forklift powershift no-go after sitting

Early 80s vintage forklift with a powershift transmission. It has served me well since purchased well-used 12 years ago (from another PM member). Of late I'm seeing a "no go" problem when I trying using it after it's been sitting awhile (which it often the case). I'll put the tranny in forward or reverse and absolutely nothing happens, not even any perceptible change in engine speed whether idling or at high revs. Then after a bit it's suddenly working. No such luck this morning.

This time I used a tow strap to give it a sharp yank with a 4WD drive truck. It didn't want to move at first (whereas I can usually tow it easily on the smooth concrete it was parked on) but then suddenly was rolling free, and at that point I could drive it normally (normal for this old girl anyway); transmission engages, inching pedal works, etc.

I don't think it's brakes sticking because (a) I never leave the parking brake engaged and (b) you can feel the engine react, even with brakes on, when it's working normally. It also didn't get below freezing last night, though I have known drum brakes to stick in warm weather. But, the brakes are the newest part of this forklift as I completely redid them (it's not a very level property and brakes are essential) and deliberately didn't run the shoe adjusters very tight.

Tranny has fluid, which was changed just a couple of years ago.

I wouldn't hesitate to tear into a gear transmission, but I have no smarts with automatic ones. Any thoughts will be appreciated.

-Steve M.

What kind of fork.....Hystermatic...or maybe one of those awful pedal valve shift things..........anyhoo.....equal in both directions?...or just one?.........First place to check is the brake valve .......most people disconnect the brake valve .....but just make sure its in the drive position.

Sounds like transmission is losing prime and not picking up oil. not sure what to do to fix it though….

That would be very unlikely,unless the filter is clogged with material off the clutch plates.........the old D9G s and Hs ,the tranny pump was several feet above the sump ,and sometimes it would take 5 minutes to pick up oil.......once it did though ,you were good to go ,even if clutch and lube pressures were well down.

Dont be afraid of tearing into that, it is way more simple than a car automatic, all these are is forward and reverse. Just some clutch disks and new seals, easy to do.
I got a repair kit from Joseph industries (not Jason) for a borg warner velvet drive on one of my pieces of equipment. Had a few questions on some simple things since I had never been inside any kind of auto box and they were very helpful on the phone.
The hardest part of the job might be identifying what model trans you have....or pulling it
edit: this is wrong link, they do hoses etc----https://www.jasonindustrial.com/about/----Wrong link
Here is the correct link to Joseph industries that does industrial trans stuff: https://www.joseph.com
All they do is industrial equipment, no cars

Edit to correct wrong link - from Jason to Joseph

The Velvet drive is the simplest powershift ever made ,although I knew a guy stuff one up by leaving out the three little bars that act as splines .........no damage ,but meant a second strip and rebuild.............All these trannys are "Power Shifts " ,not automatics.......sometimes they have a shift inhibitor ,so they cant be reversed at high engine speed.

john.k said:

What kind of fork.....Hystermatic...or maybe one of those awful pedal valve shift things..........anyhoo.....equal in both directions?...or just one?.........First place to check is the brake valve .......most people disconnect the brake valve .....but just make sure its in the drive position.

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It's a Pettibone-Mercury GA-50. When the "no go" happens it does nothing in either forward or reverse. By "brake valve" you mean the hydraulics for the inching pedal (leftmost pedal that applies the brakes and puts transmission in neutral at the same time)?

I use the inching pedal all the time, and the brake pedal pretty much never. This forklift would be unusable without it ... it runs, but not all that well and I would not be able to move it at all smoothly otherwise.

Rob F. said:

Dont be afraid of tearing into that, it is way more simple than a car automatic, all these are is forward and reverse. Just some clutch disks and new seals, easy to do.
I got a repair kit from Jason industries for a borg warner velvet drive on one of my pieces of equipment. Had a few questions on some simple things since I had never been inside any kind of auto box and they were very helpful on the phone.
The hardest part of the job might be identifying what model trans you have....or pulling it
Here is a link: https://www.jasonindustrial.com/about/
All they do is industrial equipment, no cars

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Good info, thanks. With this forklift I should be able to easily unbolt the cowling and one-piece rollbar cage and hoist the entire engine+tranny up and out. Should be even easier than the engine swap on a ag tractor I did last month, as there are no splines to line up on reassembly (just a short U-joint coupling).

But I have no clue what model of powershift transmission. It could well be a common commodity item, like the hydro pump, but I don't know enough to tell one model from another.

