B8200 no hydraulics

[MartinmMc]

If this is the correct position, still no pressure

 

[TheOldHokie]

If this is the correct position, still no pressure

I belueve that is correct. Next step would be a pump pressure test. Remove the inlet hose from the loader valve and connect cc a 3000 PSI pressure gauge to the hose. Start tractor and read pressure. Should be something in the neighborhood of 2000 PSI

I will save NIWM the trouble - start looking for a new gear housing for the pump.

Dan

 

[MartinmMc]

I'll get a gauge ordered

 

[MartinmMc]

Just out of curiosity, does the return to the transmission have a restrictor to create pressure or how does it hold pressure in the system, I'm trying to get head around it's workings.

 

[TheOldHokie]

Just out of curiosity, does the return to the transmission have a restrictor to create pressure or how does it hold pressure in the system, I'm trying to get head around it's workings.

Your quest for understanding is commendable.

This is an open center system with fixed displacement pump.

1. When the engine is running oil flows at low pressure through the center (neutral position) of all control valves and back to tank.
2. When any valve is shifted out of neutral that flow is redirected to an actuator (e.g. cylinder or motor) and pressure builds to match the load on the actuator.
3. When the valve is returned to neutral the flow to tank resumes

DAn

 

[MartinmMc]

So when the actuator opens, it closes the open circuit back to the tank and creates direct pressure from the pump to the cylinder, until the relief valve opens? (in simple terms)

 

[TheOldHokie]

So when the actuator opens, it closes the open circuit back to the tank and creates direct pressure from the pump to the cylinder, until the relief valve opens? (in simple terms)

Precisely. Of course the relief only opens if the operator holds the control valve open at end of stroke or the load is too great and stalls the cylinder.

Dan

 

[TheOldHokie]

So when the actuator opens, it closes the open circuit back to the tank and creates direct pressure from the pump to the cylinder, until the relief valve opens? (in simple terms)

I will also.point out that when you put a pressure gauge on the end of the imlet supply hose for the loader you are totally blocking the neutral flow path to tank.

The gauge will show you the maximum pressure the pump can produce limited only by the pressure setting of the relief valve.

Dan

 

[MartinmMc]

Is it possible a relief valve is stuck open, is there more than one?

 

[TheOldHokie]

Is it possible a relief valve is stuck open, is there more than one?

Its possible.The main relief valve is in the outlet block with the selector valve.

The pressure test of the loader supply hose will tell us more. If pressure is good then the pump and relief are working. If pressure is low one or both of the two is misbehaving.

While you are waiting for your gauge you can verify you are getting flow. Disconnect the pump supply hose at the loader vakve, stick the end of the hose in a bucket and start the tractor. You should get a good solid stream of oil. Dont run the engine more than 10-15 seconds or you will pump the tractor dry.

Dan

 

[MartinmMc]

Hi Everyone,
It's been a while, but I have been busy, but parts can take a while to arrive.

Anyway, this the situation at the moment, I rechecked the the pump & re-assembled it correctly, fixed the broken casting (brazed the crack & machined it back) no leaks.
Put everything back together & got hydraulic pressure back, however after about an hour of use, lost oil pressure again , so decided to get a new pump (hence the wait).
Re-fitted the new pump, got pressure, but only lasted 5 mins, that's where I'm at.........

 

[TheOldHokie]

Hi Everyone,
It's been a while, but I have been busy, but parts can take a while to arrive.

Anyway, this the situation at the moment, I rechecked the the pump & re-assembled it correctly, fixed the broken casting (brazed the crack & machined it back) no leaks.
Put everything back together & got hydraulic pressure back, however after about an hour of use, lost oil pressure again , so decided to get a new pump (hence the wait).
Re-fitted the new pump, got pressure, but only lasted 5 mins, that's where I'm at.........

Hi Everyone,
It's been a while, but I have been busy, but parts can take a while to arrive.

Anyway, this the situation at the moment, I rechecked the the pump & re-assembled it correctly, fixed the broken casting (brazed the crack & machined it back) no leaks.
Put everything back together & got hydraulic pressure back, however after about an hour of use, lost oil pressure again , so decided to get a new pump (hence the wait).
Re-fitted the new pump, got pressure, but only lasted 5 mins, that's where I'm at.........

How are you measuring pressure?

Dan

 

[MartinmMc]

I got this made up, i connected it directly from the pump outlet and straight into the the tank, to bypass any restrictions, I got zero pressure, so I replaced the pump.
The new pump created pressure, but didn't check what pressure, then after 5mins lost pressure.

 

[TheOldHokie]

I got this made up, i connected it directly from the pump outlet and straight into the the tank, to bypass any restrictions, I got zero pressure, so I replaced the pump.
The new pump created pressure, but didn't check what pressure, then after 5mins lost pressure.

How can you connect that straight to pump?

Dan

 

[MartinmMc]

How can you connect that straight to pump?

Dan

With an adapter, didn't show that

 

[TheOldHokie]

With an adapter, didn't show that

OK. When you are getting no pressure are you getting flow?

Dan

 

[MartinmMc]

OK. When you are getting no pressure are you getting flow?

Dan

Yes, quite good

 

[TheOldHokie]

Yes, quite good

How do I you explain flow but no pressure?

Dan

 

[MartinmMc]

How do I you explain flow but no pressure?

Dan

That's why I'm asking you tbh.
I'm looking at the relief valve at the moment, it's the B type.
The valve head has has ridge on it, I don't know if that's significant?
I'm also looking at distribution block for clues

 

[TheOldHokie]

That's why I'm asking you tbh.
I'm looking at the relief valve at the moment, it's the B type.
The valve head has has ridge on it, I don't know if that's significant?
I'm also looking at distribution block for clues

The relief valve is not in your test setup. Perhaps you should provide more details on how you conduct a pump pressure test using the test rig you pictured

Dan