450C HLR diag question

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psprague
440 crawler
440 crawler
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Joined: Fri Apr 29, 2016 11:47 pm
Location: Olympic Peninsula

450C HLR diag question

Post by psprague » Wed Apr 18, 2018 8:07 pm

Hi All,

I have a 450C with a quirky reverser problem. High and reverse work peachy, but when I engage low directly from neutral, it does not engage. If I shift to high or reverse, let it engage then shift to low, it works. After shifting it does not seem to have any issues with slippage in gear.

I do have a manual and understand the soft/rapid shift valving but I haven't installed a pressure gauge on the test port yet. The tranny oil is clean and I've installed a new filter but I haven't pulled and cleaned the pickup screen.

Edit: I've gone thru linage adjustment too, lifting up on the shift shaft doesn't help.

Any quick insights?

TIA!

Paul

My 12-year-old learning to love deeres.

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JD 450c forestry, JD 440A cable skidder

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psprague
440 crawler
440 crawler
Posts: 138
Joined: Fri Apr 29, 2016 11:47 pm
Location: Olympic Peninsula

Re: 450C HLR diag question

Post by psprague » Wed May 30, 2018 4:33 pm

It hasn't gotten any better, if anyone is wondering. And I know you are. Or were.

It's an odd little thing. It intermittently fails to engage low and mostly when shifting directly from neutral. I dug out an alder stump for a bit of exercise and it didn't change for better or worse. If it fails when shifted into low, shifting back to hi, letting it engage, then shifting to low makes it work just fine.
JD 450c forestry, JD 440A cable skidder

oljoe
430 crawler
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Location: Windsor, Missouri

Re: 450C HLR diag question

Post by oljoe » Thu May 31, 2018 9:46 am

Hi Paul,
Thanks for all your help with my problem.

It sounds like there is something floating around in the low clutch circuit.
Maybe it has an acorn in there. :shock:


When it’s in neutral there is no back flow of oil from the clutch pistons returning. When the hi or reverse clutch is applied the clutch spring is compressed. When released the spring returns the piston and oil is discharged from either the top or bottom of the shift valve.
Could that flow move some debris around and open the low oil passage?

The other thing I was wondering about is the pilot valve orifice and it’s affect on the bypass valve.

Joe
Straight 450 loader

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psprague
440 crawler
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Posts: 138
Joined: Fri Apr 29, 2016 11:47 pm
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Re: 450C HLR diag question

Post by psprague » Fri Jun 01, 2018 8:08 am

Hi Joe,

Thanks for the insight, I've been here ruminating about what you said.

One thing I just noticed about the manual and maybe it's me being not awake yet is: there is no description of valve positioning or oil flow when the HLR is in neutral.

Its not dumping out the pilot valve is it?

Paul
JD 450c forestry, JD 440A cable skidder

oljoe
430 crawler
430 crawler
Posts: 91
Joined: Mon Feb 13, 2012 10:53 am
Location: Windsor, Missouri

Re: 450C HLR diag question

Post by oljoe » Fri Jun 01, 2018 8:35 am

In my manual it says on page 130-5-10:

"NEUTRAL
The neutral cycle is the same as “Step 1” on page 130-5-6. Oil flow is shown in Fig. 130-5-6. The piolot valve dumps oul, allowing the bypass valve to close. This seals off the full flow passage to the clutches. At the same time, the shift valve dumps oil from the engaged clutch and the pressure slot in the shift valve is closed off."
Straight 450 loader

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psprague
440 crawler
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Posts: 138
Joined: Fri Apr 29, 2016 11:47 pm
Location: Olympic Peninsula

Re: 450C HLR diag question

Post by psprague » Fri Jun 01, 2018 11:56 am

Hi Joe,

Thanks, more coffee now. I see that now in describing a soft shift, passing thru neutral with R->H and H->R.

My question, a bit more refined by caffeine, is with the valve positioning of HLR in the N detent position. From what I can see, the shift valve is in transit between R<->H and the pilot valve is open.

I think your assumption about the pilot orifice or bypass valve is right on.

-Paul
JD 450c forestry, JD 440A cable skidder

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