Overload safety device for telescopic cranes
United States Patent 3909817
An overload safety device for jib cranes includes a transmitter for registering a working radius and a transmitter for registering a load applied to the jib wherein the crane comprises an upper carriage, a base jib member, and a luffing cylinder interconnecting the upper carriage and the base jib member, the transmitter for registering a load including a force measuring cell connected in a force path from the upper carriage through the luffing cylinder to the base jib member.
US Patent References:
LOAD LIMIT CONTROL FOR HOISTING EQUIPMENT
Greb et al. - January 1970 - 3489294
OVERLOAD SAFETY DEVICE FOR JIB CRANES
Peter et al. - January 1972 - 3638212
INDICATOR OR CONTROL FOR CRANES
Brownell et al. - April 1973 - 3724679
MOMENT MONITORING SYSTEM FOR BOOM-CABLE TYPE CRANES
Becker et al. - November 1973 - 3771667
LOAD LIMIT CONTROL FOR HOISTING EQUIPMENT
Greb et al. - January 1970 - 3489294
OVERLOAD SAFETY DEVICE FOR JIB CRANES
Peter et al. - January 1972 - 3638212
INDICATOR OR CONTROL FOR CRANES
Brownell et al. - April 1973 - 3724679
MOMENT MONITORING SYSTEM FOR BOOM-CABLE TYPE CRANES
Becker et al. - November 1973 - 3771667
Inventors:
Pietzsch, Ludwig (7500 Karlsruhe, DT)
Huhne, Gerd (7501 Morsch, DT)
Overlach, Knud (7500 Karlsruhe, DT)
Fuchs, Peter (7501 Bruchhausen, DT)
Huhne, Gerd (7501 Morsch, DT)
Overlach, Knud (7500 Karlsruhe, DT)
Fuchs, Peter (7501 Bruchhausen, DT)
Application Number:
05/353716
Publication Date:
09/30/1975
Filing Date:
04/23/1973
View Patent Images:
Export Citation:
Primary Class:
International Classes:
B66C23/90; B66C23/00; G08B21/00
Field of Search:
340/267C 217/39R,39A
Primary Examiner:
Swann III, Glen R.
Attorney, Agent or Firm:
Lerner, Herbert L.
Parent Case Data:
CROSS-REFERENCE TO RELATED APPLICATION
This is a continuation-in-part application of Ser. No. 79,589, filed Oct. 9, 1970 now abandoned.
Claims:
We claim
1. Overload safety device for jib cranes comprising transmitter means for registering a working radius and transmitter means for registering a load applied to the jib wherein the crane comprises an upper carriage member, a base jib member, and a luffing cylinder interconnecting said upper carriage member and said base jib member, said transmitter means for registering a load comprising a force measuring cell connected in a force path from said upper carriage member through said luffing cylinder to said base jib member.
2. Overload safety device according to claim 1 wherein said luffing cylinder is operatively and pivotally connected by respective pivots to said upper carriage member and said base jib member, and said transmitter means comprises at least one force measuring cell coordinated with at least one of said pivots, said one pivot being located on an intermediate carrier having a pair of spaced support locations, one of said support locations being secured to said base jib member, said intermediate carrier having a free arm, said force measuring cell being disposed as a second support location between said free arm and said base jib member.
3. Overload safety device according to claim 1 wherein said luffing cylinder is operatively and pivotally connected by respective pivots to said upper carriage member and said base jib member, and said transmitter means comprises at least one force measuring cell coordinated with at least one of said pivots, said one pivot being located on an intermediate carrier having a pair of spaced support locations, one of said support locations being secured to said upper carriage member, said intermediate carrier having a free arm, said force measuring cell being disposed as a second support location between said free arm and said upper carriage member.
4. Overload safety device according to claim 1 wherein said luffing cylinder includes a displaceable piston rod, and said force measuring cell is connected in the piston rod.
5. Overload safety device according to claim 1 wherein said luffing cylinder is operatively and pivotally connected by respective pivots to said upper carriage member and said base jib member and said transmitter means comprises at least one force measuring cell coordinated with at least one of said pivots, said one pivot being located on an intermediate carrier having a pair of spaced support locations, one of said support locations being secured to one of said members, said intermediate carrier having a free arm, said force measuring cell being disposed as a second support location between said free arm and said one member.
