Bearings – Rotary bearing – Antifriction bearing
Patent
1993-09-10
1995-04-04
Footland, Lenard A.
Bearings
Rotary bearing
Antifriction bearing
384499, 384513, F16C 3376
Patent
active
054031001
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATION
This application is a national phase of PCT/EP 92/02735 filed 27 Nov. 1992 and based, in turn, upon German national application P41 41 759.3 filed 18 Dec. 1991.
The present invention relates to a ball race for a slew bearing, having: an annular lower ball race part made up of a number of segments; a sealing ring externally enclosing said lower part and an oil collecting ring enclosed thereby; and a seal between the segments of the ball race lower part.
BACKGROUND OF THE INVENTION
Slew bearings are used, for example in open-pit mining equipment to enable the superstructure of such equipment to rotate in relation to the lower frame; they are constructed with a diameter up to several meters. The circular ball race in which the supporting balls run between the upper and lower parts of the ball race --i.e., between the superstructure and the lower frame--, has an oil lubrication system. Merely for economic considerations, oil losses must be kept as low as possible. Environmental protection also demands a construction which is substantially free from oil losses. In the prior art ball race slewing gear permanently plastic mastic or two-component silicone rubber is introduced into grooves of round cross-section in the separating lines between the segments in order to seal the ball race, which is usually made up of four to six, but also even up to twelve segments. Even with a construction which is at first (upon initial construction) satisfactory with respect to sealing tightness, due to unavoidable slight movements of the segments in relation to one another at the separating lines, sealing-tightness is reduced, so that as operations continue, leakage take place. No improvement, such as permanent sealing, results even by application of hand-cut rubber sections. Environmental protection requirements demand the detection of any leakages which may occur and their elimination. This can make considerable expense, since the superstructure must be lifted off the lower frame and the ball race parts dismantled and reassembled. Since as a rule the ball race lower part has an external sealing ring and an internal oil collecting ring, or vice-versa, these members must also be dismounted before the segments are separated from one another, for the introduction of a fresh seal.
OBJECT OF THE INVENTION
It is an object of the invention at one and the same time to provide a more reliable seal and to substantially reduce the aforementioned expense.
SUMMARY OF THE INVENTION
Accordingly, in a ball race for a body slew bearing of the kind specified, at the separating lines of annular body receiving the ball race, the segments have recesses having a plan vertical base surface and which extend at a distance from the ball race in a U-shape. The recesses have vertical arms which are open in the direction of the inside and outside of the ball race lower part and into which strand-shaped rubber or plastic sealing sections are drawn. As a result, the seal can be replaced without lifting the superstructure. All that is required is to remove the sealing ring and the oil collecting ring, which are usually made up of a number of parts, since then the outside of each recess and the inner side of the recess are exposed over the full heights of their arms. The ends of the sealing section can be folded downwards and the sealing section can be drawn out and a fresh sealing section inserted. This reduces the cost of repair to a small fraction of its previous amount. Conveniently the width of the horizontal portion of the groove and recess the width of the arms of the recesses, and the width of the seal are the same, so that the sealing sections can have a uniform cross-section over their whole length. It is also advantageous that the sealing sections should have a square cross-section.
Also advantageously on the two sides facing the segments of the annular body to be sealed against one another the sealing sections have preferably three sealing lips. The seal can also have a continuous, preferably circular
REFERENCES:
patent: 4671682 (1987-06-01), Yoshihara
Freitag Helmut
Meyenburg Bernd
Dubno Herbert
Footland Lenard A.
Krupp Fordertechnik GmbH
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