Thread: OT Oil clutch in Yale forklift...sticks?

1970 Yale G83P.....

This thing has an oil bath clutch, looks like a regular dry car/truck clutch, except the bell housing is sealed with drain back to a tank placed under the transmission. Small belt drive pump off engine circulates Dexatron ATF which actually sprays into the center of the pressure plate via a 5/16 dia. steel tube.

Push in the clutch, and 'something' drags.....only way to get into gear is to grind it severely. Then once in, it can be shifted to the other gears (FWD/REV Hi/LO) with no sign of any drag on the drive train. (Yep I adjusted it and it is disengaging 'seemingly fully' with the pedal).

But if you go back to neutral for 10-15 seconds, it's dragging again, and will grind going back into gear.
It hasn't gotten any better in a few hours of operation, and was setting for 3 years prior (before I got it).

What could this be??

Pilot bearing seized/ bad?
Clutch disk sticking on the spline and stuck up against the flywheel? (NO rust inside the bellhousing, just clean ATF).

Maybe someone will post an obvious or 'those wet clutches always do that because' answer.....

dk

do you have it apart now?

if so this is what i would do

the disk usually has radial slits from the outer edge toward the center
take and make twists in each section so its kinda like a real fine pitch fan blade (i don't know how else to describe it)

this will allow some forced seperation from the flywheel when the pressure plate releases

plates that are perfectly flat can stick to the flywheel a bit because of the oil and drag like heck. stiction (or is it sticktion?) at play. the oil gets into the rivet holes and other places and will suckup nice an tight when the pressure plate comes down on it, you might try
holding down the clutch for maybe a minute and see if it releases and goes into gear, if so stiction is likely the culprit.

actually it is my bet this is the problem.

all i know is my clutch builder always twists them before he hands them over the counter to me when i buy them, he tells me this is why its done.

i don't know but it works for me.

seems unlikely that the pilot brg is dragging, usually they have so much lubrication that they will at least slip on the pilot end of the input shaft if nothing else.

fwiw

bob g

Another possibility;
If the trans has been out and re-installed, on the re-install, if the trans is left to "hang" on the clutch disc splines without the input shaft nose being engaged into the pilot bushing in the end of the crank, the steel backing of the clutch disc can be bent. This would cause the symptoms you describe because the clutch would never totally dis-engage and would be dragging on the flywheel enough to make the input shaft spin.

No not apart....and not wanting to even think about that...

Would guess it's never been apart.....

Am hoping someone will post name of miracle additive
that pours in and makes problem go away...

Bob, sounds like you mean radial spiral slots to break up the surface area...

Still curious how this problem would develop from new to now? One time had slots in disk face but worn off now?

Sounds like the plate is just sticking to the flywheel, whether suction or fluid cling or _? If the friction material has gotten glazed in use, and/or the pattern pressed/cut into the surface is worn off, either can cause that to increase.

How long has it been since you changed the ATF?

Originally Posted by Mud

How long has it been since you changed the ATF?

That was my first thought, has it got the right grade in it?

If it's had the wrong grade in the past it can cause sticking problems with fresh fluid.

If you have changed the ATF , get it really warmed up, then deliberately slip the clutch / work it hard, then dump the ATF and refill.

FWIW some of the old Allison torque conerters would semi lock / stick if the oil wasn't changed properly.

Well.....i changed the engine oil ....twice.

Yesterday I changed the Dif and Trans 90wt, and the
hydraulic oil (10 gallons)....

Last week I changed the master cylinder and bled out all the old brake fluid.

I'm about to flush the radiator.....

And I DID top up the clutch oil tank with around a gallon of ATF .
So now.....I guess it's time to drain the clutch oil and replace ALL of it.

Who knows whats really in it??
It seems sorta pale pink to me not red.....maybe somebody put AW46 in it.

After seeing the results of the 'new brake job' (left side shoes on backwards and not even seated on the backing plate.....shoes rubbing /catching on the inside of the brake drum......ANYthing's possible!

IME anythings possible with f/lifts, one place I had to make covers to bolt over the hydraulic filler caps,.............. to keep the muppets from filling the hydraulics with diesel.

Wet clutches in motorcycles have grooves in the friction disc material. As they wear, these grooves start to disappear. When the grooves are gone or severely worn, the plates start sticking together exactly the way you describe.

Your clutch is probably ready for new friction discs.

Wayne

I got a dumb question.......
Why don't they mill radial or angled grooves in the flywheel??

Then they wouldn't wear out.....?


dk

what i meant was they have split going clear thru the disk
fanning out from the center out thru the outer edge (at least the plates they sell here as replacements)

the tweak them so when you lay the disk flat on the flywheel, the disk will lay down on it on one edge of one segment and raise up
on the opposing edge of the same segment.

this allows the springy nature of the steel inner core to pull the suction loose when the pressure plate decompresses.

i concur, the disk is likely very smooth now, and is clinging or sucked down to the disk with the oil.

you probably don't have much lining left anyway. time to replace it.


bob g

Wow. I am facing the same problem: Yale G6?P <http://franklynb.home.mindspring.com...dsc02027-m.jpg>
sat for 4 years; I got it fired up, fixed a bunch of propane leaks ...
and the clutch rotates the input shaft on the manual transmission.
If I let it warm up and force it into gear, it creeps in first and reverse,
perhaps 10' a minute.

