4020, 4320 or 4520/620 HFWA question

tlock0331 · Jul 22, 2018

I have been reading through the parts books about the hydraulic front wheel assist on the 4020, 4320 and 4520/4620.

On the 4020, i thought i saw a sticker that was on the steering console close to a 3 position toggle switch and it seemed like it was either in a low pressure forward, high pressure forward or off position, i assume it was tied to some sort of solenoid configuration. however i cant see where the hydraulic lines for the front axle are tied too. and i cant see that it would work in a reverse situation. Is that in fact the case, that the 4020 did not have power assist in reverse?

I saw that the 4020 and 4320 shared a lot of parts and the 4520/4620 did as well, but the two groups did not share much component wise.

So i guess some my questions are:

Where does the pressure for this system come from?

is there a difference in the system if it is a powershift tractor verses a syncro-range?

do either of the systems work in reverse?

how do they time the front wheels with the rear wheels?

buickanddeere · Jul 22, 2018

(quoted from post at 11:05:57 07/22/18) I have been reading through the parts books about the hydraulic front wheel assist on the 4020, 4320 and 4520/4620.

On the 4020, i thought i saw a sticker that was on the steering console close to a 3 position toggle switch and it seemed like it was either in a low pressure forward, high pressure forward or off position, i assume it was tied to some sort of solenoid configuration. however i cant see where the hydraulic lines for the front axle are tied too. and i cant see that it would work in a reverse situation. Is that in fact the case, that the 4020 did not have power assist in reverse?

I saw that the 4020 and 4320 shared a lot of parts and the 4520/4620 did as well, but the two groups did not share much component wise.

So i guess some my questions are:

Where does the pressure for this system come from?

is there a difference in the system if it is a powershift tractor verses a syncro-range?

do either of the systems work in reverse?

how do they time the front wheels with the rear wheels?

Oil was supplied from an upsized front hydraulic pump. Motors in series were high speed and low torque. Hydraulic motors in parallelwere low speed high torque .

tlock0331 · Jul 22, 2018

So HFWA tractors of that era had a larger hydraulic pump, makes sense, but i can not find the motor configuration your talking about in the parts books, whether it be a 4020,4320,4520, or 4620.

Do you have any parts list information i can look at?

Does that system work in reverse?

D- · Jul 22, 2018

Switching for synchros was mechanical exposed to dirt and moisture while power shift switches were attached to shift valve housing (more trouble free). They operated valves under the front of the tractor.

larryanderson · Jul 22, 2018

The ones I have had did assist in reverse.They were not the best but do have about $3/4K value on a 20 series for collector purposes.The ones on a combine or chopper equipted with Hydro had much better oil flow and actually worked much better. The MFWD was much improved

buickanddeere · Jul 22, 2018

(quoted from post at 12:12:59 07/22/18) So HFWA tractors of that era had a larger hydraulic pump, makes sense, but i can not find the motor configuration your talking about in the parts books, whether it be a 4020,4320,4520, or 4620.

Do you have any parts list information i can look at?

Does that system work in reverse?

Free online JD parts book.

tlock0331 · Jul 22, 2018

Okay, so...

B&D said: Oil was supplied from an up sized front hydraulic pump. Motors in series were high speed and low torque. Hydraulic motors in parallel were low speed high torque

D- said: Switching for synchros was mechanical exposed to dirt and moisture while power shift switches were attached to shift valve housing (more trouble free). They operated valves under the front of the tractor.

Larry said they did work in reverse as well.

So, based on that, did both transmission types have the same motor set ups like B&D said and the activating them was different between the two?

I have still been looking in the online parts books at deere website and i can NOT find those motors, how they are plumbed in, where they are etc etc etc....

I get it if you were coming off of a hydrostat to drive the rear wheel assist, but i'd really like to know more about how this era of syncrorange tractors worked.

is there a detailed write up in a green magazine or t/c club issue? haha

tlock0331 · Jul 22, 2018

and somehow i missed looking for "POWER" under the alphabetical search...ugh....i never have used the alphabetical search, i think maybe thats the way to go.

Any other information on the HFWA that anybody has i am still all ears, or eyes as it were....

Thanks to everybody who replied.

Tx Jim · Jul 23, 2018

Here's a parts photo of an improvement kit for HFWA control valve

4020, 4320 or 4520/620 HFWA question

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