Claims:
The embodiment of the invention in which an exclusive property or privilege is claimed and defined as follows
1. A load handling apparatus for use with a load skidding vehicle of the type adapted to hold a front end of an elongated load at a load transport position rearwardly of the vehicle and to drag the load over terrain, said load handling apparatus including:
2. The load handling apparatus of claim 1 wherein: said boom means is pivotally assembled to said vehicle for rearward pivotal movement, and said means to position the grapple means over a load includes at least one first power unit connected between the boom means and the vehicle adapted to control pivotal movement of the boom means.
3. The load handling apparatus of claim 2 wherein said power unit comprises at least one first hydraulic motor of the piston-cylinder type.
4. The load handling apparatus of claim 1 wherein said main line guide means includes: a fairlead assembly secured to the rearward portion of the vehicle, a main line roller positioned on the fairlead assembly at an elevation above said load transport position, said main line being trained over said main line roller.
5. The load handling apparatus of claim 1 wherein: the free end of each said grapple arm has a tip accommodating a pulley, said closed loop means being associated with the free ends of said grapple arms by having a portion of the closed loop means engaging each pulley.
6. The load handling apparatus of claim 1, wherein: the means for opening and closing said grapple arms include second power units connected between each grapple arm and the grapple block.
7. The load handling apparatus of claim 6 wherein: said second power units are constituted as second hydraulic motors of the piston-cylinder type.
8. The load handling apparatus of claim 1 including: coupling means pivotally coupling the grapple means and the boom means whereby the grapple means is pivotally movable relative to the boom means about a vertical and horizontal axis.
9. The load handling apparatus of claim 8 wherein said boom means is of the type having a pair of struts pivotally connected to the vehicle, a shoulder connecting the upper ends of said struts, a neck extending from said shoulder, and a head extending rearwardly from the top of the neck, said coupling means including: a closed coupling loop having a portion engaging said head and a portion engaging the grapple means.
10. The load handling apparatus of claim 8 wherein said boom means is of the type having a pair of struts pivotally connected to the vehicle, a shoulder connecting the upper ends of said struts, a neck extending from said shoulder, and a head extending rearwardly from said neck, said coupling means including: a first roller rotatably positioned at the outboard end of said head, a second roller positioned adjacent the intersection of said head and said neck, and a fixed length grapple line attached at one end to the grapple means, trained over said first and second rollers, and attached at the opposite end to the vehicle.
11. A load handling apparatus for use with a load skidding vehicle of the type adapted to hold a front end of an elongated load at a load transport position rearwardly of the vehicle and to drag the load over terrain, said load handling apparatus including:
12. A load handling apparatus for use with a load skidding vehicle of the type adapted to hold a front end of an elongated load at a load transport position rearwardly of the vehicle and to drag the load over terrain, said load handling apparatus including:
Description:
BACKGROUND OF THE INVENTION
In the field of logging, articulated vehicles termed "skidders" are employed to drag logs from the location where they are felled in the woods to a processing location. Such skidders have means, as cable loops, to engage and lift one end of each of a number of logs, and pull them through the woods, the opposite ends of the logs being dragged or skidded over the terrain. For example, see U.S. Pat. No. 3,268,090 to Wirkkala and U.S. Pat. No. 3,630,243 to Hamilton et al. In the use of such skidders, the operator usually must dismount the skidder to fasten the logs to be dragged to the rearward portion of the skidder. In more recent times skidders have been developed having tongs or grapples which are hydraulically operated and usually alleviate the need for the operator to dismount from the skidder in order to engage or disengage a load of logs. For example, see U.S. Pat. No. 3,620,394 to Symons et al. and U.S. Pat. No. 3,477,596 to Michaelson et al.
Skidders of the type described must be capable of negotiating rough, uneven terrain. They are preferably stable, having a low center of gravity, so as not to easily overturn on steep slopes or the like. However, in certain log skidders of the prior art, when a load is engaged, the center of gravity of the vehicle-load combination is raised over that of the vehicle alone. See U.S. Pat. No. 3,477,596 to Symons et al.
