FMD Weak hydraulics?

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Matt85
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FMD Weak hydraulics?

Post by Matt85 »

Hi, my '57 Major always seemed to have weak hydraulics. It could only lift 600 lbs or so. Recently I got my 6ft brush mower back. The mower weighs about 1,100 lbs. 3pt won't lift it up more than a inch off the ground. So recently I resealed the ram, pump, and spool valve and put in all new oil in it. Also I made sure that the unloading valve was free. After all that It can't lift anymore then before. I been told that I might need to shim the unloading valve. And the pump should be putting out 2,000-2,200 psi. Is there a special washer/shim or can I use normal washers? Also is there anything else that would cause weak hydraulics?

Thanks,
Matt

henk
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Re: FMD Weak hydraulics?

Post by henk »

Matt,

In the Netherlands they use to put a coin in it as a shim.
Kind regards, Henk

Fordson New Major February 1957 Mark I

Matt85
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Re: FMD Weak hydraulics?

Post by Matt85 »

Well I was able to hook up a pressure gauge tonight. The pump is only putting out 500 psi. I put two quarters in as shims and the pressure raised to 550psi. Anybody have any ideas?

Emiel
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Re: FMD Weak hydraulics?

Post by Emiel »

Hi,

Usual suspects:
-clogged filter, drain oil, remove pto shaft and drop the pump to clean.
- blown 0-rings, remove lift cover and replace
-worn pump, replace with better one

Rgds

Emiel
Best regards

Emiel

N 1937, E27N 1948, 8N 1949, E27N 1950, E1A Diesel 1953, E1ADKN PP 1956, Dexta 1959, NH Clayson M103 1964

Matt85
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Re: FMD Weak hydraulics?

Post by Matt85 »

Well I just resealed the pump a second time. Still only 500 psi. I did notice if I rev it to max power I can lift my disc maybe 1/2 inch each pull of the lever and the gauge hits 1,000psi and goes right back to 0. Right now buying a better hydraulic pump is out of the question. Good Pumps go for $500-600 if you can find one.

henk
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Re: FMD Weak hydraulics?

Post by henk »

What part you mean with the spool valve?

Could still be a blown O-ring on the pipe between cover and pump.
Kind regards, Henk

Fordson New Major February 1957 Mark I

Matt85
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Re: FMD Weak hydraulics?

Post by Matt85 »

Henk, by spool valve I meant I resealed the control lever that raises the 3pt.

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Re: FMD Weak hydraulics?

Post by shepp »

Firstly if you put a lighter load on the linkage that it manages to lift, will it hold the load in the raised position with the control lever in the mid hold position? If so that would eliminate some potential causes of the fault. Check this and post the result on the forum.

Starting at the pump there is a vertical tube with an O ring at each end that takes oil under pressure from the pump into the lift cover casting. Check that the O rings are good and the pipe is not split. Check the lift cover casting in this area is not cracked. From the lift cover casting a horizontal tube with an O ring at each end takes oil under pressure into the control valve assembly, again check the O rings and that the tube is not split. Between the control valve assembly and the lift cylinder there is a larger O ring, check this is good. Check that the lift cylinder is not split.
Take off the control valve assembly from the front of the lift cover. In the bottom of the control valve assembly there is a spring loaded check valve and also the unloading valve seat. Unscrew the check valve cap and withdraw the valve and spring. Check the valve and it's seat are not damaged and that the spring is not broken. Clean and re-assemble.

Undo the cover plate over the unloading valve on top of the control valve body and look at the top of the adjuster. If this is circular with an O ring in a groove around the circumference you have a valve of the type that was fitted to the bulk of Majors. Remove the valve and spring and check both for damage. The unloading valve itself has a pointed tip to it that seats in the unloading valve seat. The unloading valve seat can be removed from under the control valve assembly and inspected. Check the condition of the unloading valve and it's seat and the spring. Re-assemble and shim to get the required pressure.

If, when you undo the unloading valve cover plate , you see a square headed adjuster, then you have the type of unloading valve that was fitted to late production Majors and early production Power Majors. This type of valve has a small spherical ball that forms the seal between the tip of the unloading valve and it's seat. Remove the valve and spring CAREFULLY AND CHECK THAT THIS BALL IS NOT MISSING! This could be a cause of low hydraulic pressure in the system. If all components are present after removing the unloading valve then remove the seat from below the housing and check for damage, then re-assemble the seat. Stick the ball to the unloading valve tip with grease and carefully re-assemble the valve and spring after checking that the spring is good, making sure the ball is not displaced. Shim to get the required pressure.

