Patent ID: 6896306

Claim:
Actuator mechanism for a grab device ( 1 ) having two grab arms ( 9 , 10 ) structured and arranged to move as pincers, and comprising two hydraulic pivot motors respectively having pivot shafts ( 3 , 4 ) and shaft journals ( 5 , 6 ) therefor and projecting from a carrier housing ( 2 ) to support the respective grab arms ( 9 , 10 ), wherein each of said pivot motors comprises a tubular piece ( 23 , 24 ) in turn provided with an internally-threaded section structured and arranged to engage an externally-threaded section upon a respective pivot shaft ( 3 , 4 ), said tubular pieces ( 23 , 24 ) are each formed as a ring piston axially-dispaceably, but non-rotatably retained in a respective cylinder space ( 33 , 34 ) formed in said carrier housing ( 2 ), pitch of the respective internally and externally-threaded sections is sufficiently large to transmit required torque to said pivot shafts ( 3 , 4 ) by axial displacement of said ring pistons ( 23 , 24 ), a displacement path of each said ring piston ( 23 , 24 ) between two annularly-arranged cylinder chambers ( 33 , 34 ) in each said cylinder space ( 33 , 34 ) alternatively constituting high and low pressure chambers ( 33 , 34 ) which can be loaded with hydraulic oil, corresponds to required pivot angle of the two grab arms ( 9 , 10 ), and additionally comprising a transverse web ( 25 ) interconnecting said two ring pistons ( 23 , 24 ) to ensure synchronous operation of the same.