The safety device is connected in series to the throttling portioner. Upon an increase in pressure at one end of floating plunger 1, having channels in its housing at both ends through which hydraulic fluid is delivered to the grid control cylinders, the plunger is shifted, admitting fluid through port a of surplus pressure valve member 2. The fluid, which is directed by the throttling portioner to the side where the grids are already extended, has an outlet so that its flow begins again and plunger 1 is moved back. At this, plunger 1 admits fluid to the side where the grid has not yet been fully extended. When the second grid reaches its extreme extended position, plunger 1 returns to its central position, blocking off the port to the surplus pressure valve member 2.
$4268$CHP,Rg$