Overrun clutch for flail mower ?

[Paul Allwood]

For those who know more about this stuff than me (most of you), do I need a PTO overrun clutch when using a flail mower ?

This is for the mower I'm building that will run from the mid PTO that doesn't include overrun protection. On my tractor it's only on the rear PTO.

 

[Runs With Scissors]

I have seen a few “semi- different” definitions of an "over-run clutch"

(and a few different names…i.e. Sprag and One-way clutch, to name a couple)

What are you trying to prevent?

 

[SDT]

For those who know more about this stuff than me (most of you), do I need a PTO overrun clutch when using a flail mower ?

This is for the mower I'm building that will run from the mid PTO that doesn't include overrun protection. On my tractor it's only on the rear PTO.

Hard to say considering you are building your flail mower. No way to know what inertial effect your mower may have.

 

[NCL4701]

You need over run protection in the drive system somewhere. If not, the momentum of the mower will push the tractor when you’re stopping or slowing down. How much mower generated inertial push you’d have is pretty hard to predict, but it would almost certainly fall somewhere between very irritating and quite dangerous. Just an opinion.

 

[Bee-Positive]

I believe the B7200 Mid PTO system is independent (live) of the HST.
Live PTO:
The PTO spins, regardless of what you do with the transmission and transmission clutch. The PTO is connected to the engine directly separate from everything else.
Non-Live PTO:
The PTO is driven off the output shaft (counter shaft) of the transmission, and not the engine. Push in the clutch, and the PTO stops spinning.
You need to be in neutral to separate the PTO shaft from the driveshaft. Hence the nasty habit of bush hogs shoving tractors around by their rotational inertia, and the need for an overrunning clutch.

A slip clutch/shear pin and an ORC do not serve the same purpose.

Having a slip clutch instead of shear bolts would be something to look into for times you hit unseen immovable objects (you know you will).

All that said I would think having an ORC would be a good safety feature if your flail doesn’t have a gearbox with a freewheel clutch.

 

[Russell King]

Doesn’t the mid PTO of the tractor already have an over run clutch built in?

 

[North Idaho Wolfman]

You need over run protection in the drive system somewhere. If not, the momentum of the mower will push the tractor when you’re stopping or slowing down. How much mower generated inertial push you’d have is pretty hard to predict, but it would almost certainly fall somewhere between very irritating and quite dangerous. Just an opinion.

Not on an HST tractor.

 

[North Idaho Wolfman]

For those who know more about this stuff than me (most of you), do I need a PTO overrun clutch when using a flail mower ?

This is for the mower I'm building that will run from the mid PTO that doesn't include overrun protection. On my tractor it's only on the rear PTO.

No you should not need an Overrun clutch on the mid PTO drive.