JD 4700 PTO Won't Engage??? Help???

[WalterWallace]

JD 4700 PTO Won\'t Engage??? Help???

I hooked up my bush hog today and expected to promptly cut 7 acres of month old growth. I set my rpms to 2600 on the PTO mark, made sure I was in neutral and pulled up on the PTO switch. The light came on but no action??? Can anybody please suggest anything I can check before I load up and go to the shop??? Any help ya'll could give me would be greatly appreciated!!!
Thanks
WW /forums/images/graemlins/confused.gif

 

[DK35vince]

Re: JD 4700 PTO Won\'t Engage??? Help???

</font><font color="blue" class="small">( I set my rpms to 2600 on the PTO mark, made sure I was in neutral and pulled up on the PTO switch. The light came on but no action??? )</font>

When turning on PTO powered attachments I only turn on the PTO switch at very low engine speeds and gradually speed up to PTO speed.
If you are at full PTO speed before you hit the switch, Something's going to Give !!

 

[WalterWallace]

Re: JD 4700 PTO Won\'t Engage??? Help???

Just going by the owners manual. I believe on this tractor the PTO is engaged by a wet disc clutch.

 

[Bird]

Re: JD 4700 PTO Won\'t Engage??? Help???

You still want to engage the PTO at low RPMs, then increase the speed with the throttle after it's fully engaged.

 

[DK35vince]

Re: JD 4700 PTO Won\'t Engage??? Help???

I believe most Independant PTO's are engaged by wet disc clutch's.
But the blades and drive lines on a rotory cutter are heavy and should be started at slow engine speeds and gradually increase speed from there !
Does you PTO shaft to the cutter spin but not the mower.
If so starting the mower at higher speed my have brocken the shear bolt.
With the engine at slow idle and engaging the PTO, does anything try to spin ?

 

[WalterWallace]

Re: JD 4700 PTO Won\'t Engage??? Help???

Nothing spinning. I troubleshot the electrical today and I know I'm getting power to the coil on the valve that shifts the PTO into gear. The coil checks good at 10 ohms and it is pulling 1.5 amps which is right for 12-14 volts (E=IxR). I guess I'm headed to my dealer because I don't want to go into the hydraulics.

 

[DK35vince]

Re: JD 4700 PTO Won\'t Engage??? Help???

Good luck.
Don't forget to let us know what they find.

 

[WalterWallace]

Re: JD 4700 PTO Won\'t Engage??? Help???

Well I checked with my dealer today and I'm out of warranty so I guess I'm going to order some tech manuals and dive in. I checked a little further today and tried powering up the coil without the tractor running. The coil got pretty hot and it did not sound as if anything was moving??? It seems to me that I should be able to hear the spool under the coil shift? The loader and 3-point lift both feed off of this valve and they are working fine. A year ago my 3-point lift quit picking up and I had the dealer service it under warranty. They told me that a screen was plugged and that the fix for this problem was to take it out and leave it out??? The PTO shaft feels fine when I turn it by hand from the back it does not feel like anything is broken. If anyone has any advice or information I sure would appreciate it!!!

 

[dmccarty]

Re: JD 4700 PTO Won\'t Engage??? Help???

Walter,

I startup my MX6 the same way you do. I crank up the
engine to PTO speed and then engage the PTO. The engine
bogs downs a bit but that is all.

I don't like this but I do it for two reasons.

If I engage the PTO at lower RPMs that engine is going to
stall. /forums/images/graemlins/frown.gif

Two, the manual says to do it that way.... /forums/images/graemlins/grin.gif

The old MF 135 I used to work on many years ago could be
started at low engine RPM and then cranked on up....

Let us know what happens.

FYI,
Dan McCarty

 

[WalterWallace]

Re: JD 4700 PTO Won\'t Engage??? Help???

Well guys here's the latest. I took the dual scv and pto valve off and found that the pto valve was stuck. I tried to operate it electrically several times and the pilot valve would not shift. /forums/images/graemlins/confused.gif Before going into the valve I decided to give it a few wacks with a soft faced hammer. I tried to operate the valve again by hooking up the wires and the valve started shifting. I put everything back together and my pto works again. /forums/images/graemlins/grin.gif I asked my Dad, He's been a mechanic all his life, what to do next. He suggested I slap everything back together, change my hydraulic filter, and add some Lucas Transmission additive. My only concern is whether the Lucas additive is compatible with JD Hy-Gard. Any suggestions you guys have would be greatly appreciated. Got to get this bush hog hooked up and cuttin'!!! This eight acres is about to get chest high.
Thanks,
Walter