Chipper What happens if I hook up too much HP to a Woodland Mills Chipper?

[Steelkilt]

I own a Woodland Mills WC68 PTO driven chipper rated for 20-50HP and am considering trading my 50HP tractor for something in the 90-100 range. I would like to avoid replacing the chipper if possible. Both tractors run 540 PTO. As the wood chipper gear box utilizes a shear pin, would I be safe to run the chipper with the higher PTO tractor? Thanks for any advice.

 

[oosik]

You should be OK if - - you are using OEM shear pins and you do not exceed the capacity of the chipper regarding material diameter/size. If you find that you are shearing a large number of pins - bite the bullet and get an appropriate sized chipper.

 

[Egon]

With the proper shear pin in use HP is immaterial.

 

[Motorboatin]

You might want to consider a 540E option if it is available

No need to run the engine at high RPM if you don't need the HP the PTO generates. You can run at 1600 rpm and still get the PTO speed needed

 

[Ortimber]

With the proper shear pin in use HP is immaterial.

This is correct.

 

[Sawyer Rob]

With the proper shear pin in use HP is immaterial.

That really isn't true...

The smaller hp tractor most times will slow down a bit before shearing a pin. Many times it gets through the rough spot before the pin shears.

With the much higher hp tractor, for the same size shear pin, is has to much hp on tap, it shears the pin much faster and you go through more pins.

I've seen this happen many times...

SR

 

[YLee Kioti]

Sounds like opportunity for a test video.........for TTWT......

have you checked in here lately Tim....????...

 

[Egon]

The shear pin breaks when the allowable design force on it is exceeded.

 

[Ortimber]

That really isn't true...

The smaller hp tractor most times will slow down a bit before shearing a pin. Many times it gets through the rough spot before the pin shears.

With the much higher hp tractor, for the same size shear pin, is has to much hp on tap, it shears the pin much faster and you go through more pins.

I've seen this happen many times...

SR

True, but there shouldn’t be an increase of damaging the chipper.

 

[k0ua]

One of the best ways to demonstrate a principal is to use absurdity to make your point. NOW lets hook you chipper to 10,000 Horsepower source. So what happens? Well if you crowd the chipper and throw in material that is too thick and really shove it down its throat the shear pin shears very quickly. AND if you put in normal sized materiel that the chipper is designed to accept, and your feed rate is normal, the chipper just chips the materiel up and the shear pin never shears. So the end result is the chipper works as expected with this new 10,000 hp prime mover. It is going to work the same way with your 100 hp tractor as the power source, If you put in normal material at normal feed rate, the chipper will operate normally. If you over size and over feed the chipper, the shear pin will shear.

Now lets hook your chipper to a 1 Horsepower engine. What will happen is if you shove much more than a small twig into the chipper the engine stalls and the shear pin remains intact. If you shove in small twigs slowly, they are chipped up. But the shear pin never shears because the engine does not have enough torque to shear it.

There, I used absurdity to make a point. I have used this principal to think through many "thought experiments" thru the years.