Method and apparatus for operating an actuator

Abstract

A drilling or flushing medium is used in the operation of an actuator for controlling an earth working device which uses the drilling or flushing medium for its operation as well. The actuator is acted upon by the medium , which can be retained in the actuator through suitable operation of a valve assembly, while at the same time can be supplied to the earth working device to execute a desired function. The valve assembly is hereby actuated by a separate switch.

1 . A drilling or flushing medium for use in the operation of an actuator for controlling an earth working device.  
   
   
       2 . Apparatus, comprising: 
 at least one actuator for controlling an earth working device; and    a valve assembly for operating the actuator by means of a fluid selected from the group consisting of drilling medium and flushing medium.    
   
   
       3 . The apparatus of  claim 2 , wherein the valve assembly includes a camshaft, and plural valves which are operated by the camshaft.  
   
   
       4 . The apparatus of  claim 3 , wherein the valve assembly includes a cylinder which is operated by the fluid and operatively connected to the camshaft.  
   
   
       5 . The apparatus of  claim 2 , wherein the actuator is configured as lift pad.  
   
   
       6 . The apparatus of  claim 2 , wherein the earth working device is constructed for advancing along a predefined drilling route, and further comprising a tool for correcting an advance of the earth working device to compensate for a deviation from the drilling course.  
   
   
       7 . The apparatus of  claim 3  , wherein the valves are spring-biased valves.  
   
   
       8 . The apparatus of  claim 2 , wherein the fluid is bentonite.  
   
   
       9 . The apparatus of  claim 2  for carrying out any one of the operations selected from the group consisting of correcting a deviation of a drill head in a pilot bore, when the earth working machine is the drill head, correcting a deviation of an expansion head, when the earth working machine is the expansion head and lines are pulled in, opening and closing of valves or gates, operation of borehole tools, disengagement or engagement of tools in the ground, and moving out of a bore route for establishing branch lines or for exploration.  
   
   
       10 . A method for operating an actuator for controlling an earth working device, comprising the steps of: 
 subjecting the actuator to a fluid selected from the group consisting of drilling medium and flushing medium and used as the fluid for the earth working device; and    controlling an operation of a valve assembly such that the drilling or flushing medium is retained in the actuator, while at the same time is supplied to the earth working device for executing a desired operation.    
   
   
       11 . The method of  claim 10 , wherein the earth working device is a drill head or expansion head.  
   
   
       12 . The method of  claim 10 , wherein the controlling step includes the step of actuating a separate switch for adjusting the operation of the valve assembly.  
   
   
       13 . The method of  claim 10 , wherein the valve assembly includes plural spring-biased valves which return to their initial position when a pressure of the drilling or flushing medium drops below a spring force which acts on the valves.