SWING LOCK MECHANISM FOR CONSTRUCTION EQUIPMENT WITH ROTATABLE UPPER WORKS

Abstract: A swing lock mechanism for a piece of construction equipment having an upper works (12) rotatably mounted on a lower works (14), such as a crane (10), is disclosed. The crane also includes an adapter plate (30) to which the upper works (12) is releasably connected, such as by pinned links (60). The adapter plate (30) and the lower works (14) may then be maintained as a unit with a swing bearing (40) therebetween even when the upper works (12) is removed for easy transportation of the equipment. The swing lock mechanism is suspended from the adapter plate (30) and includes a swing lock segment (90) with teeth that mesh with the gear teeth on the inner race. The mechanism also includes a piston (95) actuatably mounted in a cylinder (94) for moving the swing lock segment into and out of engagement and a connector link (91) that holds the swing lock segment (90) in rigid engagement until the connector link (91) is released.

Description: SWING LOCK MECHANISM FOR CONSTRUCTION EQUIPMENT WITH ROTATABLE UPPER WORKS BACKGROUND OF THE INVENTION The present invention relates to construction equipment, such as cranes, having an upper works rotatably mounted on a lower works, and more particularly to a swing lock mechanism for use on such construction equipment. Construction equipment, such as cranes or excavators, often must be moved from one job site to another. Moving a crane or excavator can be a formidable task when the machine is large and heavy. For example, highway limits on vehicle-axle loads must be observed and overhead obstacles can dictate long, inconvenient routings to a jcb site. One solution to improving the mobility of large construction machines is to disassemble them into smaller, more easily handled components. For example, the upper rotating structure of a crane with a large- diameter, swing bearing can be removed from the mobile lower works. Because most swing bearings have at least one bolted interface, the machine can be taken down into more manageable sections for transport. The disassembly of a crane with a conventional bearing having an inner race and an outer race is both labor-intensive and time-consuming, making it a costly undertaking. The disassembly of numerous high-strength fasteners is one factor that impedes rapid undecking of machines. As an example, a 200-ton lifting crane with a 100-in. (pitch-diameter) swing bearing may have 70 or more bolts in one or both bearing rings. To disconnect and reassemble the bearing, all the bolts in one of the bearing rings must be disassembled, replaced, and uniformly torqued to a high preload. Machine disassembly can cause alignment difficulties as well. For instance, the bearing bolt holes must be aligned precisely with mounting-surface holes in the reassembly of a machine. Because the machine parts are large and heavy, such alignments can be unwieldy and time-consuming. Moreover, if the dis¬ connect is made at the outer bearing ring (most often the ring fixed to the machine rotating structure) , then the swing bearing drive also must be critically aligned during machine assembly to minimize backlash and attendant shock loading from slewing motion. Many prior art devices have the disadvantages that they are expensive. Also, the configurations are seldom interchangeable with standard bearings. Further, in many cranes, the upper works is the heaviest part of the disassembled crane, and is there¬ fore the limiting element in the transportability of the crane. Thus, a quick disconnect system should preferably not add weight to the upper works. Cranes that have a swing bearing, whether easily disconnectable or not, typically also include a swing lock mechanism to prevent rotation about the swing bearing except when under operator control. Some swing lock mechanisms, however, can engage during crane operation if there is an accidental loss of power to the swing lock mechanism. If this occurs during a swing maneuver, damage to the crane and other possible injury can result. Other swing lock mechanisms do not have certain desirable features. For instance, it is often desirable to allow a crane to "weather vane" when not in operation to reduce wind-imposed loads on the crane. If the swing lock is not designed to allow disengagement when the crane is shut down, the crane will remain locked in one position and changing wind direction will impose greater side loads than desired. SUMMARY OF THE INVENTION A swing lock mechanism for a piece of construction equipment with an upper works rotatably supported on a lower works has been invented which overcomes the deficiencies noted above and has other advantages. The