US3481489A

US3481489A - Means for extending and retracting boom sections of a crane

Info

Publication number: US3481489A
Application number: US688236A
Authority: US
Inventors: Robert E Stauffer
Original assignee: ROBERT E STAUFFER
Current assignee: ROBERT E STAUFFER
Priority date: 1967-12-05
Filing date: 1967-12-05
Publication date: 1969-12-02
Anticipated expiration: 1986-12-02
Also published as: DE1807911A1; FR1593411A; DE1807911B2; GB1192879A

Description

Dec. 2, 1969 R. E. sTAuFFER MEANS FOR EXTENDING AND RETRACTING BOOM SECTIONS OF A CRANE 2 Sheets-Sheet l Filed Deo. 5, 1967 /N VEA/rol? ROBERT ESTAUFFER, BY m United States Patent O 3,481,489 MEANS FOR EXTENDING AND RETRACTING BOOM SECTIONS F A CRANE Robert E. Staufer, 119 Edgewood Drive, Galion, Ohio 44833 Filed Dec. S, 1967, Ser. No. 688,236 Int. Cl. B66c 23/06; F02b 73/00 U.S. Cl. 212-55 3 Claims ABSTRACT 0F THE DISCLOSURE The instant invention relates to cranes that have a boom with several relatively extensible and retractable boom sections, and more particularly to an improved system for extending and retracting the boom sections relatively to each other.

Cranes find widespread applications for use in lifting and moving loads of various types. The cranes customarily `include a boom which is used to reach out to the load, and by which the load is picked up and moved to another location at which the load is set down. The crane boom is usually supported on a turntable base which permits movement of the boom to any position within the circle of operation of the crane. The boom is mounted on a pivot to permit the boom to be raised and lowered in order to reach to various elevations. In addition to these movements the boom is formed with several boom sections that may be extended and retracted relatively to each other in order to reach out in the radial direction to a particular location.

In one type of crane construction with a boom that has several extensible and retractable boom sections, the boom sections are telescoped within each other in -the retracted condition of the boom. Each successive boom section is of smaller lateral `dimension than the preceding boom section, in order to permit the telescoping operation. When the several boom sections are fully extended, the boom has the configuration of a taperingcantilever beam, since the boom sections are of successively smaller lateral dimension.

In the tapering beam configuration of the extended boom the Weakest part of the boom is that part which is of smallest lateral dimension, and the boom is of greater strength in the successively larger sections. InA the course of operating the crane it is customary to extend and retract the several sections of the boom while there is a load supported on the end of the boom. The several boom sections must be of sufficient strength to support the load which is carried by the boom. In order to most effectively operate the boom in its extensive and retractive movements, the several boom sections are extended and retracted at proportional rates of movement, which may Ebe equal, so that the tapering vbeam configuration of the boom is maintained in all steps of extension and retraction of the boom sections, in order to most effectively distribute the load on the boom.

It is an object of this invention to provide an improved system for extending and retracting the several boom sections of the boom in a crane.

It is another object of this invention to provide a crane 3,481,489 Patented Dec. 2, 1969 ICC in which the several sections of the boom are extended and retracted relatively to each other at proportional rates of movement.

It is a further object of this invention to provide an improved crane in which the boom has several boom sections of successively smaller dimension, and in which the boom sections are extended and retracted at proportional rates of movement to maintain a tapering beam configuration of the boom in all positions of extension and retraction of the boom sections.

Still another object of this invention is to provide a crane in which the boom has several boom sections that are of successively smaller dimension to be telescopically received within each other, and the boom sections are extended and retracted relatively to each other at equal rates of movement, in order to maintain the tapering beam configuration of the boom.

Other objects of the invention will appear hereinafter, the novel feaures and combinations being set forth in the appended claims.

Referring to the drawings:

FIG. 1 is a side elevational view of a crane boom constructed in accordance with this invention;

FIG. 2 is a diagrammatic illustration of the hydraulic system for extending and retracting the boom sections; and

FIG. 3 is a sectional view of the flow divider valve.

