Abstract: A rotary actuator includes a piston and rod coaxially disposed in a tube. The piston is configured for lateral displacement along the rod. Moreover, the tube includes an inner circumferential surface with a bearing portion having spherical bearing pockets in rows. Each bearing pockets in the tube includes a mated bearing for engagement with a slant groove body portion on an outer circumferential surface of the piston. The slant groove body portion of the piston includes at least two spiral grooves with a helix direction. The piston further includes an inner circumferential surface with a second spherical bearing pocket portion to engage a spiral groove portion of the axial rod disposed through the piston. As a result, linear motion of the piston engages the axial rod and forces the axial rod to rotate, thereby driving a platform affixed at an end cap of the axial rod to rotate.

Abstract: A rotary actuator includes a piston and rod coaxially disposed in a tube. The piston is configured for lateral displacement along the rod. Moreover, the tube includes an inner circumferential surface with a bearing portion having spherical bearing pockets in rows. Each bearing pockets in the tube includes a mated bearing for engagement with a slant groove body portion on an outer circumferential surface of the piston. The slant groove body portion of the piston includes at least two spiral grooves with a helix direction. The piston further includes an inner circumferential surface with a second spherical bearing pocket portion to engage a spiral groove portion of the axial rod disposed through the piston. As a result, linear motion of the piston engages the axial rod and forces the axial rod to rotate, thereby driving a platform affixed at an end cap of the axial rod to rotate.