mechanism is primarily for use with conventional swing bearings having an inner race and an outer race. The mechanism may be used with a quick disconnect system where a cranes upper works sits on an adapter plate and is releasably connected to the adapter plate by links pinned at their upper end to the body of the upper works. The swing lock mechanism of the present invention is then supported on the underside of the adapter plate. The quick disconnect system utilizes links and jacking bolts to hold the upper works and adaptor plate together. • A jacking bolt at the lower end of the link bears against the underside of the adaptor plate. The bearing outer race is secured to the bottom surface of the adapter plate. The bearing inner race is secured to the crane lower works, as in a conventional crane. When the crane is to be separated, the jacking bolt is loosened to allow the links to swing free of the adaptor plate. The upper works is then easily separated from the lower works. The adapter plate and bearing stay attached to the lower works. All of the bolts used to hold the bearing races are left intact and thus do not need to be retorqued when the crane is reassembled. The swing lock mechanism includes a swing lock segment with teeth adopted to intermesh with the gear teeth on the swing bearing. A piston is used to engage and disengage the swing lock segment. In addition, the swing lock mechanism includes a connector link connected to the swing lock segment that has a foot on one end adapted to fit into a hole in a rigid portion of the swing lock mechanism to provide rigid contact with the gear teeth and prevent the swing lock segment from disengaging. In a preferred embodiment, the swing lock mechanism also has one or more springs to urge the teeth into engaging contact. The preferred device also includes a latch to hold the swing lock segment in a disengaged position until the piston is activated to engage the swing lock. With this design, a sudden interruption of compressed air or hydraulic fluid to the piston does not result in automatic engagement of the swing lock. Also, the crane can be shut down with the swing lock left disengaged so that the crane can "weather vane" to present the least wind resistance. These and other advantages of the invention, as well as the invention itself and advantages of the quick disconnect system, will best be understood by reference to the attached drawings, a brief description of which follows. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a crane incorporating a quick disconnect system and a swing lock mechanism of the present invention. Fig. 2 is a sectional view taken along line 2-2 of Fig. 1. Fig. 3 is a sectional/plan view taken along line 3-3 of Fig. 2. Fig. 3a is an enlarged plan view taken along line 3a-3a of Fig. 3. Fig. 3b is an enlarged plan view taken along line 3b-3b in Fig. 3. Fig. 4 is an enlarged sectional view taken along line 4-4 of Fig. 3. Fig. 5 is a sectional view taken along line 5-5 of Fig. 4. Fig. 6 is an enlarged, partial sectional view taken along line 6-6 of Fig. 3, showing the swing lock mechanism of the present invention. Fig. 7 is a partial sectional view taken along line 7-7 of Fig. 6. DETAILED DESCRIPTION OF THE DRAWINGS AND PREFERRED EMBODIMENT OF THE INVENTION While the present invention will find application in all types of construction equipment, the preferred embodiment of the invention is described in conjunction with the crane 10 of Fig. 1. The crane 10 includes an upper works 12 rotatably supported on a mobile lower works 14. The upper works 12 and lower works 14 are conventional. The upper works 12 includes a boom 15 and rigging 16, backhitch 17, a gantry 18, counterweight 19 and power equipment (not shown) enclosed by a housing 20. The lower works 14 includes a body 22 and two independently powered crawler treads 24. As best seen in Fig. 2, in the crane 10 the upper works 12 is connected to the lower works 14 by a quick separation and assembly apparatus. The upper works 12 rests on an adapter plate 30, which in turn rests on a swing bearing 40. The bearing 40 in turn rests on the body 22 of the lower works 14. As described more fully hereafter, the adapter plate 30 is secured to the upper works 12 by means for releasably connecting the adapter plate 30 to the upper works 12. In the embodiment shown, the releasably connecting means comprises links 60, shown in Fig. 2, pinned to the upper works 12. With the shape of the housing 20 shown in Fig. 1,-t.he links 60 attach to the body of upper works 12 inside of the housing 20. Of course, where other housing shapes are used, the adaptor plate 30 may extend further than the housing 20, and the links 60 