1. Overload safety device for jib cranes comprising transmitter means for registering a working radius and transmitter means for registering a load applied to the jib wherein the crane comprises an upper carriage member, a base jib member, and a luffing cylinder interconnecting said upper carriage member and said base jib member, said transmitter means for registering a load comprising a force measuring cell connected in a force path from said upper carriage member through said luffing cylinder to said base jib member.
2. Overload safety device according to claim 1 wherein said luffing cylinder is operatively and pivotally connected by respective pivots to said upper carriage member and said base jib member, and said transmitter means comprises at least one force measuring cell coordinated with at least one of said pivots, said one pivot being located on an intermediate carrier having a pair of spaced support locations, one of said support locations being secured to said base jib member, said intermediate carrier having a free arm, said force measuring cell being disposed as a second support location between said free arm and said base jib member.
3. Overload safety device according to claim 1 wherein said luffing cylinder is operatively and pivotally connected by respective pivots to said upper carriage member and said base jib member, and said transmitter means comprises at least one force measuring cell coordinated with at least one of said pivots, said one pivot being located on an intermediate carrier having a pair of spaced support locations, one of said support locations being secured to said upper carriage member, said intermediate carrier having a free arm, said force measuring cell being disposed as a second support location between said free arm and said upper carriage member.
4. Overload safety device according to claim 1 wherein said luffing cylinder includes a displaceable piston rod, and said force measuring cell is connected in the piston rod.
5. Overload safety device according to claim 1 wherein said luffing cylinder is operatively and pivotally connected by respective pivots to said upper carriage member and said base jib member and said transmitter means comprises at least one force measuring cell coordinated with at least one of said pivots, said one pivot being located on an intermediate carrier having a pair of spaced support locations, one of said support locations being secured to one of said members, said intermediate carrier having a free arm, said force measuring cell being disposed as a second support location between said free arm and said one member.
Description:
BACKGROUND OF THE INVENTION
The invention relates to overload safety device for telescopic cranes and, more particularly, to such overload safety device for telescopic cranes having transmitters for registering the working radius and the load as well as an analog computer wherein the nominal value predetermined by the working radius is compared with the actual values furnished by the transmitter for registering the load, and, when the actual values are equal to the nominal values, an overload signal is released.
In heretofore known overload safety devices of this general type, the permissible load values are given as the nominal values. The load transmitters are force transmitters whose actual values are compared to the nominal values. The safety device attained in this manner is unsatisfactory especially for telescopic cranes since tilting or tipping thereof can occur not only due to a too-heavy load but also due to an excessive working radius of the jib. The moment of the jib weight can be as much as 10 times the load moment for large working radii. Besides the jib moment, external forces such as wind forces, diagonal pulling and too-great acceleration can also help produce tipping of the crane.
In copending application Ser. No. 353,715 of P. Fuchs et al. filed Apr. 23, 1973 and assigned to the same assignee as that of the instant application, there is disclosed an overload safety device for telescopic cranes comprising transmitter means for registering a working radius of a crane jib having a base jib member and transmitter means for registering a load applied to the jib, analog computer means operatively connected to both the first and second transmitter means for comparing a nominal value predetermined by the working radius with actual values furnished by the transmitter means for registering the load, and signal means responsive to a condition wherein the actual values equal the nominal value for releasing an overload signal, the nominal values being proportional to a permissible limit moment for a respective working radius, the permissible limit moment being composed of a moment of the jib weight and a moment for the permissible load, the transmitter means for registering the load being mounted at the base jib member of the crane jib and being adapted to measure the bending moment of the jib member, the transmitter means for registering the load being an elongation measuring transmitter.
It is an object of the invention to provide an overload safety device for telescopic cranes that is improved in operation over the heretofore known devices of the same general type.
SUMMARY OF THE INVENTION
With the foregoing and other objects in view, there is provided in accordance with the invention of the instant application, an overload safety device for telescopic cranes of the general type described in the aforementioned copending application, which has a transmitter for registering a load which comprises at least one force measuring cell or pressure gauge of conventional construction that is connected in the path of the force from the upper carriage through the luffing cylinder to the base jib member of a telescopic crane.
In another embodiment of the invention, the force measuring cell is connected into the piston rod of the luffing cylinder.
