Abstract: A control valve for construction equipment adapted to operate a control mechanism in which a central by-pass passage is provided with a pilot pressure generating mechanism such as an orifice or the like and which is adapted to generate a pilot pressure due to pressure loss of fluid passed through the pilot pressure generating mechanism when a valve connected to the central by-pass passage is set at an open position, resulting the pilot pressure acting to control a discharge rate of a variable discharge pump. The control valve includes a valve body, in which a first spool and a second spool are arranged in series in such a manner that inner ends of the first and second spools are opposite to each other. An outer end of the second spool faces a second pilot chamber. A centering spring is arranged so as to act on an outer end of the first spool, so that the inner ends of both spools may be abutted against each other and received in a first pilot chamber when the spools are at their normal position.

Abstract: A control valve including a change-over poppet formed into a substantially cylindrical shape, a guide pipe inserted into the change-over poppet, and a load check poppet slidably fitted on the guide pipe. The change-over poppet is formed with a communication hole. A parallel passage is provided so as to communicate through the communication hole and guide pipe with an on-off valve, and between the parallel passage and the on-off valve is arranged an orifice. Opening of the on-off valve causes fluid to flow through the orifice and pressure loss to occur across the orifice to increase a pressure on an upstream side of the orifice, which acts to open the change-over poppet.

Abstract: A fluid control valve so constructed that when a spool arranged in a valve housing is at its neutral position, a neutral passage communicates with a tank passage, whereas when the spool is changed over, communication therebetween is blocked, to thereby supply fluid in the neutral passage to an actuator. The spool is formed with a first oil communication passage communicating with a parallel passage and a second oil communication passage communicating with the actuator. Also, the spool is provided therein with a sub-spool, which is provided on an outer periphery thereof with a land and an annular groove for selectively carrying out communication between the first oil communication passage and the second oil communication passage depending on its moved position. The sub-spool has one end facing a pilot passage, which communicates at one end with the parallel passage and at the other end thereof through an orifice with an on-off valve.