Broken Discbine PTO

[sgm98z]

I have a Case IH DCX101 that I just purchased in the spring. I used it for the first time this past weekend and when I would engage the PTO the discbine would shake pretty hard until it got going. Yesterday when I engaged it (I started at low rpm) it actually stalled the tractor. It did this twice so I tried engaging the PTO at higher rpm and snapped the PTO on the discbine (where the PTO shaft universal attaches to the discbine PTO). I checked that the discs turn free which they do. The repair guy said it may be a problem with the tractor PTO/clutch. I don't see how this can be the case since I when I tried to start it at low rpm it stalled the tractor. It seems to me that there something wrong in the discbine. Am I missing something?

 

[Harry in Ky]

You broke the PTO shaft or the input shaft in the first gearbox? (as in number 18 below)

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Assuming your tractor has independent PTO? I think that valve can be engaged slowly with no adverse effect on the clutch pack. I don't think it has any built in modulation as some valves do, so it's operator discretion as to how fast the lever travels to the "PTO on" position. A little "shake, rattle, and roll" is to be expected with all the shafts, gears, boxes, and blades that all go from a static position and up to speed in just a few seconds. There may well be a learning curve to engaging the PTO since it's a new machine to you. Maybe start out at a lower RPM (not at low idle) but not so high as to snap shafts. Maybe experiment a little by moving the lever only part way towards full on for a few seconds until things begin to move then go the rest of the way.

That said, before the shaft broke did the mower (once started) come up to speed and operate smoothly without any obvious out of balance type symptoms? Does the cutter bar seem reasonably quiet considering all the moving parts? No blades hitting each other as the machine speeds up or slows down?

 

[zzvyb6]

pto shaft assembled incorrectly? sounds like its not phased correctly. bought new or used (as in "worked as intended just before it stb'd.").

 

[sgm98z]

Thanks for taking the time to comment. It's a used unit. I'm not familiar with the phasing of pto shafts. Could you elaborate?

 

[sgm98z]

You broke the PTO shaft or the input shaft in the first gearbox? (as in number 18 below)

Gearbox, Step-up | Case IH | MyCNH US Store

Find schematics, manuals, specifications and diagrams for GEARBOX, STEP-UP. Find genuine OEM parts for your needs.

www.mycnhstore.com

Assuming your tractor has independent PTO? I think that valve can be engaged slowly with no adverse effect on the clutch pack. I don't think it has any built in modulation as some valves do, so it's operator discretion as to how fast the lever travels to the "PTO on" position. A little "shake, rattle, and roll" is to be expected with all the shafts, gears, boxes, and blades that all go from a static position and up to speed in just a few seconds. There may well be a learning curve to engaging the PTO since it's a new machine to you. Maybe start out at a lower RPM (not at low idle) but not so high as to snap shafts. Maybe experiment a little by moving the lever only part way towards full on for a few seconds until things begin to move then go the rest of the way.

That said, before the shaft broke did the mower (once started) come up to speed and operate smoothly without any obvious out of balance type symptoms? Does the cutter bar seem reasonably quiet considering all the moving parts? No blades hitting each other as the machine speeds up or slows dow

You broke the PTO shaft or the input shaft in the first gearbox? (as in number 18 below)

Gearbox, Step-up | Case IH | MyCNH US Store

Find schematics, manuals, specifications and diagrams for GEARBOX, STEP-UP. Find genuine OEM parts for your needs.

www.mycnhstore.com

Assuming your tractor has independent PTO? I think that valve can be engaged slowly with no adverse effect on the clutch pack. I don't think it has any built in modulation as some valves do, so it's operator discretion as to how fast the lever travels to the "PTO on" position. A little "shake, rattle, and roll" is to be expected with all the shafts, gears, boxes, and blades that all go from a static position and up to speed in just a few seconds. There may well be a learning curve to engaging the PTO since it's a new machine to you. Maybe start out at a lower RPM (not at low idle) but not so high as to snap shafts. Maybe experiment a little by moving the lever only part way towards full on for a few seconds until things begin to move then go the rest of the way.

That said, before the shaft broke did the mower (once started) come up to speed and operate smoothly without any obvious out of balance type symptoms? Does the cutter bar seem reasonably quiet considering all the moving parts? No blades hitting each other as the machine speeds up or slows down?

It would be the input shaft in the first gearbox. It where the U joint attaches on the implement side rather than the tractor side. The tractor is a NH 6640. There's a large round button that I push and turn to engage the pto. I started at idle and it stalled the tractor twice so I increased the RPM and tried again which snapped the input shaft.

The day prior I cut almost 20 acres with it and although it started rough each time it did smooth out once the mower reached the higher rpms and I didn't notice any balance issues. The blades didn't hit each other and the discs all turn smoothly at all speeds.

Hope this makes sense and thanks for taking the time to comment.

 

[Harry in Ky]

You didn't mention the tractor model. All I saw was the Massey 255 listed. They are manually controlled. The 6640 is solenoid operated and as such will engage with little or no control on your part. There may be a way to soften that engagement but it would take some creative engineering to do so. I think there is a test port for PTO clutch pack pressure. If so it could be done should you care to try that. I've done it on other tractors with external lines involved. (I need to confirm the existence of that port before pursuing that idea) Other than that I'd say it's a matter of experimenting with different throttle positions/engine RPM to achieve a startup at the lowest RPM possible without stalling the engine.

 

[5030]

I presume it's a side swing, not a center swing. Did you open it up (tongue) prior to engaging the PTO? Usually rough turning is indicative of acute angles in the drive shaft and I have to bump up my pto slightly on my M9000's to get my discbine rolling. Never broke a pto shaft yet on mine actually.