JPH0291794U

JPH0291794U -

Info

Publication number: JPH0291794U
Application number: JP17128288U
Authority: JP
Priority date: 1988-12-28
Filing date: 1988-12-28
Publication date: 1990-07-20

Description

[Brief explanation of drawings]

第１図は本考案の実施例を示す油圧回路図、第
２図は高所作業車の側面図、第３図は多段伸縮ブ
ームの概略断面図である。１……油圧ポンプ、２……ブーム起伏シリンダ
、３……旋回モータ、４……中間ブーム伸縮シリ
ンダ、５……先端ブーム伸縮シリンダ、６……首
振りモータ、７……ウインチモータ、４０……ブ
ーム伸縮用方向制御弁、４１……第１主管路、４
２……第２主管路、４３……第３主管路、４４…
…合流管路、４７……タンク側ドレン管路、５１
……第１選択弁、５３……第１ホース、５４……
第２ホース、６１……第２選択弁、６２……バケ
ツト側入力管路、８２……バケツト側タンク管路
、８３……チエツク弁、８４……バケツト側ドレ
ン管路、８６……ドレンホース。 FIG. 1 is a hydraulic circuit diagram showing an embodiment of the present invention, FIG. 2 is a side view of an aerial work vehicle, and FIG. 3 is a schematic sectional view of a multistage telescopic boom. DESCRIPTION OF SYMBOLS 1...Hydraulic pump, 2...Boom hoisting cylinder, 3...Swivel motor, 4...Intermediate boom telescopic cylinder, 5...Tip boom telescopic cylinder, 6...Swing motor, 7...Winch motor, 40... ...Boom expansion/contraction directional control valve, 41...First main pipe, 4
2...Second main pipe, 43...Third main pipe, 44...
...merging pipe line, 47...tank side drain pipe line, 51
...First selection valve, 53...First hose, 54...
Second hose, 61...Second selection valve, 62...Bucket side input pipe, 82...Bucket side tank pipe, 83...Check valve, 84...Bucket side drain pipe, 86...Drain hose .

Claims

[Scope of Claim for Utility Model Registration] 1. A multi-stage telescoping boom that is extended and retracted by an intermediate boom telescoping cylinder and a tip boom telescoping cylinder is attached to a revolving body so as to be able to rise and fall freely, and a bucket is attached to the tip of the multi-stage telescoping boom. In a work vehicle,
Pressurized oil from a hydraulic source is outputted at the extended position of the boom extension/retraction directional control valve provided on the rotating body side, communicated with a tank at the retracted position, and blocked at the neutral position; and the directional control valve. Pressure oil from the hydraulic source is output at the shortened position, and pressurized oil is output from the hydraulic source at the neutral position of the directional control valve, and the second main pipe communicates with the tank at the extended and neutral positions. and a third main pipe that is blocked at the intermediate boom position and the shortened position, the second main pipe is connected to the oil chamber for the shortening operation of the intermediate boom telescopic cylinder, and the first main pipe and the third main pipe are merged. The merging pipe is the first
A selection valve connects the first hose and an oil chamber for extension of the intermediate boom telescopic cylinder in a switchable manner, and a second selection valve connects the tip end of the first hose to the actuator provided on the bucket side. The input port of the directional control valve that controls discharge is switchably connected to the oil chamber for extension operation of the telescopic cylinder at the tip of the boom, and the oil chamber for shortening operation of the telescopic cylinder at the tip is connected to the second main pipe through the second hose. A hydraulic circuit for an aerial work vehicle, characterized in that a bucket side tank pipe connected to a tank port of a bucket side directional control valve is merged with the tip side of the second hose via a check valve. . 2. The drain pipe provided on the bucket side is connected to the drain pipe on the rotating body side via a drain hose, and the drain port of the second selection valve is joined to the drain pipe on the bucket side. The hydraulic circuit for an aerial work vehicle according to claim 1.