3020 Diesel - tank for front hydraulic pump?

[MNBobcat]

I have a mid 1960's JD 3020 diesel. I'm told there is an 11 GPM pump that pumps hydraulic fluid from the reservoir under the seat to a front pump that is supposed to be about a 19 GPM pump.

I'm running a post pounder on the tractor and I have to let the hydraulics catch up every so often otherwise I can tell the front pump is starving for fluid. What I would like to know is if the rear pump pumps the hydraulic fluid into a tank that feeds the front pump or if the rear pump pumps hydraulic fluid through a line directly to the front pump? The reason I'm asking is because if there is a tank that feeds the front pump then it may be possible to expand that tank to hold more fluid so that the front pump doesn't end up starving for fluid. If there is a front tank, where exactly is it located?

Thanks!

 

[DT86]

No second tank afaik.

When you run the driver are you at idle?

When I had a Deere and drove posts at idle the hydraulics would some times stutter when lifting the driver weight. Bumping the rpm up solved the problem.

 

[jenkinsph]

I would check those specs again, the transmission pump in the rear should have a higher flow at a lower pressure. The front high pressure hydraulic pump will have a lower flow rate and feeds the steering and brakes through a priority valve. The rear scv's have a 6 gpm flow rate according to tractordata, no where near the 19 gals per minute.

 

[Tx Jim]

I have no access to JD 3020 service manual but IIRC trans pump output is closer to 5 GPM than 11 GPM. Hyd oil reservoir is similar to parts key 4 in photo. If I was operating post pounder I'd suggest to return oil to fitting by hyd filter in 2nd photo that has hyd hose connected to it. Attaching to this fitting puts oil from post pounder into rockshaft return line leading back to frt hyd pump.

 

[jenkinsph]

Tx jim,
Does the front hydraulic pump draw directly from the hydraulic filter and sump? I stand corrected if I misspoke but thought the transmission pump supplies the oil to the front pump. I thought the transmission pump provides lubrication for the transmission and powershift if equipped, then the goes to the front pump.

Please straighten this out for me. TIA

 

[Tx Jim]

Tx jim,
Does the front hydraulic pump draw directly from the hydraulic filter and sump? I stand corrected if I misspoke but thought the transmission pump supplies the oil to the front pump. I thought the transmission pump provides lubrication for the transmission and powershift if equipped, then the goes to the front pump.

Please straighten this out for me. TIA

Maybe I mislead you? JD piston pump can't suck hyd oil. . Yes trans pump supplies oil to frt pump & lubes trans but routing return oil to line I suggested should help trans pump performance.

 

[jenkinsph]

Maybe I mislead you? JD piston pump can't suck hyd oil. . Yes trans pump supplies oil to frt pump & lubes trans but routing return oil to line I suggested should help trans pump performance.

So if the transmission pump charges the front pump then is the 5 gpm you spoke of in excess of the oil supplied to the front pump? If the hydraulic pump has a total flow of 14 gpm including steering, brakes, rockshaft and outlets that might explain the total flow of 19 gals/minute for the transmission pump.

 

[jd110]

The problem you are experiencing sounds as if the control valve on your post driver is set up for open center hydraulics. You need closed center. Most valves are convertible with a different plug installed to convert. The hydraulic system is able to function properly due to the return oil from scv's rockshaft, and steering is sent directly back to hydraulic pump in addition to the oil from transmission pump. I assume your post driver returns direct to sump, but the post driver cylinder is such a small diameter, that your tractor should have no problem keeping up with the flow if all systems are working normally and the valve is set up for closed center.

 

[Tx Jim]

jd110
Good thought about possibly OC valve on pounder.

 

[Tx Jim]

So if the transmission pump charges the front pump then is the 5 gpm you spoke of in excess of the oil supplied to the front pump? If the hydraulic pump has a total flow of 14 gpm including steering, brakes, rockshaft and outlets that might explain the total flow of 19 gals/minute for the transmission pump.

I don't have a 3020 tech manual to research but I think trans pump is closer to 5 GPM. I doubt total hyd output on 3020 is 19 GPM. Actually trans pump & frt pump output can't be added together on a CC hyd system as CC requires trans pump output to function properly. Tractordata shows 3020 @ 14 GPM total flow which I think is more realistic.