Engine alive, wheels dead

[shak3n]

Mine is a John Deere 3020. The engine fires right up and runs smooth, but once I put it in gear there's nothing transferring to the wheels. No movement forward or backward, just the engine humming along like it's not even connected.
This tractor has been in my family since the late 70s. My dad used it for haying back when I was a kid, and when he passed it down to me a few years ago, I gave it a light refresh, filters, fluids, new tires, and kept it mainly for light work around the property. Yesterday I went to move a round bale, and that's when the issue showed up. I thought maybe I hadn't fully engaged the shifter, but after double checking and trying multiple times, still nothing. PTO spins fine, hydraulics are strong, but the wheels won't take any power.

I've heard everything from clutch packs to transmission disconnects could be at fault, but I don't have enough experience diagnosing drivetrain issues this big, so decided to reach out here

 

[Black_Pesmerga]

Start simple: make sure the disconnect lever isn't half engaged, then check shift linkage. Sometimes pins wear and you're not actually moving the internals even though the lever feels right. If those are fine, yeah, it's deeper... but don't spend on a teardown until you've ruled out the easy stuff.

 

[hauntedvertigo]

Another area to check beyond the disconnect lever and linkage is the charge pump output since weak flow there can starve the main clutch packs and give you intermittent drive loss. Have you put a gauge on the transmission test port yet to see if pressure drops when the problem shows up?

 

[Yorick]

Great tip about checking the linkage and disconnect lever. One more thing to look at is if it's a Powershift, make sure the hydraulic pressure to the clutch packs is good. A bad pressure regulator or a blown seal could be why you've lost all drive, even if everything else seems okay.