Trofimoff valve

Trofimoff valve on goods train steam locomotive no. 41 1144 in closed position. The piston valve heads are up against the support plates. The valve spindle is milled out to enable a better through-flow. The 4 piston rings on the valve heads are clearly visible. The valve on this locomotive has a diameter of 300mm

The Trofimoff valve (German: Trofimoff-Schieber) (also Trofimov, Troffimoff or Trofimof) is a springless pressure-compensation piston valve for steam locomotives.