US 3344932 A
Description (OCR text may contain errors)
" Oct. 3, 1967 F. DE GASPERIS 2 CRAB RUNWAY FOR AN OVERHEAD TRAVELLING CRANE Filed May 17, 1965 2 Sheets-Sheet l 1967 F; DE GASPERIS 3,344,932.
CRAB RUNWAY FOR AN OVERHEAD TRAVELLING CRANE Filed May 17, 1965 2 Sheets-Sheet 2 FIG. 3
United States Patent 3,344,932 CRAB RUNWAY FOR AN OVERHEAD TRAVELLING CRANE Franco De Gasperis, Turin, Italy, assignor to Societa Nazionale d'elle Officine di Savigliano, Turin, Italy Filed May 17, 1965, Ser. No. 456,097 1 Claim. (Cl. 212-18) This invention relates to travelling cranes of the type comprising a main girder of box section and two side girders transversely secured to the ends of such main girder and equipped with supporting wheels adapted to run on tracks, said main girder serving to support a crab which is movable longitudinally thereof and carries load hoisting equipment.
In cranes of the type indicated the lifting ropes are necessarily supported from the crab to overhang one side of the girder and the problem thus arises of opposing the tilting force acting on the crab when travelling under load.
It is the chief object of the invention to provide a crane of the above mentioned type which is simple and sturdy in construction and wherein the crab is conveniently guided and linked to the main girder to oppose the tilting force exerted in the loaded condition of the crab.
A further object of the invention is to provide a crane of the above mentioned type wherein the traction and torque stresses deriving from the tilting force on the crab are transmitted to the main girder at a region of reinforced strength.
A further object of the invention is to provide a crane of the above mentioned type affording an easy and safe access to the crab, thereby minimising risk of injury to operators.
With the above and further objects in view this invention provides a travelling crane of the type specified wherein the main grider is provided with a first rail extending along the top edge of that side wall of the girder facing the load suspension means, and with a second rail which is carried by a supporting structure at the other side wall of said grider in such a manner as to be disposed in spaced parallel relation to the top side of the girder, said second rail being so arranged as to overhang the girder and comprising a flat structural member having two opposing upper and lower tracks, respectively.
In order that the said invention may be clearly understood and readily carried into effect reference will now be made to the accompanying drawings which show several constructional embodiments by way of example and in which:
FIGURE 1 is an elevational view of a single girder crane along which the hook carrying crab is guided,
FIGURE 2 is a sectional view on an enlarged scale on line 11-11 of FIGURE 1,
FIGURE 3 is a view similar to FIGURE 2 showing a modified structure,
FIGURE 4 shows an enlarged partial view of FIG- URE 2,
FIGURE 5 is a perspective view of the girder.
The crane comprises a main girder 1 of box-section to the opposite ends of which transversely extending side girders 2 are secured such girders 2 being provided with wheels 2a for rolling of the travelling crane along parallel tracks 3.
In the embodiment shown on the drawing the girder 1 is of oblong shape in section and comprises two vertically extending, steel plate reinforced side walls 1a, 1b and two horizontal plate members 10, 1d forming the boom platform and bottom of the girder. A plurality of transverse partitions 20 are arranged internally of the girder in order to improve the stiffness and strength thereof, such partitions being equidistantly spaced along the length of said girder.
A crab 4 is movably mounted on the girder and comprises a fiat platform of known type, adapted to support the load lifting members comprising an electric motor 14 and a winding drum 13 driving a lifting hook 12 which overhangs from the crab along one side wall 1a of the girder 1.
The crab is provided with known means for longitudinal travel over the girder 1.
The crab 4 is provided on its side facing the lifting hook with two supporting wheels 5 movable along a rail 6 secured to the top edge of the girder side wall 1a facing the load suspension members.
A carrying structure is secured to the other side wall 1b of the girder and comprises, by way of example, a plurality of standards 17 spaced equidistantly along the length of the girder. It will be noted that the side wall 1b of the grider and the standards 17 project upwardly beyond the plane of the top side 10 of said girder.
A rail 18 is secured to the top of the standards 17 and in the embodiment illustrated comprises a flat structural member having two opposite rolling tracks facing upwardly and downwardly respectively. The rail 18 is arranged to overhang the girder and extends in spaced parallel relation with the top side 10 of the latter. The standards 17 are secured to the girder side wall 1b at those points where the stiffening partitions 20 are located so that torque stresses acting on the rail 18 will be transmitted to said partitions.
