Abstract: A machine is adapted for operation powered by any one of a plurality of interchangeable power sources. The machine may include an undercarriage configured for supporting ground engagement members that propel the machine and an upper structure rotatably supported on the undercarriage. The upper structure may include a swing frame, with the swing frame supporting an operator cab, any one of the plurality of interchangeable power sources, hydraulic components, electrical components, and a counterweight disposed at a first end of the swing frame. The counterweight may include a hollowed out portion facing toward the swing frame. The hollowed out portion of the counterweight may be centrally aligned with a center core portion of the swing frame configured for supporting any one of the plurality of interchangeable power sources, with the one power source being partially accommodated within the hollowed out portion of the counterweight.

Abstract: To provide a construction machine capable of preventing damages of batteries placed on a machine-body frame. A construction machine comprises a machine-body frame, a supporting plate installed on the machine-body frame via elastic mounts, and batteries fixed to a topside of the supporting plate. Welding is not performed on the supporting plate.

Abstract: A machine is adapted for operation powered by any one of a plurality of interchangeable power sources. The machine may include an undercarriage configured for supporting ground engagement members that propel the machine and an upper structure rotatably supported on the undercarriage. The upper structure may include a swing frame, with the swing frame supporting an operator cab, any one of the plurality of interchangeable power sources, hydraulic components, electrical components, and a counterweight disposed at a first end of the swing frame. The counterweight may include a hollowed out portion facing toward the swing frame. The hollowed out portion of the counterweight may be centrally aligned with a center core portion of the swing frame configured for supporting any one of the plurality of interchangeable power sources, with the one power source being partially accommodated within the hollowed out portion of the counterweight.

Abstract: A hydraulic working machine is provided that uses a variable displacement pump and open center type flow rate control valve for a controlling a hydraulic actuator, and has a negative control throttle disposed in a center bypass oil passage to generate a negative control pressure. A hydraulic pump control system performs virtual bleed-off control for reducing the bleed-off flow rate of the center bypass oil passage, and can operate the hydraulic actuator with the same performance as an open center control. The control system includes a bypass cut valve disposed upstream from the negative control throttle to reduce flow through the center bypass oil passages, and a negative control pressure output valve that outputs a virtual negative control pressure. The control system is configured to reduce the bleed-off flow rate by operating the bypass cut valve when virtual bleed-off control is performed, and to reduce the pump flow rate by the bleed-off reduction flow rate.

Abstract: Provided are a hydraulic circuit and a work machine capable of improving an initial motion speed of a hydraulic cylinder during a contraction of the hydraulic cylinder and securing a necessary pump flow rate while hydraulic fluid is being accumulated in an accumulator. Hydraulic oil from a head side of a second boom cylinder is regenerated in a first boom cylinder and the second boom cylinder through a second control valve of a regeneration circuit. At the same time, oil from the head side of the first boom cylinder is accumulated to a first accumulator by a pressure accumulating circuit through a first control valve. The hydraulic oil supplied under pressure from a main pump is fed to a rod side of the first boom cylinder by a boom control valve. A bleed-off valve of a bleed-off circuit communicates the first control valve to a tank at the time of initial operation of the first control valve, thereby releasing hydraulic oil from the head end of the first boom cylinder to improve an initial motion speed.

Abstract: A control device for suppressing engine load fluctuation according to main pump circuit conditions, wherein an assist torque calculation task includes a target engine torque calculation task separating smooth torque components from main pump load torque and setting a minimum value of either smooth torque component or engine setting torque as target engine torque, and a subtractor calculating target assist torque based on a difference between the main pump load torque and the target engine torque, the assist torque calculation task controlling a capacity of an assist pump based on the target assist torque and controlling switching between an assist mode and a charge mode.

Abstract: A hydraulic working machine is provided that uses a variable displacement pump and open center type flow rate control valve for a controlling a hydraulic actuator, and has a negative control throttle disposed in a center bypass oil passage to generate a negative control pressure. A hydraulic pump control system performs virtual bleed-off control for reducing the bleed-off flow rate of the center bypass oil passage, and can operate the hydraulic actuator with the same performance as an open center control. The control system includes a bypass cut valve disposed upstream from the negative control throttle to reduce flow through the center bypass oil passages, and a negative control pressure output valve that outputs a virtual negative control pressure. The control system is configured to reduce the bleed-off flow rate by operating the bypass cut valve when virtual bleed-off control is performed, and to reduce the pump flow rate by the bleed-off reduction flow rate.

Abstract: Provided are a hydraulic circuit and a work machine capable of improving an initial motion speed of a hydraulic cylinder during a contraction of the hydraulic cylinder and securing a necessary pump flow rate while hydraulic fluid is being accumulated in an accumulator. Hydraulic oil from a head side of a second boom cylinder is regenerated in a first boom cylinder and the second boom cylinder through a second control valve of a regeneration circuit. At the same time, oil from the head side of the first boom cylinder is accumulated to a first accumulator by a pressure accumulating circuit through a first control valve. The hydraulic oil supplied under pressure from a main pump is fed to a rod side of the first boom cylinder by a boom control valve. A bleed-off valve of a bleed-off circuit communicates the first control valve to a tank at the time of initial operation of the first control valve, thereby releasing hydraulic oil from the head end of the first boom cylinder to improve an initial motion speed.

