US3924752A

US3924752A - Crane boom and line safety limit warning assembly

Info

Publication number: US3924752A
Application number: US489041A
Authority: US
Inventors: Frank M Hoofnagle
Original assignee: BWB Controls Inc
Current assignee: BWB Controls Inc
Priority date: 1974-07-16
Filing date: 1974-07-16
Publication date: 1975-12-09
Anticipated expiration: 1992-12-09

Abstract

A fluid pressure warning system is provided bleed valves for use on a crane and positioned for actuation in response to the boom of a crane being elevated excessively, the block of a crane approaching its upper limit and the fast line of a crane approaching its upper limit of travel. The fluid pressure system comprises a pneumatic system and includes a pneumatically actuated audible signal developing apparatus disposed in a branch line of the pneumatic system under the control of a pneumatic relay actuatable in response to a drop in air pressure within the system.

Description

Inventor: Frank M. Hoofnagle, Houma, La.

Assignee: BWB Controls, Inc., Houma, La.

Filed: July 16, 1974 Appl. No.: 489,041

US. Cl 212/39 MS; 91/1; 91/400; 214/761 Int. Cl. B66C 13/48 Field of Search 212/39; 214/761; 91/1, 91/400; 60/328, 403

References Cited UNITED STATES PATENTS 5/1945 Thomas 212/39 A 7/1965 Bolton et a1. 91/1 United States Patent [191 [111 3, 2

Hoofnagle 5] Dec. 9, 1975 CRANE BOOM AND LINE SAFETY LIMIT 3,505,928 4/1970 Whitehouse 91/1 WARMNG ASSEMBLY 3,722,707 3/1973 Hedeen et a1 r. 212/39 A Primary ExaminerRobert J. Spar Assistant Examiner-Lawrence J. Oresky [57] ABSTRACT A fluid pressure warning system is provided bleed valves for use on a crane and positioned for actuation in response to the boom of a crane being elevated excessively, the block of a crane approaching its upper limit and the fast line of a crane approaching its upper limit of travel. The fluid pressure system comprises a pneumatic system and includes a pneumatically actuated audible signal developing apparatus disposed in a branch line of the pneumatic system under the control of a pneumatic relay actuatable in response to a drop in air pressure within the system.

10 Claims, 6 Drawing Figures US. Patent D60. 9, 1975 shfiet 1 of 2 3,924,752

Fig.6

Resfricfion Orifice 75 Safely Devices From Air Source U.S. Patent Dec. 9, 1975 Sheet 2 of2 3,924,752

H I v I f I I I I If 4 a n QIII II:

CRANE BOOM AND LINE SAFETY LIMIT WARNING ASSEMBLY BACKGROUND OF THE INVENTION Each year many accidents involving the operation of cranes occur not as a result of mechanical failure but as a result of human error. In most cases an accident occurs because the crane operator is momentarily unaware of a critical position of the cranes fast line, block or boom.

In order to reduce such accidents various types of warning devices and crane clutch deactivating mechanisms have been heretofore designed. Examples of these previous devices may be found in U.S. Pat. Nos. 1,558,635 to W. M. Rutan, dated Oct. 27, 1925, 2,840,244 to W. T. Thomas, Jr., dated June 24, 1958, 3,052,878 to J. E. Berry, dated Sept. v4, 1962, 3,094,221 to C. W. Galuska, dated June 18, 1963 and 3,565,402 to Ernest A. Linke, dated Feb. 23, 1971. However, these previous warning and crane clutch actuating devices have been constructed whereby certain operating conditions may render them inoperative or at least reduced in effectiveness.

