1980 JD 350C wont move

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jbernitt
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1980 JD 350C wont move

Post by jbernitt » Mon Apr 16, 2018 10:15 am

My son in-law has 1980 350 c crawler that wont move no forward or reverse. It was working fine and He was grading some gravel and heard a load pop and the loader stopped moving in it tracks. He told me he had been adding reverser fluid about every 10 to 12 hrs. We disassembled tractor and removed the reverser. The counter shaft was twisted in 2 at the front bearing. I assumed this was all that was wrong. We reassemble the machine and it still wont move. The reverser has about 30 psi of pressure. Questions I have.
It need 100 to 120 psi to engage the clutches and move ?
Does the steering clutches also need 100 to 120 psi for the tractor to move.
Im trying to figure out where the pressure drop is
Or if something is broken in the final drive.
When the reverser is out of the tractor and the transmission is in gear should I be able to turn the imput shaft of the transmission and the tracks not move?
I would really love to speak on the phone with someone who has knowledge of the power flow.
Any help is appreciated

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Stan Disbrow
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Re: 1980 JD 350C wont move

Post by Stan Disbrow » Mon Apr 16, 2018 12:59 pm

Hi,

Power flow is thru the Spider shaft (input) of the reverser and straight thru the center when the Forward clutch is made up by hydraulic pressure. The counter shaft is always rotating, but does nothing power flow wise until the Forward clutch is disengaged and the Reverse clutch is made up (again by hydraulic pressure). In Reverse, the straight thru shaft is the one idling.

The hydraulics to operate the reverser are internal via a small pump on the spyder shaft. You need the 120 PSI or neither clutch pack will make up. The clutch pedal operates a dump valve for the reverser hydraulic pressure. So, the reverser clutch packs act as the master engine clutch. There is Torsional Isolator at the flywheel to absorb torque load peaks.

The trans is a sliding gear one. If you have it in any gear, the input shaft won't move by hand. Sounds like you have a trans issue that busted more than the reverser. I bet some bearing bits jammed some teeth and then things got Fast 'n' Ugly... :(

The steering clutches are always made up until released by the steering levers. There is no differential, just a spool on the ring gear back there.

The most fun part of crawlers is they started with the trans and bolted everything else to it in both directions.....

Stan

Edit: I was thinking Dry steering clutches. They would be engaged always, running or not. This machine has Wet steering clutches which need hydraulic pressure from the reverser pump to engage. So, they would both be disengaged at this point and so the trans input shaft would turn. Still, the snapped reverser countershaft has me thinking something else may have happened inside the trans.
Last edited by Stan Disbrow on Tue Apr 17, 2018 6:02 am, edited 1 time in total.
There's No Such Thing As A Cheap Crawler!

Have: '58 JD 420c 5-roller w/62 inside manual blade
Have: '78 JD350C w/6310 outside manual blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Also Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

jbernitt
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Re: 1980 JD 350C wont move

Post by jbernitt » Mon Apr 16, 2018 1:55 pm

so my next step is to remove the transmission. Thanks for the good news :)

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shinnery
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Re: 1980 JD 350C wont move

Post by shinnery » Mon Apr 16, 2018 6:42 pm

I have a 440ICD, never around a 350. Is there any sort of a top cover or other plate you can remove to see in the transmission before taking the crawler all apart?
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pondhogvt
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Re: 1980 JD 350C wont move

Post by pondhogvt » Mon Apr 16, 2018 8:26 pm

Sorry for your dilemma,,, lets take this in steps.. your question on turning tranny input shaft with reverser out,, yes you can turn the input but dozer finals will not move as you have no hydraulic pressure to the steering clutches to engage them... highly unlikely you broke any final drive,,, because they would not both break at the same time.. your lack of pressure seems to be the problem but you could have broken the tranny input shaft all in the same event that the counter shaft and coupler popped... you can remove the top cover of the tranny and look for broken gears before all the work of removal... you can see almost all gears and shafts from top cover removal... and then you could also remove the rear cover to look for broken ring and pinion and or the ends of the shafts that you cannot see thru the top...

you will have to take the rod on outside of cover that both steering levers go thru off,,, there is a bolt under the left side that cannot be removed unless rod is out or pushed to the left to access the bolt.. and one under each steering cylinder rod.. they come out easily just cotter pins...

this will allow you to look for broken gears but does not have anything to do with lack of pressure in reverser... you said countershaft broke in half.. a jolt like that breaking can cause a torque reaction.. did the splines on reverser look good? the input splines that run thru the pump on the front cover??
they are much finer splines and or the splines on the pump?? you had to take this out to repair the counter shaft... look it over closely.. lets us know what you find.. good luck, Mark.
350 loader,350c dozer winch and arch,450c winch and arch,450e winch and arch,D37p komatsu lgp dozer,D85 Komatsu dozer,D8k Caterpillar.

