Stump Jumper Keeps coming loose

[Bright Raven]

Bushhog 296 Single Spindle Rotary Cutter. Single stump jumper with the usual two blades. The stump jumper is attached to the splines of the gearbox shaft with a washer and castle nut. There is a cotter key through the turrets of the castle nut.

The nut keeps coming loose and shears the cotter key. I have had the stump jumper drop off twice. It is not fun putting it back on. I just checked it after mowing this morning and it is loose again. What is a solution short of welding the dang thing on?

 

[alisonb]

Throw that nut away, it may have slack on it, try a new one...with a high tensile cotter pin/bolt. Make sure the thread is not stripped too. Is the rotary running smoothly or is there a vibration...seems like its picking up stress somewhere.

 

[Bright Raven]

Throw that nut away, it may have slack on it, try a new one...with a high tensile cotter pin/bolt. Make sure the thread is not stripped too. Is the rotary running smoothly or is there a vibration...seems like its picking up stress somewhere.

I am ahead of you. . I just put that new castle nut on Wednesday. It was $25. . Bushhog brand. The threads are perfect. I am on my way now to Fastenall to find a high tensile cotter pin.

 

[alisonb]

If you are sure there is no unusual vibration and the cotter pin shears again you may want to try double nutting it...if there is space...and if this fails, spot weld the D thing :lol:

 

[greybeard]

Worn splines on the stump jumper tapered hub, the gearbox tapered output shaft or both. Will take a pair of digital calipers or a good micrometer to know for sure.
If they are worn to the point that the hub bottoms out up on the shoulder of the output shaft, it's time to replace both the hub and the output shaft.

You need to do some serious and pretty precise measuring while the stump jumper is off to find out exactly what is going on. It's usually not the nut or pin.

 

[TennesseeTuxedo]

I told you a week ago you couldn't fix that.

 

[Bright Raven]

Thanks to all except TT. Lol

 

[TennesseeTuxedo]

Did I lie? Lol.

 

[Bright Raven]

Did I lie? Lol.

I don't know if it will work. The guy at fastenal recommended a Grade 8 Hex Cap Screw with a Nylon Insert Lock Nut (1/4 inch to replace cotter pin). If this don't work, I am tempted to do what Alison recommends. A couple spot welds. Better than replacing the shaft and/or stump jumper.

 

[5S Cattle]

Weld the **** out of it. You have nothing to lose, at this point you'll have to replace everything anyway

 

[TennesseeTuxedo]

Clean as your fields are you don't really need the jumper anyway.

 

[sstterry]

Let me just send you some of my cows to clean those fields. You don't have any weeds!

 

[greybeard]

I told you a week ago you couldn't fix that.

I've fixed more than one including the 6' Modern I have and several that came in to the Kubota dealership I worked for...there were also some that couldn't be fixed short of parts replacement , depending how long they ran with the nut loose, how many times it happened and how bad the splines were worn.
We had one, covered by Rhino warranty even tho it was out of warranty because it was bad metallurgy..they did a bad heat treat when they built the shaft for the gearbox.

 

[hurleyjd]

Throw that nut away, it may have slack on it, try a new one...with a high tensile cotter pin/bolt. Make sure the thread is not stripped too. Is the rotary running smoothly or is there a vibration...seems like its picking up stress somewhere.

I am ahead of you. . I just put that new castle nut on Wednesday. It was $25. . Bushhog brand. The threads are perfect. I am on my way now to Fastenall to find a high tensile cotter pin.

Did you check to see if there was a large washer to make the nut really tight. Nut might be bottoming out and not keeping the blade carrier tight.

 

[Bright Raven]

Throw that nut away, it may have slack on it, try a new one...with a high tensile cotter pin/bolt. Make sure the thread is not stripped too. Is the rotary running smoothly or is there a vibration...seems like its picking up stress somewhere.

I am ahead of you. . I just put that new castle nut on Wednesday. It was $25. . Bushhog brand. The threads are perfect. I am on my way now to Fastenall to find a high tensile cotter pin.

Did you check to see if there was a large washer to make the nut really tight. Nut might be bottoming out and not keeping the blade carrier tight.

Hurley. You are on to something that I have noticed. The assembly only employs one washer based on the parts diagram. But the three times I have fixed it, I notice the nut bottoms out above the hole for the cotter pin. So even though I get it tight - I am using a one inch drive breaker bar with a three foot pipe, the nut has travel space before it engages the cotter pin. It well could be due to wear.

 

[hurleyjd]

Throw that nut away, it may have slack on it, try a new one...with a high tensile cotter pin/bolt. Make sure the thread is not stripped too. Is the rotary running smoothly or is there a vibration...seems like its picking up stress somewhere.

I am ahead of you. . I just put that new castle nut on Wednesday. It was $25. . Bushhog brand. The threads are perfect. I am on my way now to Fastenall to find a high tensile cotter pin.

Did you check to see if there was a large washer to make the nut really tight. Nut might be bottoming out and not keeping the blade carrier tight.

Washer part number from bush hog is 70900

 

[bball]

Item 8 is what hurley is referencing. Still got it?
If so, GB is correct i suspect. Either weld it or replace the worn parts.

 

[greybeard]

Throw that nut away, it may have slack on it, try a new one...with a high tensile cotter pin/bolt. Make sure the thread is not stripped too. Is the rotary running smoothly or is there a vibration...seems like its picking up stress somewhere.

I am ahead of you. . I just put that new castle nut on Wednesday. It was $25. . Bushhog brand. The threads are perfect. I am on my way now to Fastenall to find a high tensile cotter pin.

Did you check to see if there was a large washer to make the nut really tight. Nut might be bottoming out and not keeping the blade carrier tight.

That was the fix that was reccomended to BR last time or first time it happened.
The washer has to have a bigger ID than the end shoulder on the shaft tho iow, Just a tad bigger than the OD of the spline at bottom of the shaft. That will push the stump jumper hub farther up onto the shaft, providing the splines have not worn so badly that the top of the hub bottoms out on the shoulder that is on the top of the shaft.


https://cattletoday.com/forum/viewtopic.php?p=1511279#p1511279

 

[Bright Raven]

Item 8 is what hurley is referencing. Still got it?
If so, GB is correct i suspect. Either weld it or replace the worn parts.

That is exactly it. I ordered it with the castle nut. I think the stump jumper (blade carrier) has worn splines. It probably needs a thicker washer. But now I got it back together. With the grade 8 bolt. If this fails, I am welding the dang thing.

 

[Bright Raven]

I am ahead of you. . I just put that new castle nut on Wednesday. It was $25. . Bushhog brand. The threads are perfect. I am on my way now to Fastenall to find a high tensile cotter pin.

Did you check to see if there was a large washer to make the nut really tight. Nut might be bottoming out and not keeping the blade carrier tight.

That was the fix that was reccomended to BR last time or first time it happened.
The washer has to have a bigger ID than the end shoulder on the shaft tho iow, Just a tad bigger than the OD of the spline at bottom of the shaft. That will push the stump jumper hub farther up onto the shaft, providing the splines have not worn so badly that the top of the hub bottoms out on the shoulder that is on the top of the shaft.


https://cattletoday.com/forum/viewtopic.php?p=1511279#p1511279

I remember that. You are correct.