Referring to FIG. l, there is illustrated alcrane boom 10 which is supported on a base 11, which may be the frame or chassis of a truck by which the crane is moved to different work locations. There is a turntable 12 on the supporting base 11, zby which the crane boom 10 may be swung to any position in the circle of operation of the crane boom 10. A pedestal 13 stands on the turntable 12,

and extends upwardly and rearwardly to support a lateral pivot pin 14, on which the boom 10 is mounted. A lift cylinder 15 is placed in the pedestal 13. The base end of the cylinder 15 is connected to the turntable 12 by a pivot pin 16, and the piston rod end of the cylinder 15 is connected to the boom 10 by a pivot pin 17. The boom 10 is swung upwardly on the pivot pin 14 to an elevated position lby extension of the cylinder 15, in order to reach to different elevations. The boom 10 is lowered by contraction of the cylinder 15.

The boom 10 extends forwardly from the pedestal 13 as a cantilever beam, and is counterbalanced by a counterweight 18 rearwardly of the pivot 14. The counterweight 18 Vis secured to a rearward extension 19 of the first or lower boom section 20. A winch 21 is placed at the rear end of the boom 10, partially within the counterweight 18, and is also secured to the rearward extension 19. A winch line 22 extends from the winch 21 over the top of the boom 10 to the head `block 23 at the forward end of the boom 10. The line 22 is reeved around the sheaves 24, 25 in the head Iblock 23, and around the sheave 26 in the hook block 27. The winch line 22 may be taken up and let out from the winch 21 by operation of the latter, which respectively raises or lowers the head block 27 to raise or lower the load which is secured or held on the hook 28.

The first boom section 20 is formed with a hollow walled construction to receive a second or upper boom section 30, which is telescoped into the first boom section 20 and may be extended and retracted relatively to the latter. The second boom section 30' is also formed with a hollow walled construction to telescopically receive the third boom section 31, which may be extended and retracted relatively to the second boom section 30. The head block 23 is secured to the outer end of the third boom section 31.

There is a first hydraulic cylinder 32 which is disposed at the bottom of the first boom -section 20 and extends longitudinally along the first boom section 20. The cylinder 32 is secured to the first boom section 20 at approximately mid-length of the cylinder 32 by a plurality of yieldable mounting, elements 33, which permit the cylinder 32 to yield in response to the bending of the boom under load. The piston rod end of cylinder 32 is connected to the second boom section 30 by a pin 34 and a depending foot 35, of which the latter is secured to the second boom section 30. The hydraulic cylinder 32 includes the usual piston and piston rod which are linearly movable, and upon extension of the piston rod the second boom section 30 is extended relatively to the boom section and retraction of the piston rod retracts the second boom section to its telescoped disposition within the first boom section 20.

There is a second hydraulic cylinder 38 which is disposed within the second and

third boom sections

30, 31. When the second boom section 30 is moved relatively to the first boom section 20, the third boom section 31 moves with the second boom section 30, and the second cylinder 38 also moves, since is connected to the second and

third boom sections

30, 31.

The cylinder or base end of the second hydraulic cylinder 38 is connected to the second boom section 30 by an upright pin 39. The piston rod end of the second hydraulic cylinder 38 is connected to the third boom section 31 by a pin 40 in an upright leg 41 that is secured to the second boom section 30 is retracted, the coil spring 45 38 includes the usual piston and piston rod, which are linearly movable. By extension and retraction of the piston rod of the second cylinder 38, the third boom section 31 is extended and retracted relatively to the second boom section 30.

Each of the

hydraulic cylinders

32, 38 is double acting, and therefore, is power operated on the extension stroke and on the retraction stroke thereof. Hydraulic operating fluid under pressure is supplied to the first and

second cylinders

32, 38 at the base ends thereof for extending the

boom sections

30, 31, or alternatively, hydraulic fluid under pressure is supplied to the piston rod ends of the

cylinders

32, 38 in order to retract the

boom sections

30, 31.

There are the usual hydraulic hoses connected to the

cylinders

32, 38, but these are not illustrated in FIG. 1 in the interests of maintaining clarity of the drawing. The cylinder 32 is supported on the first boom section 20 and does not travel. However, the second hydraulic cylinder 38 travels with the second and

third boom sections

30, 31. Therefore, the hydraulic hoses for the second hydraulic cylinder 38 are led around a movable sheave 42 to a fixed sheave 43, and then into the second boom section 30, to be connected to the second cylinder 38. The movable sheave 42 may travel along a rail 44 that extends longitudinally along the rst boom section 20. A long coil spring 45 urges the movable sheave 42 to its forwardmost position, as illustrated in FIG. 1. When the second boom section 30 is extended relatively to the first boom section 20, the hydraulic hoses are drawn around the fixed sheave 43, pulling the movable sheave 42 rearwardly against the force of the coil spring 45. When the second boom section 30 is retracted, the coil spring 45 pulls the movable sheave 42 forwardly along the rail 44, thereby pulling the hydraulic hoses out of the boom over the fixed sheave 43.