Did you ever get a fix for this problem? Thoughts of clutch replacement make me moon walk .... backwards

-frankb

Originally Posted by dkmc

1970 Yale G83P.....

This thing has an oil bath clutch...

Push in the clutch, and 'something' drags.....only way to get into gear is to grind it severely. ..

dk

Well, the good news is......I got a shop manual for the machine.
And the manual shows the procedure for clutch replacement......and it does NOT involve pulling the engine.

The transmission top cover comes off, and the input shaft comes out with the clutch disk and pres plate. A replacement disk is around $120 from HR

http://www.hrclutch.com/Industrial-Clutches.html


OTOH.......there IS silicone around the top and side inspection cover, not sure about the trans top cover........but.....it could be......if the same "mechanic" that "worked over" the brakes, replaced the clutch at some point, he may have that all screwed up too.

sat for 4 years; I got it fired up, fixed a bunch of propane leaks ...
and the clutch rotates the input shaft on the manual transmission.

$64 Dolla question: Did it do that before it sat???

Mine breaks free quite easily if I put it in gear, push in the clutch, and start it. Then there is no drag with the clutch pushed in, and no creep....foot off the brakes.

Yours sounds like an advanced stage of the same illness
The guy at HR said something about the plate bending or warping from the PP pushing on it while it sat so long....

Before I yank.....I am going to get it behind the counter weight on the 25K Clark next door, pick up to load the front tires, and apply some power while I slip the clutch a bit....just for giggles.....maybe the slots are clogged with goo and a bit of heat will 'cure' it ??
Some one also suggested a quart or 2 of Marvel Mystery oil in the tank before the 'dyno run'....

I'd like to hear from anyone that knows the true answer to this mystery, because if yours did not -stick- before it sat, that sorta rules out the 'worn out disk with missing slots' theory.

dk

Originally Posted by dkmc

:

Before I yank.....I am going to get it behind the counter weight on the 25K Clark next door, pick up to load the front tires, and apply some power while I slip the clutch a bit....just for giggles.....maybe the slots are clogged with goo and a bit of heat will 'cure' it ??

dk

It's worked for me in the past, especially on the Bonser 50Ds.

When the rear main oil seal of the David Brown diesel leaked it got in the twin plate dry clutch, a serious bit of slippin worked wonders - if only putting off the evil day

I am going to get it behind the counter weight on the 25K Clark next door, pick up to load the front tires, and apply some power while I slip the clutch a bit...

If you can form a picture of this in your mind.....

I'm just concerned if this could result in the unplanned birth of a Pallet Jack?? in 9 months or so.......?



Fornkliftacation?

Lol......

Sure glad I wasn't eating....


-----------

Think Snow Eh!
Ox

Before I yank.....I am going to get it behind the counter weight on the 25K Clark next door, pick up to load the front tires, and apply some power while I slip the clutch a bit....just for giggles.....maybe the slots are clogged with goo and a bit of heat will 'cure' it ??
Some one also suggested a quart or 2 of Marvel Mystery oil in the tank before the 'dyno run'....

Can you fill it with kerosene first, to try to desludge it? I'd be afraid that heat would bake the crud in.

Originally Posted by Mud

Can you fill it with kerosene first, to try to desludge it? I'd be afraid that heat would bake the crud in.

That's a very good point, but I wouldn't want to start an internal fire in the bellhousing or destroy the circulating pump. Guess there would have to be a substantial percentage of ATF in the mix too....

EDIT: Forgot....It holds 2.5 gal of ATF, before I put in the new, I threw in 2 quarts of diesel fuel....

Again, wish I -knew- the most probable cause here, but maybe I'll end up taking it apart to discover it, then cleaning off any sludge, or fixing hardware from that point.

...Lets see......then I can charge franklynb an absurd ammount of payola for the secret cure!

Originally Posted by dkmc

....It holds 2.5 gal of ATF, before I put in the new, I threw in 2 quarts of diesel fuel....[/COLOR]

Again, wish I -knew- the most probable cause here, but maybe I'll end up taking it apart to discover it, then cleaning off any sludge, or fixing hardware from that point.

...Lets see......then I can charge franklynb an absurd ammount of payola for the secret cure!

"As long as I owe you, you'll never be broke!"

Right about now, I'd send you a paypal fee for finding my serial number...

I checked for fluid in the reservoir that is on the driver's side of the lift; its DEAD empty.
Here's some sort of strange filler bottle contraption that is located atop this
tank:

Its located at the front edge of the hood opening. The tank on the "passenger" side of the
machine has some pretty black oil in it, and its obviously connected to the hydraulic pump, mounted on the water pump end of the engine with a pair of belts... and since the mast lifts and tilts, I'm thinking this has to be hydraulic tank -- obviously needing a fluid exchange!

I can see the flywheel through a couple of different "inspection" ports on ether side of the bellhousing; and it appears to be missng the lower bellhousing guard. If its a "wet clutch" design, I'd expect this to be a closed unit ?!?!?!?

Of course, if there actually IS a "fluid drive" style enclosed torque coupler, perhaps I'm looking in the wrong place. maybe its IN the transmisson, from clues in your previous post <thanks!>

The pressure cap on theabove tank filler has me baffled ... why would it need a safety clasp? I can't wait to buy a manual for this thing! <danged serial number ... where are you hiding?.>

All feedback appreciated.

--frankb