Can someone please post '68 3020 trans pump GPM?

Tx Jim

Well-known Member
I'm attempting to help someone on another forum. Can someone please post trans put GPM. They seem to think it's 11-14 GPM while I remember something closer to 5 GPM. If someone could scan & post the spec's from a JD service manual would help.
Thanks for any help,Jim
 
From my JD spec book for a late 3020 is 8gpm for a syncro and 9.5 for a powershift both at 1900 rpm.
 
That makes me think that regardless of what the book says, the transmission pump must be capable of providing full hydraulic flow or the front pump will cavitate.

Tractor data says 14 GPM.
 
Trans pump flow is less than main pump flow. Return oil from high pressure functions goes to the filter and then to the main pump bypassing the trans pump. The main pump can circulate full flow without much input from the trans pump as long as there are no internal leaks in the system. There is also a small reservoir built into the oil cooler on early models and a separate reservoir on later models to supply oil to the main pump when the clutch is depressed or a one way cylinder is being used.
 
Thanks for that information.

So does the transmission pump only take care of initial charge and leakage?
 
Transmission lube and oil cooler flow also. On newer tractors with hi-lo and perma-clutch, it also provides clutch oil pressure. Power shift tractors use a different trans pump but same functions including power shift operating pressure. Power shift pump runs all the time.
 

The numbers listed are transmission pump gross flow . Net flow available to the front pump is less.
In any case where hydraulic demand is more than raising or lower a cultivator at the ends of a field . The return oil needs to be returned via that rockshaft drain line or through a ported filter cover .
Under high volume oil use when oil cooling is required. There will be little to no flow through the front cooler if there is high demand from the front pump.
 
(quoted from post at 08:15:42 04/21/16)
The numbers listed are transmission pump gross flow . Net flow available to the front pump is less.

May I ask where trans pump flow ends up on a Syncro-range trans if not at frt hyd pump except the small amount that is utilized to lube the trans?
 
Jim: hear are some pages from 3020 SM. If you might happen to need for future reference..
a224439.jpg

a224441.jpg

a224442.jpg
 
Isn't it amazing how far the opinions of "experts" can vary from the info in the factory service manual!

The DEERE closed center hydraulic system sure has a lot of quirks that are not obvious to those not familiar with it!
 
(quoted from post at 14:57:07 04/22/16) Isn't it amazing how far the opinions of "experts" can vary from the info in the factory service manual!

The DEERE closed center hydraulic system sure has a lot of quirks that are not obvious to those not familiar with it!

According to the gospel of Deere CTM-7, page 01-8 .
The 3020's were built with the 2000 series front pump. Either the 40cm3/2.4 cu" rated at 23gpm at 2500rpm. Or the 50cm3/3 cu" rated at 30gpm.
Much better than the 2510 stable mate with a paltry 6gpm.
 
It looks like the manual says 6gpm @ 1900 rpm? I'm having issues w my '68 syncro and have performed a flow test of the trans pump by removing the external line and letting it flow into a bucket. I only got 2.25 gal, but I was @ 700rpm. do I need to redo the test @ 1900?
I'm waiting on my service manual and a gauge to check pressure at the remote, then ill prob start a new thread.
thanks
 

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