M51 dump or winch-control keeps PTO running?

[808pants]

I've not used my 5-ton (M-51 dump) for years now while working on it sporadically. Getting it running recently, I noticed that for some reason now, the two transmission PTO shafts spin always - the only thing that halts them is the clutch being pressed. (On this variant, one shaft runs front to the winch, the other back to the dump-bed hyd pump, and I believe the shafts must both turn for either to turn). I think there's some problem with the various linkages from the dump control - they'd have made Rube Goldberg envious, and several zercs absolutely defy greasing, so maybe one's nearly-frozen, but it doesn't look like there are any not willing to move. Anyway, even with dump lever in the "upright and locked" position, the transmission PTO shafts spin - but it feels like the lever is "sprung" in getting it there, so I think some part of the linkages is fighting my efforts to bring it up to disengage. Also, regardless of the winch-control-lever position, the shafts still spin, like there's no 'N' setting - I must have gone through them all ten times over trying to 'find' that 'N' lever setting before each time giving up and returning it to "2nd from top" as it's supposed to be...and I assume the dump-lever must override the winch-lever setting so that the hyd PTO will be driven regardless of winch-control being in N.

Any particular suggestions? Is there a TM with troubleshooting procedure for the dump-control, or maybe for the winch-control, too? I went through various portions of TM 9-2320-211-10-1 but could spend a week poking around for the right section in the right TM, if it exists...

Mahalo,

Dave

 

[patracy]

I had the same thing, turned out to be the linkage needing adjustment.

The upright and locked position is N for the PTO box. Always push the clutch in as well when trying to place it in that position.

 

[gringeltaube]

........................
Any particular suggestions? Is there a TM .....?

Stop engine. Disconnect linkages to/at both PTO shift shafts. Shift manually and confirm all shift positions according to diagram below. Place in N/OFF and start engine. No shaft should turn with clutch released.
You may also check/clean both poppet ball & springs, while there.
Re-connect linkages and adjust accordingly.

Check TM 9-2520-246-34 and -34P, PTO repair. Procedures are the same for both, Deuces and 5tons.

G.

 

[808pants]

Great stuff, gringeltaube, and thanks patracy...G - looks like you embarked on a project to update the TMs, what with that photo & markups! Your own, I assume? I'll get back on this when/if the rain ever stops here - those are just the details I need, thanks.

When I was using this truck 'for real' it worked OK, but I used to wonder about the 60's ergonomics: as with all dump trucks, you can't really see much of what the bed's doing from the driver's seat, but then again with this layout of controls, you'd have to be a contortionist to both operate the clutch AND reach over your left shoulder to operate the dump lever, if you expected to remain seated. I used to stand on the running-board, door open, with left leg up and behind me into the cab to operate the clutch pedal, while operating the dump lever with my left arm.

'Course I don't have to tell you what kind of perverse notions the handbrake lever had each time I'd get in or out...

 

[gringeltaube]

LOL... I know exactly what you mean, even if I have never operated a 5ton dump myself.

BTW, I didn't like the original set-up on my first dump-Deuce, where the bed lift has to be controlled with the left foot on the clutch pedal - thus having to sit inside while dumping. So when I built my second M35-dumper the main goal was to be able to control the whole operation from the drivers seat as well as standing outside of vehicle next to the (open) drivers door. This was accomplished by placing a hydraulic control valve in the left-rear corner of the cab floor. On this truck the pump-PTO is engaged via a small air cylinder plus switch on the dash and lifting/lowering action is independently controlled by moving the control lever up or down, out of its neutral-bypass position.
It should not be to difficult retrofitting such a simple system into any of the older 2.5 and 5ton dump trucks...?

G.

 

[808pants]

Gringeltaub - thanks...I had the chance to get into this yesterday afternoon, and found the problem. Your suggested approach worked - disconnecting both shafts still left them running regardless of winch-control lever position, so I shifted my focus to checking the fore/aft movement of the dump-control lever (which of course has a second function of regulating hydraulic valves to move dump up/down). I'd not been able to get grease into some of the 8000 zercs last time I tried, and sure enough, it turned out that a few years of rain had virtually frozen the final set of levers on the frame-mounted pillow-block in one of those un-greasable locations. But there's enough flex in the system so as not to keep the dump lever from seeming like it's able to be locked back into the upright position (though with some springback to it.) Anyway, I got that lever/shaft moving/ lubed enough to work for a while and reassembled as it got dark, and was pleased to find that at last the PTO could be made to stop spinning.

As to your mods - I like your idea of the air-cyl to engage/disengage the PTO drive, thus relieving that function from the dump-control lever, but I think whether by air or lever, the trans PTO stub should only be moved while clutching - maybe you didn't intend to suggest otherwise. On the other hand, once the hyd pump is engaged via one means or another, I don't see a reason to have to keep clutching to use even the stock dump-control lever (until/unless it's brought back all the way up, thus disengaging the PTO from hyd pump). So I think once the hyd pump is running, the dump lever's sole function is is to shift the hydraulic valve settings (no gear-meshing involved) - not so?

That being said, other than out of concern for keeping original (often an internal battle for me) I sure wouldn't miss the funky, springy, unpredictable, maintenance-intensive levers and shafts used to control the dump as stock...thanks for your help.