3-Point hitch lowering speed knob won't stay adjusted

[stendek]

I have a B2710 with 3pt lowering knob issues. I can adjusted for proper drop rate with a mower, bush hog or other implement, however, it won't stay set. I can get it set with the bush hog for instance and mow a few rows and look back and the hitch has stayed in the up position. If I then readjust the knob and it drops as expected. In other words it won't stay adjusted, it is not an issue with the hitch sticking etc. As near as I can tell, the knob itself isn't moving when this happens.

Any advice is appreciated.

 

[/pine]

I have a B2710 with 3pt lowering knob issues. I can adjusted for proper drop rate with a mower, bush hog or other implement, however, it won't stay set. I can get it set with the bush hog for instance and mow a few rows and look back and the hitch has stayed in the up position. If I then readjust the knob and it drops as expected. In other words it won't stay adjusted, it is not an issue with the hitch sticking etc. As near as I can tell, the knob itself isn't moving when this happens.

Any advice is appreciated.

The knob (usually under the seat forward)...is primarily for two purposes...set the rate of drop (how fast it falls) and to lock the 3ph (close valve) for transporting etc...

The only adjustment the know is for is how fast it lets the arms down...the heavier the implement the faster it will react but the rate of fall is what the knob is for...

Does your tractor have position control? this is likely where your issue is or with whatever controls the normal 3ph function...

 

[stendek]

Yes it does and that seems to work. I can raise and lower the 3pt just fine. For example I’ll raise the mower at the end of a row and make a turn around and lower it. It will be fine for several rows and then seemingly randomly I’ll go to lower it and it will stay up. I’ll readjust the rate knob and it will go down as before. It’s really annoying to look back and realize too late you mowed a few rows with the mower raised!

 

[Scook222]

I would adjust the rate non where it drops quicker and check and see if the pto is binding when it stays up. With the lever lowered and the mower still up hop up on the mower and see if it comes down. I have had a pto stick in full up position due to angle and be fine other times. I greased the slip shaft on the pto even though it had no grease point and haven’t had it do it anymore. You wouldn’t think a pto shaft would keep the 3 point from moving but it did.

 

[stendek]

So on further inspection my knob is actually turning on it’s on and eventually reaching where it locks the implement. So the question is now how do I stop that. I assume that’s not normal ?

 

[Scook222]

On most that I have used, the know is stiff. Look at the part diagram for it and see if there there a lock nut that you can tighten down. I’m not sure if you can remove the knob itself to put a lock but on it. If not, I would see if there was a spot to tie wire to like safety wiring. You could drill a small hole in the plastic knob and use the tie wire to hold it. You might be able to look in the workshop manual and see how the rod and nut disassembles and see if it can be removed with the tractor off and put a lock but on it or replace what is worn that is making it spin but I’m not sure if it can be fixed that way.

 

[oosik]

If you can completely remove the knob & shaft but it will not accept a lock nut. Buy a "expanded" chunk of spring. Put it on the knob shaft. Reassemble the knob. As you tighten down the knob the expanded spring will compress and just might hold the knob in position.

I've seen this same thing done with a short chunk of 1/4" diameter rubber hose.

 

[stendek]

I should clarify it’s not the knob moving in the shaft it’s the whole shaft turning. I may try the drill a hole and attach a wire idea.