Two position three-way valve controls the reversing circuit of single acting cylinder

Fig. a only uses a two position three-way valve. When there is a control signal, the piston rod extends out. When there is no control signal, the piston rod returns under the action of spring force. In Figure B, a two position three-way valve is connected in series to stop the cylinder at any position during the stroke. That is to say, if there is signal B, the piston will stop moving. IF signal B is eliminated, the piston will continue to move. However, due to the compressibility of the gas, its stop position accuracy is low.