will then be visible outside of the housing 20. The bearing 40, as best seen in Fig. 4, is of conventional design, with a one-piece inner race 42 having drive teeth 44 integrally formed thereon. The inner race 42 is bolted to the body 22 of the lower works 14 by torqued bolts 46. A finishing pad 48, machined to provide good vertical load transfer, sits between the body 22 and the inner race 42. The outer race 50 is made of two pieces, upper member 52 and lower member 53. Torqued bolts 54 hold the two members 52 and 53 together and hold the outer race 50 to the adapter plate 30. Rollers 55, 56 and 57 ride between the inner race and the outer race. A finishing pad 58 rests between the outer race 50 and the adapter plate 30. The adapter plate 30, as best seen in Figs. 3, 3a, 3b and 4, comprises a generally rectangular plate member 32 with front tangs 34 and rear tangs 39 extending at its four corners. The adapter plate 30 has circular apertures 86 through plate 32 through which drive gears fit to engage the drive teeth 44. Those gears (not shown) are journaled in brackets mounted on the upper works 12. The power generating equipment of the crane 10 is used in a conventional manner to effectuate rotation of the upper works 12 relative to the lower works 14 via power transmitted through apertures 86. A larger aperture 87 in the adapter plate provides access for other power and control connections between the upper works 12 and the lower works 14. A smaller circular aperture 83 is used to align the adapter plate 30 with the upper works 12. A pin 70 (Fig. 4) fits through a bushing 72 affixed to the floor 21 of the upper works 12, and through aperture 83. An annular shaped finishing pad 77 rests between the adapter plate 30 and the floor 21 of the upper works 12 surrounding aperture 83. Pin 70 has a head 71 that provides a shoulder to rest on bushing 72. Shear blocks 73 (Fig. 3, 3a and 3b) are welded onto the top of adapter plate 30 near rear tangs 39 on a part of the adaptor plate 30 so that the rear of the upper works 12 will fit between them. The pin 70 and shear blocks 73 transmit horizontal and torque loads between the upper works 12 and the adapter plate 30. The adapter plate 30 also includes finishing pads 78 at each corner covering the tangs 34 and 39, and a finishing pad 79 covering about fivie-twelfths of the area over the outer race 50. Pad 79 is centered in the front portion of the adapter plate 30. Threaded holes 35 through the adapter plate 30, and through finishing pad 79, accommodate bolts 54. The adapter plate 30 includes a circular reinforcing rib 31 concentric with and spaced outside of the outer race 50. The adapter plate 30 also includes a number of additional reinforcing ribs, including flat reinforcing ribs 33 extending from the circular reinforcing rib 31 to each of front tangs 34, flat reinforcing ribs 36 extending from the reinforcing rib 31 to the rear tangs 39, and an arcuate reinforcing rib 37 extending between rear tangs 39. Reinforcing ribs 31, 33, 36 and 37 are welded to the bottom of the adapter plate 30 to provide additional rigidity to the adapter plate 30. In the embodiment shown, additional plate material 38 is welded to the bottoms of the reinforcing ribs 31, 36 and 37 to form a box-like structure and add additional rigidity to the adapter plate 30. As best seen in Figs. 3a and 3b, the bottom side of both of the rear tangs 39 is covered by a doubler plate 74 of high yield steel. A counter bore 75 is made in the doubler plate 74 for attachment of the links 60, as explained below. (For clarity, links 60 are not shown in Figs. 3a and 3b.) The links 60, in conjunction with the pin 70 and shear blocks 73, releasably connect the adapter plate 30 to the upper works 12. Four links 60 are used, one at each corner of the adapter plate 30. As best seen in Figs. 4 and 5, the links 60 each comprise two spaced apart pieces of steel strap 62, spanning between the point of the connection of the link 60 to the upper works 12 and the base of the link 60. Each strap 62 is wider at its ends than in its central section. The top end 64, best seen in Fig. 2, includes a hole for a pin 63 which is used to pin the straps 62 to the upper works 12. Cotter pins (not shown) hold the pins 63 in the upper works. The bottom end 66 is rectangular in shape. As shown in Fig. 5, a base block 68 is welded between the rectangular ends of the straps 62. The straps 62 are spaced by the base block 68 so that the tangs 34 and 39 of adapter plate 30 fit between each set of straps 62. A jacking bolt 65 extends through the base block 68 and into the counter bore 75 of the doubler plate 74 on rear tangs 39. Similar counter bores 75 (Fig. 5) are formed