They are used for transferring power from the engine of a tractor, via a secondary output on the transmission, to attachments that do not have their own drive, such as a mower or trailer.
A stub shaft with a matching internal spline protruding from the tractor's gearbox connects axially with the PTO shaft's external spline to effect power transmission to the attachment.
Horn's new, high performance tool programme is designed to mill splines on a variety of PTO shafts, including those with standard diameters of 1⅜ and 1¾ inches.
Special milling cutters are available for restricted shaft clearances. The M274 tool holders have an internal coolant supply and 10 double-edged S274 carbide inserts are used. Tool diameter is 63mm.