US 3830507 A
This disclosure pertains to a novel mechanical grapple adapted for use with tracked and rubber-tired log skidders. The grapple comprises a pair of jaws pivoted at their upper ends by a main pin for scissors-like relative motion. On the main pin there is mounted a main cable sheave and intermediate the upper and lower ends of each jaw there is mounted a jaw cable sheave. A cable anchor is pivotally mounted on one of the jaws intermediate the main pin and the jaw sheave. Pivotally mounted on the main pin for free swinging pivotal motion with respect to each jaw is a swivel guide means. An opening cable is connected to each grapple jaw intermediate its upper and lower ends. Mounted on one jaw, and associated with one of the jaw sheaves, is a cable holding means which is operated by the opening cable connected to that jaw. A closing cable passes through the swivel guide means and cable-holding means, is entrained around the main cable sheave and jaw sheaves, and ultimately connected to the cable anchor. The closing cable is connected to a primary winch and the opening cables are connected to a secondary winch whereby the opening, closing, and cable-holding effects on the grapple may be controlled at will.
Description (OCR text may contain errors)
EUnrite States Patent 1 ,Eolhnson 51 Au 2a, 1974 LUG SKHDDHNG GRAPIPLE  Inventor: Norman Allen Johnson, 5325 Tenth Ave., South Delta, B.C., Canada  Filed: Feb. 21, 1973  Appl. No.1 334,239
 References Cited UNITED STATES PATENTS 2,279,570 4/1942 Kamppi 294/112 2,452,452 10/1948  ABSTRACT This disclosure pertains to a novel mechanical grapple adapted for use with tracked and rubber-tired log skidders. The grapple comprises a pair of jaws pivoted at their upper ends by a main pin for scissors-like relative motion. On the main pin there is mounted a main cable sheave and intermediate the upper and lower ends of each jaw there is mounted a jaw cable sheave. A cable anchor is pivotally mounted on one of the jaws intermediate the main pin and the jaw sheave. Pivotally mounted on the main pin for free swinging pivotal motion with respect to each jaw is a swivel guide means. An opening cable is connected to each grapple jaw intermediate its upper and lower ends. Mounted on one jaw, and associated with one of the jaw sheaves, is a cable holding means which is operated by the opening cable connected to that jaw. A closing cable passes through the swivel guide means 3,082,031 3/1963 Lindberg 294/111 and able-holding means, is entrained around the G main cable sheave and jaw sheav s and ultimately glchaelsonlet 214/92 connected to the cable anchor. The closing cable is 36907l6 911972 ggzg a connected to a primary winch and the opening cables are connected to a secondary winch whereby the Primary Examiner-Richard A. Schacher i Clogging g i effects on the Assistant Examiner-Johnny D. Cherry grapp e may e Comm 6 at 8 Claims, 12 Drawing Figures x; :56 \i 7 4i l f LOG SKIDDING GRAPPLE This invention relates to novel improvements in devices which are known in the art to which they pertain as grapples, or to devices such as clamshell buckets and tongs which belong to or are of the general character of grapples. In their simplest form, grapples and tongs are substantially four-bar mechanisms wherin two members comprise the jaws and two members actuate the jaws in either opening or closing, or both.
In the logging industry, grapples have found wide use in loading logs onto trucks, trailers, rail cars, barges and ships. They have found further use in the yarding of logs immediately after falling and bucking, the grapple being supported and transported at a setting by a cable-winch system. The present invention pertains to a grapple means adapted for use with tracked or rubbertired log skidders. Principle requirements for a log grapple suitable for use with skidders are compactness, lightness, simplicity of construction, adequacy of closing force, dependability of opening mechanism, and effective leading and interconnecting of closing and opening means to the grapple jaws. Two very important further requirements are shortness when engaged so that the grapple and load may be raised off the ground, and a manipulating means for raising, lowering, and engaging the grapple jaws. A desirable feature would be that the grapple be closed by a cable winch that is normally a standard component on skidders, and easily disconnected therefrom so that the winch may be used for conventional choking of logs not accessible to the grapple.
A further desirable feature is holding dependability; that is to say, while the grapple closing force may be adequate to prevent logs from vertically falling out of the grapple jaws, the holding characteristics of the jaws may not be such as to prevent the logs slipping out longitudinally, particularly in the skidding operation where the logs rest on and are dragged along the ground.
