US 3759564 A
A grapple including a pair of arms and a single generally upright ram for actuating the arms. The ram, wherein the cylinder and piston in addition to being relatively reciprocable are also relatively rotatable, accommodates unlimited rotation of the arms as a unit about the ram's longitudinal axis. A rotator for producing such rotation is drivingly interposed between the piston and cylinder. Pressure fluid is supplied to and exhausted from opposite ends of the ram's cylinder through fluid passages formed in the ram's piston. The piston thus performs as a sort of revolving connector in the ram. The ram and arms are interconnected in such a manner that the weight of any load gripped by the arms tends to tighten the grip on the load.
Description (OCR text may contain errors)
11 3,759,564 1 1 Sept. 18, 1973 1 GRAPPLE  Inventor: Richard D. Seaberg, Vancouver,
 Assignee: Pierce-Pacific Manufacturing, Inc.,
221 Filed: Mar. 8, 1971 21 Appl.No.: 121,847
FOREIGN PATENTS OR APPLICATIONS 1,242,339 6/1967 Germany 294/ 106 1 OTHER PUBLlCATlONS Modern Railroads, Heppenstall, July 1957 Page 92.
Primary Examiner-Evon C. Blunk Assistant Examiner-Johnny D. Cherry Attorney-Kolisch, Hartwell'& Dickinson  ABSTRACT A grapple including a pair of arms and a single generally upright ram for actuating the arms. The ram, wherein the cylinder and piston in addition to being relatively reciprocable are also relatively rotatable, accommodates unlimited rotation of the arms as a unit about the ram s longitudinal axis. A rotator for producing such rotation is drivingly interposed between the piston and cylinder. Pressure fluid is supplied to and exhausted from opposite ends of the rams cylinder through fluid passages formed in the ram s piston. The piston thus performs as a sort of revolving connector in the ram. The ram and arms are interconnected in such a manner that the weight of any load gripped by the arms tends to tighten the grip on the load.
6 Claims, 3 Drawing Figures sign of a grapple. For example,
1 GRAPPLE BACKGROUND AND SUMMARY OF THE INVENTION This invention pertains to a grapple, and more particularly, to a grapple characterized by single-ram actuation of load-gripping arms. For the purpose of illustration herein, a preferred embodiment of the invention is described in connection with so-called heel-boom logging equipment, wherein it'has been found to have particular utility.
There are several important considerations in the deit is usually desirable that a grapple have a high degree of maneuverability. In other words, it is desirable that a grapple be readily adjustable to a variety of different positions or attitudes whereby its arms can be properly oriented for handling a load. Another important consideration is that a grapple should have a minimum number of easily damaged exposedparts (such as flexible hoses and their fittings). And, this second-mentioned consideration should be taken into account without sacrificing maneuverability. Still another consideration is that a grapple should be designedto produce as sure a grip as possible on any load that it handles. More specifically, it is desirable that a grapple be designed to resist any tendency of a load to work free from the grapple s arms, except when those arms are intentionally opened to release the load.
A general object of the present invention, therefore, is to provide a novel grapple which takes these abovementioned (and other) important considerations into account in a practical and satisfactory manner.
According to a preferred embodiment of the invention, the proposed grapple features a single generally upright fluidoperated ram, which carries a loadgripping arm assembly, including a pair of opposed relatively movable arms. The ram, on actuation, moves the load-gripping portions of the arms toward and away from one another to grip and release a load. In addition, the ram and arms are interconnected in such a manner that the weight of any load gripped by the arms is carried at least partially through the ram, and tends to adjust the effective length of the ram in a direction tightening the grip of the arms on the load. As a consequence, the proposed grapple produces an extremely sure grip on any load which it carries. I
The piston and cylinder in the ram, in addition to being relatively reciprocable, are also relatively rotatable about the rams longitudinal axis. The arm assembly in the grapple is carried by the cylinder in the ram,
and as a result, it is permitted to rotate as a unit with the cylinder relative to the piston. A rotator is suitably mounted on the ram, and acts between the cylinder and piston.
