More clues to the 3 point problem

When the rockshaft is traveling from the ground to the top, I can here the engine carrying the load until it gets to the top and then the engine sound like it does not have a load and the rockshaft and implement is at the top.(Sounds like Normal Operation)

I am certain the problem is in the Rockshaft Control Valve housing, but where...I am certain the problem is NOT that the Rockshaft cylinder needs packing. It has to be in the Control valve somewhere..
Could anyone shed some light as to what I could do next? I have taken the Control Valve housing off the tractor, I am still a somewhat baffeld as to what could be going on...

This maybe a bit of review but do you have your draft control lever in D? L is load and the hitch will react to the load placed on it. LD is a mixture of load and depth and the hitch will be less resopnsive to load and more responsive to depth. D is depth and the hitch will no respond to varying loads. Loads in this case do not maen the amount of weight on the three point that you are trying to pick up but rather the amount of draft effort (pulling amount) that the bottom three point arms have on them. An example would be pulling a semi-mount plow which is only hooked to the bottom two arms. As the load increases, (draft) the sensing mechanism transmits the signal to raise the three point slightly.

The 2nd photo shows the position of the feedback roller if you are in D for depth control. This point is basically in line with the cam on the rockshaft and if the dash lever is the command input, the hitch reacts, and the cam (via linkage) cancels. The hitch holds that position.

The roller will stick out much further if you have selected L or load position. The cam has very little effect on positioning the three point when in this position. Varying draft loads, since the roller is now further down on the load sensing arm, do most of the control. Without load, the hitch will raise to the top in the last bit of lever movement and will drop to the bottom at the first bit of moving the lever to lower.

Photo 3 shows the feed back linkage. The right side is a simple differential (similar to a car rear end). The dash lever is hooked to the outside bevel gear, the feedback roller is hooked to the middle gear (spider, meshed to both bevel gears). And the LH bevel gear is hooked to the cam shaft to push the raise/lower balls off their seats. Command input rotates the RH bevel and thru the spider, rotates the LH bevel. This rotates the cam pushing open the correct ball to raise or lower. (Depends which way you moved the lever if you wnated to raise or lower) If in depth, the cam pushes on the roller which moves the spider. Since the RH bevel is held in position by the dash lever, the LH bevel reacts, the cam moves and the ball is returned to it's seat. The hitch stops at it's new position.

I put the valve housing back on last night, but here is the catch. I did not know where to put the feed back roller. I did not know if it went "between" the cam and the draft follower arm, or behind the draft follwower arm. I left my IT manuel at home so I had it stuck between the draft follower arm and the cam. When I tried it I got very different respons. This time the Rockshaft when the engine is running almost behaves like its supposed to in when the lever is set in "D". The things that were funny were this. I could not get the Lever back in the "L" position, the control valve now is responsive at a different position than before which means I would need to adjust my lever cable. So I knew something was funny just didn't know what...until I got home last night and read the IT manuel on it. But other than that it was VERY promising to see the hitch actually follow the response of the control lever up and down and in the middel like it supposed to.

Now I have to go back and see how to set the cam follower roller behind the draft follwer arm in the transmision. Then see how to make that work like it supposed to.

Here is what I am missing in my mind. When I have the valve houseing off. I see the follower roller and I see the long spring. I then can feel where I can work the roller that streches the spring. But I cant figure how either the cam or the draft follower arm actually "push" against this rolloer... I mean if the draft follower is between the cam and the valve roller how does the cam push against this roller for the feed back? I think this is the last major clue to solving this problem.....I think I am very close though.....

If you move the roller down the draft follower, LD, then you get something less than 1 to 1. It may take twice as much rockshaft cam movement to get the same roller movement as above when in D.

In L or load, the roller is so far down the draft follower that it is only the movement of the draft lever arm that can move the roller. The cam will have little if no effect. The roller is almost in line with the top of the draft lever arm. In this position, draft will have control of hitch position. (Height) That is why the dash lever cannot control hitch height, only full up or full down. The cam cannot provide any feed back to cancel and make the hitch stop.

The draft lever arm is controlled by the load sensing shaft that actually bends (deflects) when a load (draft) is placed on the bottom arms.

The load sensing shaft seals are leaking on my 4010 and I plan on changing them today. Maybe photos tomorrow.

With load (draft) on the arms, the load has no effect in D, some effect in LD, and lots of effect in L. Compared to the cam, the cam has lots of effect in D, some effect in LD, and no effect in L.

Now isn't that confusing?

1) It seems the draft follower is some what loose in that it "flops" around alot...is this correct?

2) How doe the roller keep from slipping off the draft follower?

I think my problem MAY be due to either the roller not staying on the draft follower, or the draft follower not staying on the cam, or I must not have something adjusted right....

The follower will flop towards and away from the cam. Memory tells me that it can flop from side to side a bit but not too much. Not 100% sure on that, it has been 4-5 years since I've had it apart.

The long spring keeps the roller tight to the follower.

When you reinstall the valve, you need to be sure the roller is on the follower. Usually, after you have matched the roller to the follower, you have to push forward on the valve to over come the spring a bit to get the bolt holes to line up.

Can the follower cock to the side (twist) a whole bunch? If so, the roller will have trouble staying on the follower.

How long have you had this tractor?

Any way your insight was really helpfull in my GREAT accomplishment...I was going to have to fork at AT LEAST 1000.00 to have a dealer do this...

Now I have to replace the Radiator Hose that should be VERY easy.

Thanks....

It would rare to find one that does NOT leak.

Most likely, if you repack the cylinder piston with the new-style seal, and then pull the control valves out and make sure the valves and seats are good, and then make sure the adjuster screw is set loose enought so those valves are closing fully - you'll be fine.

The Leek down problem seems very normal according to a Mechanic and several post on this forum.

The Tractor is a 1967 John Deere 4020.

I only have the IT Manuel

Yes I think I am going to take this Valve control housing to a John Deere place...

2.) As the the calibration problems, start by adjusting the lever linkage as shown in the service manual, then the other more complex valve adjustments, if needed. You need the serial # to be sure to have the service manual that pertains to your tractor.

Allan