Holding dependability in conventional logging grapples depends heavily upon large spikes or teeth on the inner surfaces of the jaws. However such spikes and teeth hve been known to cause undesirable log damage and, in any case, do not provide the holding effectiveness of conventional choker cables which bite into a log or logs to an extent which is in direct proportion to the weight thereof.
Yet another feature desired in skidding grapples and found in my invention is the ability to drop the grapple and its load of logs in an adverse skidding situation, such as a heavy incline or poor traction. In these cases, the grapple and load are dropped, the skidder moves to more favorable ground, the grapple and load are then winched up to the skidder. In order to provide such an operational feature, the grapple must be interconnected to the skidder by means whereby it may be payed out at will; in addition, means must be provided in the grapple whereby the grapple remains substantially fast around its load. The present invention is adapted for use with log skidders and is directed toward combining the operating versatility and labor saving characteristics of log grapples with the holding dependability and skidding versatility of log choker cables.
It is one object of this invention to provide an improved grapple assembly, especially designed for log skidding, of compact and light construction, wherein the cable which closes the grapple also spans the opening of the grapple jaws and bears upon and bites into a log or logs between the jaws.
It is a further object of this invention to provide ajaw closing force substantially equal to or greater than the force required to resist the force of gravity on the grappled load, irrespective of the size of the load or the working position of the grapple jaws relative to one another.
Yet another object of this invention is to provide a grapple closing mechanism such that the opening members may be either rigid or flexible, of simple construction, and wherein the closing force between the jaws does not depend upon compressive forces in the opening members.
Still another object of the invention is to provide a grapple closing mechanism which applies a closing force to the jaws below the jaw pivot pin and directly across the jaw opening.
A further object of my invention is to provide a cable-holding means which maintains the grapple substantially fast about its load when the grapple is released from the skidder.
Another object of my invention is to provide a cableoperated mechanical skidder grapple which may be payed out at will from the skidder in adverse skidding conditions.
These and still further objects and advantages of the present invention reside in the details of construction of a preferred embodiment disclosed herein and will be evident to one skilled in the art from a study of the specification and the accompanying drawings. Therefore the preferred embodiment disclosed is merely exemplary and is not intended to detract from the full scope of the invention as set out in the annexed claims.
In the drawings, wherein like numerals refer to like parts:
FIG. 1 is a rear view of a rubber-tired skidder upon which is mounted a cable-operated mechanical skidding grapple, in accordance with the present invention, with the jaws in the fully open position;
FIG. 2 is a side elevation of the arrangement in FIG.
1 with one skidder fender and wheel removed;
FIG. 3 is an elevation of the skidding grapple wherein the jaws are shown in a partially closed position;
FIG. 4 is a sectional view of an arch-fairlead taken substantially along'line 44 in FIG. 2;
FIG. 5 is a sectional view of a boom-fairlead taken substantially along line 5-5 in FIG. 2;
FIG. 6 is a sectional view of the main jaw pivot means and swivel guide means of the skidding grapple taken substantially along line 6-6 in FIG. 1;
FIG. 7 is a sectional view of a jaw pin means on one jaw of the skidding grapple taken substantially along line 7-7 in FIG. 3;
FIG. 8 is a sectional view of a cable anchor means on one jaw of the skidding grapple taken substantially along line 88 in FIG. 3;
FIG. 9 is an elevation of the cable anchor means taken substantially along line 9-9 in FIG. 8;
FIG. 10 is a plan view of a cable-holding means taken substantially along line l010 in FIG. 3;
FIG. 11 is an elevation of a cable-holding means taken substantially along line 1l-ll in FIG. 10;
FIG. 12 is a sectional view of a cable-holding means taken substantially along line 12-12 in FIG. 11.
Referring now to the drawings, FIGS. 1 and 2 illustrate two views of a preferred embodiment of the present invention where denotes the frame of a rubbertiredlog skidder, the rear wheels of which are represented by 21 and 22. A grapple support structure, generally dentoed by the numeral 23, is mounted on the rear portion 24 of skidder frame 20 and comprises arch-fairlead portion 25 and boom-fairlead portion 26. Arch-fairlead portion 25 is normally bolted or welded to frame 20 at 27. Boom-fairlead portion 26 includes strut members 28 and 29 abutted against the outer portions 30 of fender 31.
