[MrBorland]

I am going to assume this was a mod during earlier service

I never thought of that, but makes sense, since I've not yet seen any schematic showing set screws. Custom mod or not, I'll need to find that pin - the yolk was drilled for those set screws, and the hole is bigger than the diameter of the pin (see photo, post 11), so methinks I'd be asking for trouble installing a standard pin. I'll have to replace the yoke if I can't find that pin.

Thanks again

 

[GreenGabby]

Further thought. I don't understand how the set screws solve anything. With the set screws why do you need the pin? The pin isn't doing anything but filling a hole drilled in the input shaft. If the pin does protrude into the yoke and the hole diameter in the yoke is larger than the hole in the input shaft the rocking action between the yoke and shaft is only going to shear the pin again. Personally I feel you may need to replace the yoke to get the correct one on the tractor.

Again, good luck with the repair ... Gabby

 

[MrBorland]

I don't understand how the set screws solve anything...The pin isn't doing anything but filling a hole drilled in the input shaft.

I haven't measured anything yet, but off the top of my head, I sketched out how I think looks. The modified pin is a bit longer than the input shaft, and the cone-shaped set screws screw into the ends of the pin. But yeah, not sure why the set screws were needed.

If the pin does protrude into the yoke and the hole diameter in the yoke is larger than the hole in the input shaft the rocking action between the yoke and shaft is only going to shear the pin again

Correct; which is why I was thinking putting a standard pin in the existing yoke is asking for trouble.

Personally I feel you may need to replace the yoke to get the correct one on the tractor.

I'll take another stab at finding that custom pin - otherwise, I'll have to buy a yoke & pin.

 

[MrBorland]

Drop the driveshaft for a look see.

Just got in for a look-see. Drive pin looks fine to me. I suppose the next step is to button it back up and check pressures?

 

[TUDOR]

Have you corrected the leak mentioned at the start of the thread? Does the transmission work?

 

[MrBorland]

Have you corrected the leak mentioned at the start of the thread? Does the transmission work?

Thanks for checking in. I freed up the check valve plungers, and that stopped the leak, but the tractor still wouldn't move nor the hydraulics work (see post #4). It was at that point, the charge pump drive pin became suspect, which turned out to be ok.

I'm at a crossroads, now - do I re-install the driveshaft and do some pressure testing, or are there things to look at before I re-install the driveshaft? For example, when removing the charge pump, the outgoing implement line was just a smidge in the way, so I disconnected it - I was expecting fluid (or some evidence of it), but looking back, it seemed dry. Is that a clue? The implement check valve didn't seem dry and the pin seemed to be able to move freely. The charge check valve seemed ok as well. I suppose the filter could be clogged, but it's a brand new Wix hydraulic filter. Worst case, I suppose, is that the pump itself is toast.

 

[GreenGabby]

The input shaft to the charge pump is direct drive to the pto output shaft on the top rear of the transmission. If you start the tractor the input and output shaft should both be turning with no activation of the hydrostatic/hydraulic functions. Engage the hydrostats or a hydraulic function. Do both input and out continue to turn? If not you still could have a problem in the input shaft pin.

One other thing to look at. On my 314 after I replaced the charge pump I had similar issue. Nothing worked. A member informed me I installed the pump cover ... key # 8 - https://partscatalog.deere.com/jdrc/sidebyside/equipment/66822/referrer/navigation/pgId/194928 ... upside down. I didn't believe it was possible but after I rotated the cover 180° everything worked fine. Try it ... Gabby

 

[MrBorland]

The input shaft to the charge pump is direct drive to the pto output shaft on the top rear of the transmission. If you start the tractor the input and output shaft should both be turning with no activation of the hydrostatic/hydraulic functions. Engage the hydrostats or a hydraulic function. Do both input and out continue to turn? If not you still could have a problem in the input shaft pin.

Good tip

A member informed me I installed the pump cover ... upside down. I didn't believe it was possible but after I rotated the cover 180° everything worked fine. Try it

Yup - the charge pump is a bit off center between the bolt holes, so everything needs to go back on as it came off. That said, since the yoke was futzed with, I should double-check that the charge pump also wasn't futzed with and put on backwards, in which case, I might've managed to re-install it backwards as well

 

[TUDOR]

Check the shaft on the side of the transmission that controls direction and speed. There is a similar shaft on the other side that must move in harmony. It may only appear as a stub shaft that is flush with the housing, but nevertheless, it should still turn.