The skidder must also be maneuverable so as to wind around trees and rocks and so forth in the woods. Preferably, the decrease of maneuverability of the vehicle occasioned by having a load of logs in tow is minimized. However, on skidders of the type equipped with a grapple suspended from a boom, as that of U.S. Pat. No. 3,477,596 to Michaelson et al., there is not adequate provision for lateral or vertical side play of the load, and so turning of the skidder out of direct alignment with the load causes excessive loading on the boom structure through the mechanical connection of the boom structure with the grapple assembly. Even where there is provision for the grapple to swing about a universal joint, as in the aforementioned patent, the tendency is for the grapple to move out of direct alignment under the boom whereby the aforementioned excessive stresses arise. On skidders equipped with such boom and grapple assemblies for engaging a load of logs, again as that shown in the patent to Michaelson et al., the boom and grapple assembly must be strong enough to bear the weight of the logs, even though a main line and cable loop may be provided to assist in dragging the load. Excessively large and expensive boom and grapple assemblies are thus required.
Additionally, in such prior art vehicles, when a load is supported by the grapple and boom assembly, the boom acts as a lever to magnify the effort of the load in the vehicle, causing, for example, loss of weight on the front steering wheels among other things. This, along with the raised center of gravity of the vehicle-load combination, contributes to instability of the vehicle.
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a load handling apparatus for a load or log skidder of the type having a grapple assembly suspended from a pivotally mounted boom assembly. The grapple assembly is operable to encompass a load when properly positioned by the pivotal action of the boom assembly. The grapple assembly includes a pair of arcuate, interiorly opposed arms, each pivotally assembled at a first end to a grapple block. A loop means associated with the second, free ends of the grapple arms encompasses the load when the arms are closed around the load. A main line connected at one point on the loop means, is trained over a roller means provided on a fairlead assembly, and thence to a powered, take-up means. The fairlead assembly is located above the load transport position of a front end of a log load whereby upon operation of the take-up means, the load is lifted and, upon forward movement of the vehicle, is dragged by the loop means and main line. An interior loop formed in the loop means firmly engages the load as the main line takes up. No force is exerted upon the grapple or boom assembly by the weight of the load. A coupling supporting the grapple assembly relative to the boom assembly allows lateral and vertical movement or play of the grapple assembly.
An object of the invention is to provide a log skidding vehicle of the type having means to engage and disengage a load without the necessity of the operator departing the vehicle. A second object is to provide such a vehicle having a grapple and boom assembly associated with a main line and a loop means to engage a load, lift the load to a load transport position, and pull the load over the terrain. A further object of the invention is to provide such a vehicle wherein the load is lifted and pulled by the loop means and the main line without any weight, strain or fatigue being imposed upon the grapple and boom assembly. Further objects of the invention will become apparent upon the following description.
IN THE DRAWINGS
FIG. 1 is a side elevational view of a skidder vehicle equipped with the load handling apparatus of the present invention;
FIG. 2 is a fragmentary side elevational view of the skidder vehicle of FIG. 1 showing the load handling apparatus in an initial load engaging position;
FIG. 3 is an enlarged elevational view of a portion of the grapple assembly of the load handling apparatus of the invention taken along the line 3--3 of FIG. 2 with parts in section and parts broken away;
FIG. 4 is a rear elevational view of the skidder vehicle and load handling apparatus of the invention with the boom assembly lowered;
FIG. 5 is a fragmentary view of the grapple arms as when moving into position to engage a load; and
FIG. 6 is a fragmentary side elevational view of a second embodiment of the load handling assembly of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the drawings, there is shown in FIG. 1 an articulated logging or skidder vehicle 10 equipped with the load handling apparatus of the invention, indicated generally at 11, mounted on a rearward frame or chassis portion 12 of vehicle 10. Skidder vehicle 10 is particularly adapted to drag a plurality of logs over rough and wooded terrain, although it is apparent that other similar elongated loads could be handled. As shown, the vehicle portion of skidder vehicle 10 is relatively conventional, having an operator's cab 14 enclosed by a protective cage 15. A bank of controls 16 is located for easy access by the operator. A standard engine is enclosed in a suitable forward housing 18.
Load handling apparatus 11 of the invention include grapple and boom assemblies and a load lifting and pulling assembly. A boom assembly 19 has a pair of parallel, angularly inclined, upwardly extended struts 20 pivotally connected at their lower ends between a pair of upstanding mounting brackets 22 located on chassis 12. The upper ends of the struts 20 are connected by a horizontal shoulder member 23, as shown in FIG. 4. A boom neck 25 extends upward from the shoulder member 23 midway between the struts 20. A boom head 26 extends generally rearward from the top of neck 25. Boom head 26 is formed as an interiorly open box beam member, as best seen in FIG. 4. As shown in FIGS. 1 and 4, a first roller 27 is transversely, rotatably positioned in the boom head 26 adjacent the outboard end thereof. A second roller 29 is transversely, rotatably positioned at the intersection of the boom head 26 and the boom neck 25.
