Bearings – Rotary bearing – Plain bearing
Reexamination Certificate
2001-05-09
2003-02-18
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Plain bearing
C384S192000, C384S208000, C403S122000, C403S131000
Reexamination Certificate
active
06520682
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a hitch link for a three-point hitch and in particular to a hitch link having a high strength ball end.
BACKGROUND OF THE INVENTION
Many tractors, such as agricultural tractors, utility tractors and compact utility tractors, are equipped with a rear and/or front three-point hitch to connect implements to the tractor. Such hitches typically have two lower links, commonly referred to as draft links, and a single upper link. The outer ends of the links are equipped with a spherical bearing assembly having a pin hole that receives a pin to mount the implement to the link. The ends of the links are typically formed of a flat bar or a forged end of a bar to form the spherical bearing assembly. The dimensions of the bearing assembly are defined by industry standards such as standard S217.11 of the American Society of Agricultural Engineers. Through standardization, fit of the implement to the tractor hitch is assured.
The bearing assembly can be permanently assembled by placing a bushing having a spherical outer surface, into a spherical socket in the link member and then swaging the socket on one side to permanently retain the bushing within the socket. The swaging operation requires a flat surface on one side of the link member. The need for the flat surface prevents the socket from being locally thickened for added strength. Extensions or protrusions of the link member on the opposite side are known as a means to thicken the link member at the socket to increase the strength of the socket, but these are limited to a single side due to the requirements of the swaging operation.
To avoid the swaging operation, removable bearing assemblies are known in which an entry slot is provided in the spherical socket to enable the bushing to be inserted into the socket when properly aligned with the slot. The bushing is then rotated 90° to a use position in which the through bore in the bushing extends laterally of the link member. A retaining member such as a snap ring is inserted into a groove in the socket to prevent the bushing from being rotated back into alignment with the entry slot for removal. These types of removable bearing assemblies remove material from the socket to form the snap ring groove and many orient the entry slot such that material is removed from the spherical socket in the wear conduct area where the bushing engages the socket during use of the hitch.
SUMMARY OF THE INVENTION
The present invention provides a bearing assembly having a removable bushing enabling the width of the socket to be increased on both lateral sides to increase the section area. Further, no material is removed from the socket wear surface for a snap ring and the entry slot is oriented perpendicular to the length of the link member such that the wear conduct area in the longitudinal direction of the link member is not reduced by the entry slot. The result is a socket having symmetry about both lateral and horizontal planes which reduces bending loads and stresses in the link member.
The entry slot extends completely through the socket such that the bushing can be installed from either direction. This also allows the socket to be symmetrical. The bushing is installed by aligning the bushing with the entry slot, inserting the bushing into the socket and then rotating the bushing 90° so that the bore in the bushing is perpendicular to the length and extends laterally thereof. A sleeve is then inserted into the bore of the bushing. One end of the sleeve has a raised retaining lip and the opposite end of the sleeve carries a snap ring groove. A snap ring is seated in the groove and retains the sleeve in the bushing. With the sleeve in place, the bushing can no longer be removed from the socket even when the bushing is aligned with the entry slot. The bushing is thus retained in the socket without a snap ring groove in the socket that would reduce the wear contact area and strength of the socket.
REFERENCES:
patent: 3160449 (1964-12-01), Scott
patent: 3493252 (1970-02-01), Watson et al.
patent: 3876232 (1975-04-01), Pertusi
patent: 4174137 (1979-11-01), Ferris
patent: 4248486 (1981-02-01), Bradley, Jr.
patent: 4251122 (1981-02-01), McCloskey
patent: 4466631 (1984-08-01), Berg
patent: 5005991 (1991-04-01), Heumann et al.
patent: 5524987 (1996-06-01), Vigeh
Boden Shane Michael
Kletzli Daniel Benjamin
Deere & Company
Hannon Thomas R.
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