Failure to turn indicates that the spring pins locking the shafts together have worked their way out. This is a low cost but high labour time repair since the hydro has to be disassembled. However, this is separate from the implement lift since it only affects the hydro.

Back to the charge pump. The guts of the charge pump cannot be installed wrong. However, if the charge pump cover is installed wrong, the pump parts will conform to the cover and neither the implement lift nor the hydro will function.

 

[MrBorland]

Check the shaft on the side of the transmission that controls direction and speed. There is a similar shaft on the other side that must move in harmony. It may only appear as a stub shaft that is flush with the housing, but nevertheless, it should still turn.

I checked it by moving the shift lever to & fro, and the shift & stub sides move together.

Back to the charge pump. The guts of the charge pump cannot be installed wrong. However, if the charge pump cover is installed wrong, the pump parts will conform to the cover and neither the implement lift nor the hydro will function

According to the manual, the flat side of the casing should be on the relief valve side, which makes it easy to check. I double-checked this morning, and it looks correct.


I need to order to order another yoke/pin, at which point, I'm leaning towards re-installing the driveshaft to take some pressure readings. My gut is increasingly telling me, though, that it's likely the tranny needs to be dropped and the pump rebuilt. On one hand, an unexpected issue, but on another, exactly why I bought this tractor - to learn as much as I can. Getting into a hydro pump is definitely new and something useful to learn.

 

[TUDOR]

Pressures should be zero in the hydro until such time as the charge pump and implement lift system is working. The charge pump ensures that the hydro has fluid to work with.

 

[MrBorland]

Pressures should be zero in the hydro until such time as the charge pump and implement lift system is working. The charge pump ensures that the hydro has fluid to work with.

Right, but do we know for sure the issue is the charge pump? A pressure reading would be diagnostic, no? What if there turns out to be pressure in the charge circuit? - wouldn’t that suggest the hydro pump itself is the issue?

And speaking of weirdness, what are the chances there’s a blockage TO the charge pump? Filter, suction tube, etc. Easy enough to check, I suppose.

Thanks for your & Gabby’s continued help & patience - I really appreciate it 👍

 

[GreenGabby]

Another issue to look at;.does your oil level indicator hose have the breather installed above where you checkt oil level? Breather is between where you check oil level and an adapter back into the transaxle. Without this breather you will not get an accurate oil level in the tube.

Yes there could be a problem with the charge pump but I am checking simple things first. On my 314 I had to swap the pump because the pin between the driveshaft and pump input shaft wallowed out the hole in the input shaft, I was going to replace the shaft but that was a major chore. To replace the shaft required separating the pump from the transaxle. There are some delicate parts in there that need to be handled carefully. I think if these small items do not resolve your issue I would swap the charge pump from your parts tractor. A helper is handy to fit and hold parts being swapped. It's a 4-5 hour job. Replacement pump I used was from a 317. Pumps are universal between closed frame tractors.

Again offering the best with the repairs ... Gabby

 

[TUDOR]

If the implement hydraulics are working, then you might have a reason to to do pressure checks on he hydro.

Charge pump is first on the diagnostic list for a reason. Follow the path of the fluid, reservoir, filter, charge pump charge relief valves, hydro charge relief valves, and last is hydro.

 

[MrBorland]

.does your oil level indicator hose have the breather installed above where you checkt oil level? Breather is between where you check oil level and an adapter back into the transaxle. Without this breather you will not get an accurate oil level in the tube

Charge pump is first on the diagnostic list for a reason. Follow the path of the fluid, reservoir, filter, charge pump charge relief valves, hydro charge relief valves, and last is hydro

Thanks. With the driveshaft disconnected, I've visually inspected the charge pump, relief and check valves and all seem ok. At the back end, the tubing is new, and I had already installed a new breather, but I can check to make sure it's actually doing its job.

When we suspected the charge pump drive pin was sheared, I found it was easiest (and most cost-efficient) to order a replacement charge pump (which came with a pin). As mentioned, the charge pump seems ok, but I swapped it out for the replacement anyway.

Beyond this, unless there's something else to look at, I'm thinking it's time (once I get the replacement yoke & pin) to re-connect the driveshaft to see if the charge pump swap made any difference.