BRIEF DESCRIPTION OF THE INVENTION The warning assembly of the instant invention has been designed primarily for use on cranes including compressed air systems and includes structure whereby the assembly is substantially fail safe. The assembly does not include automatically actuatable crane clutch operating structure which could cause additional accidents if operated suddenly in a manner not anticipated by the operator of the crane or persons beneath a load supported by the crane, but is constructed in a manner whereby an audible signal for both the crane operator and persons who may be disposed beneath a load supported by the crane is actuated in response to the load or fast line approaching its upper limit, the block approaching its upper limit or the boom approaching a vertical position. The warning assembly is designed in a manner such that the audible signal (in addition to any other signals which may be operatively connected to the warning assembly) is rendered in sufficient time for the operator of the crane to correct the impending dangerous situation before a critical extent thereof is reached.

The main object of this invention is to provide a warning assembly for a crane which may be actuated in sufficient time in order to prevent the load or fast line or the block or dead line from reaching their upper limits and the boom of the crane from too closely approaching a vertical position.

Another object of this invention, in accordance with the immediately preceding object, is to provide a warning assembly actuatable from a cranes pneumatic system.

Still another object of this invention is to provide an apparatus in accordance with the preceding objects constructed in a manner so as to be substantially fail safe in operation.

A final object of this invention to be specifically enumerated herein is to provide a warning assembly in accordance with the preceding objects and which will conform to conventional forms of manufacture, be of simple construction and automatic in operation so as to provide a device that will be economically feasible, long lasting and trouble free.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a crane equipped with the warning assembly of the instant invention;

FIG. 2 is an enlarged fragmentary side elevational view of that portion of the warning assembly operatively associated with the fast line of the crane;

FIG. 3 is a fragmentary vertical sectional view taken substantially upon the plane indicated by the section line 33 of FIG. 2;

FIG. 4 is a side elevational view of that portion of the warning assembly operatively associated with the block lift line of the crane and with the related warning assembly components illustrated in vertical section;

FIG. 5 is a fragmentary side elevational view of that portion of the warning assembly operatively associated with the boom of the crane and with the corresponding warning assembly components illustrated in vertical section; and

FIG. 6 is a schematic view of the pneumatic system of the warning assembly.

DETAILED DESCRIPTION OF THE INVENTION Referring now more specifically to the drawings, the numeral 10 generally designates a conventional form of crane including a crawler carriage referred to in general by the reference numeral 12 from which a cab and boom support structure referred to in general by the reference numeral 14 is supported by means of a turntable 16.

The crane 10 includes a boom 18 of conventional design which may be raised and lowered by means of a cable or line 20 and a block 22 is supported from the upper end of the boom 18 by means of a block line 24. Further, the boom 18 includes an extension 26 over whose outer end a fast line 28 provided with a hook 30 is guided. The

lines

20, 24 and 28 may be reeled inwardly and paid out by the operator of the crane 10 as is conventional.

Secured to the lower end of the boom 18 is an abutment plate 32' and a pressure relief valve 34 is connected to one end of an air vent line 36 and supported from an upper portion of the cab 14. The pressure relief valve 34 includes a spring-biased reciprocal piston 38 including a valve head 40 on one end for engagement with a sealing ring 42 disposed about the outlet end of a vent bore 44 formed through the body 46 of the valve 34. The other end of the piston 38 projects outwardly of the opposite end of the bore 44 and includes an abutment head 48 thereon which may be abutted by the plate 32 when the boom 18 approaches a near vertical position as a result of the line 20 being reeled in too far.

As the plate 32 engages the abutment head 48 and shifts the piston 38 to the left as viewed in FIG. 5 against the biasing action of the compression spring 50, the head 40 is unseated from the seal 42 and the line 36 is vented through the bore 44.

In addition, a second pressure relief valve 34 of substantially the same construction as the pressure relief valve 34 but including a longer piston 38' has its body portion 46 pivotally supported from the upper end of the boom extension 26 as at 52. The abutment head 48 carried by the lower end of the piston 38' is disposed for engagement by an abutment disc 54 secured to the fast line 28 by means of setscrews 56. The abutment disc 54 is spaced slightly above the free end of the fast line 28 and therefore is disposed for engagement with the abutment head 48 to upwardly displace the piston 38' in order to unseat the head 40 from the upper end of the bore corresponding to the bore 44 through which the piston 38 is slidable. The line 36 includes a branch line 36 whose end remote from the line 36 is attached to the body 46 of the pressure relief valve 34' and opens into the bore thereof corresponding to the bore 44.

