Traversing hoists – Boom position lock
Reexamination Certificate
1999-11-24
2001-02-20
Brahan, Thomas J. (Department: 3652)
Traversing hoists
Boom position lock
C212S349000
Reexamination Certificate
active
06189712
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to a crane with a telescope jib having a plurality of telescoping sections which are individually moved into and out of a base jib.
2. Description of the Prior Art
In a prior art crane with telescope jib known from EP 0 661 234 A1, individual telescoping sections which can telescope out are moved out and in only by a single-stage piston-cylinder unit after locking pin connections are released, and are bolted in the respective moved out or moved in positions by locking bolts which are spring-loaded in the direction of their locked positions. A piston rod of the single-stage piston-cylinder unit is articulated at the jib articulation point which terminates the inner end of the outer section. A driver device which can be coupled with receptacles of the telescoping sections is arranged in the area of the end of the cylinder from which the piston rod emerges. The driver device comprises a hydraulic block with cylinders located on opposing sides of the hydraulic block. Bolts are formed by pistons of the cylinders and can be moved in and out, of the cylinders. A hydraulic piston-cylinder unit is arranged perpendicular to the locking bolts for actuating the respective locking bolt. The hydraulic elements of the driver device are in an operative connection such that the radially located piston-cylinder unit for pulling in the respective locking bolt can be actuated only when the driver device is coupled, via the locking bolts, with the section which is to be telescoped out or in.
A comparable prior art telescoping system is known from EP 0 754 646 A1. This telescoping system has a base section and at least two sections which can telescope relative to the base section. The sections are fixed in their respective position relative to one another by removable insertion bolts (locking bolts) penetrating the walls of adjoining sections. The telescoping system further has a, preferably single-stage, lift cylinder which is limited by the sections and which is acted upon at both sides by pressure medium. This lift cylinder is provided with drivers which can be brought into an operative engagement with the respective section to be displaced. As is the case in the prior art mentioned above, the piston rod of the piston-cylinder unit is articulated at the inner end of the outer section. Both known suggestions have the disadvantage that the oil supply to the piston-cylinder unit is carried out on the inside and long distances and with the formation of a corresponding turbulence for returning the oil supply to the oil supply storage tank. This reduces the telescoping speed. Further, the weight of the main jib head is increased by the quantity of oil located in the piston-cylinder unit, which reduces the useable load.
Another prior art crane is disclosed in DE 31 25 603 A1 including a telescope jib with a base jib and three telescoping sections which can be moved in and out directly or indirectly via chain drives by means of a single-stage piston-cylinder unit. The cylinder housing of the piston-cylinder unit is articulated by its rear end at the inner end of the base jib. The piston rod is connected at the front end, via a bolt, with a cylinder box which encloses the moved out piston rod and which is connected in the vicinity of its inner end by a bolt with the side walls of the first telescoping section. This construction is disadvantageous in that all three telescoping sections can only be moved in and out jointly and it is not possible to purposely move only one telescoping section in and out of the base jib.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a crane with a telescopic jib which can be produced economically while retaining the principle of the individual telescoping capability of the sections by means of a piston-cylinder unit and which enables an increased telescoping speed compared with the known prior art and whose useable load is greater.
The object of the invention is met by a crane with a telescopic jib, the telescopic jib comprising a base jib having an inner end and an outer end, first and second jib sections arranged in the base jib and axially movable therein between moved-in and moved-out positions, a piston-cylinder unit having a cylinder housing and a piston rod having a free end articulated at the inner and of the base jib, a first securing and locking unit arranged at an inner end of the cylinder housing and a second securing and locking unit arranged at an outer end of the cylinder housing, the first and second locking units having securing bolts selectively connecting to one of the first and second jib sections, and locking bolts arrangeable in recesses of the first and second jib sections for holding the first and second jib sections in the moved-in or moved-out position.
The object of the invention is also met by a crane with a telescopic jib, the telescopic jib comprising a base jib having an inner end and an outer end, first and second jib sections arranged in the base jib and axially movable therein between moved-in and moved-out positions, a piston-cylinder unit having a cylinder housing and a piston rod, the cylinder housing having a front end and a rear end articulated at the inner end of said base jib, a guiding and pulling device connected at a front end of the piston rod and extending parallel to the piston-cylinder unit, a first securing and locking unit arranged at a front end of the guiding and pulling device and a second securing and locking unit arranged at a rear end of the guiding and pulling device, the first and second locking units having securing bolts selectively connecting to one of the first and second jib sections, and locking bolts arrangeable in recesses of the first and second jib sections for holding the first and second jib sections in the moved-in or moved-out position.
In contrast to the known prior art, a securing and locking unit that can be coupled with recesses in the sections which can telescope out is fastened respectively to the inner and outer end of a displaceable element of a piston-cylinder unit. Optionally, the displaceable element of the piston-cylinder unit may be the cylinder housing, in which case the piston rod is articulated by its rear end at the inner end of the base jib, or the displaceable element of the piston-cylinder unit can be the piston rod, in which case the cylinder housing is articulated by its rear end at the inner end of the base jib. In either case, it is advantageous that the length of the piston-cylinder unit amounts to only about 50% of the length of the main jib due to the arrangement of two securing and locking units. A shorter piston-cylinder unit means a shorter bending length, so that the piston-cylinder unit may be designed more favorably with respect to dimensioning while retaining the same lifting force. This, in turn, has a direct effect on the weight which, despite the added weight due to the arrangement of a second securing and locking unit, is lower in comparison to a piston-cylinder unit which extends 100-% of the length of the main jib. Two lift procedures are required for fully telescoping each individual telescoping section. The embodiment with a cylinder housing articulated at the base jib is preferably selected, wherein the piston rod is connected with a guiding and pulling device oriented parallel to the piston-cylinder unit. Two securing and locking units are fastened to the inner and outer end of the guiding and pulling device. The guiding and pulling device has a crosspiece fastened to the front end of the piston rod and two guide elements located, respectively, to the right and left of the cylinder housing. The front end of the guide element is connected with the crosspiece on one side and the front end area of the guide element is connected with the second securing and locking unit on the other side and the rear ends are connected with the first securing and locking unit. The crosspiece preferably has a flat section or profile which is stiffened by a web plate and the guide
Conrad Klaus
Fery Jens
Irsch Michael
Krebs Thomas
Brahan Thomas J.
Cohen & Pontani, Lieberman & Pavane
Mannesmann AG
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