# Shear bolt and slip clutch



## JGPenfield (Mar 10, 2016)

Do all rotary cutters have a shear bolt or do some have a slip clutch only with no shear bolt? I know you can add a slip clutch on so you don't keep breaking shear bolts. But a slip clutch without a shear bolt sounds dangerous because the slip clutch can freeze up and not slip and without the shear bolt you have nothing to protect your tractor. 
One other question. I thought tractors only went from category 0 to 5 and 5 was only for the swinging drawbar. But I saw a rotary cutter that said it had a category 6 CV drive. Can someone explain what a CV drive is and what the categories mean? It must be different from the categories for the three point hitch.


----------



## deerhide (Oct 20, 2016)

Some have only a slip clutch. If it 'seizes up', which they are unlikely to do, your tractor will stall out before it does damage.
Tractors are Cat 0, I -II -III although I have never seen a Cat. III. The Category number is a rating for the 3pt hitch and the pto (usually lift pin size or pto shaft size). the rating goes up with horsepower(vague explanation). It is very important that the shear bolt is kept TIGHT, not loose at all, use a locknut or lock washer. A CV drive seems to me to id. a 'constant velocity' joint; an improvement(questionable) on a universal joint, which your brush cutter has 2 or 3 of.


----------

