7211 Hydraulics

[smystaki]

Trying to maintain a 7211 tractor that was out of action for more than 7 years I am facing a strange issue.

The hydraulic lift can not keep upper possition all the times.

When the operator moves his hand from the lever then hudraulic cylinder retracts.
This could be 2 things.
1st Piston seals damaged and/or
2nd main Valve piston under heavy wear or a safety valve is leaking.

I have made a proper repair to the lifting cylinder but the system behaves the same way. In the operators manual there are not enough information for a manifold inspection.

Are there any documents for the 7211 hydraulic system available to any forum member?

 

[Renze]

Give the spring that puts friction on the 3pt lever, some more pressure. Its a common thing for them to jump down as soon as you take away your hand.

 

[smystaki]

So the whole load is secured by this spring?
The valve for internal hudraulics is without middle position?
There is zero dead band?

Thanks a lot for the tip.

 

[Renze]

No, just the lever is secured by that spring. If you put the lever fully up, you can see it from behind the tractor.

 

[askinner]

I have made a proper repair to the lifting cylinder but the system behaves the same way.

Are you aware there are two cylinders on this tractor? One external, and one internal. The internal one is the one that normally bypasses, causing the drift.

 

[smystaki]

Are you aware there are two cylinders on this tractor? One external, and one internal. The internal one is the one that normally bypasses, causing the drift.

I am talking about the cylinder indicated in this photo.

This circuit is refereed as "internal". Just found a zetormatic manual and there is no reference to any other cylinder. Can you please be more specific?

 

[dave_peters]

The ram you have pointed to is only an assister ram, the ram that does most of the work and is the only ram on the smaller tractors is in the casting under the seat and is very much bigger. To reseal this ram the hydraulic top cover has to be removed after taking the floor and back panel out of the cab. You will probably need an engine hoist of some kind as its very heavy

 

[smystaki]

Give the spring that puts friction on the 3pt lever, some more pressure. Its a common thing for them to jump down as soon as you take away your hand.

Right on the spot. Thanks for the tip. Problem solved.