It will be apparent to one skilled in the art that struts 28 and 29 may be interconnected in many ways to frame 20; the main requirement being that they transfer a portion of the grapple loading from boom-fairlead 26 to skidder frame 20. Boom fairlead portion 26 and archfairlead portion 25 may be bolted together at 32 and struts 28 and 29 bolted to fender 31 to permit removal of the boom-fairlead portion, thus converting the log skidder into a conventional arch-choker skidder.
A scissors-type grapple assembly in accordance with my invention, generally denoted by the numeral 33, is supported by structure 23 by means of opening members 34 and 35, each at one end interconnected respectively to grapple jaws 36 and 37. The interconnection of opening member 34 to jaw 36 is achieved by passing member 34 through faired cable anchor 38 and interconnecting it to cable-holding means 39; member is interconnected to jaw 37 by passing member 35 through cable anchor 40 and securing it thereto. Where members 34 and 35 are cables, the use of conventional cable knobs or ferrules serve to secure member 34 to cable-holding means 39 and cable 35 to anchor 40. The other ends of opening members 34 and 35 are operatively secured to a lifting means which includes cable 41 and secondary winch 42; where members 34 and 35 are cables, hand-spliced eyes 43 may be used to interconnect them to cable 41, whereby to permit the interconnection to pass through fairlead 44 when the grapple assembly 33 is raised by winch 42.
Jaws 36 and 37 have upper end-portions 45 and lower end-portions 46. Jaw pivot means 47 interconnects upper-end portions 45 for scissors-like motion of one jaw with respect to the other. Whereas FIG. 1 illustrates jaws 36 and 37 in their most open position, FIG. 3 illustrates the jaws partially closed with their lower end-portions slightly overlapping. Pivotally mounted on jaw pivot means 47 for free swinging motion relative to the jaws is swivel guide means 48, which not only guides closing cable 49 into the grapple assembly but also controls and guides the grapple assembly with respect to support structure 23. Mounted intermediate upper end-portion 45 and lower end-portion 46 of each jaw are jaw pin means 50 on jaw 36 and jaw pin means 51 on jaw 37. Cable anchor means 52 is operatively mounted on jaw 36 intermediate jaw pin means 50 and jaw pivot means 47. Closing cable 49 passes through swivel guide means 48, is entrained about jaw pivot means 47, passes through cable-holding means 39, is entrained about jaw pin means 50 and 51, and ultimately secured to cable anchor means 52. Closing cable 49 is interconnected to primary winch means 53 of conventional design mounted on skidder frame 20.
FIGS. 1, 2 and 4 illustrate details of construction of arch-fairlead portion 25 of support structure 23. Main roller 54 is rotatably supported by means of shaft 55 in arch side plates 56. Side rollers 57 are required primarily for choker skidding and are rotatably mounted on brackets 58 by means of shafts 59; brackets 58, in combination with plates 56, form an integral part of archfairlead 25. Closing cable 49 passes over roller 54 and between rollers 57.
FIGS. 1, 2 and 5 illustrate details of construction of boom-fairlead 26 of support structure 23. Boom roller 60 is rotatably mounted in side channels 61 by means of shaft 62. Side rollers 63 are rotatably mounted on brackets 64 by means of shafts 65. Brackets 64, side channels 61, and web plate 66 form the essential structure of boom-fairlead portion 26. Intermediate fairlead roller 67 rotatably mounted on shaft 129 is equivalent to main roller 54 in arch-fairlead portion 25, closing cable 49 passing over roller 67 en route to winch 53. Swivel guide means 48 may be pulled against roller 67 to permit the full force of winch 53 to close grapple 33 irrespective of the load in the grapple.
