breaking shear pins on Agrex spreader

[Builder]

Used a new Agrex spreader for salt/limestone chips in snow removal biz over the winter. Must have gone thru 25 shear pins. They were the small ~3/16" hollow split pin drilled through the spinner and through the vertical spinner shaft. Jumped up to a hardened bolt, broke those, too. Drilled spinner & shaft out to 5/16". Broke soft bolt in 5 minutes. Jumped up to grade 8 bolt and too my surprise, broke them too. Can't figure this one out. Nothing seems abnormal, PTO spins shaft freely. I baby the PTO when I turn it on. Not bumping spinner into anything. Can't go any bigger on the bolt, or it'll weaken the spinner shaft too much. Can't imagine what could possibly be causing a 14" spinner to shear through bolts that hard. Even the agitator in the hopper has a small shear pin and I only broke 2 of them, but the agitator has to churn up 1,000 lbs of material, so that's understandable.

 

[Glen Watkins]

What did the dealer/manufacturer have to say about it? Doesn't sound good!

 

[Builder]

Dealer wants it back to take a look. Just a hassle when you need it, all the driving & BS.

 

[greg_g]

What is the PTO horsepower rating of the tractor on which the spreader is mounted, and what is the input horsepower rating of the spreader transmission? Also, what is the rated hopper capacity of the Agrex? I ask, because you mentioned 1000 pounds, and Agrex makes spreaders rated between 330 and 1100 pounds.

Salt/limestone chips - individually or mixed - are quite dense, more so when cold and wet. I suspect the agitator simply can't turn in all that dense stuff, hence the busted bolts. Granted, the manufacturer may specify the max capacity of the hopper, but it doesn't actually mean you can always spread a full hopper.

The spreader's I've owned have fine print in the instructions that told me how many pounds of what kind of material the agitator extension was capable of handling. I could fill mineto the top (or max weight capacity) with seed or dry pelletized lime, no problem.That stuff doesn't require the agitator extension. The agitator extension on the other hand is used with stuff that clumps. As such, no way could mine spin in a hopper full of ag lime (powdered) or sand for example, especially if the sand was wet. I had to throw reduced hopper loads of the heavy stuff that clumps, and I suspect the same may be true for your cold/wet salt and grit

//greg//

 

[TracTrac]

Have you tried lowering the rpms? More rpms=more torque.
I want to say remove or modify the agitator, but I'm not familiar with your brand so I won't say that.

 

[Builder]

The agitator shear pin is not giving me trouble, the circular spinner shear pin is. The spinner broke ~25 shear pins up to 5/16" grade 8 bolts. The agitator broke a few very light shear pins.

The agitator has a much tougher job trying to spin in all that heavy material. The spinner has almost no load at all on it, yet eats shear pins for lunch.

 

[greg_g]

Ok, we use different terms then. I call that small one at the bottom the scraper, and call the removable extension the agitator. Perhaps you're looking at a bent/crooked transmission output shaft that is causing the scraper to bind. Have you watched what it's doing (without the agitator attached) when the hopper's empty?

//greg//

 

[Builder]

Yeah, looks perfect. Spins like a top. No excessive wobble.

 

[Glen Watkins]

Will the dealer swap it out for a new one?