A drive transmission device in one embodiment of the disclosure includes a pair of output shafts, a differential, a clutch (power transmission unit), and a control unit. The pair of output shafts connected to a pair of speed reducers that are disposed to face each other. The differential receives a driving force from a drive source and outputs the driving force to the pair of output shafts; The clutch acts on the differential and takes a first state in which a load imbalance between the pair of output shafts is adjusted or a second state in which the pair of output shafts are rotated directly by the driving force. The control unit switches the state of the clutch based on difference information regarding a difference in rotation between the pair of speed reducers.

An operation control device for a working vehicle comprises a hydraulic actuator to drive the hydraulic working device, operating oil supply source for driving the hydraulic actuator, an operating oil supply control device that performs control to supply operating oil to the hydraulic actuator, an operating device to be operated to make the hydraulic actuator work and a working gain setting device that sets a gain of working speed of the hydraulic actuator corresponding to the operation of the operating device. The operating oil supply control device controls operating oil supply from the operating oil supply source to the hydraulic actuator based on the operation output signal from the operating device and the working speed gain set by the working gain setting device.

In a hydraulic drive system performing the load sensing control by using a pump device having two delivery ports whose delivery flow rates are controlled by a single pump controller, surplus flow is prevented and energy loss at an unload valve and a pressure compensating valve is reduced in combined operations in which two actuators are driven at the same time while producing a relatively large supply flow rate difference therebetween. A boom cylinder 3a is connected so that the hydraulic fluids delivered from delivery ports P1 and P2 of a pump device 1a are merged and supplied to the boom cylinder 3a. An arm cylinder 3h is connected so that the hydraulic fluids delivered from delivery ports P3 and P4 of a pump device 1b are merged and supplied to the arm cylinder 3h. A travel motor 3d is connected so that the hydraulic fluid delivered from one (delivery port P2) of the delivery ports of the pump device 1a and the hydraulic fluid delivered from one (delivery port P4) of the delivery ports of the pump device 1b are merged and supplied to the travel motor 3d. A travel motor 3e is connected so that the hydraulic fluid delivered from the other (delivery port P1) of the delivery ports of the pump device 1a and the hydraulic fluid delivered from the other (delivery port P3) of the delivery ports of the pump device 1b are merged and supplied to the travel motor 3e.

A motor-generator (27) is connected mechanically to an engine (21) and a hydraulic pump (23). The hydraulic pump (23) delivers pressurized oil to cylinders (12D) to (12F) in a working mechanism (12), a traveling hydraulic motor (25) and a revolving hydraulic motor (26). The revolving hydraulic motor (26) drives a revolving device (3) in cooperation with a revolving electric motor (33). An HCU (36) reduces outputs of the revolving electric motor (33), the revolving hydraulic motor (26), the boom cylinder (12D) and the like such that a ratio of a revolving speed of an upper revolving structure (4) and a movement speed of raising a boom (12A) is held to a ratio in a normal mode (NMODE) at the time of performing a compound movement of a revolving movement and a boom-raising movement in a low speed mode (LSMODE).

An excavator according to the present disclosure includes a display device, a control unit, a limit height setting unit, and a warning height setting unit. The display device displays shapes of a boom, an arm, and a bucket of an excavator and a terrain where the excavator is located. The control unit calculates maximum heights of the boom, the arm, and the bucket from the ground. The limit height setting unit is provided in the display device and is set with a limit height required for work in the terrain where the excavator is located by a user. The warning height setting unit is provided in the display device and is set with a warning height lower than the limit height. The display device displays the limit height and the warning height together with the terrain where the excavator is located.

A drive transmission device of the present disclosure includes a first member and a second member, a drive source, two bracket portions, a shaft portion, a reduction unit having an output portion, and a housing portion. The first member and the second member are coupled to each other so as to be rotatable about a rotation axis. The two bracket portions are provided on the second member and are spaced apart from and opposed to each other. The shaft portion is connected to the first member and positioned between the bracket portions. The output portion is attached to the shaft portion and attached to an opposed surface of a first bracket portion. The housing portion is coupled to the shaft portion so as to be rotatable about the rotation axis, the housing portion being attached to an opposed surface of a second bracket portion.

A pivot control apparatus of construction equipment is provided for reaching a desired swing angle by controlling the brake torque of a swing motor during a loading operation using an excavator, along with a control method therefor. The swing control apparatus of construction equipment according to one embodiment of the present invention includes first and second hydraulic pumps and a pilot pump; a boom cylinder, an arm cylinder, and a bucket cylinder which are driven by the hydraulic fluid of the first and second hydraulic pumps; an operation apparatus control valve for controlling the hydraulic fluid which is supplied from the first and second hydraulic pumps to the boom cylinder, the arm cylinder and the bucket cylinder; a swing motor Which is driven by the hydraulic fluid of any one of the first and second hydraulic pumps to swing an upper swinging, body; a swing control valve; a swing operation lever, a direction control valve which applies a pilot pressure to the swing control valve according to the swing operation lever or a semi-automatic swing mode selection; electronic proportional variable relief valves capable of variably adjusting the relief setup pressure of the swing motor; and a controller which, when a semi-automatic swing mode is selected and the operation apparatus is actuated at the time of swing return, applies an electric signal to the variable relief valve at the outlet side, from among the electronic proportional variable relief valves, so as to increase or decrease the relief setup pressure.

An excavator arm includes at least: a frame including i) a boom linkage part to swingably link excavator arm to an excavator boom about a boom axis, and ii) a tool linkage part to swingably link the excavator arm to a tool about a tool axis, the boom axis and the tool axis extending in a frame plane, an arm linear actuator extending along a longitudinal axis, the arm linear actuator having i) a proximal linkage pan linked to the frame about a proximal linkage axis and ii) a distal linkage part linked to the frame about a distal linkage axis, the proximal linkage axis and the distal linkage axis extending in an actuator plane, and an electric motor configured to drive the arm linear actuator. Electric motor is arranged between the frame plane and the actuator plane.

A system and method for storing potential energy for a material handler. The system and method involves actuating a machine element using hydraulic cylinders; measuring a position of the machine element; controlling the hydraulic cylinders with a hydraulic circuit by an electronic control unit; determining a maximum target pressure for at least one gas actuator coupled to the machine element; calculating a target pressure for the at least one gas actuator at the position; measuring a gas pressure measurement from the at least one gas actuator; comparing the target pressure to the gas pressure measurement; and adjusting a hydraulic adjustment valve to increase or decrease an amount of hydraulic fluid within a hydraulic chamber of an accumulator thereby changing a gas pressure within the at least one gas actuator to correspond to the target pressure.

A valve system, including first, second, third and fourth ports, a first flow path connecting the first and second ports, a second flow path connecting the third and fourth ports, with valves connected in the first and second flow paths, and energizable to block the same. A third flow path connects the first and second ports and a fourth flow path connects the third and fourth ports. The third and fourth flow paths are more restricted than the respective first and second flow paths. A fifth flow path connects the first and fourth ports and a sixth flow path connects the second and third ports. When the third and fourth flow paths are open, the first, second, fifth, and sixth flow paths are blocked. When the first and second flow paths are open, the third, fourth, fifth, and sixth flow paths are blocked. When the fifth and sixth flow paths are open, the first, second, third, and fourth, flow paths are blocked.