The crab 4 is provided with at least one wheel 7 at that side remote from the load lifting members. The wheel 7 is adapted to engage the bottom surface of the rail 18 in order to transmit to the girder the tilting force acting on the crab 4 under load.
The force due to the eccentricity of the load with respect to the axis of the girder 1 is transmitted to the girder by the supporting wheels 5 and wheel 7 which latter engages the underside of the .rail 18, so that this force is taken up by the girder structure at the partitions 20.
In the embodiment illustrated the crab is provided with a further auxiliary wheel 8 so arranged as to engage the top surface of the rail 18, as shown in FIGURE 4, in order to transmit to this rail a part of the weight of the crab when the latter is not loaded.
Under no load the vertical axis extending through the centre of gravity of the crab is situated between the rails 6 and 18, and the crab weight is transmitted to the girder by the supporting wheels 5 and wheel 8, the bottom wheel 7 being inoperative. If however the crab is of such construction that under no load the vertical axis extending through the centre of gravity is situated externally of the girder on the side of the load suspension members, then the wheel 7 will engage the underside of the rail 18 also under no load condition of the crab. In the latter case the wheel 8 might be dispensed with. However, the wheel 8 is preferably provided in any case, since it transmits to the girder horizontally directed stresses due mainly to accelerations and decelerations in the movement of the main girder 1.
The number of the supporting wheels and auxiliary wheels may be varied depending upon the loads to be transported.
The power drive for the movement of the crab is transmitted to only one of the supporting Wheels. However, with larger capacities, it may be transmitted, to two or four of the wheels.
The top deck of the crab 4 carrying the hoisting members is provided with a protecting handrail 21 acting as a guard for maintenance personnel.
The top deck is accessible by way of a ladder 15 secured to the side of the crab side wall. Access to the ladder 15 is afforded by a platform 16 fixed to the girder 1 at the side wall 1b.
The platform serving as a safety passage for personnel is provided with a handrail 22, so that operators walking along the platform are protected at the outside by a handrail and at the'inside by the girder side wall 1b.
With the above described arrangement the crab frame 4 does not exceed the outer dimensions of the girder 1, on the side remote from the hook 12. The crab is simplified in construction because the supports for the Wheels 7, 8 can be directly fixed to the crab frame 4, which results in an improved overall strength and reduced weight.
Shortening of the structure afforded, as explained above by the arrangement of the auxiliary wheels, results in further advantages of a constructional, economic and structural nature.
According to a further modification shown in FIG- URE 3 the girder 1 is provided with another rail 19 directly secured to the top side 1c thereof and beneath the overhanging rail 18. The crab 4 is then equipped with an auxiliary wheel 8 arranged beneath the wheel 7 and adapted to engage from above the top surface of the rail 19 in order to transmit to the latter the weight of the crab under no load condition.
The cra-b according to this invention is advantageous in that is avoids any risk to operators walking over the service platform 16, the auxiliary wheels being arranged out of reach of the operators and screened by the supporting structure 17 of the rail 18.
What I claim is:
A crab runway for an overhead traveling crane, comprising a. main grider, a crab frame mounted on said girder for movement therealong, a first rail attached to said girder extending along the stop of said girder at one side thereof and having its running surface facing upwardly, load suspending means carried by said crab frame disposed laterally outwards of said first rail at one side and tending to tilt said crab frame in one direction about said first rail, a second rail having a running surface facing downwardly and carried by a supporting structure comprising a plurality of standards fitted to that side wall of said girder remote from said load suspension means at points coinciding with the location of bracing partitions within said grider, the said standards extending vertically beyond said top side and having secured to the top thereof said second rail in such a manner that the latter is disposed in spaced parallel relation to the top side of the girder and is arranged to overhang the latter, a third rail having its running surface facing upwardly directly secured to the top side of said girder beneath said second rail, at least one wheel mounted on said crab frame adapted to cooperate with said first rail and a pair of wheels mounted directly on the crab frame, adapted to cooperate with said second and third rail, respectively, the transverse dimension of the crab frame being kept within the overall dimension of the girder on the side remote from the one supporting the load suspension members.
References Cited UNITED STATES PATENTS 3,040,675 6/1962 Rudolfi 104-118 X FOREIGN PATENTS 1,344,767 10/ 1963 France. 1,3 67,874 6/1964 France. 5 1,375,775 9/1964 France. 1,117,278 11/1961 Germany EVON C. BLUNK, Primary Examiner.
SAMUEL F. COLEMAN, Examiner.
A. LEVINE, M. L. AJEMAN, Assistant Examiners.