It will of course be appreciated that by suspending the pressure relief valve 34' at its upper end in a pivotal manner the longitudinal extent of the pressure relief valve 34' and the piston 38' will be maintained vertically disposed throughout angular changes of the boom and'that the piston 38 will therefore always parallel the fast line 28 to ensure that the abutment disc 54 will be engageable with the abutment head 48'.

With attention now invited more specifically to FIG. 4 of the drawings there may be seen a third pressure relief valve 34" to which one end of a second branch line 36" is connected. The block 22 includes an outwardly projecting plate 58 supported therefrom for engagement with the abutment head 48" carried by the piston 38" of the pressure relief valve 34". Of course, the piston 38" includes a head 40" at its end remote from the abutment head 48" and corresponding to the head 40 and continued upward movement of the block 22 after initial engagement of the plate 58 with the abutment head 48" will cause the piston 38" to be displaced upwardly to the phantom line position thereof illustrated in FIG. 4 in order to vent the branch line 36" through the bore 44" corresponding to the

bores

44 and 44.

However, rather than the pressure relief valve 34" being stationarily supported from the upper end of the boom 18 adjacent the block line 24 the body 46" of the valve 34" includes a vertical bore 60 extending therethrough including an upper end counterbore 62. The dead line 24' extends through the bore 60 whereby the body 46" is slidingly disposed on the dead line 24' and a slightly deformable sleeve 64 is seated within the counterbore 62 and snugly receives the lower end of a compression spring 66 whose upper end is anchored in position on an upper portion of the dead line 24 by means of a clamp assembly 68. The body 46" includes setscrews 70 for slightly inwardly deflecting and deforming the sleeve 62 in order that the latter may clampingly engage the lower end of the compression spring 66 disposed about the dead line 24. Accordingly, the body 46" is supported on the dead line 24' against downward sliding therealong by resistance of the spring 66 to expansion and yet may be moved upwardly along the dead line 24 in the event upward movement of the block 22 and the plate 58 is sufficient to fully collapse the compression spring 50" corresponding to the compression spring 50 and apply direct upward force on the body 46" of the valve 34". Accordingly, even though the block 22 may be elevated sufficiently to fully upwardly displace the piston 38 (and in the process vent the branch line 36" through the bore 44) further upward movement of the block 22 is possible as a result of upward sliding of the body 46" along the dead line 24.

With attention now invited more specifically to FIG. 6 of the drawings it may be seen that the crane 10 includes an air pressure line 76 extending from a suitable source of air under pressure. The line 76 includes a pressure gauge 78 and a pressure regulator 80 is serially connected in the line 76. The line 76 extends to a first port 82 in a pneumatic relay 84 and a branch or bypass line 86 extends from the line 76 downstream from the regulator 80 to a second port 88 in the pneumatic relay 80. The inlet end of a discharge line 90 is connected to a third port 92 in the relay 84 and the outlet end of the discharge line 90 is connected to a pneumatically operated audible signalling device 94. Further, the line 76 has a restriction orifice 96 disposed therein intermediate the inlet end of the bypass line 86 and the port 82 and a second pressure gauge 98 is communicated with the line 76 intermediate the restriction orifice 96 and the port 82. Further, the inlet end of the line 36 opens into the line 76 intermediate the restriction orifice and the port 82. In operation, if any of the

