2018 Toolcat 5600 2100 hours charge pressure dropping when warming up !

[RichardV-Quebec]

When cold at 2,000+rpm, charge pressure port show 360+ but it drops rapidly after a couple of mins. It could not be air in the system ?

 

[oldnslo]

When cold at 2,000+rpm, charge pressure port show 360+ but it drops rapidly after a couple of mins. It could not be air in the system ?

Air in a static system will show same pressure and have little to no effect on the charge pressure.

How difficult is it to access the pump? To isolate a leak in the charge circuit I would disconnect the line from the “G” port on the pump feeding the pilot controls. You will not be able to release the brakes but be curious to see if charge pressure still drops since it would now be isolated to HST circuit.

When charge pressure drops the pump destrokes from loss of pilot pressure which is another reason machine slows or stops.

 

[oldnslo]

Try doing a search for RE 93430. That is the data sheet number for a Rexroth A30 pump. Does your pump look like the diagram in the data sheet?

 

[RichardV-Quebec]

Air in a static system will show same pressure and have little to no effect on the charge pressure.

How difficult is it to access the pump? To isolate a leak in the charge circuit I would disconnect the line from the “G” port on the pump feeding the pilot controls. You will not be able to release the brakes but be curious to see if charge pressure still drops since it would now be isolated to HST circuit.

When charge pressure drops the pump destrokes from loss of pilot pressure which is another reason machine slows or stops.

That is a great idea ! The pilot manifold is in front of the rear right wheel and there is a procedure to remove it in the TC service manual. But it feeds the 'servo enable SD' which I think is used to move the swash plate (I am not sure about that). But iT sure beats trying to cap all the break lines !

 

[RichardV-Quebec]

Try doing a search for RE 93430. That is the data sheet number for a Rexroth A30 pump. Does your pump look like the diagram in the data sheet?

It does look like it. 3 pictures I took and one of the picture from the service manual.

 

[oldnslo]

It does look like it. 3 pictures I took and one of the picture from the service manual.

The name plate is a Rexroth product and description fits the A30. Pump was manufactured 36th week of 2017.

 

[oldnslo]

That is a great idea ! The pilot manifold is in front of the rear right wheel and there is a procedure to remove it in the TC service manual. But it feeds the 'servo enable SD' which I think is used to move the swash plate (I am not sure about that). But iT sure beats trying to cap all the break lines !

The enable valve is supplied by the Ps port and will operate with the “G” port capped off. Ps is the pilot pressure to the pump control. Unloading that line prevents pump from being able to come on stroke. Don’t know exact numbers but suspect need around 100 PSI for pump to start to stroke and 250 - 300 PSI for full displacement at full drive pressure.

 

[RichardV-Quebec]

The enable valve is supplied by the Ps port and will operate with the “G” port capped off. Ps is the pilot pressure to the pump control. Unloading that line prevents pump from being able to come on stroke. Don’t know exact numbers but suspect need around 100 PSI for pump to start to stroke and 250 - 300 PSI for full displacement at full drive pressure.

So capping the G line going to P1 on the pilot manifold and checking pressure on the front looped work lines is what I should do ?

 

[oldnslo]

The looped lines will show charge pressure in neutral and should have minimal change if trying to drive

If trying to drive rear wheel motor will take some charge flow for flushing valve I the motor but should have minimal change in charge pressure.

Does charge pressure drop just sitting stationary for a few minutes? If yes does motor case get warm or hot vs pump? I would expect pump to get warm sitting still.

 

[RichardV-Quebec]

The looped lines will show charge pressure in neutral and should have minimal change if trying to drive

If trying to drive rear wheel motor will take some charge flow for flushing valve I the motor but should have minimal change in charge pressure.

Does charge pressure drop just sitting stationary for a few minutes? If yes does motor case get warm or hot vs pump? I would expect pump to get warm sitting still.

I will try this in the week-end. The charge pressure drops while sitting still in low idle. I never checked the temperature of the motor case nor the pump but engine temp is low.