Abstract: A control device for suppressing engine load fluctuation according to main pump circuit conditions, wherein an assist torque calculation task includes a target engine torque calculation task separating smooth torque components from main pump load torque and setting a minimum value of either smooth torque component or engine setting torque as target engine torque, and a subtractor calculating target assist torque based on a difference between the main pump load torque and the target engine torque, the assist torque calculation task controlling a capacity of an assist pump based on the target assist torque and controlling switching between an assist mode and a charge mode.

Abstract: An inexpensive engine assist device capable of performing stable energy regeneration from an accumulator and a working machine on which the engine assist device is mounted are provided. A variable capacity type main pump and a variable capacity type assist pump are directly connected to an engine. A return pressure oil flowing out from a fluid pressure actuator is temporarily accumulated by a sub-accumulator and is supplied to an inlet of the assist pump, and the assist pump pressurizes the return fluid pressure oil and supplies the return fluid pressure oil to a main accumulator. A controller calculates and controls an assist pump swash plate angle, and assist starting torque or charge starting torque, and introduces a pressure-accumulated fluid discharged from the main accumulator to the inlet of the assist pump or introduces a pressurized fluid discharged from an outlet of the assist pump into the main accumulator.

Abstract: Provided is a hydraulic circuit capable of efficiently recovering one and the other hydraulic energies for utilization by separating and recovering the same, one hydraulic energy being extruded from a hydraulic cylinder and the other hydraulic energy being extruded in starting and stopping rotation of a hydraulic motor, so as to allow an energy density of an accumulator to increase. The hydraulic circuit has: a first accumulator that accumulates pressure of hydraulic oil extruded from a boom cylinder; and a second accumulator that accumulates one pressure of the hydraulic oil relieved when the rotation of a swing motor is started and another pressure of the hydraulic oil extruded from a motor driving circuit with inertial rotation of the swing motor when rotation of the swing motor is stopped. A solenoid switch valve in passages that connect the first second accumulators closes the passages when pressure is accumulated in the second accumulator opens when the pressure in the second accumulator is discharged.

Abstract: The hydraulic circuit has: main pumps driven by an engine; a boom cylinder including a piston operating by hydraulic oil supplied from the main pumps, one chamber and the other chamber respectively partitioned and formed by the piston; an accumulator accumulating pressure of the hydraulic oil extruded from one chamber of the boom cylinder; and an assist pump motor suctioning the hydraulic oil from the accumulator when pressure continues to be accumulated in the accumulator and the accumulator pressure rises.

Abstract: Provided is a hydraulic circuit capable of saving a pump flow rate while hydraulic fluid is being accumulated in an accumulator. The hydraulic circuit has: a couple of boom cylinders that simultaneously operate the same operation by the hydraulic oil supplied under pressure from main pumps; an accumulator in which pressure of the hydraulic oil is accumulated; a pressure accumulating circuit that accumulates the pressure of the hydraulic oil extruded from one boom cylinder in the accumulator; and a regenerating circuit that regenerates the hydraulic oil extruded from the other boom cylinder to the boom cylinders.

Abstract: An inexpensive engine assist device capable of performing stable energy regeneration from an accumulator and a working machine on which the engine assist device is mounted are provided. A variable capacity type main pump and a variable capacity type assist pump having a motor function and a pump function are directly connected to an engine. A return pressure oil flowing out from a fluid pressure actuator is temporarily accumulated by a sub-accumulator and is supplied to an inlet of the assist pump, and the assist pump pressurizes the return fluid pressure oil and supplies the return fluid pressure oil to a main accumulator.

Abstract: An aromatic polycarbonate containing a structural unit of the formula: ##STR1## wherein R.sup.1 is a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, Ar.sup.1 is a substituted or unsubstituted aryl group and Ar.sup.2 and Ar.sup.3 are independently a substituted or unsubstituted arylene group. The aromatic polycarbonate is capable of transferring charges and is used for forming a photosensitive layer of an electrophotographic photosensitive medium.

Abstract: An aromatic polycarbonate containing a structural unit of the formula: ##STR1## wherein R.sup.1 is a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, Ar.sup.1 is a substituted or unsubstituted aryl group and Ar.sup.2 and Ar.sup.3 are independently a substituted or unsubstituted arylene group. The aromatic polycarbonate is capable of transferring charges and is used for forming a photosensitive layer of an electrophotographic photosensitive medium.

Abstract: An electrophotographic photoconductor includes an electroconductive support, and a photoconductive layer formed thereon containing as an effective component an aromatic polycarbonate resin having a repeat unit of formula (I), or two repeat units of formula (II) and formula (III): ##STR1## wherein n, Ar.sup.1, Ar.sup.2, Ar.sup.3, R.sup.1, R.sup.2 and X are as specified in the specification, ##STR2## wherein k and j are also as specified in the specification.