Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
  • B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
  • B66C23/06—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes with jibs mounted for jibbing or luffing movements
  • B66C23/08—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes with jibs mounted for jibbing or luffing movements and adapted to move the loads in predetermined paths
  • B66C23/10—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes with jibs mounted for jibbing or luffing movements and adapted to move the loads in predetermined paths the paths being substantially horizontal; Level-luffing jib-cranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
  • B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
  • B66C23/62—Constructional features or details
  • B66C23/82—Luffing gear

Definitions

• the invention relates to a crane in which topping is eff ⁇ ected " by coupling the topping rigging to the hoisting rig- ging in such a way that no topping tower or mast is requi ⁇ red, to provide a compact, low-profile crane.
• the topping rig ⁇ ging extends from a topping tower or mast to the head end of the jib and is controlled independently of the hoisting rigging " by means of a topping winch.
• the necessary weight and overall height of a crane provided with a top ⁇ ping tower or mast has disadvantages and so alternative means, such as a fluid-operated piston-cylinder assembly must he provided to effect topping of the jih.
• a crane comprising a jib having a tail end and a head end; first pulley means mounted on the tail end of the jib, second
• OMPI and third pulley means mounted on the head end of the jib, and fourth pulley means reciprocable between the first pulley means at the tail end of the jib and the second and third pulley means at the head end of the jib; mounting means for supporting the jib for pivotal move ⁇ ment about a horizontal axis extending transversely of the jib; a double-acting, piston-cylinder assembly ext ⁇ ending between the jib and the mounting means for pivot ⁇ ing the jib about the horizontal axis; fifth pulley means fixedly mounted on the mounting means below the first pulley means at the tail end of the jib; at least one topping line extending around the first and fifth pulley means and having opposite ends respectively connected to the fourth pulley means and to one of the first and fifth pulley means; a hoisting winch; and a hoisting line ext ⁇ ending from the hoisting winch to the second pulley means, around the second and fourth
• the fourth pulley means therefore tend to move towards the head end of the jib so that the topping rigg ⁇ ing tends to pull the first pulley means down to the fixed fifth pulley means, thus tending to raise the jib.
• topping of the jib can be effected merely by releasing the piston-cylinder assembly or by applying a very small lift- ing force by means of the piston-cylinder assembly.
• the mounting means must be prevented from tilting and, for this purpose, it is convenient to use a counter-weight which is supported on the mounting means on the opposite side of the hori ⁇ zontal pivotal axis of the jib to the load.
• the components of the crane may be constructed so that this counter-weight is not excessive and the total weight of the crane is less than an equivalent crane provided with a topping tower or mast.
• the second and fourth pulley means may each be provided with a plurality of pulleys so that there is a two or more part purchase between these two pulley means.
• the loading transmitted from the hoisting line to the topping rigging is twice the weight of the load.
• topping lines where a plurality of topping lines are used, it is possible to ensure that the loading on each such topping line does not exceed the loading on the hoisting line by ensuring that the number of topping lines equals the number of lengths of the hoisting line extending from the fourth pulley means to the second and third pulley means.
• the third and fifth pulley means must also each contain the pulleys for each of the topping lines.
• the fourth pulley means may be mounted for movement along guide means which extend along a rectilinear axis between the first pulley means at the tail end of the jib and the second and third pulley means at the head end of the jib.
• the first pulley means and the fifth pulley means may be dis ⁇ posed at different distances from the horizontal pivotal axis so that the axis of the first pulley means is movable into an end position alongside the fifth pulley means on a radial plane containing the horizontal pivotal axis and the axis of the fifth pulley means.
