A valve system (13, 15) comprising a stationary valve member, the valve member comprising a cylindrical bushing inside which a cylindrical reciprocal member is provided with a cylinder axis equal to a cylinder axis of the bushing and reciprocally movable inside the bushing along the cylinder axis between a first position and a second position; wherein a transverse canal extends through the stationary valve member and through the bushing; the transverse canal having a first transverse canal section on one side of the bushing and a second transverse canal section on another side of the bushing; wherein the reciprocal member comprises a transverse throughput section for flow of liquid through or around the reciprocal member transversely to the cylinder axis; wherein the throughput section of the reciprocal member is arranged for being remote from the transverse canal in the first position for closing the transverse canal and wherein the throughput section of the reciprocal member is arranged for being aligned with the transverse canal only in the second position for flow from the first transverse canal section through the throughput section to the second transverse canal section, characterized in that a first canal and a second canal are provided in the stationary valve member parallel to the cylinder axis and on different sides of the bushing, wherein the first canal is connected to the bushing through the first transverse canal section, and the second canal is connected to the bushing through the second transverse canal section, and that a rear chamber is provided into which rear chamber lubricant is feed, which rear chamber is connected with the first canal whereby the lubricant flows into the first canal and into the front part of the bushing and from the first canal into the first transverse canal section of the transverse canal, but not through the transverse canal to the second canal due to the blocking of the transverse canal by the reciprocal member in its first position. wherein a transverse canal extends through the stationary valve member and through the bushing; the transverse canal having a first transverse canal section on one side of the bushing and a second transverse canal section on another side of the bushing; wherein the reciprocal member comprises a transverse throughput section for flow of liquid through or around the reciprocal member transversely to the cylinder axis; wherein the throughput section of the reciprocal member is arranged for being remote from the transverse canal in the first position for closing the transverse canal and wherein the throughput section of the reciprocal member is arranged for being aligned with the transverse canal only in the second position for flow from the first transverse canal section through the throughput section to the second transverse canal section, characterized in that a first canal and a second canal are provided in the stationary valve member parallel to the cylinder axis and on different sides of the bushing, wherein the first canal is connected to the bushing through the first transverse canal section, and the second canal is connected to the bushing through the second transverse canal section, and that a rear chamber is provided into which rear chamber lubricant is feed, which rear chamber is connected with the first canal whereby the lubricant flows into the first canal and into the front part of the bushing and from the first canal into the first transverse canal section of the transverse canal, but not through the transverse canal to the second canal due to the blocking of the transverse canal by the reciprocal member in its first position.