To control a rate of increase of a delivery flow rate of a pump for a swing operation in response to a moment of inertia and an operation amount and to achieve both energy efficiency and operability with respect to the swing operation, a work machine including a swing structure 2 disposed on an upper portion of a track structure 1, a work implement 3 disposed in the swing structure 2, a swing motor 16, a hydraulic pump 22, a regulator 24, a directional control valve 31, and an operation device 34 further includes: a target maximum flow rate calculation section 53 configured to calculate a target maximum flow rate Qmax of the pump to correspond to a swing operation amount Ps; a flow rate rate-of-increase calculation section 55 configured to calculate a rate of increase dQ of a command flow rate of the hydraulic pump 22 on a basis of the moments of inertia of the swing structure 2 and the work implement 3 and the swing operation amount Ps; a command flow rate calculation section 56 configured to calculate a command flow rate Q(t) on a basis of the rate of increase dQ with the target maximum flow rate Qmax set as an upper limit; and an output section 57 configured to output a command signal Sf to the regulator 24 corresponding to the command flow rate Q(t).

Provided is a construction machine on which a hydraulic closed circuit for driving a single rod-type hydraulic cylinder and a swing hydraulic motor is mounted and that has good swing deceleration responsiveness. In this construction machine that drives each of a single rod-type hydraulic cylinder and a swing hydraulic motor in a closed circuit, a minimum passage area from a second flushing valve to a tank in a case the second flushing valve is fully open is smaller than a minimum passage area from a first flushing valve to the tank in a case the first flushing valve is fully open.

A drive system of a construction machine includes: a controller that controls a fuel injection valve, so an actual rotation speed of an engine is adjusted to a setting rotation speed; a hydraulic circuit including a boom cylinder supplied with hydraulic oil from a pump driven by the engine, configured so energy is regenerated as motive power owing to the pump being driven by pressurized oil discharged from the boom cylinder at boom lowering; and a boom operation device including a boom operation lever. At boom lowering, the controller cuts a fuel supply to the engine when a cutting condition is satisfied, which is defined to include that an operating amount of the lever is less than or equal to a first threshold, and resumes the fuel supply when the cutting condition stops being satisfied or when the actual rotation speed of the engine becomes less than a second threshold.

A center pintle hub to be affixed to a base of a machine. The center pintle hub includes a base portion and a support portion. The base portion is formed to be affixed to the base. The support portion extends from the base portion and has a frusto-conical shape that can receive a center pintle shaft. The center pintle shaft can support a frame of the machine and provide rotation of the frame with respect to the base.

A hydraulic system for recovering potential energy of a load implement of a mobile construction vehicle. The hydraulic system includes first and second actuators and control valving. The first and second actuators are configured to be coupled to the load implement for controlling raising and lowering of the load element. The control valving is operable between a first position at which, during a lowering of the load implement, the control valving directs hydraulic fluid from one of the first and second actuators to an accumulator to charge the accumulator, and a second position at which the control valving directs hydraulic fluid from the accumulator to one or more of the first and second actuators to power the one or more of the first and second actuators to raise the load element.

A shovel includes a lower-part traveling body; an upper-part swing body rotatably provided above the lower-part traveling body; an object detecting device provided in the upper-part swing body; a controller as a control device provided in the upper-part swing body; and at least one driven body configured to be operated by an actuator. The object detecting device is configured to detect another shovel in a detection space set around the shovel. The controller is configured to vary a movable range being a range accessible to the driven body, based on a state of an object detected by the object detecting device.

A shovel includes a lower traveling body, an upper turning body turnably attached to the lower traveling body, an actuator mounted on the lower traveling body or the upper turning body, and a controller configured to set a prohibited area for an obstacle located in a work area and restrict movement of the actuator. The controller determines whether the shovel has entered the prohibited area, and slows or stops movement of the shovel in response to determining that the shovel enters the prohibited area.

The present disclosure relates to a method for controlling a swing motor in a hydraulic system and a hydraulic system. The method for controlling the swing motor in the hydraulic system and the hydraulic system according to the exemplary embodiment of the present disclosure may ensure the sufficient amount of hydraulic oil in a make-up line in a situation in which the hydraulic oil needs to be supplementarily supplied to the swing motor in the hydraulic system. Therefore, it is possible to prevent the occurrence of cavitation in the swing motor by stably supplying the amount of hydraulic oil at the point in time where the hydraulic oil needs to be supplementarily supplied to the swing motor. In addition, it is possible to prevent the occurrence of abnormal noise which is harsh to the ear when the cavitation occurs.

A control section determines a monitoring region, a region wherein an obstacle is to be monitored, the monitoring region not including the lower travelling body. The control section changes the monitoring region so as not to include the lower travelling body based on a turn angle detected by the turn angle detection section. The control section limits operation of at least one of travelling of the lower travelling body and turning of the upper slewing body when the obstacle detection section detects an obstacle being present in the monitoring region.

The construction machine includes: an input interface which permits an input of a provisional target position of the attachment in a virtual space; a target position calculation part which calculates an actual target position that is a target position of the attachment in a real space from the provisional target position; an operational amount calculation part which calculates an operational amount required to make a current position of the attachment coincide with the actual target position of the attachment coincide with the actual target position with respect to at least one driven target selected from a lower traveling body, an upper slewing body, a working device, and the attachment; and a control part which controls an operation of one of the actuators for driving the driven target in accordance with the calculated target operational amount.