pondhogvt
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Re: 1980 JD 350C wont move

Post by pondhogvt » Mon Apr 16, 2018 8:38 pm

Mark here again as I just remembered you said son in law was putting gallons of fluid in reverser.... where was it going?? it can only go a couple of places,,, out the front cover where there is a seal for the reverser input shaft-pump seal... out the back seal between the reverser and the tranny where the spline stripped.... was there oil in either the front around the flywheel.. or the back by tranny???... that many gallons it should be obvious..

if not what about a leaky oil line from reverser to oil cooler by radiator.. there is a rubber coupler up there that is very prone to leak..
.leak = low pressure... you never said if you fixed the leak when you fixed the countershaft,,, so better find the leak first.. Mark
350 loader,350c dozer winch and arch,450c winch and arch,450e winch and arch,D37p komatsu lgp dozer,D85 Komatsu dozer,D8k Caterpillar.

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Stan Disbrow
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Re: 1980 JD 350C wont move

Post by Stan Disbrow » Tue Apr 17, 2018 5:59 am

Hi,

I am sorry, I was thinking Dry steering clutches, not Wet.

Dry ones use a pressure plate to make up the clutch pack until the lever is pulled. Wet ones incorporate a valve which sends hydraulic pressure from the reverser pump to the clutch pack to make them up when the lever is forward. And, then the valve removes the pressure when the lever is pulled back to steer.

So, Mark is correct. With no hyd pressure the steering clutches are released and you can then move the trans input shaft.

It still bothers me that the reverser countershaft snapped. Makes me think something jammed up and gave it a heck of a shock.

Stan
There's No Such Thing As A Cheap Crawler!

Have: '58 JD 420c 5-roller w/62 inside manual blade
Have: '78 JD350C w/6310 outside manual blade
Useta Have: '68 JD350, '51 Terratrac GT-25
Also Have: 1950 M, 2005 x495, 2008 5103 (now known as 5045D)

jbernitt
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Re: 1980 JD 350C wont move

Post by jbernitt » Sun Apr 22, 2018 8:20 pm

Sorry for the long delay in getting back. thank you for the response's.
Here is the latest. I took the cover off of the rear differential and when turning the trans input shaft the pinion rotates so power is transferring that far.
Stan: you are correct: It still bothers me that the reverser countershaft snapped. Makes me think something jammed up and gave it a heck of a shock.
But the front bearing on the counter shaft was gaulded to the shaft. I'm sure it got hot and this is what made the shaft snap under load.

Marks comment: With no hydraulic pressure the steering clutches are released :
I have the reverse disassembled again.
I will check the input shaft tomorrow and report its condition.
The front pump look good no groves or scoring.
I air checked both pistons on the main shaft and they are holding air pressure. They engage the clutches.
Is there a way to check clearance of the clutch pack while assembled or do I just mic the plates?
I also fixed the reverser fluid leak at the radiator ( a lose hose clamp)
back to my problem.
Pressure loss.

I don't see anything inside the reverse that could be causing the pressure loss.
Could it possible be in the steering clutches. How could I check this with the unit disassembled?

What else do I need to check inside the reverser? Keep in mind this machine was working fine and He was grading some gravel and heard a load pop and the loader stopped moving in it tracks. He told me he had been adding reverser fluid about every 10 to 12 hrs. It has not moved since.

Can we post pictures to this board? I would like to upload picture of a part that came off the control Valve.

Thanks in advance for everyones help.

jbernitt
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Re: 1980 JD 350C wont move

Post by jbernitt » Mon Apr 23, 2018 2:11 pm

update on what I found today. I took apart valve body and I don't see any stuck valve or for that matter anything wrong with it. actually look remarkable good for as old as it is
the input splines that run thru the pump on the front cover are good so are the splines on the pump??
Last edited by jbernitt on Mon Apr 23, 2018 6:08 pm, edited 2 times in total.

dtoots1
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Re: 1980 JD 350C wont move

Post by dtoots1 » Mon Apr 23, 2018 4:27 pm

yes you can pst pics to this board....but..you must register with Lavoy either send email or pm with your choice of login and password so that he can validate your access.....once you have that done....you will need to log in to jdcrawler site and pull up the board index and at the bottom of the page you will see the Question and Answer forum....in that is "New Pic Server" heading....read all info...and NO you cannot upload pics directly from the phone to the board....go to your laptop or pc to upload pics....choose the album that conforms to your pictures....any problems advise and will help you thru it.

dtoots1

jbernitt
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Re: 1980 JD 350C wont move

Post by jbernitt » Sat Apr 28, 2018 7:30 pm

I am going to put new seals on the main shaft does anyone have the direction for getting the pistons off of the reverser main-shaft?

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