PTO's

On Pto for Allison Auto there are 2 types

Constant Mesh - allways running. Hydraulic System dumps flow to Tank via electric operated valve, Switch in cab can switch hydraulics on/off

Or Hotshift - This type of PTO has an internal clutch between PTO output and the drive gear. Clutch is opperated by an electric solenod valve which give the internal clutch pressure to engage.