Actuator mechanism for a two-bucket grab device

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-displaceably, but non-rotatably retained in a 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),
• a transverse web (25) interconnects said two ring pistons (23, 24) to ensure synchronous operation of the same, and
• the threads of each said respective shaft (3, 4) are located in a region of only one half (17, 18) of said carrier housing (2) containing said cylinder space or chamber (33, 34) corresponding to a peripheral shape of said two ring pistons (23, 24) connected by said web (25).

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-displaceably, 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 section 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 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),
• additionally comprising a transverse web (25) interconnecting said two ring pistons (23, 24) to ensure synchronous operation of the same, and
• said carrier housing (2) comprising two halves (17, 18), with a respective cylinder chamber (33, 34) formed in each said half (17, 18) for receiving a respective one of said pieces (23, 24).