One of the important features in the invention, in addition to those already mentioned, is that fluid for extending and'contracting'the ram is supplied through fluid passages which are formed in the rams piston. The piston thus acts as a sort of rotating connector in .the ram, and obviates the need for flexible hose connections to opposite ends of the cylinder. Among the important consequences of this novel construction are that flexible hose connections, which might easily be damaged, are not needed for the cylinder in the ram,
and the rotating connection afforded by the piston permits unlimited rotation of the arm assembly in the grapple. Were flexible hose connections required for the for operating these rams cylinder, such connections would limit the amount of rotation permitted the arm assembly.
Also featured in the piston of the ram is a fluid passage whose opposite ends open to the opposite ends of the cylinder in the ram. Disposed within this fluid passage is a check valve which, under circumstances of a load being gripped and held by the arms in the grapple permits internal fluid flow (or transfer) in one direction only between the opposite ends of the cylinder to facilitate ram-length adjustment, whereby the weight of the load is effective to tighten the arms grip on the load.
DESCRIPTION OF THE DRAWINGS These and other objects and advantages obtained by the invention will become more fully apparent as the description which follows is read in conjunction with the accompanying drawings, wherein:
FIG. 1 is a fragmentary simplified side elevation illustrating heel-boom logging equipment employing a grapple as contemplated herein;
' FIG. 2 is an enlarged view taken line 22 in FIG. 1, illustrating the equipment of FIG. 1; and
FIG. 3 is a fragmentary cross-sectional view on a larger scale than FIG. 2, taken generally along the line 3-3 in FIG. 2 and illustrating details of construction of a ram in the proposed grapple, with the ram shown removed from certain other parts in the grapple.
DETAILED DESCRIPTION OF THE INVENTION generally along the details of the grapple in connected inner, intermediate, and outer boom sections 18, 20, 22, respectively. Conventional hydraulic rams 24, 26, 28 are provided at the locations indicated for adjusting the relative positions of the various boom sections in assembly 16. Hydraulic fluid under pressure rams is supplied by the usual hydraulic fluid supply system provided in vehicle 10.
Rigidly mounted on the inner end of outer boom section 22 is a conventional heel plate 30; and mounted through apivot connection 32 on the outer end of boom section 22 is a to the present invention.
The equipment drawn in FIG. 1 is illustrated in a condition holding a log (shown partially at 36) above the ground. More specifically, log 36 is gripped by grapple 34 at a point spaced toward the left end of the log in FIG. 1 from its center of gravity, with the left end of the log in the figure pressing upwardly against heel plate 30 1 Considering in detail the construction of grapple 34,
grapple 34 constructed according The outside of fitting 50 is sealed to the inside of tube 46 through a seal 52.
Piston 44 includes an elongated piston rod 54 and a piston head 56. Rod 54 preferably is formed as a unitary member, and with the configuration illustrated, and includes an elongated generally cylindrical stem 58, about midway between upper and lower ends of which is a radially outwardly projecting flange 60. Extending axially a considerable distance along and through stem 58 are a pair of bores 62, 64. These two bores substantially parallel one another, and extend from the bottom end of stem 58 upwardly a considerable distance beyond flange 60. The upper ends of bores 62, 64 communicate through radially extending bores 66, 68, respectively, with the outside surface of the stem. Conventional hose-coupling fittings 70, 72 are screwed into bores 66, 68, respectively. At a point considerably below flange 60, and somewhat above the bottom end of stem 58, passage 64 communicates through a radially extending bore 74 with the outside of the stem. The respective combinations of: bores 62, 66; bores 68, 74 and that part of bore 64 which extends between bores 68, 74; and bore 74 and that part of bore 64 which extends from bore 74 to the base of stem 58; each comprise a fluid passage herein.
Suitably mounted adjacent the bottom end of stem 58 as contemplated herein, and disposed within the lower end of bore 64, is a check valve, or check valve means, 76. Under circumstances which will be more fully explained later, check valve 76 permitsfluid to flow from the upper end of cylinder 42 to the lower end of the cylinder through bore 74 and the lower portion of bore 64. The check valve, however, blocks flow in the reverse direction.
Piston head 56 is fitted and keyed on the lower end of stem 58 as shown, and is held in place on the stem between a shoulder 78 thereon, and a nut 80 which is screwed onto the stem beneath the head. Head 56 is sealed to stem 58 by means of an O-ring seal 82. Interposed between the outside surface of the head and the inside of tube 46 are bushings 84 which act as bearings between the tube and head. Also interposed between the head and tube are seals 86.
