dfkrug
Super Member
- Joined
- Feb 3, 2004
- Messages
- 7,197
- Location
- Santa Cruz Mtns, CA
- Tractor
- 05 Kioti CK30HST w/ Prairie Dog backhoe, XN08 mini-X
The only problem I see with multiple RV's on the open center cirquit, is that if they all are on the same setting, before they are fully opened, they will start leaking a little at the same pressure. That will make some increase in leakage power losses. I like when the RV stay completely closed all the way up to the opening pressure, then I want it fully opened. Some of these valve I have used have even lowered the pressure a few psi after opening. They are flow compensated. They were common on mobile equipment where operator use throttle (rpm to increase pump flow).
The RV on one of those Prince stack valves is just a preloaded spring and
an adjustment bolt. I bought those for my CADDigger. It will gradually
open enough to drop the pressure in the system....not flow-compensated.
I agree with the OP, that a second RV in the AUX valve stack is redundant.
When I add a AUX valve or backhoe or whatever, I set the additional RV
right AT the specced system pressure. I want to make the max use of the
design pressure available. If I am happily using my 2500psi tractor, and
I add a hoe or AUX valve or FEL, and set ITS RV at 2450, I have lost some
valuable pressure that was available for ANY implement before.
When a maker sells a valve, they don't know if the user will have
any other RV available in the system, so they offer a RV. Conversely,
if a tractor maker always installs an AUX or FEL valve, they can make do
with only one RV. My Kioti and Bobcat tractors are that way...no system
RV; the RV is in the FEL valve.
Another case can be made for setting the AUX valve RV to the same pressure
as the other RVs in an OC system. If the user goes to relief very often,
as in dirt work, multiple RVs opening simultaneously should reduce the amount
of fluid heating you get. This is minor compared to the above reason,
however.