A rotary actuator comprising: a housing ; a clamp arrangement (30; 230, 330) rotatably mounted to the housing , the clamp arrangement (30; 230, 330) operable to apply a clamping force to a shaft (16; 316), the clamp arrangement (30; 230, 330) including: a first bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing ; a second bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing ; a gear portion (90; 290; 390) interposed between the first and second bearings ; characterised by a clamp for applying the clamping force to the shaft (16; 316), the clamp and the gear portion (90; 290; 390) positioned at a same axial position along the shaft axis ; and wherein the clamp arrangement (30; 230; 330) includes a pair of casing member halves , the casing member halves providing the first and second bearings , the casing member halves attached to the gear portion (90; 290; 390) such that rotation of the gear portion (90; 290; 390) about the axis rotates the casing member halves , and wherein the first and second bearings define apertures that are coaxial about the shaft axis , the apertures for receiving the shaft (16; 316) therethrough along the shaft axis . a housing ; a clamp arrangement (30; 230, 330) rotatably mounted to the housing , the clamp arrangement (30; 230, 330) operable to apply a clamping force to a shaft (16; 316), the clamp arrangement (30; 230, 330) including: a first bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing ; a second bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing ; a gear portion (90; 290; 390) interposed between the first and second bearings ; characterised by a clamp for applying the clamping force to the shaft (16; 316), the clamp and the gear portion (90; 290; 390) positioned at a same axial position along the shaft axis ; and wherein the clamp arrangement (30; 230; 330) includes a pair of casing member halves , the casing member halves providing the first and second bearings , the casing member halves attached to the gear portion (90; 290; 390) such that rotation of the gear portion (90; 290; 390) about the axis rotates the casing member halves , and wherein the first and second bearings define apertures that are coaxial about the shaft axis , the apertures for receiving the shaft (16; 316) therethrough along the shaft axis . a first bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing ; a second bearing for rotatably supporting the clamp arrangement (30; 230, 330) relative to the housing ; a gear portion (90; 290; 390) interposed between the first and second bearings ; characterised by a clamp for applying the clamping force to the shaft (16; 316), the clamp and the gear portion (90; 290; 390) positioned at a same axial position along the shaft axis ; and wherein the clamp arrangement (30; 230; 330) includes a pair of casing member halves , the casing member halves providing the first and second bearings , the casing member halves attached to the gear portion (90; 290; 390) such that rotation of the gear portion (90; 290; 390) about the axis rotates the casing member halves , and wherein the first and second bearings define apertures that are coaxial about the shaft axis , the apertures for receiving the shaft (16; 316) therethrough along the shaft axis . <EOS>