As can be seen particularly in FIG. 3, the lower portion of stem 58, Le, that portion which is below flange 60 in the figure, extends through the central opening in fitting 50. A bushing 88 is interposed between the stem and the fitting to act as a bearing therebetween, and the stem and fitting are sealed by means of an O-ring seal 90. Also interposed between the stem and fitting, adjacent the upper end of the latter, is a conventional wiper 92 which prevents dust and other foreign matter from being carried into the inside of the cylinder in the ram.
It will be apparent from the construction of ram 38 just described, that cylinder 42 and piston 44 are not only relatively reciprocable, but also are relatively rotatable. In particular, it will be noted that insofar as the ram construction is concerned, the piston and cylinder are permitted unlimited relative rotation.
Referring now to FIG. 2, it will be noted that it is through the upper end portion of stem 58, that grapple 34 is attached (through pivot connection 32) to the outer end of boom section 22. More specifically, directly mounted on the outer end of boom section 22 through pivot connection 32, is a mounting yoke 94, the base member 95 in which includes a bore 97 that freely receives the upper end of stem 58. A nut 96 screwed onto the upper end of the stem above member 95, and suitably locked to the stem, prevents axial retraction of the stem from this bore.
Considering now the construction and mounting of arm assembly 40, this assembly includes a pair of movable arms 98, 100. These two arms are similar in construction, having substantially the same curved profiles (as shown in FIG. 2), but with arm 100 somewhat wider than arm 98 (as can be seen in FIG. 1). The upper end portions of the arms are bifurcated, so-to-speak, and straddle the base of cylinder 42, to which the arms are pivoted by means of axially aligned pins 102. Pins 102 are received in mounts 104 and outrigger brackets 106, which are welded in the respective places shown on the outside of tube 46. Because of the slightly greater width in arm 100, the upper end portion of this am straddles the upper end portion of arm 98, as well as cylinder 42.
The lower end portions of arms 98, 100, i.e., those portions which are below pins 102, are referred to herein as load-gripping portions in the arms. The lower end portion of arm 100 is bifurcated to permit limited overlap (or crossover) of the lower ends of the anns to permit the arms to handle relatively small loads.
With arms 98, 100 so mounted on cylinder 42, it will be apparent that the arms move substantially as a unit with the cylinder. In particular, it will be noted that the arms will rotate as a unit with the cylinder relative to piston 44.
Pivotally connected at 108, to the upper ends of arms 98, 100, respectively, are the lower ends of links 112, 114, respectively. The upper ends of links 112, 114 are pivoted at 116, 118, respectively, to lugs 120, 122, respectively, which are secured, as by welding, to a ring structure 124. Ring structure 124 is made up of a pair of welded-together parts 124a, 124b, with these parts having the respective cross-sectional configurations shown. As can be seen, ring structure 124 freely surrounds the upper portion of stem 58 immediately above flange 60. The ring structure is mounted for rotation on flange 60 through a roller bearing assembly 126, which is interposed between this flange and a flange in part 124a. Interposed between part 124b, and the outside of stem 58, is another roller bearing assembly 128.
Suitably joined to the outside of part l24b in ring structure 124 is an annular gear 130. The teeth in this gear mesh with the teeth in a pinion 132 which is fastened to the lower end of the downwardly projecting output shaft 134 of a conventional hydraulic motor 136. Motor 136 is supported on a mounting assembly 138, which is suitably anchored to the outside of stem 58. Motor 136 constitutes a rotator means herein.
Hydraulic fluid under pressure for operating ram 38 and motor 136 is supplied from the supply system previously mentioned on vehicle 10, through elongated flexible hoses (not illustrated) which connect with fittings 70, 72in the piston of the ram, and with the usual fittings in motor 136. It will be noted that the places where the outer ends of these hoses connect are well above the region occupied by arms 98, 100, and links 1 12, 114.