in the underside of front tangs 34 for receiving jacking bolts 65 for the links 60 at the front of the adaptor plate. A jam nut 67 is used to prevent the bolt 65 from getting loose during crane operation. The weight of the upper works 12 and the tension in the links 60, transferred through the pins 63 and jacking bolts 65, holds the upper works 12 firmly onto the adapter plate 30. A swing lock mechanism is used to prevent rotation of upper works 12 about the lower works 14 when the crane 10 is used in a mode where rotation is to be avoided, or when not in operation and it is not desired to let the crane "weather vane." A preferred swing lock mechanism for use in conjunction with the adapter plate 30 is shown in Figs. 6 and 7. The mechanism is held to the underside of adapter plate 30 by welded plates 88 and 89. The swing lock mechanism comprises a swing lock segment 90, a connector link 91, a latch 92, a rod end 93, an air cylinder 94 with a piston rod 95 to which the rod end 93 is attached by a bolt 96, side plates 98, a bottom plate 99 and end plate 100. Two return springs 97 are positioned between end plate 100 and swing lock segment 90. The ends of springs 97 are held in bores 108 in the end of swing lock segment 90 and cup members 109 fixed to end plate 100. A pin 110 pivotly holds the connector link 91 to the swing lock segment 90. Swing lock segment 90 has three teeth which intermesh with drive teeth 44 on the inner race 40 when the piston 95 is extended to engage the swing lock mechanism. The rod end 93 is a clevis-shaped member which goes along both sides of the back of connector link 91. A downward pointing triangular slot 101 is formed horizontally in rod end 93. The slot 101 accepts a pin 111 fixed in the end of connector link 91 apposite pin 110. The faces of rod end 93 oriented towards the drive teeth 44 are sloped forward at an approximate 600 angle. The top surface of connector link 91 includes a notch 102. The bottom surface of connector link 91 includes a leg 103 for sliding along the bottom plate 99, and terminates in a foot 104 which fits into a hole 105 formed in bottom plate 99, directly below the pin 111. When the swing lock mechanism is to be disengaged, air cylinder 94 is activated to retract piston rod 95. This forces the rod end 93 to start moving toward end plate 100. As it does so, the pin 111 starts to ride up in slot 101, lifting foot 104 out of hole 105. Once pin 111 reaches the upper corner of slot 101, further retraction of piston rod 95 draws connector link 91, pin 110 and swing lock segment 90 away from drive teeth 44, compressing springs 97. When the swing lock mechanism is in its fully retracted position, latch 92, which is also clevis-shaped with its open end opposite the open section of rod end 93, falls over notch 102 of connector link 91 and rests against the sloped face of rod end 93. The latch 92 holds the swing lock segment 90 from engaging drive teeth 44 in case of failure of the pneumatic system or when weather vaning is desired. When the swing lock mechanism is to be re¬ engaged, air cylinder 94 is activated so as to force piston rod 95 outward. As piston rod 95 moves rod end 93 forward, latch 92 slides up the sloped face of rod end 93, disengaging notch 102 on connector link 91. Return springs 97 are then free to push swing lock segment 90 back into an engaged position as shown in Figs. 6 and 7. As connector link 91 moves toward teeth 44, foot 104 is again free to drop into hole 105, which provides a rigid contact to keep the swing lock segment 90 engaged with drive teeth 44. Should drive teeth 44 not be lined up with the teeth on swing lock segment 90, the piston rod 95 is free to move to its fully extended position because the pin 111 can move to the back side of triangular slot 101. Once the teeth are aligned, springs 97 will force the swing lock segment 90 forward and rod end 93 will move to the position shown in Fig. 6. The latch 92 of the swing lock mechanism provides a means to prevent the swing lock segment 90 from engaging the drive teeth in the event of a power failure such as a break in the air line to cylinder 94. Also, the latch 92 can be left engaged while the crane is shut down so that the swing lock mechanism does not prevent the crane from rotating in response to changes in wind direction. On the other hand, connector link 91 with foot 104 mated with hole 105 provides a means for rigidly holding the swing lock segment 90 in its engaged position to prevent the swing lock segment 90 from disengaging when resisting a swing torque, rather than relying only on the force of springs 97 or the cylinder 94 to prevent the swing lock segment 90 from disengaging. The springs 97 allow