If all this leads to no improvement then you are back to the pump as the issue.
1946 E27N, 1952 Major Diesel, 1959 Power Major, 1962 Dexta, 1962 Super Dexta, 1963 Super Dexta NP, 1964 Super Major NP, 1965 Super Dexta 3000, 1966 Major 4000, 1967 3000 PF, 1994 5640,plus Basildon built NH.

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Re: FMD Weak hydraulics?

Post by henk »

You say that you have change the "spool valve". This valve needs a very small tollerance. It has to fit on a special way. They told me there were colours use to see what tollerance it had. It had to mach with the hole.
The procedure was to put special oil on the valve and in the hole and put the valve block vertical. The spool was dropped in the hole and the time was messured. To fast the valve was to small, to long the spool was to thick.

When there is to much play between the spool it will leak oil and the lift arms will drop slowly. I think that is what my tractor has. Could also be a groove in the hole that will leak oil.

Was this spoolvalve new or used? I have not found a suplier that sells new ones.
Kind regards, Henk

Fordson New Major February 1957 Mark I

Matt85
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Re: FMD Weak hydraulics?

Post by Matt85 »

Henk, I still have the original spool valve/control valve. When I said I resealed it I only did the check valve and unloading valve.

Shepp,

The 3pt with a blade on it will stay up for about three days before starting to lower. I checked both pipes and the lid for cracks. They all look fine. Also the O-rings on the pipes look good. The lift cylinder has a brand new seal and O-ring. I took the control valve off and the check valve spring and O-ring looks good. My unloading valve is the round style. I did notice on the actual unloading valve the tip is flat and not pointed.

This is driving me crazy. The only thing I did was change the seals in the pump and it got weaker.

https://youtu.be/dTCHQ0725oQ

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Re: FMD Weak hydraulics?

Post by shepp »

Right, if the hydraulics will stay up for 3 days with an implement on the linkage that eliminates everything except the pump, the unloading valve, and possibly the spool valve as being the cause of the reduced lift capacity - although I doubt very much that the spool valve is responsible.

Returning to the unloading valve, 3 versions of this valve were encountered with the Major and Power Major tractors. I have tried to upload a scan of the 3 types but the system does not seem to have a facility to do this from my computer.

a) The first type was fitted to the majority of Major tractors and was the type with a circular adjuster top with an O ring around the circumference. The valve body did not have any holes in it and the valve tip was conical and this conical section fitted into the valve seat and formed the seal.

b) The second type was fitted to very late production Major tractors and early production Power Major tractors. This type had a square adjuster top, the valve body had I think 2 holes in it around the circumference, the tip of the valve was more or less flat, and under the tip was a steel ball that formed the seal between the valve body and the valve seat.

c) The third type was fitted to later production Power Major tractors, and from the time it was introduced it was the only type available for service replacement situations - if a new unloading valve was needed to be fitted to a Major or Power Major then this was the type supplied. You had to change the complete assembly i.e. the valve and the valve seat from under the control pack.
This type had a circular top, underneath that was a shim pack and then a tubular stop that prevented the unloading valve body from rising too far against the spring pressure when it discharged. The valve body had I think 2 holes in it around the circumference, the tip of the valve was more or less flat, and again under the tip was a steel ball that formed the seal between the valve body and the valve seat.

You say that your unloading valve has a circular top but that the tip of the valve body is flat. If your valve has the tubular stop and the valve body with holes in it then the tractor has had a replacement unloading valve fitted at some point. Many tractors were upgraded with this latest improved unloading valve because it had a reduced tendency to discharge prematurely.

The important point is that the steel ball MUST be present for the valve body to form an effective seal against the valve seat. You need to check this and see if the ball in your valve is missing. If so this will be the cause of your problem, you will need to find a ball of the correct size ( by trial and error) and fit it. There are various suppliers of steel balls, some are on Ebay. When you have found a ball of the correct size then adjust your shim pack to give the correct blow-off pressure.

If there are no issues with the unloading valve then your lack of lift problem has got to be in the pump.

Good luck!
1946 E27N, 1952 Major Diesel, 1959 Power Major, 1962 Dexta, 1962 Super Dexta, 1963 Super Dexta NP, 1964 Super Major NP, 1965 Super Dexta 3000, 1966 Major 4000, 1967 3000 PF, 1994 5640,plus Basildon built NH.

Matt85
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Re: FMD Weak hydraulics?

Post by Matt85 »

Shepp, I have the unloading valve thats pictured all the way on the left in the picture. But on mine there's one single 1/16th? hole drilled at a angle down by the tip.

Image

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Re: FMD Weak hydraulics?

Post by shepp »

Hi

You have uploaded the picture that I was trying to post.