The various advantages of the proposed grapple just described are apparent. Only a single ram is required to actuate the arms, and flexible hose type fluid connections to the opposite ends of the cylinder in the ram are not required. The latter feature results from the novel use of fluid passages inside the ram s piston to deliver and exhaust fluid. With such construction, unlimited relative rotation is permitted between the cylinder and piston, with the piston performing as a revolving connector in the ram. As a consequence, a very high degree of maneuverability is afforded the grapple arms.
With the arms attached to the ram as described, a portion of the weight of any load gripped by the arms is carried axially and in tension through the ram. With fluid flow into and out of the upper ends of bores 62, 64 blocked (which will typically be the situation with the arms adjusted to grip and hold a load), and with the weight of the load being above a certain amount, check valve "76 allows fluid inside the upper end of cylinder 42 to transfer to the lower end of the cylinder. This permits the ram to extend, with resultant tightening of the arms grip on the load. The load weight required to produce such action is a matter of choice, and may be selected through properly selecting the pressure differential required across the check valve to cause it to open.
Because fluid hose connections are disposed well above the region occupied by the arms and other moving and rotating parts in the grapple, the likelihood of hose damage is greatly minimized.
. While a preferred embodiment of the invention has been described herein, it is appreciated that variations and modifications may be made thereinwithout departing from its spirit.
I claim: l. A grapple comprising a pair of relatively movable arms having loadgripping portions which are movable toward and away from each other to grip and'release a load, a generally upright fluid-operated ram',-having a cylinder and a piston including a rod, operatively connected to said arms, operable on extension to move said load-gripping portions toward one another, said ram being disposed whereby it carries, axially and in tension, at least a portion of the weight of any load gripped by said load-grippingportions, check valve means operatively interposed between the opposite ends of said cylinder, operable, with said load-gripping portions gripping a load, to accommodate extension of the ram while preventing I contraction of the ram, and
rotator means operatively interposed between said cylinder and piston operable to produce relative rotation therebetween about said axis.
2. A grapple comprising a pair of relatively movable arms having loadgripping portions which are movable relatively toward and away from each other to grip and release a load,
a generally upright fluid-operated ram having a cylinder and a piston including a rod,
means mounting said arms on said ram whereby changes in different directions in the rams effective length cause said load-gripping portions to move toward and away from one another, and whereby 6 the weight of any load gripped by the load-gripping portions is carried through said arms and said ram, and tends to change the effective length of the ram in a direction tending to tighten the grip of the load-gripping portions on the load,
means defining first and second fluid passages communicating with opposite ends of said cylinder for supplying fluid to and exhausting it from said ends, with the supply of fluid through said first fluid passage to one of said ends producing a change in the rams effective length that moves said loadgripping portions toward one another, and with the supply of fluid through said second fluid passage to the other end producing the reverse operation,
means defining a third fluid passage interconnecting said opposite ends of said cylinder, and
check valve means in said third fluid passage which accommodates fluid flow therethrough from said other end to said one end of said cylinder and blocks such flow in the reverse direction.
3. The grapple of claim 2, wherein said first, second and third fluid passages are formed within said piston.
4. The grapple of claim 2, wherein, said arms are pivoted intermediate their ends to said cylinder, and there is means operatively interconnecting the upper end portions of said arms and said rod.
5. The grapple of claim 2, wherein said cylinder and piston are relatively rotatable about the longitudinal axis of the ram,and which further comprises rotator means operatively interposed between said cylinder and said piston operable to produce relative rotation therebetween about said axis.
6. A grapple comprising a pair of relatively movable arms having loadgripping portions which are movable toward and away from each other to grip and release a load,
a generally upright, fluid-operated ram having a cylinder at the base thereof and a piston including a piston rod extending upwardly from said cylinder, said cylinder and piston rod being relatively rotatable about the axis of the piston rod,
means mounting said arms on said rain whereby with elongation said ram causes said load-gripping portions to come together and with the weight of any load carried by said arms tending to elongate said ram, said means including pivot means pivotally mounting the arms intermediate their ends on said cylinder and means operatively connecting upper nds of said arms to said rod,
first and second fluid passages extending through said rod opening to the interior of said cylinder for the supply and exhaust of pressure fluid to opposite ends of said ram, and
rotator means operatively interposed between said cylinder and said rod operable to produce relative rotation of the cylinder with respect to said rod about said axis.