JPH01156247U - - Google Patents

Description

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram showing a first embodiment of a working machine according to the present invention, Fig. 2 is a hydraulic circuit diagram showing a second embodiment, and Fig. 3 is a hydraulic circuit diagram showing a third embodiment. FIG. 4 is a hydraulic circuit diagram showing a fourth embodiment. FIG. 5 is a schematic side view of a working machine to which the present invention is applied. DESCRIPTION OF SYMBOLS 1...Tractor body, 2...Lift arm, 3...Work equipment, 4...Lift cylinder, 5...Dump cylinder, 11...Directional switching valve for lift cylinder, 14...
2-position switching throttle valve, 19...bypass oil passage, 21...
Hydraulic pump, 22...Oil tank, 28a...2 position switching valve, 28b...2 position switching throttle valve, 32...Dump cylinder directional switching valve, 36...3 position switching throttle valve.

Claims (1)

[Claims for Utility Model Registration] (1) A lift arm whose base end is pivotally attached to the tractor body and has a working device at the tip, and a lift cylinder that moves the lift arm up and down are connected to hydraulic pressure via a directional control valve. In a work machine equipped with a lift arm drive hydraulic circuit formed by connecting a pump and an oil tank, the lift arm drive hydraulic circuit has two ports on the cylinder side and two ports on the pump side.
A two-position switching throttle valve is installed, which has a bypass port that communicates with the oil tank through ports and bypass oil passages, and a part of which has a throttle passage that controls the return oil from the lift cylinder. In the left position of the throttle valve, the bypass port is closed and the ports on the hydraulic pressure sending side and the return oil distribution side are communicated, and in the right position, the bypass port is communicated with the ports on the hydraulic pressure sending side and the return port is closed. A work machine characterized in that each port on the oil circulation side is configured to communicate with each other. (2) A lift arm whose base end is pivotally attached to the tractor body and has a working device at the tip, and a lift cylinder that moves the lift arm up and down are connected to a hydraulic pump and an oil tank via a directional control valve. In a work machine equipped with a lift arm drive hydraulic circuit, the lift arm drive hydraulic circuit has a port communicating with one of the chambers of the lift cylinder on the cylinder side, and a hydraulic pressure circuit on the pump side. A port that communicates with either the pump or the oil tank, a two-position switching valve on the bypass port that communicates with the oil tank via a bypass oil passage, and a port that communicates with the other chamber of the lift cylinder on the cylinder side and the pump side. and a 2-position switching throttle valve each having a port communicating with either the oil tank or the hydraulic pump, and a part of which has a throttle passage for controlling return oil from the lift cylinder, are installed in parallel, In the left position, the 2-position switching valve closes the bypass port and communicates each port on the cylinder side and the pump side, and in the right position, the bypass port communicates with both the ports on the cylinder side and the pump side, and the 2-position switching valve closes. A work machine characterized in that the variable throttle valve is configured such that in the left position, both ports on the cylinder side and the pump side communicate with each other, and in the right position, both ports communicate with each other via a throttle passage. (3) a lift cylinder that moves up and down a lift arm whose base end is pivotally connected to the tractor body; and a dump cylinder that moves a working device attached to the tip of the lift arm to dump and scoop operations;
A work machine comprising a directional control valve for each cylinder connected to the lift cylinder and the dump cylinder, respectively, and a hydraulic pump and an oil tank commonly connected to each of the directional control valves, the hydraulic pump and the oil tank. and the directional switching valve for each cylinder, having two ports on the cylinder side that are branched and connected to each directional switching valve, and
The pump side has a pump port connected to a hydraulic pump, a tank port connected to an oil tank, and a bypass port, and a part thereof has first and second throttle passages for controlling return oil from each cylinder. In the neutral position, the bypass port is closed and each port on the hydraulic pressure sending side and each port on the return oil distribution side are communicated with each other, and in the left position, the bypass port is closed. In the right position, each port on the hydraulic pressure sending side is communicated with each port on the hydraulic pressure sending side, and each port on the return oil distribution side is communicated via the first throttle passage, and in the right position, the bypass port is communicated with each port on the hydraulic hydraulic sending side, and A work machine characterized in that each port on the return oil distribution side is configured to communicate with each other via a second throttle passage.