Regulator

Regulator is a control device found in steam engines . It serves a similar function to throttle in other powertrain types . Regulator sets the flow of steam from the boiler to the steam chest. Steam chest is an intermediary reservoir from where it can be admitted, using cutoff , to the vehicle's cylinders and propel the vehicle.

The regulator does not directly control a vehicle's acceleration. Rather, steam chest in combination with cutoff does, which is why it has a dedicated gauge to read pressure from. When the regulator is closed, steam stops flowing to the chest, but the vehicle stills accelerate until the chest runs out.

Delay in regulator operation doesn't need to exist only when closing it. If a vehicle uses an early version of superheaters, time it takes from opening the regulator until the steam chest start charging is delayed, too.