9n hyraulics

[DenisW]

Finally, got back to 9n. 3 point will lift 100-200 lbs only. Pressure test with arms chained will go to 350 psi at idle, 400 at pto speed. Lifting 100 pounds, lift is smooth as can be. Leak someplace, no oil dropping from top cover. Relief valve is good, no oil escaping there. Adapted Z. Sherman grease gun test, drained all oil, put grease zerk on test port and pumped 3/4 of full gun into system. Got lift arms to move up with touch control in neutral. Pulled pump this morning, grease is in bottom of pump at control valve. Could control valve be bad, or control valve port be bad, or pump casting be bad? Any other possibilities? Need help to further diagnose this problem.
Thank You
Denis W

 

[TheOldHokie]

(quoted from post at 14:16:53 08/16/12) Finally, got back to 9n. 3 point will lift 100-200 lbs only. Pressure test with arms chained will go to 350 psi at idle, 400 at pto speed. Lifting 100 pounds, lift is smooth as can be. Leak someplace, no oil dropping from top cover. Relief valve is good, no oil escaping there. Adapted Z. Sherman grease gun test, drained all oil, put grease zerk on test port and pumped 3/4 of full gun into system. Got lift arms to move up with touch control in neutral. Pulled pump this morning, grease is in bottom of pump at control valve. Could control valve be bad, or control valve port be bad, or pump casting be bad? Any other possibilities? Need help to further diagnose this problem.
Thank You
Denis W

Grease isn't going to leak like oil will. What do you think you learned with that test? How much weight was on the lift when you got them to raise using the gun?

TOH

 

[HCooke]

JMOR has a diagram of 9 potential leak points in the 9N hydraulic system. He he doesn't show up soon I'll see if I can find it somewhere for you.

 

[Plane Bart]

What happens when you open the inspection port and move the linkage arms by hand? Will it lift more than two hundred pounds?
If so you may need to adjust your quadrant.
Are your linkage arms installed correctly? Flat boss on the lower arm should point to the front of the tractor.
Where do you have your spring connected too?
Should be from the ram cylinder to the notch on the upper linkage arm.
I spent a day messing with my 9N hydraulics here recently to find y weak and slow moving hydraulics were being caused by the above problems.
Post back

 

[DenisW]

It's true grease will not leak like the oil would. The grease leaves me a trail, which the oil would not. it's possible that there are other leaks in the system. I am convinced that my pump is 99.9% and its output is good. I chained the lift arms and there was a lift of about 1" before the chain tightened, with a slight increase in pressure on the grease gun handle.
I am sure that there is a leak somewhere in the system and I think I have localized it to the area inside the pump at or near the control valve, in front of the yokes.
I have done everything to the pump to get it working well, yokes, inlet and outlet valves, bushings, relief valve, gaskets all new. When it is lifting 100 lbs operates as smooth as possible.
DenisW

 

[JMOR]

(quoted from post at 16:51:06 08/16/12) It's true grease will not leak like the oil would. The grease leaves me a trail, which the oil would not. it's possible that there are other leaks in the system. I am convinced that my pump is 99.9% and its output is good. I chained the lift arms and there was a lift of about 1" before the chain tightened, with a slight increase in pressure on the grease gun handle.
I am sure that there is a leak somewhere in the system and I think I have localized it to the area inside the pump at or near the control valve, in front of the yokes.
I have done everything to the pump to get it working well, yokes, inlet and outlet valves, bushings, relief valve, gaskets all new. When it is lifting 100 lbs operates as smooth as possible.
DenisW

"Got lift arms to move up with touch control in neutral." I think that this invalidated your test. Why? Because with touch control in neutral as you say, then I suspect that such left the control valve in something other than a fully closed position, thus allowing your grease to escape out the exhaust valve.

 

[DenisW]

Test may be invalid for the reason you cite. It's possible that I have been chasing my tail for all this time.
Have used this tractor for 10 years +_. It would lift heavy disk, front wheels barely gripped for steering in transport. Was using it to move stuff worked fine. Next load would not lift. If I use external power to lift the load it will hold the load in lifted position. Should have gone directly to the problem, instead of throwing time and money into it for no result. Still need to diagnose the problem!!

 

[DenisW]

Moving linkage does not help. Quadrant adjustment seems to be OK. Arms are ok, as system was working well until the last load. Spring is connected to ram cylinder and notch on upper linkage.
DenisW

 

[JMOR]

"If I use external power to lift the load it will hold the load in lifted position."

If it hold a load up for even 5 minutes, then the 9 leak points are not going to be your problem. Sounds like the pump just can't pump, IF the intake control is pushed fully forward so as to open intake to pump.

 

[TheOldHokie]

(quoted from post at 18:19:35 08/16/12)
"If I use external power to lift the load it will hold the load in lifted position."

If it hold a load up for even 5 minutes, then the 9 leak points are not going to be your problem. Sounds like the pump just can't pump, IF the intake control is pushed fully forward so as to open intake to pump.

