Brakes – Wheel – Continuous
Reexamination Certificate
1998-12-07
2001-07-24
Butler, Douglas C. (Department: 3613)
Brakes
Wheel
Continuous
Reexamination Certificate
active
06264013
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is directed toward an improved, snubbed, pivot connection.
2. Description of the Prior Art
Grapples are employed in loading or skidding logs in the forest industry. The grapple has a pair of grapple arms pivotally suspended from the end of a boom, the arms operable to grapple or grab a load of logs. The pivot connection connecting the grapple arms to the boom comprises two pivots, with the axis of the two pivots at right angles to each other to permit universal movement of the grapple arms. To prevent the grapple arms from swinging uncontrollably about the pivots, which swinging could cause damage and/or injury, and which causes excessive wear on the pivots, dampers or snubbers are provided in the pivots to dampen the swinging movement.
Each pivot usually employs a link member pivotally connected by a pivot pin between the arms of a yoke member. The snubber employed is usually a dual snubber having a pair of opposed brake means in the pivot to balance the braking load and reduce wear. Examples of such dual snubbers are shown in U.S. Pat. No. 4,572,567, Johnson, issued Feb. 25, 1986, and in U.S. Pat. No. 4,573,728, Johnson, issued Mar. 4, 1986, by way of example. These dual snubbers are usually operated by hydraulic means. The use of fluid to actuate the brake means in the dual snubber presents a problem in that the fluid leaks. Leakage of fluid changes the braking effect. In addition, the hydraulic actuating means employed in these dual snubbers are often complicated in construction and thus expensive. The known dual snubbers also have wear problems due to the type of brake means employed. Brake disks, as employed in U.S. Pat. No. 4,573,728, for example, wear unevenly because it is difficult to apply pressure uniformly. Often the brakes are quite small, as in U.S. Pat. No. 4,572,567, for example, and thus tend to wear out quite quickly because of the load applied.
It is known to provide snubbers that are mechanically rather than hydraulically operated. These single snubbers employ a tapered brake sleeve in the brake means cooperating with a tapered braking surface. These brake means increase the braking efficiency because of their size, and being self-centering, braking force is applied more evenly, thus reducing wear of the brake means. The tapered brake sleeve, being operated mechanically rather than hydraulically, ensures that the braking force remains more constant. Examples of such snubbers are shown in U.S. Pat. No. 5,451,087, Beaulieu, issued Sep. 19, 1995. However, these single snubbers do not provide balanced braking and thus have excessive wear. In addition, the adjustment means employed to control their braking force are still quite complicated and thus expensive. Further, the single snubbers require enlarged yokes to be properly used in some embodiments, and in other embodiments, the single snubbers are exposed to damage.
Other examples of double mechanically operated snubbers are found in U.S. Pat. No. issued Feb. 3, 1998. These double snubbers are an integral part of the load bearing structure at the pivot connection and subject to uneven wear of the breaking surfaces leading to a reduced dampening ability of the snubber.
SUMMARY OF THE INVENTION
It is the purpose of the present invention to provide a dual snubber for a pivot connection, employing a link member within a yoke member, which dual snubber is mechanically operated in a simple and easy manner.
It is another purpose of the present invention to provide a mechanically operated dual snubber in which the braking force is easily adjusted.
It is another purpose of the present invention to provide a dual snubber employing tapered brake cores which are mounted in a compact manner in a protected environment.
It is another purpose of the present invention to provide a dual snubber for a pivot connection, wherein the load is not borne by the brake cores.
In accordance with the present invention, there is provided a pivot connection having a pivot pin member between the arms of a yoke member and a link member having a journal-portion journalled on the pivot pin between the arms of the yoke member. Tapered brake cores are provided adjacent each side of the journal-portion of the link member, mounted for axial sliding movement on the pivot pin. Recesses are provided on each side of the journal portion of the link for receiving the respective brake cores. The recesses define conical brake surfaces to be contacted by the brake cores. The recesses in the link member for receiving the cores provide a compact mounting for the cores and also protect the cores.
The improved pivot connection also includes mechanical means on the pivot pin at one end of the pin for biasing the brake core adjacent the one end into contact with the link member, which biasing action simultaneously biases the other brake core into contact with the other side of the link member. The braking force is easily adjusted by the mechanical means and remains the same, once set, except for wear of the brake surfaces. The location of the mechanical means provides easy access for adjustment of the braking force.
The invention is particularly directed toward a pivot connection having a link member with a journal-bore at one end, a yoke member with spaced-apart parallel arms receiving the one end of the link member therebetween, bores in the arms, and a pivot pin mounted through the bores in the arms in the yoke member and the journal-bore in the link member to pivotally connect the two members together. Tapered, counter-bored brake surfaces are provided in each side of the link member concentric with the journal-bore. Tapered brake sleeves are slidably mounted on the pin and located in the counter-bores facing each other, each core located between an arm of the yoke and the link member. A nut, threaded on the end of the pin outside the yoke, applies axial pressure through a mechanical connection to one of the cores to force both cores against the brake surfaces to brake the link member relative to the yoke member.
REFERENCES:
patent: 3009747 (1961-11-01), Pitzer
patent: 4572567 (1986-02-01), Johnson
patent: 4573728 (1986-03-01), Johnson
patent: 5096247 (1992-03-01), Killen
patent: 5451087 (1995-09-01), Beaulieu
patent: 5713688 (1998-02-01), McCallum
patent: 5779383 (1998-07-01), McCallum
patent: 1470500 (1966-03-01), None
patent: 1498491 (1966-07-01), None
patent: 864472 (1961-04-01), None
Burch Melody M.
Butler Douglas C.
Canada Incorporated
Swabey Ogilvy Renault
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