Locked up and nowhere to go

[J_J]

The more I look at the my PT the more I think that the High Pressure filter is a good idea. I am not sure how they work (Do they really filter 100% of the oil or just skim bypass) - seems hard for me to see how 3000PSI and X-GPM could get a quick cleaning in such a small filter.

Anyway... I know my fliter caught debris from a dying hose. In the long run it did not save me from having to rebuild the accumulator, but it may have helped.

Carl,

What circuit is the filter located. If it is located in the steering circuit, then it is filtering only when you use a certain function, and at other times, it is doing nothing. If a portion of that fluid is going to your brakes, then a piece of crud could cause big trouble.

 

[woodlandfarms]

Brakes, steering, and lift and tilt. It works when I works ;-)

 

[woodlandfarms]

I do not have all my hoses switched, I still have some low pressure ones that could stand to go, but money is tight so, emergency repairs only per the CFO.

You hit the nail on the head in terms of heat and system loss. I wonder what that filter kills. I am not sure it filters 100% as there is some sort of bypass, Not sure if it bypasses most stuff and filters a little or visa versa It seems like a small filter to handle the demands of steering lift and brakes.

 

[ponytug]

Dear Carl,

The HP kill is pressure drop times flow. Most fine filters bypass at about 20-40psi, so the drop has to be less than that, plus any plumbing losses.

It isn't a big deal, but it is an additional load. (Just for order of magnitude, 40psi times 5gpm=0.12HP.)

I don't know how your machine is plumbed, but unlike JJ, mine is plumbed so the auxiliary pump is always pumping, which would have the filter as a constant (small) load.

All the best,

Peter

I do not have all my hoses switched, I still have some low pressure ones that could stand to go, but money is tight so, emergency repairs only per the CFO.

You hit the nail on the head in terms of heat and system loss. I wonder what that filter kills. I am not sure it filters 100% as there is some sort of bypass, Not sure if it bypasses most stuff and filters a little or visa versa It seems like a small filter to handle the demands of steering lift and brakes.

 

[J_J]

Peter,

Now don't laugh, but do you have a complete hydraulic schematic for your machine?

I only have one filter and that is for the charge pump. All three of my pumps are running all the time, and of course, wasting energy.

 

[woodlandfarms]

I would venture a guess that Peter and my system is pretty close to the same in terms of hydraulic schematic. Saddly, nothing on paper that is even close.

Uninformed, just observational, my pump runs all the time. It goes from the pump, to a PTO actuator block, This block activates the PTO circuit (from a seperate pump). There is a bypass valve for the Steering, Brake, Lift and Tilt circuit. They bypass goes back to the tank. If you continue forward it goes to the high pressure filter, then to the accumulator. I think there is a bypass in the accumulator, but I have yet to follow all those hoses (I would do it if I was up north.).

Anyway, hope that helps...

 

[Bob999]

I would venture a guess that Peter and my system is pretty close to the same in terms of hydraulic schematic. Saddly, nothing on paper that is even close.

Uninformed, just observational, my pump runs all the time. It goes from the pump, to a PTO actuator block, This block activates the PTO circuit (from a seperate pump). There is a bypass valve for the Steering, Brake, Lift and Tilt circuit. They bypass goes back to the tank. If you continue forward it goes to the high pressure filter, then to the accumulator. I think there is a bypass in the accumulator, but I have yet to follow all those hoses (I would do it if I was up north.).

Anyway, hope that helps...

ponytug said: "I don't know how your machine is plumbed, but unlike JJ, mine is plumbed so the auxiliary pump is always pumping, which would have the filter as a constant (small) load."

If I understand woodlandfarms description correctly the filter is only adding load to the system when the steering, brake circuit, or lift tilt is actually doing work--otherwise the flow is bypassed back to the tank prior to the filter. I think this allows the use of a very small filter but that it also means that the filter doesn't see very much flow. If I am correct the HP loss to the filter on average would be very small and the amount of fluid actually filtered would also be very small.

 

[ponytug]

Agreed.

The big question would be is the filter before the charging valve (always on) or after ( on and off).

All the best,

Peter

ponytug said: "I don't know how your machine is plumbed, but unlike JJ, mine is plumbed so the auxiliary pump is always pumping, which would have the filter as a constant (small) load."

If I understand woodlandfarms description correctly the filter is only adding load to the system when the steering, brake circuit, or lift tilt is actually doing work--otherwise the flow is bypassed back to the tank prior to the filter. I think this allows the use of a very small filter but that it also means that the filter doesn't see very much flow. If I am correct the HP loss to the filter on average would be very small and the amount of fluid actually filtered would also be very small.

 

[woodlandfarms]

My filter is before the charging valve. Pump - Filter - Charging valve... I think that is what you are asking....

 

[ponytug]

Perfect! So that means it is always filtering the full output of the pump, which out to mean that your oil gets pretty clean.

All the best,

Peter

My filter is before the charging valve. Pump - Filter - Charging valve... I think that is what you are asking....