An interesting test would be to start the tractor and use a come-a-long or similar hoist to assit the tractor hydraulics in raisng a loaded 3pt. Then shut it off and measure the leakdown time.

TOH

 

[DenisW]

The pump does work, at least enough to lift 150 lbs, more or less. Since it will hold a load, I think the system is ok between the ram and the exhaust valve, that leaves the intake valve and pressure chamber. How can I test that?
DenisW

 

[DenisW]

Thanks, I have a copy of that diagram.
DenisW

 

[DenisW]

BTDT, It will hold the load, without any significant leakdown.

 

[JMOR]

(quoted from post at 18:54:28 08/16/12) The pump does work, at least enough to lift 150 lbs, more or less. Since it will hold a load, I think the system is ok between the ram and the exhaust valve, that leaves the intake valve and pressure chamber. How can I test that?
DenisW

y 'pressure chamber' I guess that you mean the 4 cylinders of the pump & each cylinder's associated inlet & outlet valve? Intake control valve.........if it is in fact moving all the way into the pump, so as to uncover the port in the bushing, then unless it is obstructed by trash it is probably OK.
This isn't a obvious as it sounds, since the control valve doesn't have "hard" linkage, but rather internal spring, so you may push rod to limit & compress internal spring & still not have a full open intake port. You could measure volume at about ~2.8 GPM @ 2000 rpm by letting test port pump into a bucket. If no leaks, then failure to produce even 25% of proper pressure is in/around pump. If not adequate volume, then that might help you in recognizing a pump problem.

 

[ZANE]

Be sure that the spring between the two control arms and the end of the ram cylinder eyelet is strong enough to push the control valve all the way in.

This spring is designed to take up the shock loads created by the draft linkage and prevent beating up the linkage. They do get weaker over time just like all springs do. I would take it out and remove about an inch off it's length and replace it.

Zane

Zane

 

[wvfarmerboy]

edit

 

[DenisW]

Lift has held pallet fork(100+ lbs)up for two days now.
Pressure test: lift arms chained to axle, pto on, touch control up, pressure 200 at idle, 300 at pto speed, volume at pto speed 2.4 gpm. Have plastic tube on relief valve, no oil from there.
Inspection port open on right side, no oil coming from above, reach in to pressure tube, feel no oil escaping from top to bottom of tube.
Only oil movement is at back of pump above valves small circle(dime size)going clockwise with touch control down. When I move touch control to lift position the circle moves to back of the sump and gets a little larger(nickel size).
Upper spring from fork to cylinder is strong and correctly placed. Only question is on the spring on the control valve, it does seem to move control valve. Don't know where else to look or test.
Any suggestions are appreciated.
Denis

 

[JMOR]

(quoted from post at 11:40:43 08/28/12) Lift has held pallet fork(100+ lbs)up for two days now.
Pressure test: lift arms chained to axle, pto on, touch control up, pressure 200 at idle, 300 at pto speed, volume at pto speed 2.4 gpm. Have plastic tube on relief valve, no oil from there.
Inspection port open on right side, no oil coming from above, reach in to pressure tube, feel no oil escaping from top to bottom of tube.
Only oil movement is at back of pump above valves small circle(dime size)going clockwise with touch control down. When I move touch control to lift position the circle moves to back of the sump and gets a little larger(nickel size).
Upper spring from fork to cylinder is strong and correctly placed. Only question is on the spring on the control valve, it does seem to move control valve. Don't know where else to look or test.
Any suggestions are appreciated.
Denis

OK, since the problem can't seem to be isolated, let us split the potential problem areas apart. You have experience in removing the pump, but won't need to to begin this test, but might need to in order to replace gasket at later time if gasket gets damaged in this operation. Loosen pump bolts enough to insert a piece of shim stock so as to cover the point #4 (hole to vertical tube) in my diagram above. Blocks flow from pump. Tighten bolts. Crank with starter, touch control full UP, and measure pressure.

 

[TheOldHokie]

(quoted from post at 12:02:38 08/28/12)

(quoted from post at 11:40:43 08/28/12) Lift has held pallet fork(100+ lbs)up for two days now.
Pressure test: lift arms chained to axle, pto on, touch control up, pressure 200 at idle, 300 at pto speed, volume at pto speed 2.4 gpm. Have plastic tube on relief valve, no oil from there.
Inspection port open on right side, no oil coming from above, reach in to pressure tube, feel no oil escaping from top to bottom of tube.
Only oil movement is at back of pump above valves small circle(dime size)going clockwise with touch control down. When I move touch control to lift position the circle moves to back of the sump and gets a little larger(nickel size).
Upper spring from fork to cylinder is strong and correctly placed. Only question is on the spring on the control valve, it does seem to move control valve. Don't know where else to look or test.
Any suggestions are appreciated.
Denis

OK, since the problem can't seem to be isolated, let us split the potential problem areas apart. You have experience in removing the pump, but won't need to to begin this test, but might need to in order to replace gasket at later time if gasket gets damaged in this operation. Loosen pump bolts enough to insert a piece of shim stock so as to cover the point #4 (hole to vertical tube) in my diagram above. Blocks flow from pump. Tighten bolts. Crank with starter, touch control full UP, and measure pressure.

