Lock set proof against prize up

A tamper-proof lock, comprising, in combination:

• an outer sleeve, said outer sleeve having a groove formation, an aperture for mounting a respective short tube in said outer sleeve, and radially extending holes for respective tumbler pins;
• a hollow inner sleeve positioned in said outer sleeve, said inner sleeve having radially extending holes for respective tumbler pins, said inner sleeve including an exteriorly projecting formation adapted to cooperatingly engage said groove formation of said outer sleeve, and said inner sleeve including an interiorly projecting formation;
• a lock strip operatively connected to said inner sleeve;
• a pivot mounted in said hollow inner sleeve, said pivot having a cam formation terminus for cooperation with said interiorly projection formation of said hollow inner sleeve, said pivot having a plate terminus remote from said cam terminus, and said pivot including a keyhole formation;
• first teeth arranged in a circular pattern on said plate terminus to axially project at a diameter which is greater than the outer diameter of said pivot;
• a short tube mounted in said outer sleeve, said short tube having a central keyhole formation and a set of second teeth to rotate said pivot by meshingly engaging said first teeth of said pivot;
• tumbler pins adapted to be positioned in said radially extending holes of said outer sleeve and said inner sleeve, and said tumbler pins being spring biassed by respective spring;
• a spring for each tumbler pin;
• a key, said key having a key head and a key stem releasably secured at said key head by means of a respective coupling;
• and
• a coupling for securing said key stem to said key head;
• wherein turning of said key imparts rotational movement to said inner sleeve by meshing cooperation of said first teeth of said pivot and said second teeth of said short tube for bringing said key stem to a first position in which said tumbler pins are moved to the respective shear line to open the lock, and for bringing said key stem to a second position in which said tumbler pins are moved to preclude opening of said lock.