Patent Application
20070189846
Several types of heavy machines incorporate articulated frames. Examples of articulated frames include wheeled tree harvesters, wheeled loaders, articulated compaction machines and motor graders. It is advantageous under some circumstances to prevent articulation of the machine. An articulation lock preserves the relative position of the parts of the machine frame: generally a two-part frame and prevents articulation.
As a class, heavy machines are those frequently used for earth movement, civil works, agriculture, and construction applications.
In the case of a motor grader, an operator may wish to prevent articulation to complete certain operations. Since the motor grader has steerable front wheels, directional control of the motor grader can be maintained while articulation is limited. On the machines making use of articulation for steering, the articulation lock may be used while transporting the heavy machine by truck or rail. Further utility arises from use of the articulation lock by service mechanics when working on the vehicle, particularly when working in the vicinity of the articulated joint.
Known articulation locks make use of an upper, lower pad-eye on a first portion of the articulated frame and a center pad-eye on a second portion of the articulated frame with an appropriately sized pin. In the locked position the pin is placed through the upper, center and lower pad-eye to prevent articulation of the portions of the vehicle frame. While for convenience of explanation and illustration the invention is described in terms of an upper, lower, and center pad-eyes, an articulated joint may comprise a plurality of pad-eyes not dissimilar from a hinge.
Steering of articulated heavy vehicles is generally accomplished by hydraulic cylinders positioned so as to alternatively push or pull one frame part to angularly rotate the frame part about a hinge point. The hinge point generally comprises a vertical hinge pin(s) in a plurality of pad-eyes located along the vehicle front-to-rear mid-line.
The articulation lock is generally located laterally from the hinge point at a location approximately orthogonal to the vehicle front-to-rear mid-line. Known pins 40 incorporate a through-hole and a roll pin extending beyond the diameter of the lock pin, or a washer 42 welded to the top of the lock pin or a similar feature used as a retainer to keep the pin in the articulation lock from falling through the articulation lock because the influence of gravity. Known retaining features such as roll pins are incapable of removal from the lock pin without requiring hand tools such as a hammer and drift punch. While such features serve the function of resisting the influence of gravity on the lock pin, removal of the lock pin can be complicated by the presence of the retainer.
When it is desired to remove the lock pin having a retainer feature it is necessary to lift the pin vertically as the retainer feature performs its function to prevent the lock pin from falling downward out of the pad-eyes forming the articulation lock. Unless the articulated frame members are positioned in near perfect alignment, the articulation lock pin may be held in position by the transverse pressure applied across the pad-eyes. Thus for a single individual, removal of the lock pin may involve incrementally adjusting the steering of the heavy vehicle in effort to find a position where no transverse pressure is applied to the lock pin. This effort to locate a position of no transverse pressure may involve a few, or many trips from the operator station, back to the location of the lock pin, only to be frustrated that the pin was not movable by muscle power.
Alternatively, removal of the lock pin may be a two-person operation with an operator incrementally changing the position of the articulated frames by operating the hydraulic steering mechanism, while an assistant maintains vertical force on the lock pin to remove the same. While this two-person sequence may be faster as it saves the operator's time and effort of repeatedly climbing from the lock pin location to the operator station, it suffers from the disadvantage of requiring an assistant and more importantly places the assistant in a vulnerable position on a possibly wiggling heavy vehicle.
The instant invention provides an improved articulation lock primarily by providing an improved lock pin retaining device and system. Removal of the retainer may be accomplished without the need for tools. The articulation lock may be removed with the assistance of gravity, without repeated operator effort climbing from the lock pin location to the operator station, and without placing an assistant in a hazardous location on the heavy machine.
The invention is further described in terms of an embodiment of an articulated joint of a heavy machine and a locking pin therefore.
An embodiment of the instant invention includes an articulation lock 10 including conventional upper 12, lower 14 , pad-eyes on a first articulated frame member and a center pad-eye 16 on a second articulated frame member. The lock pin 18 of sufficient length to pass through the upper and lower pad-eye is prevented from falling through the pad-eyes by a removable retainer pin inserted in a through-a first hole 20 in the lock pin. In one embodiment, the lock pin includes a second through-hole 22 like the first positioned to locate below the lower pad-eye when the lock pin is in positioned in the pad-eyes. Conveniently, the lock pin may incorporate tapered or chamfered 24 ends.
The removable retainer pin may take many forms such as a conventional bolt and nut or other retaining means to prevent the lock pin from inadvertently falling through the pad-eyes of the articulation lock. A useful and inexpensive retainer pin may be conveniently obtained as a commercial item frequently sold as a safety retainer clip 30 for an automotive trailer hitch having a resilient metal bail 32 that may be rotated about one enlarged end 34. The resilient bail may be extended with hand force to permit insertion and withdrawal of the retainer pin from a through-hole 20, 22 of the lock pin.
The through-hole 20, 22 of the lock pin sized appropriately to receive a removable retainer pin. Likewise, the diameter of the lock pin for heavy machinery is often of a size from 25 to 127 mm (1-5 inches) diameter as the size of the machine may require.
In use, the operator may advantageously insert the chamfered or tapered end of the lock pin in the upper pad-eye with the retaining pin in place to prevent the lock pin from falling through the pad-eyes. In the event the pad-eyes are not aligned to receive the lock pin the operator may cautiously articulate the frame members to permit the influence of gravity to position the lock pin as the pad-eyes pass one another and reach alignment. Insertion of the inventive alignment pin is not materially different from the insertion of the alignment pins known in the art.
In the event the articulated frame members are aligned without transverse force on the alignment pin, the inventive lock pin may be removed by lifting the lock pin up ward in the manner for removal of known lock pins having fixed retaining features.
The lock pin of the instant invention is useful in the event the articulated frame members are aligned such that a transverse force against the lock pin prevents lifting the pin. Removal of the alignment pin held in place by transverse force is facilitated by complete removal of the retaining pin 30. Then in the manner of lock pin insertion, the operator may remove the lock pin with the assistance of the influence of gravity by initiating back-and-forth steering movements, and/or possibly moving the vehicle forward and backward so as to arrive at a position of the articulated vehicle frame that assert no lateral force on the lock pin such that it is free to drop from the pad-eyes.
In a further preferred embodiment, the retainer pin or another fastener may be fastened to a lower through-hole of the lock pin before initiating efforts to remove a lock pin held in place by lateral forces. The retainer pin or other fastener is then preferably tethered 34 to the vehicle such as by a light chain, or cable. With the lock pin thus connected to retainer pin, which in turn is tethered to the vehicle, the lock pin may be easily retrieved by the operator as soon as the vehicle articulates freely indicating that the lock pin is free of the pad-eyes.
The utility of feature of affixing the lock pin through the lower through-hole is enhanced by the fact that heavy machines are intended, and most often used, to move soil, rocks and other earth forms. Thus, were the lock pin to fall from the pad-eyes to the ground, it may be difficult to locate in disturbed terrain and involve an avoidable expenditure of time to find.
The lower through-hole of the lock pin may also be utilized while the heavy machine is in operation by fastening a second retainer pin in lower through-hole. Thus placed, a second lower retainer pin reduces the risk that the lock pin would work itself out of the pad-eyes against the influence of gravity, and the associated potential loss of the lock pin altogether at a heavy equipment work site.
Further features of the invention is the use of the preferred retainer pin, including the bail thereof to hold the lock pin in a bracket on the machine when the lock pin is not in place in the pad-eyes. When not in place on a machine, or in a storage bracket, the resilient bail of the preferred retaining pin provides a convenient handle for manual carrying the lock pin with the retaining pin inserted through a through bore therein.
