Just like on a farm tractor: PTO's were used for countless applications.
Here in the South you should have seen the pulpwood loaders back in the 60's that operated off the PTO.
The trucks just used the bare frame to haul 6 ft. lengths of pulpwood loaded crossways. There was an old car rear-end mounted on the rear of the frame. A long shaft ran to a car 3-speed transmission to give you 3 speeds. Then ran back to the pinion yoke on the car rear end. You cut out part of the housing and made a winch out of it, and used a master cylinder to lock the brakes. The cable ran up to a rig with a swinging arm. Thus...you had a loader with a couple hundred feet of cable to drag the logs out of the woods and load them onto the truck.