In still another embodiment of the invention, the force measuring cell is coordinated to a pivot point of the luffing cylinder or respective force measuring cells are connected to each pivot point of the luffing cylinder in such a way that the respective pivot point is located at an intermediate carrier which is secured at one end thereof to the base jib member or the upper carriage, and is provided with the force measuring cell between the other free end thereof and the base jib member or upper carriage.
In this embodiment of the invention, the forced measuring cell is located distant from the parts of the luffing cylinder that are directly displaced during operation thereof. The farther the pivot point is located away from the force measuring cell, the smaller the part of the load is that is transmitted through the force measuring cell, whereby this load component remains representative, however, for the respective total load. The force measuring cell of this embodiment can consequently be of smaller dimensions than if the entire load were transmitted therethrough. A preferred spacing of the pivot point from the secured end of the intermediate carrier is substantially equal to half the spacing between both support locations of the intermediate carrier. The stress applied to the force measuring cell is therefore only half as great as the component to be applied by the luffing cylinder which is normal to the base jib member.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as overload safety device for telescopic cranes, it is nevertheless not intended to be limited to the details shown, since various modifications may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
BRIEF DESCRIPTION OF THE DRAWING
The invention, however, together with additional objects and advantages thereof will be best understood from the following description when read in connection with the accompanying drawings, in which:
FIGS. 1a and 1b are side elevational views of two embodiments of a telescopic crane of mobile type having a conventional construction;
FIG. 2 is a fragmentary enlarged view of FIG. 1 showing the luffing or whipping cylinder of the telescopic crane with a load transmitter according to the invention;
FIG. 3 is another view of FIG. 2 showing a modified form of the load transmitter thereof; and
FIG. 4 is a fragmentary view of the upper end of the luffing cylinder showing another arrangment of the load transmitters of FIGS. 2 and 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawing and first particularly to FIGS. 1a and 1b thereof, there is shown therein a mobile telescopic crane which includes an undercarriage 101 and an upper carriage 103 rotatable about a vertical axis 102 with respect to the undercarriage 101. At the rear end of the upper carriage 103, the rear end of the base jib member 104 is pivotally connected, while a luffing cylinder 106, 106' is pivotally connected at 105 to the upper carriage 103. The luffing cylinder 106 is pivoted at 107 and the luffing cylinder 106' is pivoted at 107' to the base jib member 104.
The luffing cylinder 106 and the pivot 107, on the one hand, and the luffing cylinder 106' and the pivot 107', on the other hand, are two alternative embodiments of conventionally employed means for pivoting the luffing cylinder or the base jib member. Whereas the luffing cylinder 106 is inclined in the same direction as that of the base jib member 104, although at a lesser angle of inclination with respect to the vertical, in the second type of support shown in FIG. 1b, the luffing cylinder 106' is generally inclined in opposite direction to the inclination of the base jib member. The invention of the instant application is applicable equally to both of the types of support shown in FIGS. 1a and 1b, however, in FIGS. 2 to 4, only the application of the invention to the type of support of FIG. 1a i.e. the luffing cylinder 106 at the pivot 107, is shown.
In FIGS. 2 to 4, the same or similar members are identified by the corresponding reference numerals employed in FIG. 1a.
In the embodiment of the invention shown in FIG. 2, the luffing cylinder 106 is not directly connected articulatingly to the base jib member 104. Rather, the upper pivot point 117 is provided at an intermediate carrier 108 which is secured at one of its ends 109 to the base jib member 104, and between the other free end 110 thereof and the base jib member 104, there is mounted a force measuring box 111. The force measuring box 111 can be secured to the end 110 of the intermediate carrier 108 or to the base jib member 104. From FIG. 2, it is apparent that the force to be applied altogether by the luffing cylinder 106 is divided at the two support locations 109 and 111 of the intermediate carrier, the ratio of the forces transmitted through the support locations 109 and 111 being determined from the spacings between the pivot point 107 and the respective support locations 109 and 111.
Only the respective components of the load portion applied to the support location 110 and extending normally to the base jib member is measured with the force measuring box 111. Since the angular position of the jib is registered, however, through the working radius transmitter and is relied on for forming the actual value, the load measurement yields a value representative for the entire load which is employable for each angular position of the jib.
The contstruction of the embodiment of FIG. 3 differs from that of FIG. 2 in that the intermediate carrier 108 is coordinated with the force measuring box 111 to the lower pivot point 115 of the luffing cylinder 106 instead of to the upper pivot point 107 thereof. In this case, the intermediate carrier 108 is secured by one end 109 thereof to the upper carriage 103, while the force measuring box 111 is disposed between the other, free end 110 of the intermediate carrier and the upper carriage. The pivot point 115 is also provided in this case again between both support locations 109 and 111 at the intermediate carrier 108.