There is a guard 46 for the first hydraulic cylinder 32. Such guard 46 extends along the underside of the cylinder 32, and there is a movable guard section 47 that moves outwardly with the second boom section 30 when the latter is extended, to guard the piston rod of the cylinder 32.

Referring to FIG. 2, there is illustrated therein the hydraulic operating system for the first and second

hydraulic cylinders

32, 38, by which the several boom sections are extended. The hydraulic fluid is supplied under pressure by a pump 50 to a manual valve 51, which in its centered position directs the liuid to the tank 52. The valve 51 may be operated in one direction to direct the hydraulic operating fluid to the line 53, and the return hydraulic fluid from line 54 is directed through the valve 51 to the tank 52. The valve 51 may be operated in the opposite direction to direct the hydraulic operating fiuid from the pump 50 to the line 54, and the line 53 then is the return line, and the return hydraulic operating fluid is then directed by the valve 51 to the tank 52. The valve 51 has return springs for the Valve spool to return the latter to its centered position in either direction of operation of the spool.

The line 53 is connected toa pressure compensated flow divider valve 55, which has the function of proportionally dividing the supply flow of hydraulic operating fluid from the line 53 into two supply fiows of operating fluid in

lines

56, 57. When the line 53 functions as a return line for the hydraulic fluid, the flow divider valve 55 functions to proportionally combine the return flow of hydraulic fiuid from the

lines

56, 57 to the return line 53.

The line 53 functions as la supply line for hydraulic fluid when the second and

third boom sections

30, 31 are extended by extension of the second and

third cylinders

32, 38, respectively. The supply flow of hydraulic fiuid is through the line 56, the check valve 58 and line 59, the latter being connected to the base or cylinder end of the first cylinder 32. The operating fluid from the line 59 extends the piston and piston rod of the cylinder 32. The return hydraulic fiuid from the piston rod end of the cylinder 32 flows through the return line 60, the line 54 and the valve 51 to the tank 52.

The line 57 from the ow divider valve 55 is also a supply line for hydraulic operating liuid under pressure, and such hydraulic fiuid flows through the line 57, the check valve `61 and the line 62 to the base or cylinder end of the second cylinder 38 to extend the piston and piston rod thereof. The return flow of hydraulic fiuid is from the piston rod end of the cylinder 38 through the line 63, the line 54 and the valve 51 to the tank 52.

When the second and

third boom sections

30, 31 have been extended to the desired point of extension by operation of the first and

second cylinders

32, 38, as described above, the valve 51 is returned to its centered or neutral position. The check valves 58, 61 block the return flow of hydraulic fluid from the base or cylinder ends of the

cylinders

32, 38, respectively, which holds the latter in their selected extended positions.

The line 54 functions as the supply line for the hydraulic operating fluid under pressure when the second and

third boom sections

30, 31 are retracted. The hydraulic operating fluid iiows through the line 54 and the line 60 to the piston rod end of the first cylinder 32 to retract its piston rod. The supply hydraulic liuid from the line 60 also flows into the pilot line 64 which opens the pilot operated relief valve 65 for return iiow of hydraulic iiuid from the base or cylinder end of the first cylinder 32 through the line 59, the relief valve 65 and the line 56 to the flow divider valve 55.

The supply hydraulic fluid for the second cylinder 38 flows through the line 54 and the line 63 to the piston rod end of the second cylinder 38 to retract its piston rod. The supply hydraulic iiuid also flows to the pilot line 66 to open the pilot operated relief valve 67 for return flow of hydraulic uid from the base end of the second hydraulic cylinder 38 through the line 62, the relief valve 67 and the line 57 to the ow divider Valve 55.

The return flows of hydraulic fiuid from the

lines

56, 57 are combined at proportional rates of flow by the iiow divider valve 55 into the line 53 leading to the control valve 51 and then to the tank 52. The flow divider valve 55 combines the return flows of hydraulic uid from the

lines

56, 57 to the line 53 at the same proportional rates of liow as the divided rates of flow of the supply hydraulic fluid.

