Abstract:
A shovel according to one embodiment of the present invention is provided with a main pump 14, hydraulic actuators including a swing hydraulic motor 21, a control valve 17 configured to control a flow of a working oil between the main pump 14 and the hydraulic actuators, and two accumulators 420A and 420B connected between the swing hydraulic motor 21 and the control valve 17. The two accumulators 420A and 420B can respectively release the working oil at an upstream of the main pump 14.
Abstract:
A shovel according to one embodiment of the present invention is provided with a main pump 14, hydraulic actuators including a swing hydraulic motor 21, a control valve 17 configured to control a flow of a working oil between the main pump 14 and the hydraulic actuators, and an accumulator part 42 configured to release the working oil between the main pump 14 and the control valve 17, and between the swing hydraulic motor 21 and the control valve 17. The accumulator part 42 can release the working oil at an upstream of the main pump 14.
Abstract:
An object is to prevent a decrease in an operating speed of an external hydraulic work machine when actuation and turning operation of the external hydraulic work machine are performed at the same time. A hydraulic apparatus for a hydraulic work vehicle capable of supplying pressure oil to any of a bucket cylinder (20), an arm cylinder (21), a boom cylinder (22), a swing cylinder (25), a blade cylinder (13), a turning hydraulic motor (62), a left traveling hydraulic motor (63), a right traveling hydraulic motor (64), and a PTO hydraulic motor (65) by a first hydraulic pump (PI), a second hydraulic pump (P2), or a third hydraulic pump (P3) is configured in such a manner that pressure oil can be branched off from a discharge oil passage (28) of the third hydraulic pump (P3) and supplied through an external pipe (71) to a downstream side of a load check valve (46) disposed on an oil passage communicating with a pump port (36p) of a PTO control valve (36) for switching supply of pressure oil from the second hydraulic pump (P2) to an external hydraulic work machine (16).
Abstract:
The invention provides a rotation control device (5) capable of reducing a loss of a power of a hydraulic pump (15) in a backward direction operation and also provides a construction machine (1) including the same. The controller (24) controls a capacity of the hydraulic pump (15) such that, in a forward direction operation in which an operating direction detected by the operation sensor (18A, 18B) and a rotating direction detected by a rotation sensor (23) coincide with each other, the capacity of the hydraulic pump (15) is increased in accordance with an increase in the operation amount detected by an operation sensor (18A, 18B), on the other hand, restricts the capacity of the hydraulic pump (15) more in a backward direction operation, in which the operating direction detected by the operation sensor (18A, 18B) and the rotating direction detected by the rotation sensor (23) are reverse to each other, than in the forward direction operation.
Abstract:
A shovel includes a swing hydraulic motor 21, a swing drive hydraulic circuit configured to drive the swing hydraulic motor, an assist hydraulic motor 40 connected to an engine 11 and configured to be supplied with hydraulic oil discharged from the swing drive hydraulic circuit, and a controller 30 configured to control the driving of the shovel. The controller 30 is configured to detect the load condition of the engine, and control the supply of the hydraulic oil to the assist hydraulic motor 40 at the time of swing deceleration, based on the detected load condition.
Abstract:
Provided is a construction machine capable of both of cavitation prevention and reduction in a power loss. The construction machine includes: a lower traveling body; an upper slewing body; a front attachment; a plurality of hydraulic actuators including traveling motors (13 and 14); hydraulic pumps (10 and 11); a plurality of control valves (16 to 21) for the hydraulic actuators; a plurality of operation units (22 to 27) for the control valves (16 to 21); traveling operation detectors (38 and 39) that detect operations for the operation units (25 and 26) for the traveling motors of the operation units; a back-pressure compensation valve (29) generating back pressure in a return pipe line (28) connecting each of the control valves and a tank and having a setting pressure switchable between low and high pressure setting values; and a back-pressure control section (31 and 32) performing a back-pressure lowering control of making the setting pressure of the back-pressure compensation valve (29) be the low pressure setting value when traveling operation amounts in the traveling operation units are large.
Abstract:
A construction machine includes: a swing structure (20); hydraulic and electric motors (25) mechanically coupled to each other; a hydraulic pump (41) that supplies hydraulic fluid to the hydraulic motor; swing control lever (72) that instructs the swing structure to make a swing motion; and a control device (80) that controls at least either a delivery flow rate of the hydraulic pump or an output torque of the electric motor in such a manner that meter-out and meter-in pressures of the hydraulic motor that is run together with the electric motor approach each other when the demanded torque necessary for the swing motion of the swing structure instructed by the swing control lever can be produced by the electric motor alone.
Abstract:
A hydraulic system for a work machine includes a first hydraulic actuator, a second hydraulic actuator, a hydraulic pump to discharge an operation fluid, a first control valve serving as a control valve to control the first hydraulic actuator, the first control valve including a first direction switch to switch the operation fluid and a pressure compensator to maintain a differential pressure to a constant pressure, the differential pressure being generated between a pressure of the operation fluid inputted and a pressure of the operation fluid to be outputted. And, the hydraulic system includes a second control valve serving as another control valve to control the second hydraulic actuator, the second control valve including a second direction switch to switch the operation fluid and a flow rate prioritizer to prioritize a flow rate of the operation fluid that is to be outputted to the second hydraulic actuator.