pistons

40, 40' and 40" are unseated from the adjacent ends of the corresponding bores 44, 44' and 44" the line 36 is vented and pressure to the port 82 of the relay 84 is reduced and maintained reduced by the restriction orifice 96. However, higher air pressure is maintained in the bypass line 86 extending to the port 88 and thus the relay 84 is actuated. Upon actuation of the relay 84 the port 92 is communicated with the port 88 whereby the pneumatically actuated audible signalling device 94 is placed in direct communication with the full pressure of the line 86 as regulated by the regulator 80. Of course, actuation of the audible signalling device 94 is sufficient to warn the operator of the crane 10 of a dangerous operating condition and the operator may take corrective steps.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. In combination with a crane including first and second components with the first component movable relative to the second component in opposite directions Steward and away from the second component and in one-of said directions toward a predetermined limit position, an abutment portion on one of said components, a normally closed pressure relief valve on the other of said components and including an actuator engageable by said abutment portion upon movement of said first component in said one direction to a position adjacent said limit position to open said pressure relief valve, a fluid pressure system including a fluid pressure line having an inlet end adapted for connection to a source of gas under pressure and an outlet end, an air pressure operated relay including a normally closed air passage extending therethrough and a pressure inlet port to which gas pressure must be supplied to maintain said air passage closed, said relay being operative to automatically open said passage in response to a drop in air pressure at said port below a predetermined value, said outlet end being communicated with said port and said pressure line including air flow restricting means intermediate said inlet and outlet ends, a first branch line including an inlet end opening into said pressure line between said flow restricting means and said outlet end and an outlet end communicated with one end of said flow passage, a second branch line including an inlet end communicated with the interior of said pressure line intermediate said flow restricting means and the outlet end of said pressure line and an outlet end under the control of said pressure relief valve, and a signal supply line having an inlet end communicated with the other end of said passage and an outlet end adapted to be communicated with a pneumatically actuatable signalling device.

2. In combination with a crane including first and second components with the first component movable relative to the second component in opposite directions toward and away from the second component and in one of said directions toward a predetermined limit position, an abutment portion on one of said components, a normally closed pressure relief valve on the other of said components and including an acutator engageable by said abutment portion upon movement of said first component in said one direction to a posi tion adjacent said limit position to open said pressure relief valve, a source of pressurized gas, a fluid pressure system including a fluid pressure line having an inlet end adapted for connection to said source of gas under pressure and an outlet end, a branch line including an inlet end communicated with said pressure line and an outlet end, a pneumatically actuatable signalling device connected to the outlet end of said branch line, said branch line including a normally closed valve serially connected therein and to which the outlet end of said pressure line is connected and operable to open said valve in response to a drop in pressure at said inlet port caused by the opening of said pressure relief valve, air flow restricting means in said pressure line between the inlet end of said branch line and the outlet end of said pressure line, and a pressure relief line including an inlet end opening into said pressure line between its outlet end and said flow restricting means and an outlet end under the control of said pressure relief valve, further said source of pressurized gas operates said pneumatically actuactable signalling device.

3. The combination of claim 1 wherein said pressure relief valve includes a valve body having a bore formed therethrough, a piston extending through said bore including a first end portion of reduced diameter provided with an enlarged head disposed outwardly of the corresponding end of said bore and shiftable toward said body to sealingly close said bore, the other end of said piston being snugly slidable through the other end portion of said bore and projecting outwardly of said body, spring means operatively connected between said piston and said body yieldingly biasing said piston toward a position with said head sealingly closing said corresponding end of said bore, said body including a pressure inlet port opening into said bore out of registry with said other end of said piston, the outlet end of said pressure relief line being connected to said inlet port.

4. The combination of claim 3 wherein said crane includes a boom mounting structure and a boom pivotally supported from said structure for oscillation about a generally horizontal axis, said mounting structure and boom comprising said components.

5. The combination of claim 4 wherein said abutment portion is carried by said boom and said pressure relief valve is carried by said mounting structure.

6. The combination of claim 3 wherein said crane includes a boom structure having a free end portion and a fast line received over the free end portion of said boom structure, said boom structure and fast line comprising said components.