Turning now to the structure of grapple assembly 33, FIG. 6 illustrates the relationship between jaws 36 and 37, jaw pivot means 47 and swivel guide means 48. Jaw pivot means 47 comprises shaft 68 and retainer washers 69 and 70 welded to each end thereof. In logging machinery such as grapples, retainer washers 69 and the like are often preferred to be welded in place and are removed by established techniques when maintenance so requires. Swivel guide means 48 comprises a pair of leg portions 71 and 72 extending downward from transverse portion 73. Leg portions 71 and 72 are mounted on shaft 68 for pivotal movement with respect to jaws 36 and 37. In the case illustrated, washer 69 is secured by weld 74 to leg 71, jaws 36 and 37 being pivotally mounted on shaft 68. Fairlead 75, through which closing cable 49 passes, forms an integral part of transverse portion 73. Extension 76 of transverse portion 73 serves to aid the interaction of swivel guide means 48 and roller 67 as aforementioned. Cable sheave 77 is rotatably mounted on shaft 68, closing cable 49 entrained thereabout. Cable guard means 78 is secured to jaw 36 to prevent closing cable 49 from interfering with sheave 77. Transverse portion 73 has an outside surface 79 and an inside surface 80. Inside surface 80 interacts with the upper surfaces 81 of jaws 36 and 37 to limit the most open position of jaws 36 and 37.
FIG. 7 illustrates a section through jaw 37 wherein jaw pin means 51 is shown to comprise shaft 82 and retainer washers 83 and 84 welded thereto. Sheave pocket 85 comprises plate 86 substantially parallel to jaw 37, secured to transverse member 87 and cable anchor 40 (not shown in FIG. 7). Washer 83 is secured to plate 86 by weld 88. Cable sheave 89 is rotatably mounted on shaft 82 and closing cable 49 entrained thereabout.
FIGS. 8 and 9 illustrate a section through jaw 36 wherein cable anchor 52 is shown to comprise a shaft 90 having enlarged portion 91. Retaining washer 96 Se cures cable anchor 52 axially while permitting pivotal movement whereby anchor 52 may accommodate changes in direction of pull of cable 49 as grapple 33 is opened or closed. Cable 49 passes through hole 92 and is secured by cable knob or ferrule 93 which nests in counterbore 94. Closing stop means 95 is secured to jaw 36 and interacts with jaw 37 to limit the closing movement of jaws 36 and 37.
Referring now in detail to the FIGS. 10, 11 and 12, cable-holding means 39 is shown to comprise a sheave pocket 97 comprising plate 98 parallel with jaw 36, and member 99 and clamping member 100 substantially perpendicular to jaw 36 and plate 98.
Pivotally mounted in bearing block 101 and jaw 36 is jaw pin means 50 comprising an actuating portion 102 and an eccentric shaft portion 103. Sheave 104 is rotatably mounted on eccentric shaft portion 103. The pivotal axis 105 of actuating portion 102 and the axis of rotation 106 of sheave 104 on shaft portion 103 are in spaced relation separated by a distance referred to herein as the shaft eccentricity. Clearly, pivotal movement of eccentric shaft portion 103 about pivotal axis 105 will cause a change in location of sheave axis of rotation 106 with respect to sheave pocket 97. Pivotal movement of eccentric shaft 103 in direction 107 will cause sheave 104 to move toward clamping member 100 and in direction 108 will cause sheave 104 to move away from clamping member 100. Moreover, closingcable 49 entrained in the groove of sheave 104 will be carried with sheave 104 in its movement with respect to sheave pocket 97. Movement of sheave 104 toward member 100 will ultimately cause cable 49 to contact clamping surface 109 of member 100; further movement will ultimately cause cable 49 to be squeezed out of shape and the periphery 110 of sheave 104 will itself contact clamping surface 109, provided that the crosssectional area bounded by the groove of sheave 104 and surface 109 is greater than that of cable 49.
Secured to actuating portion 102 of jaw pin means 50 is torque actuating means 111 comprising torque levers 112 secured at one end to actuating portion 102, spring seat means 113 pivotally mounted in the other end of levers 112, spring means 114 interconnecting spring seat means 113 and jaw 36, opening cable 34 interconnected to torque actuating means 111. In the embodiment of my invention here disclosed, spring means 114 is a mechanical compression coil spring 115, spring seat means 113 comprises a pin 116 and washers 117 welded thereto, and counter-bored holes 118 and 119 on opposite sides of pin 116. Faired cable anchor 38 having counter-bored hole 120 is secured to jaw 36 and serves as a guide to cable 34. Spring 115 is seated in holes 118 and 120. Opening cable 34 passes through anchor 38 and through the coils of spring 115 terminating with a cable knob 121 seated in hole 119.
