What am I missing ? Hydraulics Bobbing

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Livewire84
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What am I missing ? Hydraulics Bobbing

Post by Livewire84 »

I have a 62 super major. The lift top has a block off plate on top of the lift top, where alot of others seem to have things like flow control, tipping pipe, etc. Mine doesn't have any of that. It is only the lift top, with the check valve in the front, and the pressure relief valve. Other than that is has the up and down for quadrant control, and it does have the draft control lever.
I have had my pump overhauled at a machine shop.
I have totally gone through the entire lift top, and put new orings on everything. I even put the correct Ford only oring on the unload valve. New oring on the lift cylinder piston too.
I have put a new ball bearing in the check valve.
I did notice that the sides of the check valve ( non return valve ) are freshly polished looking,and I am not sure why.
I am not sure if pressure going past it, is making it look clean and almost like it has been sanded, or if it is somehow bottoming out against the valve seat.
I am not real sure on how that particular part of supposed to operate, compared to the spring and ball moving inside of it.
Lightly polished everything with a finishing wax, to get swirl marks out of a paint job, so it is very non abrasive, trying to get the surfaces to re mate themselves together in the check valve and pressure relief valve.
My tractor will lift a 2000 pound rotary mower at idle.
The pressure gauge shows a steady rise in pressure if I raise the mower slowly, and will build around 1500 psi, but seems that is all that's needed to lift it slowly.
If I lift it quickly, from the ground, it will go up to 2000 psi and then kick out.
The problem is that the hydraulics are constantly correcting themselves with the heavy mower on there.
When I say constantly, I mean like every 3-4 seconds.
It shakes the tractor at a idle, and reving the engine past idle does nothing.
I would like to be able to use the tractor without feeling like I am riding a earthquake.
The only thing I have not replaced is the safety valve that is under the lift top, behind the ram cylinder.
I have not replaced the pressure relief valve, or the check valve ( non return valve) either.
Lastly, if I raise the mower up about 3/4 of the way, and turn the tractor off, it will bleed down rather quickly, so I apparently still have a pretty large loss of pressure or ability to hold pressure somewhere.
What am I missing, or need to replace to stop the pressure loss ?
Do I need a new ram cylinder and piston, or could it be a valve mentioned that i haven't replaced yet, not holding pressure with the engine off ?
I am open to any auggestions !
Thank you.

mathias1
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Re: What am I missing ? Hydraulics Bobbing

Post by mathias1 »

How fast does it drop when you stop the pto?
Fordson Super Major New Performance
County Super 4 built on the Fordson Super Major
Selene built on the Fordson Super Major New Performance with Silvant winch

Livewire84
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Re: What am I missing ? Hydraulics Bobbing

Post by Livewire84 »

With the 2000 pound brush mower, it will drop about 4 inches in maybe 10 seconds.
Basically from a high cutting heighth, back to the ground, in 10 seconds or less.
The blades edges are about 3 inches high, inside the deck, so I carry it about 3-4 inches high, and then re cut it lower.

SvendH
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Re: What am I missing ? Hydraulics Bobbing

Post by SvendH »

Sounds like the blanking plug that covers the unloading valve is loose,
Easily fixed with locktite :D

Livewire84
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Re: What am I missing ? Hydraulics Bobbing

Post by Livewire84 »

Are you saying I should put locktite on the plug that has to be pulled out, to be able to get the unload valve out ?
That thing was a beast to get pulled out, and i had to tap it back in, very lightly with a small chissel hammer.
It seemed tight, but I will for sure try the locktite on the plug.
Any particular color or type of locktite you would suggest ?
Thank you very much !

mathias1
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Re: What am I missing ? Hydraulics Bobbing

Post by mathias1 »

Livewire84 wrote:
Sat Jun 06, 2020 10:56 am
Are you saying I should put locktite on the plug that has to be pulled out, to be able to get the unload valve out ?
That thing was a beast to get pulled out, and i had to tap it back in, very lightly with a small chissel hammer.
It seemed tight, but I will for sure try the locktite on the plug.
Any particular color or type of locktite you would suggest ?
Thank you very much !
Adrian had the same problem a while back, he used loctite 603 for it.
It's also on my working list for my NP, but since it has a midmounted mower, it isn't a big problem..
Fordson Super Major New Performance
County Super 4 built on the Fordson Super Major
Selene built on the Fordson Super Major New Performance with Silvant winch

SvendH
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Re: What am I missing ? Hydraulics Bobbing

Post by SvendH »

I used Locktite 518,worked perfekly.
I discovered the leaking plug by applying compressed air to the unit laying on my work-bench.The plug frothed around the edge!

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