LOADING CRANE BOOM Russian patent published in 2017 - IPC B66C23/70 

FIELD: machine building.

SUBSTANCE: invention relates to hydraulic crane booms. Hydraulically controlled boom (100) for loading crane (101) includes, at least, two boom extensions (1, 2), one boom extension is made in form of boom external extension (1), and second boom extension is made in form of boom internal extension (2), at least, two telescopic cylinder (11, 21) for extension and retraction of said, at least, two boom extensions (1, 2). Hydraulic circuit for working medium (5), particularly oil, includes retraction pipeline (6) for telescopic cylinders (11, 21) retraction with pressure supply, retraction pipeline (6) ends in boom external extension (1) telescopic cylinder (11), working medium (5) supply tank, distributing valve (22), which when boom external extension (1) certain retracted position is achieved, in particular, when boom external extension (1) is, substantially, completely retracted, can be switched into open position and upon that supplies boom internal extension (2) telescopic cylinder (21) with pressurized working medium (5). Working medium (5) of retracting pipeline (6) between tank and return point (12) into boom external extension (1) telescopic cylinder (11) in any position of boom internal extension (2) telescopic cylinder (21) is not communicated with boom internal extension (2) telescopic cylinder (21), until boom external extension (1) is reached its retracted position.

EFFECT: enabling hydraulic boom improvement.

15 cl, 6 dwg