Power means to control the pivotal movement of the boom assembly includes a first pair of hydraulic motors of the piston-cylinder type. As shown in FIG. 1, the end of a piston rod 30 of a hydraulic motor 31 is pivotally connected to an extension 33 on an arm 20. The opposite end of hydraulic motor 31 is pivotally connected to the mounting bracket 22 on chassis 12 at a location spaced logntiudinally forward of the pivotal connection of the arm 20. A second hydraulic motor disposed opposite the motor 31 similarly connected to an arm 20 is hidden from view in FIG. 1. Suitable fittings 32 connect the motor 31 to a hydraulic fluid source (not shown). Conventional operation of the hydraulic motor 31 is effective to pivot the boom assembly 19 rearwardly to any intermediate position between the upright position, as shown in FIG. 1, and the angularly orientated position, shown in FIG. 2.
The grapple assembly includes a fixed length grapple line 35 secured at one end to the frame 12 in proximity to the pivot point of the cylinder end of the hydraulic motors 31. Grapple line 35, extending from chassis 12, is trained over the second and first rollers 29, 27, respectively, of the boom assembly 19, and is secured to and supports at the opposite end a grapple assembly 36. Grapple assembly 36, as shown in FIG. 4, has a grapple block 37 comprised of two parallel spaced apart connected plates 38; and a pair of arcuate, interiorly opposed arms 39 pivotally connected to the grapple block 37 between the plates 38 movable between an open position, as shown in phantom in FIG. 4, and a closed position defining a closed, arcuate geometric figure.
The opening and closing of the grapple arms 39 is controlled by power means constituted as a second pair of power units or hydraulic motors 40 of the piston-cylinder type operatively associated with the grapple. Each motor 40 has a rod 41 pivotally connected to an extended nub 43 on an arm 39. The cylinder portion of each hydraulic motor 40 is pivotally connected to the grapple block 37, as at 43, at a location slightly above the pivotal connection of the arm 39 to the grapple block 37. Usual and preferred hydraulic connections 44 are provided for use in actuating the motors 40 in unison. It may be seen that extension of the motor rods 41 effects closure of the arms 39 while retraction of the rods 41 opens the arms. For convenience and economy, the second hydraulic motors 40 may be connected to the same hydraulic source as the first hydraulic cylinders 31 with suitable selective valving controls provided.
The load lifting and pulling assembly of the load handling apparatus of the invention includes loop means associated with a main line and means to draw in the main line for engaging, lifting and pulling the load. The loop means is associated with the grapple arms 39 to engage the front end of a load. As shown in FIG. 1, a main line 45, being connected to a take up means, is wound about the winch drum of a winch 47 internally located in the chassis 12. A fairlead assembly 48 is mounted at the rear of vehicle 10 beneath the boom assembly 19. Fairlead assembly 48 includes a pair of parallel upright braces 49 rearwardly inclined, and a fairlead block 51 mounted between the braces 49. A main line guide or roller 52 is mounted in the upper portion of fairlead block 51. Main line roller 52 is located at an elevation above the normal transport position of the front end of a load. Main line 45 extends from the winch 47 over the main line roller 52 and thence rearwardly of the vehicle 10. A skid plate 53 is mounted on the back end of vehicle 10 in proper position to protect the rear tires and rearward portion of the vehicle. Skid plate 53 is also usable to push a load rearwardly.
The free end of main line 45 is connected to a cable loop 55 as shown in FIGS. 4 and 5. Loop 55 may be constituted, for example, as a portion of main line 45 formed by fastening the end to an intermediate section by a suitable connector 56. Alternatively, the loop 55 may be made readily detachable from the main line for conventional use of the main line. Referring to FIG. 3, each tip 57 of the grapple arms 39 has mounted therein a pulley 59 rotatably mounted on a suitable pin 60 provided in an opening 61 defined in the tip 57. A portion of the cable loop 70 is trained over each of the pulleys 59 whereby said loop 70 is integral with the tips 57 of grapple arms 39. The tips 57 of arms 39 are pointed, as shown in FIG. 3, to facilitate their movement to a position beneath the load.