7. The combination of claim 6 wherein said abutment portion is carried by said fast line and said relief valve is dependingly supported from said boom structure with said other end of said piston disposed lowermost and alongside the downwardly extending free end portion of said fast line, the upper portion of said relief valve body being pivotally supported from said boom structure for oscillation about a horizontal transverse axis.

8. The combination of claim 3 wherein said crane includes a boom structure having a free end portion and a block line received over said free end portion as well as a dead line anchored at its upper end to said structure, the lower ends of said block and dead lines being joined and supporting a block therefrom, said abutment being carried by said block and support means supporting said valve from said dead line with said other end of said piston lowermost and extending along said dead line.

9. The combination of claim 8 wherein said support means includes means supporting said valve body from said dead line for limited shifting along the latter and yieldingly biasing said body toward its lowermost limit position on said dead line.

10. The combination of claim 9 wherein said valve body includes a through bore generally paralleling the first-mentioned bore and said through bore includes an enlarged counterbore at its end corresponding to said corresponding end of first-mentioned body bore, said support means comprising a coiled combined expansion and compression spring disposed about and slidable on said dead line above said valve body, the lower end of said spring being anchored in said counterbore and the upper end of said spring being anchored to said deadline.

Claims

1. In combination with a crane including first and second components with the first component movable relative to the second component in opposite directions toward and away from the second component and in one of said directions toward a predetermined limit position, an abutment portion on one of said components, a normally closed pressure relief valve on the other of said components and including an actuator engageable by said abutment portion upon movement of said first component in said one direction to a position adjacent said limit position to open said pressure relief valve, a fluid pressure system including a fluid pressure line having an inlet end adapted for connection to a source of gas under pressure and an outlet end, an air pressure operated relay including a normally closed air passage extending therethrough and a pressure inlet port to which gas pressure must be supplied to maintain said air passage closed, said relay being operative to automatically open said passage in response to a drop in air pressure at said port below a predetermined value, said outlet end being communicated with said port and said pressure line including air flow restricting means intermediate said inlet and outlet ends, a first branch line including an inlet end opening into said pressure line between said flow restricting means and said outlet end and an outlet end communicated with one end of said flow passage, a second branch line including an inlet end communicated with the interior of said pressure line intermediate said flow restricting means and the outlet end of said pressure line and an outlet end under the control of said pressure relief valve, and a signal supply line having an inlet end communicated with the other end of said passage and an outlet end adapted to be communicated with a pneumatically actuatable signalling device.

2. In combination with a crane including first and second components with the first component movable relative to the second component in opposite directions toward and away from the second component and in one of said directions toward a predetermined limit position, an abutment portion on one of said components, a normally closed pressure relief valve on the other of said components and including an acutator engageable by said abutment portion upon movement of said first component in said one direction to a position adjacenT said limit position to open said pressure relief valve, a source of pressurized gas, a fluid pressure system including a fluid pressure line having an inlet end adapted for connection to said source of gas under pressure and an outlet end, a branch line including an inlet end communicated with said pressure line and an outlet end, a pneumatically actuatable signalling device connected to the outlet end of said branch line, said branch line including a normally closed valve serially connected therein and to which the outlet end of said pressure line is connected and operable to open said valve in response to a drop in pressure at said inlet port caused by the opening of said pressure relief valve, air flow restricting means in said pressure line between the inlet end of said branch line and the outlet end of said pressure line, and a pressure relief line including an inlet end opening into said pressure line between its outlet end and said flow restricting means and an outlet end under the control of said pressure relief valve, further said source of pressurized gas operates said pneumatically actuactable signalling device.

10. The combination of claim 9 wherein said valve body includes a through bore generally paralleling the first-mentioned bore and said through bore includes an enlarged counterbore at its end corrEsponding to said corresponding end of first-mentioned body bore, said support means comprising a coiled combined expansion and compression spring disposed about and slidable on said dead line above said valve body, the lower end of said spring being anchored in said counterbore and the upper end of said spring being anchored to said dead line.