| 摘要 |
A sealed rotary rock bit is disclosed in which a combined manual venting and pressure relief system is located within the lubrication reservoir of the rock bit. The seal rotary rock bit comprises a main bit body having a plurality of legs extending downwardly therefrom. Each leg has a rolling cone cutter rotatively mounted thereon. A lubrication system is provided in each leg to provide lubricant to the bearing area between the cutter and the leg. The lubrication system includes a reservoir of lubricant communicating via passageways with the bearing area. The reservoir further includes a rubber boot molded around a metal stiffener sleeve. A cover cap is attached to the rubber boot. The rubber boot is in the form of a resilient membrane and is exposed through the cover cap to the exterior of the rock bit and through the passageways to the interior of the lubricated bearing area. The vent and pressure relief system comprises an annular seat formed in the wall of the reservoir. A valve face is formed on the rubber boot and is biased against the annular seat by means of a belleville spring acting on the cover cap. If any excessive pressure develops within the lubricant reservoir, the excess is blown off through the valve seat. Any internal pressures can also be manually vented without removing the cover cap by a slight prying action on the cover cap.
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