It consistes of a splined shaft on the tractor which matches a shaft and coupler connected to a powered implement. The PTO shaft on the tractor is driven by the engine through the transmission. Live or continuous PTO was developed so that an implement could be powered while the tractor's transmission was declutched from the engine, or while the tractor was stopped. Massey-Harris' first implementation of live PTO involved a clutch on the differential which detatched power to one of the drive wheels when the operator wanted to stop the tractor but keep the PTO running. This allows complete replacement of the cylinder bore without reboring the block to a larger size.
Sleeves can be either wet or dry .
Wet sleeves are inserted directly into the engine's water jacket to allow for more effecient cooling of the cylinder. Dry sleeves are inserted into a cast bore in the engine block, requiring a thermal transfer between the sleeve and the engine block, and the engine block and the coolant.