for quick engagement of the swing lock segment 90 without requiring further movement of the piston, avoiding dragging the piston out of the cylinder and working against the attendant friction and other forces present. The described embodiment of the quick disconnect system provides numerous advantages. The crane 10 can be quickly disassembled by loosening jacking bolts 65, swinging links 60 free of the adaptor plate 30 and lifting upper works 12 off of the adapter plate 30. Reassembly is also rather simple, only requiring alignment of bushing 72 with aperture 83, drive gears with apertures 86 and the outside of upper works 12 between shear blocks 73. As shown in Fig. 4 and 3a, the lower end of pin 70 and the upper parts of shear blocks 73 are rounded to facilitate alignment. Because of the rigidity of the adapter plate 30, it may be possible to reduce the thickness of the floor 21 and other members of the upper works 12, thus making the upper works 12 lighter. Most importantly, the quick disconnect system is relatively inexpensive because it uses conventional swing bearings, and may also therefore be interchangeable with other bearings on other crane parts. The adaptor plate 30 is particularly useful with swing bearings using rollers as shown, as well as ball-type swing bearings. In the preferred embodiment of the crane 10, the various elements are made of steel, sized in accordance with good engineering design practice for the crane with which the adapter plate will be used. A preferred steel for the doubler plates 74 has a 100,000 psi yield. Of course, a number of modifications may be made to the preferred embodiment disclosed above. For example, depending on the size of the crane, an additional pin such as pin 70, rather than shear blocks 73, may be required on the back of the adapter plate 30 to prevent twisting between the upper works 12 and the adapter plate 30. A hydraulic cylinder could be used in place of the air cylinder 94. Freely floating rods could be placed inside of return springs 97 to act as anti-buckling elements where the spring material is not heavy enough on its own to prevent buckling. In a less preferred embodiment, the adapter plate 30 could be releasably connected to the lower works, with the bearing and adapter plate 30 staying fixed to the upper works when the equipment is disassembled for transport. It should be appreciated that the apparatus and methods of the present invention are capable of being incorporated in the form of a variety of embodiments, only a few of which have been illustrated and described above. The invention may be embodied in other forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive and the scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims: I Claim 1. A swing lock mechanism for a crane having an upper works, a lower works, and a swing bearing connecting the upper works and the lower works so as to allow the upper works to be rotatable with respect to the lower works, the lower works further comprising a gear with teeth thereon for use in causing rotation of the upper works; the swing lock mechanism comprising: aj a swing lock segment comprising teeth adapted to intermesh with said gear teeth when the swing lock segment is in an engaged position, b) a piston actuatably mounted in a cylinder, the cylinder being secured to the upper works and the piston being connected to said swing lock segment so as to move said swing lock segment into and out of said engagement position upon actuation of the piston and cylinder, and c) a connector link connected to said swing lock segment, said connector link having a means for rigidly holding said swing lock segment is in its engaged position to thereby prevent the swing lock segment from disengagement when resisting a swing torque. 2. The swing lock mechanism of claim 1 further comprising at least one spring normally biased to force said swing lock segment into its engaged position. 3. The swing lock mechanism of claim 2 further comprising a latch to hold said swing lock segment in a disengaged position against the bias of said spring until said latch is forced out of its latching position during reengagement of said swing lock segment. 4. The swing lock mechanism of claim 1 further comprising a slotted connection between the piston and the swing lock segment such that the piston can be in a fully extended position even if the teeth on the swing lock segment are not meshed with the gear teeth. 5. The swing lock mechanism of claim 1 further comprising two side plates extending downwardly on opposite sides of the swing lock segment and secured to said upper works such that the side plates prevent the upper works from rotating when said swing lock segment is in its engaged position. 