets on the back of the tractor, then you only have one remote valve.  The hoses from both wing lift cylinders can't be plugged into both couplers of the same remote valve.  Either one wing would raise while the other is lowering, or they would fight against each other which sounds like what happened when you moved the hose.  You would either need the 3 spool control valve, or more remote valves on the tractor, or you could connect both wing cylinder hoses together with a tee fitting and have one hose going to the tractor so both wings lift together from one valve.  I hope I have not confused you more than you were before!