Oil Recirculation in closed loop system

[woodlandfarms]

So I took my steering cylinders apart this week. Put a clear bucket underneath to capture the oil. It came out kind a dark. Was surprised at how dark it was. I took a syringe and pulled from the tank and the tank was a lot clearer.

I am just wondering on the PT as many of the systems look to me to be closed looped if they should not be drained and allowed to refill from the tank every now and then (This is the steering circuit, but I am thinking the wheel motor circuit as well).

 

[J_J]

The wheel motor circuit is a closed loop hyd circuit, and recirculates the oil until some leak or bypasses the wheel motor themselves.

I have case drains in my wheel motors, and that fluid is sent back to the cooler and tank.

The tram pump also makes up any fluid lost for any reason using the charge pump.

Some of the fluid is flushed through the pump case and back to the cooler and tank.

Those wheel motors that have no case drains, may keep the same fluid for a long time.

The fluid in the closed loop is not filtered except when the charge pump is replenishing the fluid.

If anything comes apart in the wheel motor circuit, you have all the hyd motors, pump and hoses to clean.

I only have the one 10 micron suction filter in the closed loop circuit on my machine, a PT-1445.

Some of you could go return line filters, or even high pressure filters in each circuit.

Someone had the thought that if everything in the tank was clean, everything that uses fluid would have clean fluid.

The charge pump, when replenishing the fluid is pumping at about 10% of main pump flow.

You could probably put a tee in the wheel motor circuit and feed some of the wheel motor fluid to tank, and the charge pump would replenish the closed loop with fresh filtered fluid.

 

[MossRoad]

So I took my steering cylinders apart this week. Put a clear bucket underneath to capture the oil. It came out kind a dark. Was surprised at how dark it was. I took a syringe and pulled from the tank and the tank was a lot clearer.

I am just wondering on the PT as many of the systems look to me to be closed looped if they should not be drained and allowed to refill from the tank every now and then (This is the steering circuit, but I am thinking the wheel motor circuit as well).

Yeah, unless your cylinders leak past the seals, and even if they do, you're probably never going to get that fluid rotated out of the steering circuit. It just pushes and pulls, but doesn't pass trough. The good news I guess is that the nasty oil in the cylinders will probably stay there forever and not contaminate the rest of the system.

 

[KentT]

JJ,

Since the wheel motors are reversible, and frequently used in reverse, how could you tee in a return to tank line into a line that becomes a high-pressure line and not a return line, based on treadle position?

 

[MossRoad]

JJ,

Since the wheel motors are reversible, and frequently used in reverse, how could you tee in a return to tank line into a line that becomes a high-pressure line and not a return line, based on treadle position?

I think you'd lose some power at the wheels.

 

[SpringHollow]

I always thought the joystick valve had a return to the tank and you would be getting the cylinders purged with use. Shows what I know.

Ken

 

[MossRoad]

I always thought the joystick valve had a return to the tank and you would be getting the cylinders purged with use. Shows what I know.

Ken

- Small PTO pump section supplies the steering valve.
- The steering valve's power beyond port powers the AUX PTO and FEL valve bank.
- The AUX PTO and FEL valve bank returns the fluid to the tank.
- The knee bone connected to the thigh bone...

 

[J_J]

I think you'd lose some power at the wheels.

I did not mean for anyone to leave the tee valve open to tank.


That valve would be to add a supply of filtered oil to the closed loop.

He said his fluid was almost black, meaning the fluid had been recirculating in the loop a long time

The fluid could have been burnt or well used with anything in it.

The fluid is only filtered by the charged pump when providing makeup fluid, and pump flushing.

 

[MossRoad]

OK, gotcha.

 

[Raw Dodge]

Most closed loop systems do leak about a pint to quart an hour so the whole system is filtered just slower, and trash will circulate, which is why high pressure loop filtering is required anytime the closed loop is opened. The steering cylinders will not leak unless the seals are bad and they will keep circulating the same fluid, and the fluid gets bad after a while...