Turning now to the operation of cable-holding means 39, it will be evident from the foregoing description that spring 115 actuates jaw pin means 50 in direction 107 and cable 34 moving in direction 122 actuates it in direction 108. Spring 115 moves closing cable 49 and sheave 104 into contact with clamping surface 109 and opening cable 34 moving in direction 122 moves them both away from surface 109. Therefore, spring 115 actuates cable-holding means 39 to clamp and cable 34 to release closing cable 49.
Sheave axis of rotation 106 separated by a shaft eccentricity from pivotal axis 105 of jaw pin means 50 in the relation illustrated in F 1G. 11, that is, on the side of axis 105 where cable 49 enters the groove of sheave 104 in direction 123, will clearly make the cable holding means 39 self-energizing. That is, a tensile force in portion 124 of cable 49, tending to pull cable 49 around sheave 104 in direction 123, will tend to increase the normal force of cable 49 and sheave 104 on clamping surface 109, thus increasing the friction force resisting the movement of cable 49. Moreover, if the shaft eccentricity is small enough in relation to the friction co-efficients between cable 49, surface 109, and sheave 104, then to one skilled in the art it will be clear that the cable clamping force will provide a friction force always greater than the aforementioned tensile force in portion 124 of cable 49; consequently cableholding means 39 will not only be self-energizing but self-locking.
When clamping occurs and self-energizing is inherent in the proportions of cable-holding means 39, then only a small spring force in spring means 114 will be required to cause clamping, provided that opening cable 34 is substantially slack or otherwise free to move in direction 125. On the other hand, the tensile force in cable 34 required to release the clamping of cable 49 must be sufficient to overcome the force of spring means 114 and the wedging or jamming forces between cable 49, sheave 104 and clamping surface 109. At the same time, a tensile force on portion 126 of cable 49 in direction 127 will substantially assist release of cable 49. Clearly, in a cable operated grapple where cable 34 is a slack opening cable and cable 49 is a tight closing cable, continuous incremental self-adjusting 0r tightening of cable 49 will be permitted in direction 127 as the grapple load shifts or bounces.
The operation of my present invention may now be considered, with reference to the foregoing explanation of cable-holding means 39. Grapple assembly 33 may be raised or lowered by taking in or paying out cable 41 of secondary winch 42. Cable 49, by means of primary winch 53, is taken in to close and payed out to open grapple assembly 33. Grapple assembly 33 is positioned over a turn of logs by a log skidder through use of support structure 23, lowered onto the logs by paying out cable 41, and closed by taking in cable 49. Up to now, tension has existed in opening cable 34 thereby de-energizing cable holding means 39 and permitting closing cable 49 to move freely into and out of grapple assembly 33. As closing cable 49 continues to be taken in by primary winch 53, and grapple 33 closes about its turn of logs, cable 49 bites into the upper portion of the logs, thereby providing three-sided contact with the turn of logs, and swivel guide means 48 guides grapple 33 along cable 49 until ultimate contact between swivel guide means 48 and roller 67 is achieved; at this point the full power of winch 53 may be used to obtain as tight a hold on the turn of logs as possible. Cable 41 and opening members 34, if not already slack, should now be slackened to permit free movement of grapple 33 with respect to structure 23 and to place cable-holding means 39 into effect. Movement of the skidder and logs will now progress with cable-holding means 39 permitting further tightening of the grapple on the turn of logs, but substantially preventing any slackening of the grapple holding force.
In the event of adverse skidding conditions, cables 49 and 41 may be slacked off with grapple 33 still remaining fast on its turn of logs. The skidder is then moved ahead to more favorable ground, cables 49 and 41 being payed out as required. The skidder is then stopped and the grapple and logs winched up to the skidder by cable 49 and primary winch 53, cable 34 being taken in substantially slack at the same time by secondary winch 42. Once the skidder reaches a landing, cable 34 is taken in by winch 42, thus releasing cable-holding means 39; cable 49 is released by winch 53, and grapple 33 thus dumps its turn of logs.
