Proell Governor and Valvegear
The Proell Governor was used either on its own controlling a throttle valve or other valvegear, or as part of the Patented Proell Governor and Valvegear.
Governor
This shows the 'stand alone' Proell governor minus drive pulley or sprocket on the input shaft, the lever to the left transmits governor movement to whatever speed control mechanism is fitted to the engine, the handwheel on the right varies the governor setting to alter the governed speed.
This shows the geometry of the governor both at rest and at speed (dotted lines)
Valvegear
The Proell valvegear used a rocking or reciprocating movement developed from an eccentric on the crankshaft to provide timing and lift for the steam inlet valves, these were a form of drop valve and the rocking action imparted to the lever lifted them off their seats allowing steam into alternate ends of the cylinder, the amount of lift and length of opening time is controlled by a trip mechanism which in turn is controlled by the governor position.
The sectional view above shows Proell's governor and valvegear used together, I will describe how this works in the future - watch this space.