The flow divider valve 55 divides the supply flow of hydraulic fluid so as to provide two predetermined proportional rates of flow of fluid to the first and second

hydraulic cylinders

32, 38. The rates of extension of the first and second

hydraulic cylinders

32, 38 is then commensurate with the predetermined proportionally divided flow rates of hydraulic fluid as supplied through the flow divider valve 55. In this manner, the second and

third boom extensions

30, 31 are extended at the same time at proportional rates so that the tapering beam configuration of the -boom is maintained in all positions of extension of the crane boom 10. The flow divider valve 55 functions in the same manner to combine the return flows of hydraulic fluid from the first and

second cylinders

32, 38. The return flows of hydraulic fluid are combined at the predetermined proportional rates of flow, and accordingly, the second and

third boom extensions

30, 31 are retracted at rates that are commensurate with said predetermined proportional rates of flows of the return hydraulic fluid from the

respective cylinders

32, 38.

The hydraulic circuit includes a relief valve 68 which is connected across the flow divider valve 55 from the line 56 to the line 57. If the first cylinder 32 should complete its stroke and bottom out before the second cylinder 38 completes its stroke, then the flow in line 56 is blocked. The increased pressure of the fluid in line 56 is operative to open the relief valve 68 to permit the flow of hydraulic fluid to the line 57, with the effect that the second cylinder 38 receives the total supply of fluid to complete its stroke.

There is a second relief valve 69 which is connected from the line 57 to the line 56. If the second cylinder 38 should complete its stroke and bottom out before the first cylinder 32 completes its stroke, then the second relief valve 69 opens in response to the increased pressure of the fluid to permit flow of hydraulic fluid to the line 56, so that the first cylinder 32 then receives the total supply of uid to complete its stroke.

The flow divider valve S5 is illustrated in FIG. 3. There is a valve body 71 with a valve port 72, a first cylinder port 73, and a second cylinder port 74. The line 53 connects to the valve or inlet port 72, the line 56 connects to the cylinder or outlet port 73, and the line 57 connects to the cylinder or outlet port 74, as represented in FIG. 3.

At the one side of the flow divider valve 55 there is a first sleeve 75 which is retained in the valve body by a threaded end cap 76. A first spool 77 is slidably received in the first sleeve 75, with a coil spring 78 disposed between the end cap 76 and the spool 77 to urge the latter to the right, as viewed in FIG. 3. The spool 77 has several orifices 79 which communicate with the valve port 72. The spool 77 has several more orifices 80 which are downstream of the orifices 79. The sleeve 75 has several orifices 81, which are disposed adjacent to and in communication with the orifices 80. The flow of hydraulic fluid is from the valve port 72, through the orifices 79, through the orifices 80, and then through the orifices 81 to the cylinder port 73.

The other side of the flow divider valve 55 is identical to the left side thereof, which has been described above. There is a second sleeve 85 which is received in the valve body 71 and secured therein by a threaded end cap 86. A second spool 87 is slidably received in the sleeve 85, and there is a coil spring 88 that is disposed between the second spool 87 and the threaded end cap 86 to urge the second spool 87 to the left, as viewed in FIG. 3. The spool 87 has several orifices 89 which communicate with the valve port 72. The second spool 87 has several more orifices 90 which are downstream from the orifices 89. The sleeve 85 has several orifices 91 which are adjacent to the orifices 90 and in communication therewith. The flow of hydraulic fluid is from the valve port 72 through the orifices 89, through the orifices 90, and through the orifices 91, to the cylinder port 74.

The first spool 77 has a claw 92 which extends towards the center of the valve 55. The second spool 87 has a similar claw 93, which also extends towards the center of the valve 55. The

claws

92, 93 are engaged to mechanically link the first and

second spools

77, 87. A coil spring 94 surrounds the

claws

92, 93 and acts against the first and

second spools

77, 87 in opposite directions.

