Power beyond problem?

Fred2016

New member

Equipment
Gzd21
Nov 21, 2021
2
0
1
Scotland
Hi all.
Gzd21 zero turn mower. Pto to blades turns then stops. We have fitted a new pto clutch and oil pump. Pressure is good at tipping rams but when testing the PB port the pressure starts at 2 bar quickly dropping to zero. The manual states we should have 10 bar at the PB port. Any ideas?
 

Dave_eng

Well-known member
Lifetime Member

Equipment
M7040, Nuffield 465
Oct 6, 2012
4,330
488
83
Williamstown Ontario Canada
Hi all.
Gzd21 zero turn mower. Pto to blades turns then stops. We have fitted a new pto clutch and oil pump. Pressure is good at tipping rams but when testing the PB port the pressure starts at 2 bar quickly dropping to zero. The manual states we should have 10 bar at the PB port. Any ideas?
I do not know your machine so my comments are general in nature.

Assuming your machine has open center hydraulics, then the only time pressure builds in any out line from a valve or out a PB line is when that out flow is restricted by a cylinder or hydraulic motor. Otherwise the flow is constantly circulating at low pressure from the pump, through a valve(s) and back to the reservoir..

Because you are a new forum member you cannot post photos etc for a while. I will send you my personal email in a private forum conversation. Send me some manual photos and I will post them in your thread.

Dave
 

Fred2016

New member

Equipment
Gzd21
Nov 21, 2021
2
0
1
Scotland
We have now tested the spool valve at which point we have 1800psi. The PB port tests the same when dead headed. When the PB port is T'd to the flow to the pto clutch we get 120psi which we expected however at the clutch operating valve we get 35 psi which rapidly falls to zero. We are now thinking something is seriously wrong inside the casing or the clutch operating valve itself.