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.

 

[jonsstihl]

I always use extremes also when I am thinking a project through. it helps me visualise what is happening. and makes it easier to spot mistakes with dimensional factors.

 

[Sawyer Rob]

True, but there shouldn稚 be an increase of damaging the chipper.

Agreed, but the post I was quoting was so general, it just needed to be corrected.

Using a chipper, other than when first starting out, a bigger hp tractor shouldn't be a problem. You just have to be carful not to engage the pto too forcefully.

SR

 

[k0ua]

I always use extremes also when I am thinking a project through. it helps me visualise what is happening. and makes it easier to spot mistakes with dimensional factors.

I often use the 10,000 pounds of ballast weight on the 3 point when I am trying to demonstrate to an "unbeliever" that putting weight on the 3pt. REALLY DOES unload and take weight off of the front axle. This concept will still be debated by some people that cannot wrap their head around the concept that a tractor is a teeter totter with two fulcrum points. The front axle and the rear axle.

So put 10,000 pounds of weight behind the rear axle and tell me the front axle won't lift skyward. But if you just put a 1000 pounds out back, many will erroneously debate that it doesn't remove even a pound of pressure on the front axle. They cannot see it, but the 10,000 pound example will usually get them to thinking. Another absurd example is to put a 100 foot boom pole on the 3 point and then put 100 pounds of weight at the end of the 100 foot boom pole. Think about that one for a bit. Yes, using absurdity to explain the logical, can work to enlighten.

 

[JDAOWNER]

I THINK MOST TRACTORS WILL GIVE YOU AN ENGINE PRM --ON TACH-- TO ACHIEVE THE CORRECT PTO SPEED--540 OR 1000. IF YOU RUN THE TRACTOR AT THAT RPM, IT SHOULDN'T MAKE ANY DIFFERENCE WHAT THE HORSE POWER IS AS LONG AS IT'S BIG ENOUGH. IMO

 

[CalG]

When I overload the chipper shredder with tops or fibrous material while driving with the 15 hp tractor, the tractor engine bogs.

When the overloading occurs when the chipper shredder is being driven by the 35 hp tractor, the duplex drive belt slips (squeals and smokes to get my attention in doing so)

Sort of an overload slip clutch with a short service life ;-)

 

[oosik]

My PTO engagement lever on my M6040 can be feathered. So with the tractor at idle - no problem getting the chipper spinning. This is the DIRECT opposite of the PTO on my JD riding mower. JD is electro-mechanical. It's either on or off. Pull the button - you are 100% engaged. No slipping, no feathering, no easing into rotation.

 

[JethroB]

I have wondered about this and understand the argument that the shear pin should do its job regardless of HP used. I still have this nagging thought that some excess power or jolt is going to ‘slip through’ before the pin shears. Electrical fuses and surge suppressors come to mind. A 1 million volt lightening strike isn’t going to be stopped by a little fuse or small UPS. (extreme example).

Call me daft but I still will not allow my nephew to borrow my 65 HP rated 5 ft Bush hog to use on his 100 HP JD.

 

[Reb954]

I often use the 10,000 pounds of ballast weight on the 3 point when I am trying to demonstrate to an "unbeliever" that putting weight on the 3pt. REALLY DOES unload and take weight off of the front axle. This concept will still be debated by some people that cannot wrap their head around the concept that a tractor is a teeter totter with two fulcrum points. The front axle and the rear axle.

So put 10,000 pounds of weight behind the rear axle and tell me the front axle won't lift skyward. But if you just put a 1000 pounds out back, many will erroneously debate that it doesn't remove even a pound of pressure on the front axle. They cannot see it, but the 10,000 pound example will usually get them to thinking. Another absurd example is to put a 100 foot boom pole on the 3 point and then put 100 pounds of weight at the end of the 100 foot boom pole. Think about that one for a bit. Yes, using absurdity to explain the logical, can work to enlighten.

I was going to let this go but I can't help myself.

The question isn't if that scenario will take weight off the front axle, it's when will it take weight off the front axle and when will it add weight to the front axle? Use your scenario but add an additional 20,000 lbs. to the bucket. The fulcrum just changed from the back axle to the front axle and your 10,000 lbs. on the back added to the weight now on the front axle. But we all know it is absurd to think anyone would ever actually put any amount of load in the bucket of their tractor.

Back to your regularly scheduled program.

 

[k0ua]

I was going to let this go but I can't help myself.

The question isn't if that scenario will take weight off the front axle, it's when will it take weight off the front axle and when will it add weight to the front axle? Use your scenario but add an additional 20,000 lbs. to the bucket. The fulcrum just changed from the back axle to the front axle and your 10,000 lbs. on the back added to the weight now on the front axle. But we all know it is absurd to think anyone would ever actually put any amount of load in the bucket of their tractor.

Back to your regularly scheduled program.

I see your 20,000 lbs in the bucket, and to keep those rears on the ground I raise you 30,000 lbs on the 3pt. Now your stinking 20,000 lbs is up in the air... And I may break out the 100 foot boom pole too...

 

[k0ua]

Whoops.. Our tractor chassis just exploded in a hail of cast iron. :shocked: