The Woolshed.

This is the engine that drives the shearing gear.  It is a Lister.
Oil circulation within the engine is by splash.  Starts with a crank.
            The carbeurettor (to the left of the engine) is a piece of pipe
with petrol dripping in to the airstream.   Magneto ignition.
Single cylinder.  No rings.  About 300cc & 600 RPM.
Cooling is by convection into a tank holding about 100 litres of water.
 Might be half a horsepower.  But strong enough for the job.