There seems to be consensus that it is a tranny problem. Any idea why the drivetrain seems "stuck" when this happens, and why towing the forklift (temporarily) fixes it?

Seems like something in the tranny is busted .,if its hard to tow ,then frees up...have to come apart......just hope you can get bits for it....TVH is probably the best bet for parts.

Rob F. said:

Dont be afraid of tearing into that, ...
Here is a link: https://www.jasonindustrial.com/about/
All they do is industrial equipment, no cars

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FYI, just called them (630-752-0600, now "Megadyne America"); was told they do belts and hoses only. Also tried 973-227-4904 and got a recording to the same effect. ???

john.k said:

Seems like something in the tranny is busted .,if its hard to tow ,then frees up...have to come apart......just hope you can get bits for it....TVH is probably the best bet for parts.

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I called TVH America (800-255-4109) and as soon as they realized I didn't have an account they transferred me to their "sister company" Minnpar. Mia there was very friendly but not encouraging, though she did take the model and serial number to "send to research".

From my notes I see I bought a part for this forklift in 2013 from Tiffen (I remember talking to an old codger who plowed through paper catalogs). I called them and was told they don't have any powershift parts and are soon going to stop carrying Pettibone parts entirely. But she did promise to E-mail me their complete list of all Pettibone-Mercury parts they do have. Could be handy -- for awhile -- as I have a parts catalog with part numbers.

Yeah, getting parts is the challenge. But then I drive a 27 year old truck and have several machines in my shop 80 years and older.

Nothing rules out moisture build up in the trans fluid causing sticking or even minute rusting of a spool or shuttle in a valve housing. When it does get moving, run it hard awhile, warm it up, drive out moisture.
Perhaps adding some solvent like Seafoam to the trans oil would help evaporate water, unstick spools, etc. Heat in the fluid will evaporate the Seafoam, no harm done.

dkmc said:

Nothing rules out moisture build up in the trans fluid causing sticking or even minute rusting of a spool or shuttle in a valve housing. When it does get moving, run it hard awhile, warm it up, drive out moisture.
Perhaps adding some solvent like Seafoam to the trans oil would help evaporate water, unstick spools, etc. Heat in the fluid will evaporate the Seafoam, no harm done.

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Hmmm ... interesting thought. I generally don't run the forklift for long when I use it, e.g. yesterday I shuffled five cubes of concrete block and that was it, less time on that than I spent getting it moving initially.

I've used Seafoam in engines only. Are you talking about that regular Seafoam ("motor treatment"), or "Sea Foam Trans Tune"?

Steve Marquess said:

FYI, just called them (630-752-0600, now "Megadyne America"); was told they do belts and hoses only. Also tried 973-227-4904 and got a recording to the same effect. ???

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Sorry, I had the wrong company, It is Joseph Industries, Not Jason...
Here is the link: https://www.joseph.com
I also edited my earlier post...

Steve Marquess said:

Hmmm ... interesting thought. I generally don't run the forklift for long when I use it, e.g. yesterday I shuffled five cubes of concrete block and that was it, less time on that than I spent getting it moving initially.

I've used Seafoam in engines only. Are you talking about that regular Seafoam ("motor treatment"), or "Sea Foam Trans Tune"?

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Never heard of trans tune. My thought was the solvent in seafoam (Naphtha and/or Toluene) would help evaporate moisture from condensate. Probably any method that would warm up the trans oil past 140F would be best. That includes a hard run for 30 minutes or more. Cars that have the trans 'cooler' in the bottom tank of the engine radiator have the added benefit of warming trans fluid in cold weather, and driving out moisture. Although complicated, if in fact moisture is causing your problems, a way to heat the trans oil using engine jacket water might solve the issue. Forklifts can live a hard life doing light intermittent duty, while idling a lot of the time.

Rob F. said:

Sorry, I had the wrong company, It is Joseph Industries, Not Jason...
Here is the link: https://www.joseph.com
I also edited my earlier post...

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Eureka ... had a hard time getting through on the phone, but while I was waiting on hold I poked around on their web site and found they show a bunch of part numbers from the old parts catalog I have. For reference:


and


Best of all they actually have at least most of that in stock, including the friction disks and even the gasket and seal kit ($236, a bargain IMHO). Good lead and I think I may find the courage to tear into this if the Seafoam doesn't work. I might as well try that first, far cheaper and easier if it actually works.