Method of increasing the off bottom load capacity of a bearing assembly

{
  "publication_number": "US5150972A",
  "country": "US",
  "kind": "A",
  "title": "Method of increasing the off bottom load capacity of a bearing assembly",
  "abstract": "A method of increasing the off bottom load capacity of a bearing assembly having an outer tubular member, an inner tubular member telescopically received within the outer tubular member, and bearings disposed between the inner tubular member and outer tubular member to facilitate relative rotation of the outer tubular member and inner tubular member while bearing radial and axial loads. The method consists of the following described steps. Firstly, form a first shoulder and a second shoulder in opposed spaced relation on an interior surface of the outer tubular member. Secondly, form a first shoulder and a second shoulder in opposed spaced relation on an exterior surface of the inner tubular member. The shoulders on the inner tubular member are generally parallel to the shoulders on the outer tubular member thereby defining a containment chamber. Thirdly, place at least one thrust bearing in the containment chamber. The thrust bearing having a first side race and a second side race. When the bearing assembly is placed in compression the first shoulder of the outer tubular member bears against the first side race and the second shoulder of the inner tubular member bears against the second side race. When the bearing assembly is placed in tension the second shoulder of the outer tubular member bears against the second side race and the first shoulder of the inner tubular member bears against the first side race.",
  "claims": [
    "1. A method of increasing the off bottom load capacity of a bearing assembly having an outer tubular member, an inner tubular member telescopically received within the outer tubular member, and bearings disposed between the inner tubular member and outer tubular member to facilitate relative rotation of the outer tubular member and inner tubular member while accommodating radial and axial loads, comprising the steps of: a) firstly, forming a first shoulder and a second shoulder in opposed spaced relation on an interior surface of the outer tubular member; b) secondly, forming a first shoulder and a second shoulder in opposed spaced relation on an exterior surface of the inner tubular member, the shoulders on the inner tubular member being generally aligned with the shoulders on the outer tubular member thereby defining a containment chamber; and c) thirdly, placing at least one thrust bearing in the containment chamber, the thrust bearing having a first side race and a second side race, such that when the bearing assembly is placed in compression the first shoulder of the outer tubular member bears against the first side race and the second shoulder of the inner tubular member bears against the second side race, and when the bearing assembly is placed in tension the second shoulder of the outer tubular member bears against the second side race and the first shoulder of the inner tubular member bears against the first side race.",
    "2. An improvement in a bearing assembly having an outer tubular member, an inner tubular member telescopically received within the outer tubular member, and bearings disposed between the inner tubular member and outer tubular member to facilitate relative rotation of the outer tubular member and inner tubular member while bearing radial and axial loads, the improvement comprising: a) a first shoulder and a second shoulder in opposed spaced relation on an interior surface of the outer tubular member; b) a first shoulder and a second shoulder in opposed spaced relation on an exterior surface of the inner tubular member, the shoulders on the inner tubular member being generally parallel to the shoulders on the outer tubular member thereby defining a containment chamber; and c) at least one thrust bearing disposed in the containment chamber, the thrust bearing having a first side race and a second side race, such that when the bearing assembly in placed in compression the first shoulder of the outer tubular member bears against the first side race and the second shoulder of the inner tubular member bears against the second side race, and when the bearing assembly is placed in tension the second shoulder of the outer tubular member bears against the second side race and the first shoulder of the inner tubular member bears against the first side race.",
    "3. The improvement as defined in claim 2, having biasing means disposed in the containment chamber whereby a preload is maintained on the thrust bearing."
  ],
  "description_excerpt": "The present invention relates to a method of increasing the off bottom load capacity of a bearing assembly.\n\nA downhole bearing assembly used in earth drilling consists of an outer tubular member, an inner tubular member telescopically received within the outer tubular member, and bearings disposed between the inner tubular member and the outer tubular member to facilitate relative rotation of the outer tubular member and the inner tubular member while accommodating radial and axial loads. Axial loading can be in either of two directions; commonly referred to as compression or tension. Compression loading is the greater of the two in an earth drilling application as the weight of the drill string is brought to bear on the bearing assembly. Tension loading is placed on the bearing assembly whenever the drill bit is lifted off the bottom of the bore hole.\n\nIt is the practise in the art to separate the function of the thrust bearings when designing bearing assemblies. One group of bearings take compression loads and a different group of bearings take tension loads. Of course, the load capacity of the bearings taking the compression loads must be much greater than the bearings taking the tension loads. The bearings taking the tension loads, commonly referred to as the \"off bottom\" bearings have become a weak link in the design of bearing assemblies. Generally, a single off bottom bearing is used. However, should the drill string temporarily become stuck in the bore hole the upwardly jarring force used to dislodge the drill string often exceeds the load capability of the off bottom bearing and damages the bearing assembly.",
  "cpc": [
    "E21B 4/003",
    "F16C 2352/00",
    "Y10T 29/49679"
  ],
  "ipc": [
    "E21B 4/00"
  ],
  "inventors": [
    "William R. Wenzel"
  ],
  "filing_date": "1991-09-26",
  "publication_date": "1992-09-29",
  "grant_date": "1992-09-29",
  "priority_date": "1990-10-01",
  "application_number": "US-76601691-A",
  "family_id": "4146077",
  "cited_by_count": 17,
  "citations": [
    "US3449030A",
    "US4029368A",
    "US4501454A",
    "US4729675A",
    "US4511193A"
  ]
}