A load-controlled hydraulic supply for an attachment attached to an agricultural tractor includes a hydraulic high-pressure source providing a volume flow in a supply line, a return line leading to a hydraulic reservoir, and a load-indicating line connected to a device for pressure limiting. The volume flow is adjusted based on pressure feedback prevailing at the load-indicating line.

An actuator includes a casing having a first annular groove formed in an inner peripheral portion thereof; a piston having a second annular groove formed in an outer peripheral portion thereof, provided in the casing to form a pressure chamber together with the casing, and driven by a drive fluid from an outside of the actuator; and an annular seal member having a first fitting portion to be fitted into the first annular groove and a second fitting portion to be fitted into the second annular groove to seal the pressure chamber.

An actuator includes: a casing; a pressure reducing valve and a piston. The pressure reducing valve is provided in the casing to reduce a pressure of a driving fluid supplied from an outside of the casing to a predetermined level. The piston is provided in the casing to form a pressure chamber together with the casing. The piston is driven by the driving fluid that has been pressure-reduced to the predetermined level.

A valve device with pressure-reducing function, comprised of at least one logic valve (V1); one lock valve (V2); and one pressure-reducing valve (V3),
wherein the inlet (1) of the logic valve (V1) may be connected to a pressure supply source (HD), characterized in that the outlet (V1.2) of the logic valve (V1) and the outlet (V3.1) of the pressure reducing valve (V3) are connected together to an outlet or user port (A); and that the lock valve (V2) is connected with its inlet (V2.1) to the inlet (V1.1) of the logic valve (V1) as well as to a control side (V1.3) of the same, and with its outlet (V2.2) to an inlet (V3.2) of the pressure-reducing valve (V3).

An example valve includes: (i) a pilot seat member comprising a first channel and a second channel, a pilot seat, and a pilot sleeve portion comprising a pilot chamber and a cross-hole; (ii) a pilot check member disposed in the pilot chamber and subjected to a biasing force of a setting spring, wherein the pilot check member is configured to be subjected to fluid force of fluid in the second channel; and (iii) a solenoid actuator sleeve slidably accommodated about the pilot sleeve portion, wherein the solenoid actuator sleeve comprises a cross-hole and an annular groove, wherein the cross-hole of the solenoid actuator sleeve is fluidly coupled to a second port of the valve, and the annular groove is configured to selectively fluidly couple the first channel to the second channel based on a position of the solenoid actuator sleeve.

An example valve includes: (i) a pilot seat member comprising a first channel and a second channel, a pilot seat, and a pilot sleeve portion comprising a pilot chamber and a cross-hole; (ii) a pilot check member disposed in the pilot chamber and subjected to a biasing force of a setting spring, wherein the pilot check member is configured to be subjected to a fluid force of fluid in the second channel; and (iii) a solenoid actuator sleeve slidably accommodated about the pilot sleeve portion, wherein the solenoid actuator sleeve comprises a cross-hole and an annular groove, wherein the cross-hole of the solenoid actuator sleeve is fluidly coupled to a second port of the valve, and the annular groove is configured to selectively fluidly couple the first channel to the second channel based on a position of the solenoid actuator sleeve.

A control system for construction machinery includes a main control valve installed in a hydraulic line between a hydraulic pump and actuators, and including a first group of electro proportional pressure reducing valves outputting a secondary pressure in proportion to an external pressure command signal to a first spool for controlling a first group of actuators of the actuators, and a second group of electro proportional pressure reducing valves outputting a secondary pressure in proportion to an external pressure command signal to a second spool for controlling a second group of actuators of the actuators, a first pressure sensor configured to detect the secondary pressure outputted from the first group of electro proportional pressure reducing valves and a second pressure sensor configured to detect the secondary pressure outputted from the second group of electro proportional pressure reducing valves, and a controller configured to output pressure command signals to the electro proportional pressure reducing valves corresponding to a manipulation signal of the construction machinery, and configured to compare the secondary pressures detected by the first and second pressure sensors and the pressure command signals to determine to determine whether or not the electro proportional pressure reducing valves fail.

An example valve includes: (i) a pilot seat member comprising a first channel and a second channel, a pilot seat, and a pilot sleeve portion comprising a pilot chamber and a cross-hole; (ii) a pilot check member disposed in the pilot chamber and subjected to a biasing force of a setting spring, wherein the pilot check member is configured to be subjected to fluid force of fluid in the second channel; and (iii) a solenoid actuator sleeve slidably accommodated about the pilot sleeve portion, wherein the solenoid actuator sleeve comprises a cross-hole and an annular groove, wherein the cross-hole of the solenoid actuator sleeve is fluidly coupled to a second port of the valve, and the annular groove is configured to selectively fluidly couple the first channel to the second channel based on a position of the solenoid actuator sleeve.

A pilot valve assembly (10) includes a cylindrical connector (12) having a first end portion (16) with external threading (18) for engaging a threaded control socket (106) of a hydraulic valve (100), and a second end (20) with an array of teeth (22) arrayed around its edge. A circumferential slot (24) around connector (12) is spaced from second end (20). The assembly also includes a pilot valve (26) with a mechanism for controlling a pressure within the hydraulic control valve actuator chamber. Pilot valve (26) is formed with a recess (28) having a complementary teeth (30) for engaging teeth (22) of connector (12) in a range of angular orientations. A clamping arrangement engages slot (24) and clamps pilot valve (26) to second end (20) of connector (12), thereby fixing an angular orientation of the pilot valve.

An improved method and circuitry for fluid power applications that provides energy savings through the recycling of normally exhausted pressure by direct transfer and accumulation of exhaust pressure for additional use, including from one end of the actuator to the opposite end or within the actuator itself and for use by other devices in separate systems.