Patent ID: 8667884

Claim:
A hydraulic valve device comprising: a double acting hydraulic motor (D), in particular a double acting hydraulic cylinder, with a first engine port (L) and a second engine port (N); a tank (T); a pump (I); a hand valve (H), connecting the first and second engine ports (L, N) to the tank (T) and the pump (I), said hand valve (H) having first and second open positions, wherein, in the first open position, the pump (I) is connected to the first engine port (L) via a first line (F), and the tank (T) connected to the second engine port (N) via a second line (G), and wherein, in the second open position, the pump (I) is connected to the second engine port (N) via the second line (G), and the tank (T) is connected to the first engine port (L) via the first line (F); a first nonreturn valve ( 1 A, 8 ), arranged to operate between the pump (I) and the second engine port (N) and opens towards the second engine port (N); a piston ( 2 ) that, by means of a load pressure in the first engine port (L) via a third line (E), governs the first nonreturn valve ( 1 A, 8 ), such that the first nonreturn valve ( 1 A, 8 ) is kept closed as long as a pump pressure does not exceed said load pressure; a second nonreturn valve configured to, as long as the hand valve (H) is in the second open position, connect the first engine port (L) to the second engine port (N) and opens in a direction towards the second engine port (N); and a back-pressure valve ( 4 ) on a fourth line (K) towards the tank (T) to create a resistance in said fourth line (K) towards the tank (T).