[135] Delockable non-return valve

The 4/2-way valve is actuated, the hydraulic fluid passes through the non-return valve against the force of the return spring and the piston rod advances. When the 4/2-way valve is reset, the outlet on the piston side is closed by the non-return valve, and the cylinder remains advanced. The 3/2-way valve is now actuated, the pilot piston is reversed and the outlet flow released; the piston rod begins to retract. During the return stroke, the 3/2-way valve is brought temporarily into its normal position. This causes the outlet to be closed again, and the piston rod and load remain in their current position. When the 3/2-way valve is actuated again, the piston rod travels to its retracted end position.