It will be appreciated that the foregoing discloses only a preferred embodiment of my present invention. Further, many changes, modifications, and equivalents will readily occur to one skilled in the art, particularly in view of the above teachings. For instance, grapple support structure 23 may be hinged to skidder frame 2t), struts 28 and 29 being replaced by linear actuators. Boom-fairlead portion 26 may be hinged to archfairlead portion or made telescopically extensible. Opening members 34 and 35 may be cable, chain, or rigid members. Torque actuating means 111 might include a spring means interconnected directly to eccentric shaft portion 103. Torque actuating levers 112 might be actuated to clamp cable 49 by means of mechanical or pneumatic springs, fluid powered linear ac tuators, cables, struts, or any combination thereof. Clamping surface 109 might be flat, arcuate, grooved, or concave. Therefore, the present invention is not to be construed as limited to the specific details illustrated and described above.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A scissors-type grapple assembly comprising a pair of jaws each having upper and lower end-portions, jaw pivot means pivotally interconnecting said upper endportions of said jaws, a pair of opening members, each one of said pair of opening members operatively connected at one end to one jaw of said pair ofjaws intermediate said upper and lower end-portions, the other ends ofsaid opening members operatively connected to a lifting means, jaw pin means mounted on each of said jaws intermediate said upper and lower end-portions, cable anchor means mounted on one of said jaws, swivel guide means pivotally mounted on said jaw pivot means to swing freely with respect to said pair of jaws, cable-holding means including a clamping member secured to one of said pair of jaws in spaced relation to said jaw pin means, said jaw pin means having an eccentric portion in opposed relation to said clamping member, a closing cable passing through said swivel guide means and said cable-holding means and entrained about said jaw pivot means and said jaw pin means and operatively connected to said cable anchor means, torque actuating means interconnected to said eccentric portion, pivotal actuation of said eccentric portion by said torque actuating means in one direction causing said closing cable to be clamped between said clamping member and said eccentric portion and in the other direction causing said closing cable to be re leased.
2. A scissors-type grapple assembly as defined in claim 1, wherein said swivel guide means comprises a pair of leg portions interconnected by a transverse portion having outside and inside surfaces, said leg portions pivotally mounted on said jaw pivot pin means, a fair-lead mounted on said transverse portion and through which said closing cable passes, the inside surface of said transverse portion interacting with the upper end-portions of said pair of jaws to limit the opening motion of said jaws.
3. A scissors-type grapple assembly as defined in claim 1, further comprising a faired cable anchor mounted on each of said pair ofjaws intermediate their upper and lower end-portions, one of said pair of opening members operatively connected to each of said faired cable anchors.
4. A scissors-type grapple assembly as defined in claim 1, wherein said cable anchor means is pivotally mounted whereby to accommodate the direction of pull of said closing cable in any relative position of said pair of jaws.
5. A scissors-type grapple assembly as defined in claim 1, one of said opening members operatively connected to said torque actuating means whereby tensioning thereof causes said closing cable to be released by said cable-holding means.
6. A scissors-type grapple assembly as defined in claim 1, wherein a compression spring interposed between said one of said pair of jaws and said torque actuated means whereby to force said cable sheave against said clamping member, one of said opening members operatively connected to said torque actuated means whereby tensioning thereof causes said closing cable to be released by said cable-holding means.
7. A scissors-type grapple assembly as defined in claim 6 wherein said clamping member is secured to that one of said pair ofjaws upon which said cable anchor is mounted, whereby the cable-holding force of said cable-holding means is applied to two cable reeving passes in said pair of grapple jaws.
8. A scissorstype grapple assembly comprising a pair of jaws each having upper and lower end-portions, jaw pivot means pivotally interconnecting said upper endportions of said jaws, a pair of opening members, each one of said pair of opening members operatively connected at one end to one jaw of said pair ofjaws intermediate said upper and lower end-portions, the other ends of said opening members operatively connected to a lifting means, jaw pin means mounted on each of said jaws intermediate said upper and lower end-portions, cable anchor means mounted on one of said jaws intermediate said jaw pin means and said jaw pivot means, swivel guide means pivotally mounted on said jaw pivot means to swing freely with respect to said pair ofjaws, cable-holding means including a clamping member secured to one of said pair ofjaws and an eccentric shaft portion mounted on said jaw pin means in opposed relation to said clamping member, one of said opening members interconnected to said cable-holding means, a closing cable passing through said swivel guide means and said cable-holding means and entrained about said jaw pivot means and saidjaw pin means and operatively connected to said cable anchor means, whereby slackening said opening members causes said cable'holding means to hold said closing cable and tensioning said opening members causes said cable-holding means to