Why do PTO drive shafts have grooves?

[wwwfarmer]

Basically the title - Why do all PTO drive shafts have grooves? The groove radius varies a little, from 6.7mm to 8.3mm (6.8mm to 8.4mm according to the book I am reading).

 

[K5lwq]

The book should cover that as well. It is so the coupling shaft has a way to lock on the PTO.

 

[oosik]

And - why the different sizes and styles of PTO stubs on tractors. JMHO - it's the style that is used by the PTO shaft manufacturer that is the low bidder.

I'm somewhat surprised that there is some standardization between tractor manufacturers and implement manufacturers. Imagine the problems of - one size/style on tractors and another on implements.

 

[K5lwq]

And - why the different sizes and styles of PTO stubs on tractors. JMHO - it's the style that is used by the PTO shaft manufacturer that is the low bidder.

I'm somewhat surprised that there is some standardization between tractor manufacturers and implement manufacturers. Imagine the problems of - one size/style on tractors and another on implements.

The book probably covers that as well. I mean if it is a book about PTO's they pretty much have to cover everything to get enough pages to be considered a book. Otherwise it would just be a article.

 

[wwwfarmer]

The book probably covers that as well. I mean if it is a book about PTO's they pretty much have to cover everything to get enough pages to be considered a book. Otherwise it would just be a article.

Thanks. I case I haven't made the question clear. These are the grooves that puzzle me:

 

[RickB]

The groove accepts a quick disconnect pin or pinch bolt. That's how the female yoke is retained on the male shaft.

 

[K5lwq]

I am the one that probably was not clear. Rick did a better job.

 

[wwwfarmer]

Ahh I see. Sorry for newbie question. Never attached a pto before.

 

[stuckmotor]

Ahh I see. Sorry for newbie question. Never attached a pto before.

Just FYI the pto shaft on what's left of my Allis Cjalmers WD has a hole going across it's center. I've had couplers with corresponding holes so a bolt could be inserted cross ways and secured with a nut. They might violate some safety rule today but came in handy when the button coupler was out of whack.

 

[s219]

That groove is to lock the collar onto the shaft. Some collars have a spring-loaded pin that you have to release to get the collar on and off. Other collars (usually the ones on the implement end, meant to be attached once and stay there) will have a tapered and threaded pin that you drive through the hole and groove and lock in with a nut. This is what that pin would look like: