A surgical apparatus comprising: a handle assembly; an elongated body portion extending distally from the handle assembly and defining a first longitudinal axis; a tool assembly pivotally supported on the distal end of the elongated body portion about a pivot axis substantially orthogonal to the first longitudinal axis, the tool assembly defining a second longitudinal axis and being movable between a first position in which the second longitudinal axis is aligned with the first longitudinal axis to a second position in which the second longitudinal axis is positioned at an angle to the first longitudinal axis; and an axial drive assembly including: a flexible knife drive beam extending from a position proximal of the pivot axis to a position distal of the pivot axis, the flexible knife drive beam having a distal end which is movable in relation to the tool assembly to actuate the tool assembly; and a gear drive assembly (355, 355', 356) interfacing with the flexible knife drive beam to enable movement of the distal end of the flexible knife drive beam in relation to the tool assembly, wherein at least one of advancing and retracting of the knife drive beam at a distal end thereof in relation to the tool assembly actuates the tool assembly; characterised in that the gear drive assembly (355', 355', 356) comprises: a primary drive gear meshing with the flexible knife drive beam to effect the movement of the flexible knife drive beam, and the primary drive gear is a crown gear (360, 360', 361) having first and second opposing surfaces (360a, 360b), the crown gear (360, 360', 361) including a support shaft centrally disposed therein defining an axis of rotation of the crown gear (360, 360', 361), the crown gear (360, 360', 361) including on the first surface a spiral cam, the crown gear (360, 360', 361) being configured such that the spiral cam meshes with the flexible knife drive beam wherein rotation of the crown gear (360, 360', 361) around the support shaft causes the spiral cam to at least one of advance and retract the flexible knife drive beam to effect the movement of the distal end thereof. a handle assembly; an elongated body portion extending distally from the handle assembly and defining a first longitudinal axis; a tool assembly pivotally supported on the distal end of the elongated body portion about a pivot axis substantially orthogonal to the first longitudinal axis, the tool assembly defining a second longitudinal axis and being movable between a first position in which the second longitudinal axis is aligned with the first longitudinal axis to a second position in which the second longitudinal axis is positioned at an angle to the first longitudinal axis; and an axial drive assembly including: a flexible knife drive beam extending from a position proximal of the pivot axis to a position distal of the pivot axis, the flexible knife drive beam having a distal end which is movable in relation to the tool assembly to actuate the tool assembly; and a gear drive assembly (355, 355', 356) interfacing with the flexible knife drive beam to enable movement of the distal end of the flexible knife drive beam in relation to the tool assembly, a flexible knife drive beam extending from a position proximal of the pivot axis to a position distal of the pivot axis, the flexible knife drive beam having a distal end which is movable in relation to the tool assembly to actuate the tool assembly; and a gear drive assembly (355, 355', 356) interfacing with the flexible knife drive beam to enable movement of the distal end of the flexible knife drive beam in relation to the tool assembly, wherein at least one of advancing and retracting of the knife drive beam at a distal end thereof in relation to the tool assembly actuates the tool assembly; characterised in that the gear drive assembly (355', 355', 356) comprises: a primary drive gear meshing with the flexible knife drive beam to effect the movement of the flexible knife drive beam, and the primary drive gear is a crown gear (360, 360', 361) having first and second opposing surfaces (360a, 360b), the crown gear (360, 360', 361) including a support shaft centrally disposed therein defining an axis of rotation of the crown gear (360, 360', 361), the crown gear (360, 360', 361) including on the first surface a spiral cam, the crown gear (360, 360', 361) being configured such that the spiral cam meshes with the flexible knife drive beam wherein rotation of the crown gear (360, 360', 361) around the support shaft causes the spiral cam to at least one of advance and retract the flexible knife drive beam to effect the movement of the distal end thereof.