Naturally, it is also possible to visualize an embodiment of the invention wherein both the lower as well as the upper ends of the luffing cylinder 106 are supported through an intermediate carrier 108 and a force measuring box 111 on the upper carriage 103 and on the base jib member 104.
In the embodiment of FIG. 4, a force measuring box 121 is directly connected into the piston rod 122 of the luffing cylinder 123. In this case, the total force transmitted along the luffing cylinder is measured by the force measuring box 121. As shielding against undesired outer influences, a casing 124 connected at 125 to the foot of the piston rod 122 is provided, the casing 124 being slidingly guided by an inner guide member 126 on the outer peripheral surface of the luffing cylinder 123.
The invention relates to overload safety device for telescopic cranes and, more particularly, to such overload safety device for telescopic cranes having transmitters for registering the working radius and the load as well as an analog computer wherein the nominal value predetermined by the working radius is compared with the actual values furnished by the transmitter for registering the load, and, when the actual values are equal to the nominal values, an overload signal is released.
In heretofore known overload safety devices of this general type, the permissible load values are given as the nominal values. The load transmitters are force transmitters whose actual values are compared to the nominal values. The safety device attained in this manner is unsatisfactory especially for telescopic cranes since tilting or tipping thereof can occur not only due to a too-heavy load but also due to an excessive working radius of the jib. The moment of the jib weight can be as much as 10 times the load moment for large working radii. Besides the jib moment, external forces such as wind forces, diagonal pulling and too-great acceleration can also help produce tipping of the crane.
In copending application Ser. No. 353,715 of P. Fuchs et al. filed Apr. 23, 1973 and assigned to the same assignee as that of the instant application, there is disclosed an overload safety device for telescopic cranes comprising transmitter means for registering a working radius of a crane jib having a base jib member and transmitter means for registering a load applied to the jib, analog computer means operatively connected to both the first and second transmitter means for comparing a nominal value predetermined by the working radius with actual values furnished by the transmitter means for registering the load, and signal means responsive to a condition wherein the actual values equal the nominal value for releasing an overload signal, the nominal values being proportional to a permissible limit moment for a respective working radius, the permissible limit moment being composed of a moment of the jib weight and a moment for the permissible load, the transmitter means for registering the load being mounted at the base jib member of the crane jib and being adapted to measure the bending moment of the jib member, the transmitter means for registering the load being an elongation measuring transmitter.
It is an object of the invention to provide an overload safety device for telescopic cranes that is improved in operation over the heretofore known devices of the same general type.
SUMMARY OF THE INVENTION
With the foregoing and other objects in view, there is provided in accordance with the invention of the instant application, an overload safety device for telescopic cranes of the general type described in the aforementioned copending application, which has a transmitter for registering a load which comprises at least one force measuring cell or pressure gauge of conventional construction that is connected in the path of the force from the upper carriage through the luffing cylinder to the base jib member of a telescopic crane.
In another embodiment of the invention, the force measuring cell is connected into the piston rod of the luffing cylinder.
In still another embodiment of the invention, the force measuring cell is coordinated to a pivot point of the luffing cylinder or respective force measuring cells are connected to each pivot point of the luffing cylinder in such a way that the respective pivot point is located at an intermediate carrier which is secured at one end thereof to the base jib member or the upper carriage, and is provided with the force measuring cell between the other free end thereof and the base jib member or upper carriage.
