Valve for hydraulic rock drill

Abstract

A concentric valve for a hydraulic rock drill featuring simple and direct fluid connections, especially suited for use with fluid storage volumes.

I claim:  
     
         1 . A hydraulic rock drill, comprising 
 a. a housing having a piston bore and valve bore formed therein    b. a piston axially disposed in said piston bore and a valve axially disposed in said valve bore    c. said valve bore being concentric with said piston bore    d. said housing containing a high pressure fluid reservoir    e. said housing containing a low pressure fluid reservoir    f. said piston bore having short and direct connections to said high pressure reservoir    g. said piston bore having short and direct connections to said low pressure reservoir    h. said valve bore having short and direct connections to said high pressure reservoir    i. said valve bore having short and direct connections to said low pressure reservoir    
     
     
         2 . A hydraulic rock drill as in  claim 1  wherein said valve moves under the influence of pressure alone without physical contact between said valve and said piston.