Traversing hoists – Boom position lock
Reexamination Certificate
2000-04-27
2001-03-27
Brahan, Thomas J. (Department: 3652)
Traversing hoists
Boom position lock
C212S349000
Reexamination Certificate
active
06206213
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the priority of German Patent Application Serial No. 199 20 634.1, filed Apr. 29, 1999, the subject matter of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates, in general, to a crane with a luffing jib.
German Pat. No. DE 198 24 672 A1 describes a crane having a luffing jib which includes a main boom and a plurality of individual jib members configured to telescope in and out after a disengagement of locking bolted connections results in a release of the jib members to permit their in-and-out movement through coupling with a single-stage hydraulic piston and cylinder unit. In the extended or retracted position, the jib members can be locked, whereby the cylinder housing of the piston and cylinder unit is secured at its rearward end to an inner end of the main boom. The piston rod is connected at the forward end to a guide and traction device which is positioned in parallel relation to the piston and cylinder unit and has an inner end secured to a coupling and locking unit which can be coupled and locked with receptacles of the luffing jib members. The coupling and locking unit has two coupling bolts which are actuated mechanically via a slider formed with grooves. The coupling bolts are positioned in a horizontal plane and, to the right and left, can be pushed in and withdrawn from receptacles arranged at the inner end of the respective jib member. Actuation of the slider is implemented by an axial piston and cylinder unit which is connected to the coupling and locking unit, whereby the spring-loaded locking bolt can be retracted only when the coupling and locking unit is coupled with the receptacles of the jib member being extended or retracted, and release of the coupling bolt with the respective jib member can only be effected when the respective spring-loaded locking bolt is engaged.
European Pat. No. EP 0 661 234 A1 describes a crane with a luffing jib whose individual telescopic jib members can be extended and retracted after disengagement of locking bolts connections using only a single-stage piston and cylinder unit. The jib members are bolted in the respective extended or retracted positions by locking bolts which are spring-loaded toward their locked positions. The piston rod of the single-stage piston and cylinder unit is articulated to a joint member forming the inner end of the outer jib member. An entraining device can be coupled with receptacles of the telescopic jib members and is arranged in a part of the end of the cylinder, from which the piston rod projects out. The entraining device includes a hydraulic block with confronting cylinders for the extendible and retractable bolts formed by the pistons of the cylinders and locking the respective jib member, and a hydraulic piston and cylinder unit which is arranged perpendicular to the hydraulic block for actuation of the respective locking bolt. The hydraulic elements of the engagement device so interact that the radial piston and cylinder unit can be actuated for retraction of the respective locking bolt only when the engagement device is coupled with the jib member to be extended or retracted via the locking bolt.
German Pat. No. DE 196 41 191 A1 describes a luffing jib, in particular for stationary and mobile cranes, including telescopic jib members which move in and out by means of two continuous cables, which have each an entrance side and an exit side, in conjunction with a cable drive and cable deflecting rollers. In the retracted and extended positions, the jib members are secured against relative movement in axial direction by operatively connecting each jib member to a locking device. The cable drive and two cable deflecting rollers are arranged at the base of the main boom, and a third cable deflecting roller is arranged at a cable-drive-distal end of a guide tube which is supported within each jib member via a collar and rigidly secured to the main boom. The points of attachment of the cable end are received in a holding device which is equipped with a gripper unit and slides along the guide tube.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to improve a crane with a luffing jib in such a manner that the coupling and locking unit is simplified to thereby save space and weight.
This object, and others which will become apparent hereinafter, are attained in accordance with the present invention by providing a luffing jib having individual telescoping jib members; a locking device configured for linkage of jib members and movable between an engagement position in which the jib members are locked together and a release position in which a first one of the jib members can be moved in and out relative to the a second one of the jib member, with the locking device being supported in the first jib member and received in an opening of the second jib member; an actuating device defining an axis and including a shifter, movable in a direction of the axis, for shifting the locking device via a coupling device between the engagement and release positions, wherein the coupling device extends perpendicular to the axis and is connected to the shifter, with the coupling device having a coupling member movable in a radial direction to effect an interlocking engagement with the locking device, which is movable in a same axis as the coupling member, wherein the locking device forms together with the coupling member a coupling between the shifter and the first jib member, and wherein in a transition phase between release and engagement positions, a projecting portion of the coupling member enters in interlocking engagement with the locking device, thereby realizing a safety mechanism that prevents the telescoping jib member to drop into the surrounding jib member.
To date, the functions, coupling and locking, were assumed by two components that had to be actuated separately, whereas in the transition phase both functions had to be operatively interconnected to ensure a secure bolting of the respective jib member in every operational phase, either via the coupling bolt or via the locking bolt or locking bolts. In accordance with the present invention, these two functions are now combined so that less components are required, thereby saving weight while still being reliable in operation in connection with implementing a secure bolting of the jib members during locking or coupling phases. In addition, as a result of the reduced number of components, the demand for space is reduced and thus, the present invention is applicable even for smallest telescoping jib members.
The actuating device for moving the jib members may be a cable drive, a single-stage or multistage piston and cylinder unit, or several piston and cylinder unit operated in parallel, for moving the jib members. When using a piston and cylinder unit, the piston rod or the cylinder housing may be securely fixed with the joint member of the main boom.
According to another feature, the form-fitting connection of the coupling member and the locking bolt is realized via a mushroom-shaped coupling piece positioned at the inner end of the locking bolt and engaging a recess formed in the coupling member. In conjunction with very small and lightweight luffing jibs, it is sufficient to provide only one locking device which can be disposed in the telescoping jib member centrally at the top or centrally at the bottom. The associated receptacle of the jib member enclosing the telescoping jib member is then suitably provided in the upper wall or bottom wall, respectively. In conjunction with bigger jibs, the provision of two locking devices may be suitable as a consequence of torque applied on the actuating device, wherein the axes of both locking devices and their interacting coupling devices intersect the center axis of the actuating device at a right angle. Suitably, both locking devices are arranged in opposing sidewall regions. However, an arrangement with both locking devices arranged in the top wall and bottom wall may be su
Brahan Thomas J.
Feiereisen Henry M.
Mannesmann AG
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