working on a 680k right now, had to reseal the pump with the trans filter due to previous owners crappy seal job, noticed it leaking when neighbor bought it, he was told everything works but wont go forward or reverse i checked out out found the shift spool stuck, freed it up and got the machine to move, drove it and told the neighbor, he went to drive it wouldn't move, i went back and in fact it would go in gear, brakes would release but it wouldn't move neither did drive shaft it just free spun by hand which tells me its not actually shifting into gear but can see that the spool is, sensor is disconnected on valve body
i believe my issue is the clutch cut out, when i pull the lever up it does nothing, i would assume to hear air pressure of sort from it. hose seems okay to brake but seeing pictures now the line from lever that goes to spool is on the side not on top
If it worked ok with the hoses connected the way they are, it is quite possible the clutch cut-out cylinder needs servicing. In the service manual, the procedure starts in section 6210, page #129.
Started it up this morning and it drove about 20 ft thought maybe it’s okay, shut it down, started it up again and wouldnt move, can tell I’m in neutral as drive shaft spins with wheels in the air. Only thing I can think of is lock out, they don’t make access very easy to if
If the driveshaft is turning like you describe, are the wheels turning also ? Driveshafts don't spin if the shuttle and /or gear box are in neutral. You cannot simply by-pass the clutch cut-out. If the valve spool is in the neutral position it will stay there unless it is moved by the cylinder assembly that operates it. Earlier model 680's had an exposed rod that could be moved by hand to operate the "clutch" cut out.
The service manual I have it explains yes wheels spin when I spin drive shaft, im assuming air pressure is what actives the cut out?
I wish the machine was closer it’s an hour away, for some reason when I started it up yesterday morning it moved about 20-30 ft I stopped when to move again and acted like it wasn’t in gear
This one does not have an exposed spool, has the switch for the cut out that attaches to the Treddle valve on left brake, and line that goes to it but seeing diagrams I think previous owner broke off the air line to the cut out cylinder
I am aware that the G's don't have an exposed spool control. If there isn't any air going to the cylinder you are never going get the transmission to stay in or out of gear. Repair the air line going to it and see if that fixes the problem. If it I suspect there may be a problem within the cylinder assembly or in the transmission control valve.
Thank you, hope to get back out there this week ! Hopefully it’s just air line not to sure how I will get to it tho it’s sure is tight fit with no access
There is always access to things like that cut-out cylinder. You just have to remove everything that prevents getting to it. I had to remove the batteries and the tray that holds them to get to the control valve on my 680CK.
I will take a look! Batteries are on that side so here’s to hoping! Thank you
I'm guessing that there is a broken spring on the clutch cut-out plunger. That would explain why the tractor goes and stops randomly. Easy to determine after you remove the air operated control cylinder. The air line may have been removed to enable the transmission to go into gear.
Thanks, I’m hoping something like that, just gotta get it to be able to drive on a float so it can be moved closer to me, that would explain why it’ll move sometimes then acts like it’s not in gear seconds later
If the hyd's. work, use them to push/pull it on a trailer.
So finally Got time to get out to the backhoe, looked at battery box and there is not access to clutch cut out, just frame and air line seems to be inserted properly, assuming I have to remove valve to gain access to cutout Of cutout
The lever that connects the hose from brake valve and cut out should have air pressure going to it no? I removed the line that goes to cut out and flipped the lever up and down but herd no air
With 120 psi of air in the tank you need to step on the brake pedal to supply air to the cut-out valve. That is what throws the transmission into neutral. When the cut-out valve (the one with the lever) is in the position to block any air from going to cut-out valve on the transmission the tractor should move in both directions. If it doesn't move then you will need to determine if the clutch cut-out cylinder ( the one on the transmission control valve) has a problem or if it is the spool it controls.
Max I see air pressure gauge get to is around 75, I removed the valve body and will check cutout cylinder tomorrow, anything in particular I should look out for? The shift and range spools move up and down very easily, I thought there would be a little force behind them when pushing in or pulling up to select gear but they just slide in and out on their own
Is the shuttle full of oil ??? The engine should be idling and the oil warm before checking it. The dipstick is covered with a removable steel plate in the floorboard. There is a plug in the bottom front of the shuttle case the has a filter screen behind it. I would suggest removing it and cleaning it. Verify that cut-out assembly is clean and free to move. Hopefully it is simply bound up with dirt. If the problem isn't there it may be the spool in the valve.
I have a different style valve assembly Don’t have shuttle shift just fnr and H&l Cleaned cut out and spool all move freely will remain install this weekend
It was always called a shuttle until the 680K's came out. Then it is referred to as a forward and reverse transmission. I have a bad habit of calling all of them shuttles. My bad ! I referenced a 680G control valve. It was the center spool and the the spring that pushes it that you say moves freely, correct ? Have you checked the control valve and determined if it is functioning ? Be absolutely certain the stop for the cut-out spool is in place when you reinstall the spool.
Not a problem! Yes all seems to move freely, If was to give it compressed air would I see it move, didn’t see a spring in there, just a poppet style plunger that moves freely so removed the clip and removed the spool and cleaned and re installed.
Although you can move the spool by hand, when the control valve is assembled and bolted to the transmission, the spool won't move if the (#24) spring is missing or broken. If the spring is missing or broken, the air control cut-out valve won't work either. That spring has to push the spool against the plunger in the air operated control valve. That would explain why the tractor moves intermediately. Make sure the hex plug (#23) is in the spool to.