A high-pressure unit (HPU) skid for greasing and actuating a frac tree valve includes one or more hydraulic pumps, a grease pump, a hydraulic reservoir, and two or more accumulators all of which are mounted on a portable frame. The HPU skid further includes fluidic connections to connect the frac tree valve to an output of the grease pump and fluidic connections to connect the frac tree valve to at least one of the two or more accumulators. The hydraulic pumps are configured to withdraw hydraulic fluid from the hydraulic reservoir for charging the accumulators, operating the grease pump, or charging the accumulators and operating the grease pump at a same time.

A confluence control part of a slewing-type construction machine controls a confluence switch valve such that the confluence switch valve is switched to a suspension state when a slewing and boom raising manipulation action is performed. A pump capacity control part of the slewing-type construction machine executes a capacity control when the slewing and boom raising manipulation action is performed, the capacity control including regulating a first pump capacity and a second pump capacity respectively in such a manner that the first pump capacity increases and the second pump capacity decreases as an operating pressure difference resulting from the subtraction of a slewing operating pressure from a boom operating pressure increases, and the first pump capacity decreases and the second pump capacity increases as the operating pressure difference decreases.

A multi-control valve unit includes a housing with built-in spools that are parallel to each other. The housing includes pilot chambers formed therein, the pilot chambers corresponding to both ends of the spools. Solenoid proportional valves are mounted to the housing, such that the solenoid proportional valves are connected to the respective pilot chambers. A hydraulic pressure generator is mounted to the housing, such that the hydraulic pressure generator is connected to the solenoid proportional valves. The hydraulic pressure generator includes an electric motor and a pump.

This disclosure relates to a hydraulic system for a hydro-mechanical machine comprising a rotary mechanism and a boom cylinder The hydraulic system includes a primary accumulator configured to receive and store high-pressure fluid in response to starting and stopping of the rotary mechanism. A control system configured to enable passage of the high-pressure fluid stored in the primary accumulator to a rotary control valve configured to control the rotary mechanism, and a boom control valve configured to control the boom cylinder through the hydraulic supply circuit, based on a predefined pressure threshold associated with the primary accumulator. A secondary accumulator coupled to the primary accumulator and the control system via the hydraulic supply circuit is configured to store surplus high-pressure fluid provided by the primary accumulator through the hydraulic supply circuit.

A failure detection apparatus for a hydraulic system, to a hydraulic, failure detection-capable system, and to a method of operating a failure detection apparatus. The failure detection apparatus comprises a monitoring and failure detection unit that receives first and second pressure values from first and second pressure sensors and comprises a failure detection unit that detects a failure of at least one hydraulically operated device when a 2-tuple of a plurality of 2-tuples is within a first and outside a second predetermined tolerance range of relative pressure values, and wherein the failure detection unit 260 detects a failure of the pump when a 2-tuple of the plurality of 2-tuples is outside the first predetermined tolerance range of relative pressure values.

A regeneration device includes: a regeneration valve that controls the flow rate of an operating fluid being drained from one port of a cylinder; a non-return valve that allows a regenerative flow of the operating fluid from the regeneration valve to the other port of the cylinder and blocks an opposite flow of the operating fluid; and an exhaust valve that controls the flow rate of the operating fluid output from the regeneration valve being drained to a tank. The regeneration valve controls the flow rate independently of the exhaust valve.

A hydraulic distributor includes at least one main spool configured to define a delivery branch, and a discharge branch, a feed branch and a pressure compensator configured such that a local pressure acts on a first side thereof and a maximum Load Sensing pressure acts on a second side characterizing either the working pressure of the hydraulic section, in the case in which there is only one hydraulic section, or, in the case in which there is a plurality of hydraulic sections, each one defining a respective characteristic pressure, of the maximum pressure among the characteristic pressures of the hydraulic sections. The pressure compensator is arranged such as to respectively intercept said delivery branch and said discharge branch.

A hydraulic system includes: a slewing motor; a mechanical brake; and a slewing control valve interposed between a main pump and the slewing motor. A first pilot port of the slewing control valve is connected to a first solenoid proportional valve by a pilot line. A second pilot port of the slewing control valve is connected to a second solenoid proportional valve by a second pilot line. The first solenoid proportional valve and the second solenoid proportional valve are connected to an auxiliary pump by a primary pressure line. A switching valve is interposed between the auxiliary pump and the mechanical brake. The switching valve includes a pilot port that is connected to the first pilot line by a switching pilot line. The valve switches from a closed to an open position when a pilot pressure led to the pilot port becomes higher than or equal to a setting value.

A construction machine that makes it possible for an operator to linearly push a bucket simply by operating an arm in a pushing direction is provided. A controller 50 is configured to, in a case where a straight locus is selected by a bucket locus selecting device 52, calculate a constant flow rate ratio α according to a boom initial angle that is an angle of a boom 2 sensed by a boom angle sensor 33 at a time point when an arm 4 is operated in a pushing direction by an operation device 51, and control the delivery flow rate of a first hydraulic pump 12 such that a hydraulic fluid is discharged from a cap chamber 1a of a boom cylinder 1 at a flow rate Qb obtained by multiplying a flow rate Qa of a flow supplied to a cap chamber 3a of an arm cylinder 3 by the flow rate ratio α while the arm 4 is operated in the pushing direction by the operation device 51 and there is not an instruction for operation of the boom 2.

A hydraulic drive apparatus includes a flow-path selector valve and a flow-path switching control unit that operates the valve. The flow-path selector valve has a first position for a single operation state and a second position for a combined operation state, configured to, at the first position, form a first flow path connected to a first pump, a second flow path connected to a second pump, and a connecting flow path providing communication between the first flow path and the second flow path. When a driving state of a work actuator is deviated from an allowable range in the combined operation state, the flow-path switching control unit reduces an opening area of the connecting flow path as compared with that when the driving state is within the allowable range.