To start the engine, the driver eases open the steam throttle valve until the in-
The driver cannot see the beam, instead he relies upon observation of movement of the plug rod. When the beam has completed about half of its travel, with his left hand, the driver grasps the equilibrium valve lever to prevent it from dropping, then with his right hand, he depresses the exhaust valve lever. This releases the equilibrium valve lever, which without the driver’s intervention, would open the equilibrium valve fully and allow the in-
The driver repeats the above cycle of controlled action until the water pump is primed (i.e. delivering water). He can tell this has occurred by observation of the return stroke but it is also normal at Crofton to have an assistant watching the launders to confirm that there is ‘water up’ (the pump is delivering water). Once he has ‘water up’ the driver can safely allow the equilibrium lever to fall without manual constraint. Throughout this part of the start, the driver is also monitoring development of the vacuum, which he does by watching the vacuum gauge on the wall behind him. He can also gauge the vacuum by the response of the engine during the power stroke. Once he has ‘water up’ and a fully developed vacuum, the driver can begin progressively opening the steam throttle to increase the stroke, until it becomes sufficient for the valves to trip themselves without intervention. The start cycle is then complete and it remains the driver’s job to monitor the stroke of the beam and adjust the steam throttle so as to keep the stroke within acceptable limits, allowing for variations of steam pressure.
Stopping the Engine
At a point in the cycle where the equilibrium valve is full up (steam piston at the top of its stroke), the drive grasps the equilibrium valve lever and holds it there. The engine completes the power stroke and then stops with the in-