• the topping line extending between corresponding pulleys in the first and fifth pulley means are substantially aligned with the radial plane and so, as the first pulley means move into this position, the turning moment imposed on the jib by each said topping line progressively decreases to zero. In fact, elevation of the jib beyond this inclina ⁇ tion results in the imposition of a restoring force in each said topping line which urges the jib to pivot in the opposite direction.
• Figure 1 is a schematic view of a preferred embodiment of the invention, showing a jib and its mounting means in phantom outline;
• Figure 2 is a view of the hoisting and topping riggings of the crane shown in Figure 1;
• Figure 3 is a schematic view of the hoisting and topping riggings of an alternative form of crane.
• Figure h is a schematic view of the riggings shown in Figure 3, when the crane is topped.
• the crane shown in Figure i has a jib i formed of two triangular frames 16 which are held together by cross braces 17 so as to converge towards the head end 3 of the jib 1.
• First pulley means in the form of two pulleys 11 are mounted at the tail end 2 of the jib 1, adjacent one of the apices of each of the triangular frames 16.
• Second and third pulleys 12 and 13 are mounted at the head end 3 of the jib i, adjacent another of the apices of each of the triangular frames 16.
• a hoisting line 9 extends from a hoisting winch 8 supported on a mounting platform k and is trained around the second pulley 12, around a fourth pulley Ik , between the tail and head ends 2 and 3 of the jib 1, and over the third pulley 13 to a depending load hook 18.
• the mounting platform k also supports a shaft 5 which in turn supports the jib 1 for pivotal movement about a horizontal axis extending transversely of the jib 1 and coinciding with the third of the apices of each of the triangular frames 16.
• the mounting platform 4 also supports fifth pulley means, in the form of two
• pulleys 15 which are arranged below the pulleys 11 of the first pulley means at the tail end 2 of the jib i.
• Opp ⁇ osite ends of the two topping lines 7 are respectively attached to one of the pulleys 11 and to one arm of a yoke 19 supporting the fourth pulley Ik and the two topp ⁇ ing lines are trained around the first and fifth pulleys 11 and 15.
• the mounting platform is mounted above a fixed ring gear 20 and provided with a pinion 21 meshing with the ring gear 20.
• a motor 22 carried by the mounting plat ⁇ form k is operable to drive the pinion 21 to thereby cause a rotation of the mounting platform 4 about a ver ⁇ tically extending axis 23 through the centre of the ring gear 20.
• Part 24 of the mounting platform 4 serves as a counter-weight ' for at least partly balancing loads ' carr ⁇ ied by the load hook 8.
• the upper members 10 of the two triangular frames 16 serve as rectilinear guides for the yoke19 connecting the two topping lines 7 to the fourth pulley 14 so as to allow the fourth pulley 14 to move backwards and forwards along a rectilinear path between the two pulleys 11 of the first pulley means at the tail end 2 of the jib 1 and the second and third pulleys 12 and 13 at the head end 3 of the jib 1.
• a light-weight hydraulic piston-cylinder 6 extends from the jib 1 to the mounting platform 4.
• topping line 7 there is only one topping line 7 and a load L suppor- ted by the load hook 18 induces a tension of 2L in this single topping line 7.
• the topping line 7 must be capable of withstanding twice the loading in the hoisting line 9.
• the .hoisting line 9 extending from the hoisting winch 8 to the second pulley 12 passes through or close to the axis of the shaft 5 so as to en ⁇ sure that the clockwise turning moment exerted by the topping line of lines 7 is not substantially counteracted by the tension in the hoisting cable 9 extending between the jib 1 and the hoist 8.
• the centre distance 24 between the shaft 5 and the first pulley 11 is greater than the cen ⁇ tre distance 25 between the shaft 5 and the fifth pulley 15.
• the first pulley 11 moves to an end position.along ⁇ side the fifth pulley 15 such that the axes of the first and fifth pulleys (Hand 15) lie on a radial plane 26 containing the axis of the shaft 5.
• the tensile loading in the topping -line 5 urges the jib to return to the posi ⁇ tion it occupies for the arrangement shown in Figure 4.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Jib Cranes (AREA)

Applications Claiming Priority (2)

Publications (1)

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Citations (9)

• 1979
  • 1979-03-30 WO PCT/GB1979/000054 patent/WO1979000915A1/en unknown
  • 1979-03-30 JP JP50053479A patent/JPS55500460A/ja active Pending
  • 1979-04-03 NL NL7902596A patent/NL7902596A/xx not_active Application Discontinuation
  • 1979-04-10 CA CA325,287A patent/CA1098489A/en not_active Expired
  • 1979-11-19 EP EP19790900302 patent/EP0016761A1/de not_active Withdrawn

Patent Citations (9)

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