A locking apparatus comprising: (a) a plurality of buttons provided on a cover plate which is coupled with a base, wherein one of the plurality of buttons is a code change button; (b) an actuating hub rotatably mounted on the base, a circumference of the actuating hub formed with a recessed portion defining two projections; (c) a grip handle connected with the actuating hub; (d) a first control plate disposed adjacent to the actuating hub and having one end formed with a raised portion, the two projections of the actuating hub being abutted against two sides of the raised portion of the first control plate respectively, such that when the actuating hub rotates clockwise or anticlockwise, one of the two projections presses against a corresponding one of the two sides of the raised portion of the first control plate, the first control plate further comprising two longitudinal side plates, and a plurality of teeth projecting inwardly from at least one of the two longitudinal side plates; (e) at least one locking tumbler (18, 20), the or each locking tumbler (18, 20) comprising a central axle mounted on the base; (f) a series of button engagement disc clutch plates mounted on the central axle of the or each locking tumbler (18, 20), each button engagement disc clutch plate comprising a pair of button pin engagement levers for engagement therein between with a protruded portion of a button pin of the button; and (g) a series of coding disc clutch plates mounted on the central axle of the or each locking tumbler (18, 20), and engaging respectively with the series of button engagement disc clutch plates, each coding disc clutch plate comprising a cut-out aperture; (h) whereby pressing a selected group of the buttons, which correspond to an access code, rotates their respective button engagement disc clutch plates and in turn their respective coding disc clutch plates such that the cut-out apertures align with the teeth of the first control plate, thereby allowing movement of the first control plate and rotation of the actuating hub when the grip handle is rotated. (a) a plurality of buttons provided on a cover plate which is coupled with a base, wherein one of the plurality of buttons is a code change button; (b) an actuating hub rotatably mounted on the base, a circumference of the actuating hub formed with a recessed portion defining two projections; (c) a grip handle connected with the actuating hub; (d) a first control plate disposed adjacent to the actuating hub and having one end formed with a raised portion, the two projections of the actuating hub being abutted against two sides of the raised portion of the first control plate respectively, such that when the actuating hub rotates clockwise or anticlockwise, one of the two projections presses against a corresponding one of the two sides of the raised portion of the first control plate, the first control plate further comprising two longitudinal side plates, and a plurality of teeth projecting inwardly from at least one of the two longitudinal side plates; (e) at least one locking tumbler (18, 20), the or each locking tumbler (18, 20) comprising a central axle mounted on the base; (f) a series of button engagement disc clutch plates mounted on the central axle of the or each locking tumbler (18, 20), each button engagement disc clutch plate comprising a pair of button pin engagement levers for engagement therein between with a protruded portion of a button pin of the button; and (g) a series of coding disc clutch plates mounted on the central axle of the or each locking tumbler (18, 20), and engaging respectively with the series of button engagement disc clutch plates, each coding disc clutch plate comprising a cut-out aperture; (h) whereby pressing a selected group of the buttons, which correspond to an access code, rotates their respective button engagement disc clutch plates and in turn their respective coding disc clutch plates such that the cut-out apertures align with the teeth of the first control plate, thereby allowing movement of the first control plate and rotation of the actuating hub when the grip handle is rotated.