Farm Equipment - Allis C Hydraulic plow lift

Allis C Hydraulic plow lift

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Topic: Allis C Hydraulic plow lift

Posted By: Burlington Bob
Subject: Allis C Hydraulic plow lift
Date Posted: 14 Oct 2010 at 1:49pm

I have an allis C with a one bottom lift plow I just purchased with a hydraulic lift cylinder. Plow lifts only a few inches and not all the way up. I checked the fluid level, put new seals on ram and new shaft seal on pump. Tried to bleed air out by loosening large top nut on ram, don't get any fluid or air to come out. Anyone have any ideas of what I might try next, any help appreciated.

Replies:

Posted By: morton(pa)
Date Posted: 14 Oct 2010 at 2:21pm

I'm not trying to bash you or question your intelligence or anything like that, but I'm wondering where you checked the fluid level at. The hydraulic system takes it's fluid from the tranny case. Also, the PTO must be engaged for the hydraulic pump to work.

Posted By: Burlington Bob
Date Posted: 14 Oct 2010 at 2:48pm

Yeah, the obvious stuff has been checked, as you have metioned. I am somewhat mechanicallly inclined having taught automotive technicians for the past 30 plus years. I have read the allis chalmers service manual and believe everything is connected correctly, the pump is engaged with the pto and the ram does move about 4 inches, but will not continue to lift the plow. Thanks for the obvious comments.

Posted By: Bryan Smith (SC)
Date Posted: 14 Oct 2010 at 3:20pm

The other obvious points -

(1) The hydraulic pump is a two-plunger affair that has arms riding on lobes on the pto shaft. Either the shaft lobes or the arms could be worn, preventing higher pressure.

(2) Is the hydraulic cylinder original? A new cylinder may have a higher oil capacity, which would exhaust the oil level before it is raised.

(3) Have you checked the pressure relief valve(s) on the pump? As I recall there are some spring/check valve ball assemblies that hold pressure for you. If these have trash in them or are worn or mis-aligned, you'll have problems. My B has that (haven't been able to get the two bottom ones out yet), which means for me it raises fine, but won't hold the implement up at all. It's either pumping and up or not pumping and down.

(4) Be sure to check your hydraulic hoses if they are aged. Being an instructor you'll probably have run into this - we had a rubber brake line on a 1952 Dodge truck. Brakes worked fine, but wouldn't relase on one wheel. Turned out the hose allowed flow one way, but would not the other (I guess it was inner lining coming off and plugging the back flow). You couldn't even blow through it in one direction. Replacing the hose fixed it, of course.

I hope you find one of those useful.

Bryan

Posted By: Rick of HopeIN
Date Posted: 14 Oct 2010 at 5:00pm

seems like a check ball in the pump may be bad. But also may try removing the plow lift links and see if the rockshaft and cyllinder moves freely on it's own. You can even move it by hand on mine. That would check and make sure the cylinder or rockshaft is not binding.
You have to let the air out of the cylinder line when you first hook it up if I remember right, mine has a leaky gland seal so that pretty much takes care of itself over time.

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1951 B, 1937 WC, 1957 D14, -- Thanks and God Bless

Posted By: CTuckerNWIL
Date Posted: 14 Oct 2010 at 6:07pm

Maybe you could disconnect the cylinder and try to extend it with a little armstrong resistance just to see if you are getting enough oil to it to make it work. If it extends that way, I would guess you need to look at the relief ball.
When I rebuilt the pump for the "Build a B" I had a hard time getting the relief valve set up high enough. I had pressure but not up to specs. I used a porta power pump and gauge to check the relief setting on the bench. I don't remember the exact pressure but I think you need at least 2800-3000 psi.
Do you have an original B-C cylinder? Like said, if you have an after market cylinder you might run out of oil in the system before the cylinder is extended.
I believe the IT manual mentions flushing the system with kerosene. There are several spring loaded balls in the pump that need to seat good and if the tractor sat for a time with contaminates in the system it might need new check balls to work properly. Any little piece of dirt or rust on a ball or seat will let these check valves leak. Charlie

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http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com
Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF

Posted By: wkpoor
Date Posted: 14 Oct 2010 at 7:07pm

Very first thing I would do is plumb a gauge in place of the cylinder to see if the system will make pressure. Air in the cylinder will not stop the extend as it would be forced out by the fluid or just compress to the same pressure as the system. My bet is with what Tucker said " Your loosing pressure through the relief valve ".

Posted By: Burlington Bob
Date Posted: 15 Oct 2010 at 3:12pm

Thanks for all your thoughts and ideas, I am going to check the relief valve next. The tractor is up north and I won't be going that way for a week or two. Thanks again