You say you have the valve type shown on the left of the picture, valve (a), which is the original type unloading valve fitted to the bulk of Major tractors. The small hole you refer to allows oil to flow through the passages in the control valve body to allow the check valve to close when the unloading valve opens. With this earlier system, as soon as the unloading valve opens the check valve closes to hold the lift cylinder and linkage in the raised position, if the lift lever is held in the raised position oil flow from the pump continues to hold the relief valve open and the pressure in the pump circuit drops to around 40 psi , but the lift cylinder circuit is isolated and the linkage is held raised. When the lift lever is returned to the neutral position the unloading valve closes. The later valves shown at (b) and (c) are used with a control valve body which is different to the earlier body - I made a slight mistake in my previous posting, the later valve (c) can only be used to service the valve (b) and not the earlier valve (a). Valve (a) uses the earlier control valve body, valves (b) and (c) use the later body that has different oil passages. With valves (b) and (c) when they open full hydraulic pressure is still maintained in the lift cylinder circuit and the check valve does not close until the control lever is moved to the neutral position - when that happens both the check and unloading valve close.


Be that as it may the RELEVANT point is that from what you say you do have the original Major type unloading valve. As you can see from the diagram this should have a conical tip to it that seats in the valve seat to seal the circuit - BUT you say that the tip is flat?? This sugests that the valve tip is very badly worn to the extent that it will not make a good enough pressure seal with the seat.

All I can suggest is that you take out both the valve AND the seat and put the two together so that you can see how good the seal they are making is. If, as I suspect, it is a poor seal then that is where your pressure loss is. You would then have to get either a good earlier type valve and it's original seat from a Major that is being broken which is compatible with your control valve body , OR the complete control valve assembly with lever from a Power Major that is being broken - it will fit your Major hydraulic cover. Unloading valves for the Super Major hydraulics are being made by the aftermarket parts suppliers but I do not know of anyone making them for the Majors and Power Majors.

The problem can ONLY be in the unloading valve ( which looks to be the prime candidate) OR the pump.

Good luck.
1946 E27N, 1952 Major Diesel, 1959 Power Major, 1962 Dexta, 1962 Super Dexta, 1963 Super Dexta NP, 1964 Super Major NP, 1965 Super Dexta 3000, 1966 Major 4000, 1967 3000 PF, 1994 5640,plus Basildon built NH.

Matt85
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Re: FMD Weak hydraulics?

Post by Matt85 »

Here's a picture of the valve and valve seat.
Image

Image

Is it normal for the valve seat to have a bevel on the inside?

Matt85
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Re: FMD Weak hydraulics?

Post by Matt85 »

I want to thank everybody for thier help. I found my problem it was the O-rings that are in the pipe that goes from the pump to the chest/lid. I took everything apart tonight after work and rechecked everything to make sure it was right. Putting it back together I was thinking maybe I should try the old O-rings on the pipe. I was thinking it couldn't get any worse then it is right now. Then I bolted everything back together and fired it up and checked the gauge and it read 1,300 psi. Took it and picked up my 650lb disc and it lifted it without any effort. Tomorrow I'm going to see if it will pick up my 1,100 lb brush mower. I know I still need to shim the unloading valve to get 2,200 psi.

Image

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Re: FMD Weak hydraulics?

Post by shepp »

Well, we went all the way round the block with that one, only to return to the first suspect that I and other contributors raised - the O rings on the pressure pipes!!
You must have fitted new O rings that were not compatible, don't forget these are Imperial O rings, also O rings have different thicknesses for the same size.

Your unloading valve tip is conical as it should be and not flat as you originally reported! It is normal for the valve seat to have a bevel on it. It looks perfectly serviceable.
1946 E27N, 1952 Major Diesel, 1959 Power Major, 1962 Dexta, 1962 Super Dexta, 1963 Super Dexta NP, 1964 Super Major NP, 1965 Super Dexta 3000, 1966 Major 4000, 1967 3000 PF, 1994 5640,plus Basildon built NH.

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Re: FMD Weak hydraulics?

Post by henk »

:clap: :buddies: :clap:
Toverhoed we dan do nany things
:scratchhead:
Sometimes my Phone correct words in someting else and I found out later. This is one of them. :eyes:

Here's the correct one.
Together we can do many things.

Better not write on my Phone again. :oops:
Last edited by henk on Sun May 20, 2018 8:49 pm, edited 1 time in total.
Kind regards, Henk

Fordson New Major February 1957 Mark I

Matt85
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Re: FMD Weak hydraulics?

Post by Matt85 »

Shepp, I used the O-rings that the online parts diagram called for. Which are -115 O-rings. And about the valve being "flat". Aguy by me said it should have a point on the end like a perfect cone.

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Re: FMD Weak hydraulics?

Post by Matt85 »

The Beast is back! The Major picked up the brushmower only about a foot off the ground before shimming. Once I shimmed the unloading valve and got it at 2,200 psi. It will picked it all the way up.

Image

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