In this embodiment of the invention, the forced measuring cell is located distant from the parts of the luffing cylinder that are directly displaced during operation thereof. The farther the pivot point is located away from the force measuring cell, the smaller the part of the load is that is transmitted through the force measuring cell, whereby this load component remains representative, however, for the respective total load. The force measuring cell of this embodiment can consequently be of smaller dimensions than if the entire load were transmitted therethrough. A preferred spacing of the pivot point from the secured end of the intermediate carrier is substantially equal to half the spacing between both support locations of the intermediate carrier. The stress applied to the force measuring cell is therefore only half as great as the component to be applied by the luffing cylinder which is normal to the base jib member.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as overload safety device for telescopic cranes, it is nevertheless not intended to be limited to the details shown, since various modifications may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
BRIEF DESCRIPTION OF THE DRAWING
The invention, however, together with additional objects and advantages thereof will be best understood from the following description when read in connection with the accompanying drawings, in which:
FIGS. 1a and 1b are side elevational views of two embodiments of a telescopic crane of mobile type having a conventional construction;
FIG. 2 is a fragmentary enlarged view of FIG. 1 showing the luffing or whipping cylinder of the telescopic crane with a load transmitter according to the invention;
FIG. 3 is another view of FIG. 2 showing a modified form of the load transmitter thereof; and
FIG. 4 is a fragmentary view of the upper end of the luffing cylinder showing another arrangment of the load transmitters of FIGS. 2 and 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawing and first particularly to FIGS. 1a and 1b thereof, there is shown therein a mobile telescopic crane which includes an undercarriage 101 and an upper carriage 103 rotatable about a vertical axis 102 with respect to the undercarriage 101. At the rear end of the upper carriage 103, the rear end of the base jib member 104 is pivotally connected, while a luffing cylinder 106, 106' is pivotally connected at 105 to the upper carriage 103. The luffing cylinder 106 is pivoted at 107 and the luffing cylinder 106' is pivoted at 107' to the base jib member 104.
The luffing cylinder 106 and the pivot 107, on the one hand, and the luffing cylinder 106' and the pivot 107', on the other hand, are two alternative embodiments of conventionally employed means for pivoting the luffing cylinder or the base jib member. Whereas the luffing cylinder 106 is inclined in the same direction as that of the base jib member 104, although at a lesser angle of inclination with respect to the vertical, in the second type of support shown in FIG. 1b, the luffing cylinder 106' is generally inclined in opposite direction to the inclination of the base jib member. The invention of the instant application is applicable equally to both of the types of support shown in FIGS. 1a and 1b, however, in FIGS. 2 to 4, only the application of the invention to the type of support of FIG. 1a i.e. the luffing cylinder 106 at the pivot 107, is shown.
In FIGS. 2 to 4, the same or similar members are identified by the corresponding reference numerals employed in FIG. 1a.
In the embodiment of the invention shown in FIG. 2, the luffing cylinder 106 is not directly connected articulatingly to the base jib member 104. Rather, the upper pivot point 117 is provided at an intermediate carrier 108 which is secured at one of its ends 109 to the base jib member 104, and between the other free end 110 thereof and the base jib member 104, there is mounted a force measuring box 111. The force measuring box 111 can be secured to the end 110 of the intermediate carrier 108 or to the base jib member 104. From FIG. 2, it is apparent that the force to be applied altogether by the luffing cylinder 106 is divided at the two support locations 109 and 111 of the intermediate carrier, the ratio of the forces transmitted through the support locations 109 and 111 being determined from the spacings between the pivot point 107 and the respective support locations 109 and 111.
Only the respective components of the load portion applied to the support location 110 and extending normally to the base jib member is measured with the force measuring box 111. Since the angular position of the jib is registered, however, through the working radius transmitter and is relied on for forming the actual value, the load measurement yields a value representative for the entire load which is employable for each angular position of the jib.
The contstruction of the embodiment of FIG. 3 differs from that of FIG. 2 in that the intermediate carrier 108 is coordinated with the force measuring box 111 to the lower pivot point 115 of the luffing cylinder 106 instead of to the upper pivot point 107 thereof. In this case, the intermediate carrier 108 is secured by one end 109 thereof to the upper carriage 103, while the force measuring box 111 is disposed between the other, free end 110 of the intermediate carrier and the upper carriage. The pivot point 115 is also provided in this case again between both support locations 109 and 111 at the intermediate carrier 108.
Naturally, it is also possible to visualize an embodiment of the invention wherein both the lower as well as the upper ends of the luffing cylinder 106 are supported through an intermediate carrier 108 and a force measuring box 111 on the upper carriage 103 and on the base jib member 104.
In the embodiment of FIG. 4, a force measuring box 121 is directly connected into the piston rod 122 of the luffing cylinder 123. In this case, the total force transmitted along the luffing cylinder is measured by the force measuring box 121. As shielding against undesired outer influences, a casing 124 connected at 125 to the foot of the piston rod 122 is provided, the casing 124 being slidingly guided by an inner guide member 126 on the outer peripheral surface of the luffing cylinder 123.