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Class Information
Number: 175/297
Name: Boring or penetrating the earth > Below-ground (1) hammer, or (2) impact members > Fluid-operated > Restricted orifice for initially delaying escape of restraining fluid
Description: Apparatus in which said relieving means comprises a restricted orifice through which said fluid may escape when placed under pressure to allow unrestrained movement of said hammer or impact device after a predetermined amount of said fluid has escaped.

Patents under this class:
1 2 3

Patent Number Title Of Patent Date Issued
3987858 Hydromechanical drilling jar Oct. 26, 1976
3955634 Hydraulic well jar May. 11, 1976
3949821 Drill string jarring and bumping tool with piston disconnect Apr. 13, 1976
RE28768 Jarring and bumping tool for use in oilfield drilling strings Apr. 13, 1976

1 2 3

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