The operation of the load handling apparatus of the invention may now be described. The operator maneuvers the rear end of skidder vehicle 10 into loading proximity relative to an intended load 63 of logs or the like, as shown in FIG. 2. With the grapple arms 39 in the open position, the operator manipulates the appropriate control to actuate the hydraulic motors 31 extending the cylinder rods 30 of hydraulic motors 31 to pivot the boom assembly 19 rearwardly to a position where the grapple assembly 36 is located over the end of the load 63. The control of winch 47 is in the free spool position to allow play out of main line 45. As the grapple 36 is lowered over the logs, as shown in FIGS. 4 and 5, an interior loop 64 is formed around the logs from a portion of the loop 55. When the grapple has been lowered to a position shown in phantom in FIG. 4, with the grapple arm tips 57 adjacent the ground, the operator manipulates the appropriate control to actuate the second hydraulic motors 40, extending the cylinder rods 41 to close the grapple arms. The interior loop 64 is closed around the ends of the logs. The operator activates winch 47 in a winding direction to draw up main line 45. The load is drawn up to skidding position by main line 45 pulling on loop 55 and interior loop 64. The raised or transport position of the load is at a lower elevation that the main line roller 52. The weight of the load is borne by the main line 45. The boom assembly 19 and grapple assembly 36 are free of stress, and the grapple support line 35 is slack. After engaging the load with the grapple 36, the operator may optionally lift the boom assembly to lift the load a short distance with the grapple before engaging the winch 47. Such a short lift will impose minimal stress on the boom assembly and grapple assembly.
The load is drawn up to a transport position relative to the vehicle 10, approximately adjacent the skid plate 53 as shown in FIG. 1. The load is supported by the main line 45 and the loop 55. The grapple arms 39 serve to maintain the interior loop 64 closed about the load. As the vehicle moves over the terrain, the skidding force is exerted by the main line 45. As the vehicle negotiates turns in the woods, grapple cable 45 allows free pivotal movement of the grapple assembly 36. As the grapple assembly 36 and boom assembly 19 carry none of the weight of the load, and exert none of the pulling force, they may be of a much lighter construction than those grapple assemblies of the prior art. Likewise, as the weight is not supported by the grapple assembly 36, the center of gravity of a vehicle is maintained in a low position for greater stability. The boom 19 does not exert a lever effect upon the vehicle to decrease stability. The chassis, frame and other component parts of the vehicle may be of lightweight construction as there is no necessity to support a heavy boom and grapple rigging.
A second embodiment of the invention is shown in FIG. 6 where like reference numerals are used to designate like parts. A skidder vehicle 10 has a load handling apparatus 11 including a boom assembly 19 pivotally mounted between a pair of upstanding side brackets 22 and pivotally movable by a pair of hydraulic cylinders 31. A main line 45 is wound around the drum of a winch 47 and extends over a main line roller 52 located in a fairlead assembly 48. A grapple assembly 36 is suspended from the boom head 26. A pivotal coupling 66 connects the grapple assembly 36 and supports it relative to the boom head 26. Coupling 66 could be a length of cable or a chain or the like but is preferably constituted as a coupling loop 67 formed from cable or other suitable material. The upper portion of loop 67 encircles a bar 68 located at the end of boom head 26. The lower portion of loop 67 engages an eye or clevis 69 located on the upper portion of the grapple block 37.
The operation of the load handling apparatus of FIG. 6 is the same as that previously described. The coupling loop 67 provides a convenient and economical connection which will allow free pivotal movement of the grapple assembly 36 as a load is skidded through wooded terrain. As there is no loading on the coupling 66, it need not be large and bulky. When the loop 67 is twisted upon pivotal movement of grapple assembly 36, a slight return torque is developed by the loop 67 to bias the grapple assembly into normal alignment with the vehicle 10.
A particular attribute of the load handling apparatus of the present invention is that is it readily adaptable to many conventional skidder vehicles presently available and in use. The winch, fairlead and main line assemblies are all normal components of conventional skidders. With the attachment of suitable mounting brackets and the installation of a grapple assembly as described, existing machines may be converted in accordance with the present invention. To reach trees inaccessible with the grapple assembly, the main line is disconnected from the loop means and fitted with conventional chokers for use as a conventional machine.