440 hydraulics

GaCatskinner · Post by **GaCatskinner** » Mon Oct 12, 2015 6:54 pm

Mine has the hydraulic 6 way blade. Every other dozer I've ever run could lift the front of the machine up with down pressure from the blade. Is this the case with the 440? I think one of my lift cylinders is bypassing but I didn't want to tear into them if the machine wasn't capable of lifting itself up.

gregjo1948 · Post by **gregjo1948** » Mon Oct 12, 2015 7:07 pm

It should easily lift it's nose.May have an issue in the control valve. gregjo1948

GaCatskinner · Post by **GaCatskinner** » Mon Oct 12, 2015 7:57 pm

That's what I thought. I'm trying to decide which to tear into first. I've rebuilt tons of cylinders through the years but I don't think I've ever been in a valve. The blade lifts fine but leaks down very slowly when you let off the valve. It lowers fine but when it gets to the ground it starts bypassing instead of giving down pressure.

gregjo1948 · Post by **gregjo1948** » Tue Oct 13, 2015 4:17 am

Sounds like no fluid or not enough being delivered to the lift/down pressure cylinders. I'd check the valve body for the problem. Check to see if you have good pressure on the other cylinders in both directions before tearing it apart.. gregjo1948

whiteclipse16 · Post by **whiteclipse16** » Tue Oct 13, 2015 5:27 am

You should check the relief valve setting/spring. The spring may be broke or backed out so far that it kicks into relief (bypass) too easily.

GaCatskinner · Post by **GaCatskinner** » Tue Oct 13, 2015 6:13 am

Is the relief valve built into the pump?

pop pop · Post by **pop pop** » Tue Oct 13, 2015 6:28 am

sounds like your valve body is the culprit.
relief valve is on the valvebody.

Stan Disbrow · Post by **Stan Disbrow** » Tue Oct 13, 2015 6:38 am

Hi,

The valve makes a buzzing sound when it opens.

Stan

GaCatskinner · Post by **GaCatskinner** » Tue Oct 13, 2015 9:52 am

Okay the 2 problems were the detent between down pressure and float is wore out or it just doesn't have one and there is a fine line between neutral, down and float. Air in the cylinder was another problem. I got it to raise the front end up after I figured out where the right spot to hold the valve was. One thing else though is that you have to find the right spot on the valve and hold it there for a few seconds for it to start lifting.

gregjo1948 · Post by **gregjo1948** » Tue Oct 13, 2015 10:29 am

Sounds like you were floating, which is a nice option but not when you're trying to dig in. gregjo1948

whiteclipse16 · Post by **whiteclipse16** » Wed Oct 14, 2015 6:21 am

Seems like something is wore or bad in your spool, causing you to have to have it in the "sweet spot" so it will raise. I could be wrong though.
I'm still trying to figure out why mine will raise the front end and hold it up, however when the blade is up in the air it can't hold itself up and will drift down.

Stan Disbrow · Post by **Stan Disbrow** » Wed Oct 14, 2015 7:14 am

Hi,

Mine drifts down because the rod seals drip.

Not bad enough for me to bother replacing them yet. Maybe when it hits 60 years old (she is a 58 )....

Besides, what does one do with the used Hygard drained out of a hydrostat?
Yep. Put it into something drippy! Self-changing oil. It isn't a bug. It's a Feature!!

Stan

Edit: Hmmm. (58 ) with the right paren against the 8 turns into (58)

whiteclipse16 · Post by **whiteclipse16** » Wed Oct 14, 2015 10:15 am

Maybe that's why mine drifts down also then. My rod seals leak. One is pretty bad. I should take it off over winter. I hate the thought of hydro oil everywhere. I should've put quick connects on all the hoses like I initially wanted, then it'd be a breeze to take a cylinder/ the whole blade off.

notmeu · Post by **notmeu** » Wed Oct 14, 2015 3:15 pm

whiteclipse16 wrote:Maybe that's why mine drifts down also then. My rod seals leak. One is pretty bad. I should take it off over winter. I hate the thought of hydro oil everywhere. I should've put quick connects on all the hoses like I initially wanted, then it'd be a breeze to take a cylinder/ the whole blade off.

If you do put on quick connect fittings just watch what size you put on. They are rated by gpm of flow, which is pretty low to begin with on these old girls... it could slow down you cylinder movements a little bit.

Post by **Lavoy** » Wed Oct 14, 2015 5:17 pm

In the last 20 plus years, I have only had one crawler blade drift due to the valve, and I had just rebuilt the valve incorrectly. ALL others were bad cups in the cylinders. Not that it can't be, but I have never found that to be the case.
Lavoy

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440 hydraulics

440 hydraulics

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