6. The swing lock mechanism of claim 1 wherein the piston and cylinder comprise either an air cylinder or a hydraulic cylinder. 7. The swing lock mechanism of claim 1 wherein the rigid holding means comprises a foot attached to said connector adapted to fit in a hole in a rigid portion of the swing lock mechanism. 8. A crane having an assembly for allowing quick separation of crane upper works from crane lower works comprising: a) an adapter plate secured to the upper works by link members extending from the adapter plate to the body of the upper works; b) one or more horizontal-load bearing pins extending through apertures in the base of the upper works and the adapter plate; c) a swing bearing first race bolted to the bottom of the adapter plate; d) a swing bearing second race, with drive teeth integrally formed thereon, bolted to the lower works; and e) a swing lock mechanism actuatable into and out of a position wherein the mechanism engages the drive teeth of the second race to prevent rotation between the upper works and the lower works. 9. The crane of claim 8 wherein the swing lock mechanism comprises a swing lock segment having teeth adapted to intermesh with the drive teeth when the swing lock segment is in an engaged position. 10. The crane of claim 9 wherein the swing lock mechanism further comprising a piston in a cylinder for withdrawing and engaging said swing lock segment. 11. The crane of claim 9 wherein the swing lock mechanism further comprises at least one spring normally biased to force said swing lock segment into its engaged position. 12. The crane of claim 9 wherein the swing lock mechanism further comprises a connector link connected to said swing lock segment, said connector link having a foot extending from one end thereof adapted to 'fit into a hole when said swing lock segment is in its engaged position to thereby prevent the swing lock segment from disengagement when resisting a swing torque. 13. The crane of claim 12 wherein the swing lock mechanism further comprises a latch to hold said swing lock segment in a disengaged position against the bias of said spring until said latch is forced out of its latching position during reengagement of said swing lock segment. 14. The crane of claim 12 wherein the swing lock mechanism further comprises a slotted connection between the piston and the swing lock segment such that the piston can be in a fully extended position even if the teeth on the swing lock segment are not meshed with the drive teeth. 15. The crane of claim 8 wherein the swing lock mechanism comprises: a) a swing lock segment comprising teeth adapted to intermesh with said teeth of said second race when the swing lock segment is in an engaged position, b) a piston actuatably mounted in a cylinder, the cylinder being secured to the upper works and the piston being connected to said swing lock segment so as to move said swing lock segment into and out of said engagement position upon actuation of the piston and cylinder, and c) a connector link connected to said swing lock segment, said connector link having a foot extending from one end thereof adapted to fit into a hole in a rigid portion of said swing lock mechanism when said swing lock segment is in its engaged position to thereby provide a rigid contact between the teeth of the swing lock segment and said gear teeth. 16. The crane of claim 8 wherein the adapter plate is generally rectangular and comprises four tangs, one of each extending from each corner of the adapter plate. 17. The crane of claim 16 wherein the links each comprise two strap members spaced so that the tangs fit between the straps and rest on a bolt extending through a block welded between the ends of the straps extending below the tangs. 18. The crane of claim 8 wherein the link members are pinned to the body of the upper works. 19. The crane of claim 8 further comprising reinforcing ribs extending vertically downward from the bottom of the adapter plate, including a circular rib concentric with said swing bearing first race. 20. The crane of claim 8 further comprising shear blocks wherein said one or more horizontal-load bearing pins and shear blocks are adapted for transferring horizontal and torque loads between said upper works and said adapter plate. 21. The crane of claim 8 wherein the adapter plate comprises a plate member with apertures therethrough such that power generating means on the upper works can effectuate rotation of the upper work relative to the lower works.

Inventors: PECH DAVID, PECH, DAVID
Applicants: MANITOWOC CO, THE MANITOWOC COMPANY, INC.
Application year: 1992
Main classification: B66C23
IPC codes: B66C23