I like that idea. This and a couple other similar threads had me thinking along the same lines. Came up with this idea but I'm not sure if I can get a good enough seal in the unfinished casting to get a reasonable test reading. What do you think?

TOH

 

[JMOR]

(quoted from post at 17:33:48 08/28/12)

(quoted from post at 12:02:38 08/28/12)

(quoted from post at 11:40:43 08/28/12) Lift has held pallet fork(100+ lbs)up for two days now.
Pressure test: lift arms chained to axle, pto on, touch control up, pressure 200 at idle, 300 at pto speed, volume at pto speed 2.4 gpm. Have plastic tube on relief valve, no oil from there.
Inspection port open on right side, no oil coming from above, reach in to pressure tube, feel no oil escaping from top to bottom of tube.
Only oil movement is at back of pump above valves small circle(dime size)going clockwise with touch control down. When I move touch control to lift position the circle moves to back of the sump and gets a little larger(nickel size).
Upper spring from fork to cylinder is strong and correctly placed. Only question is on the spring on the control valve, it does seem to move control valve. Don't know where else to look or test.
Any suggestions are appreciated.
Denis

OK, since the problem can't seem to be isolated, let us split the potential problem areas apart. You have experience in removing the pump, but won't need to to begin this test, but might need to in order to replace gasket at later time if gasket gets damaged in this operation. Loosen pump bolts enough to insert a piece of shim stock so as to cover the point #4 (hole to vertical tube) in my diagram above. Blocks flow from pump. Tighten bolts. Crank with starter, touch control full UP, and measure pressure.

I like that idea. This and a couple other similar threads had me thinking along the same lines. Came up with this idea but I'm not sure if I can get a good enough seal in the unfinished casting to get a reasonable test reading. What do you think?

TOH

hat keeps it in the hole? Some kind of o-ring compression for expansion or what? NEVER MIND! I see that you are using the test port, but going in deep enough to get ahead of the vertical tube. H311 yes! Try it. Unless it leaks too much it could still yield a good measurement. When do I get my "evaluation sample"? :lol:

 

[TheOldHokie]

(quoted from post at 17:46:08 08/28/12)

(quoted from post at 12:02:38 08/28/12) What keeps it in the hole? Some kind of o-ring compression for expansion or what? NEVER MIND! I see that you are using the test port, but going in deep enough to get ahead of the vertical tube. H311 yes! Try it. Unless it leaks too much it could still yield a good measurement.

Don't have a running tractor to test on right now but I just did a a quick mock-up and dry fit - looks promising. The 1/2-20 thread retains the hex body in the test port against hydraulic pressure and the extended nose with the o-ring seals off the pump outlet passage just before the riser port. The nose is a pretty snug fit to the passage and I can feel the o-ring compress on insertion so I like my chances. As usual a trip to the machine reveals manufacturing issues ;-) Too hard to make as drawn. Next one I'll make the body a couple inches long and drill and tap the outboard end for a 1/8" NPT port. Screw your favorite flavor of hydraulic adapter into that port for connection to a gauge.

If you want a freebie to try out Denis give me a yell. You too Jesse - I just saw your edit....

TOH
[email protected]
301.655.0631

TOH

 

[DenisW]

Yes, I'd like to try your design. It can tell me if the pump is making pressure and easier for me than draining the oil, loosen bolts, shove in a shim, tighten bolts, fill oil and possibly lose a gasket and ..?
Denis

 

[DenisW]

How can I be sure that the control valve is fully opening the intake port?
The 2.4 gpm volume test is low, not a lot, but enough to be significant.
Denis

 

[TheOldHokie]

(quoted from post at 01:14:19 08/29/12) How can I be sure that the control valve is fully opening the intake port?
The 2.4 gpm volume test is low, not a lot, but enough to be significant.
Denis

The difference in your measured rate is not significant for a a number of reasons.

• [*:6998ea7bbe]Pressure will build to the limit of the pump regardless of the flow rate - just takes longer. [*:6998ea7bbe]If you have a leak that is bleeding off anything close to 2.4 GPM and preventing pressure to build it's massive and should be readily obvious.[*:6998ea7bbe]The flow rate is a function of pump speed and is at best a guestimate[/list:6998ea7bbe]If you are getting a 2.4 GPM flow out of the pump the intake port is opening enough to allow that volume of oil in. Whether that is 100% or not is really not a concern wrt your problems.
  
  TOH

 

[DenisW]

My next test is this: Raise lift to medium-low height and start to load it up until front wheels come off ground and see how long that holds or lift drops with heavy load. It's already broken somewhere, maybe this will make it show up and I'll be able to see it.
Denis