The 2557 pneumatic control heads, with four compensating regulating valves, were designed for 2 controllable pitch (CP) propeller and engine speed functions. The 2557 can also be used for twin engine, single lever control for CP propeller and engine speed.
The 2556 is available with illuminated side scales, and have a maximum supply pressure of 150 PSI (10.3 BAR) and 1/8" NPT.