In the flow divider valve 55 as illustrated in FIG. 3, the hydraulic fluid is proportionally divided into equal rates of flow of the supply hydraulic operating fluid, or is proportionally combined at equal rates of ow to maintain the return flows of hydraulic fluid at equal rates. If the flow should tend to increase to the cylinder port 73, then there is a flow induced pressure drop across the first spool 77, which causes the spool 77 to shift its position to the left, as viewed in FIG. 3. Such movement of the first spool 77 produces a restriction of the flow passage through the orifices 8.0, 81 until the proportionally divided flows of hydraulic fluid are returned to equal rates of flow. The same mode of operation occurs with respect to the flow of hydraulic fluid through the second valve spool 87. The flow divider valve 55 acts in similar manner with respect to the return flows of hydraulic fluid to proportionally combine such return flows of hydraulic fluid at equal rates of flow.

In the embodiment of the invention which is described herein, the second and third `

boom sections

30, 31 are extended and retracted at the same time, and at the same rates of movement, so as to maintain the tapering beam configuration of the iboom 10 in all positions of extension and retraction. In any construction in which the extensible and retractable boom sections are of different lengths, `such boom sections could be extended and retracted at the same time, and at different rates of movement that are proportional to the respective lengths of the boom sections, thus to maintain the tapering beam configuration of the boom in all positions of extension and retraction.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention, and applicant therefore wishes not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of the invention, what it is desired to secure by Letters Patent of the United States is:

1. An extensible and retractable lboom construction comprising, a first boom section, a second boom section, a third boom section, power means to extend and to retract said boom sections relatively to each other in which said second boom section forms an extension of said first boom section and said third boom section forms an extension of said second boom section, said power means including a first fluid operated actuator and a second fluid operated actuator, means to connect said first fluid operated actuator to said first boom section and to said second boom section, means to connect said second fluid operated actuator to said second boom section and to said third boom section, means to supply operating fluid for said power means to extend and to retract said boom sections relatively to each other, flow divider means for said operating fluid to divide the operating fluid into predetermined proportional rates of flow to said first fluid operated actuator and to said second fluid operated actuator, respectively, in order to extend said second :boom section relatively to said first boom section and to extend said third boom section relatively to said second boom section at rates of movement that are commensurate with said predetermined proportonally divided flow rates of fluid to said first and second actuators, respectively, a first pressure responsive relief valve connected in one direction across said fiow divider means from said first fluid operated actuator to said second fluid operated actuator to supply the combined operating fluid to the second fluid operated actuator when the operation of the first fluid operated actuator is restrained, and a second pressure responsive relief valve connected in the opposite direction across said flow divider means from said second fluid operated actuator to said first fluid operated actuator to supply the combined operating fluid to the first fiuid operated actuator When the operation of the second fluid operated actuator is restrained.

2. An extensible and retractable boom construction as recited in claim 1 in which said flow divider means cornprises an inlet port for actuating fluid, a first outlet port for actuating uid to said first fluid operated actuator, a second outlet port for actuating fluid to said second fluid operated actuator, a first flow restricting passage from said inlet to said first outlet and a second ow restricting passage from said inlet to said second outlet to proportionally divide the flow of actuating fluid from said inlet port to said first outlet port and to said second outlet port, respectively, said first pressure responsive relief valve being connected to said first outlet port of said flow divider means, and said second pressure responsive relief valve being connected to said second outlet port of said flow divider means.

3. An extensible and retractable boom construction as recited in claim 1 in which said flow divider means comprises an inlet port for actuating iiuid, a first outlet port for actuating fluid to said first fiuid operated actuator, a second outlet port for actuating fluid to said second fluid operated actuator, a first flow restricting passage from said inlet to said first outlet and a second ow restricting passage from said inlet to said second outlet to proportionally divide the fioW of actuating fluid from said inlet port to said first outlet port and to said second outlet port, respectively, said first pressure responsive relief valve being connected to said first outlet port and to said second outlet port of said flow divider means in one direction from the first outlet port to the second outlet port, and said second pressure responsive relief valve being connected to said second outlet port and to said first outlet port of said ow divider means in the opposite direction from the second outlet port to the first outlet port.

References Cited UNITED STATES PATENTS 2,643,664 6/1953 Willett 6097 2,882,688 4/1959 Billen 91-412 3,300,060 l/1967 Lado 212- 3,315,821 4/1967 Grove 212-55 3,344,940 10/ 1967 Burgess 60--97 HARVEY C. HORNSBY, Primary Examiner U.S. Cl. X.R. -97; 91-412