초록 ▼

An impulse generating tool for breaking up rock has a barrel, a breech body for a cartridge (50) loaded with gas producing propellant (70) and a firing mechanism for firing the cartridge. A hole is drilled in the rock and filled with water. The barrel is passed down the hole and the cartridge is fir

An impulse generating tool for breaking up rock has a barrel, a breech body for a cartridge (50) loaded with gas producing propellant (70) and a firing mechanism for firing the cartridge. A hole is drilled in the rock and filled with water. The barrel is passed down the hole and the cartridge is fired. Shockwaves break up the rock. A firing pin (42) of the firing mechanism is off-set (56) from a centerline (54) of the breech body, and the cartridge, which is of a shotgun type, has a rim-fire percussion cap (63) complemental to the off-set of the firing pin. Conventional shotgun ammunition cannot be fired with the tool, and cartridges for the tool cannot be fired by a conventional shotgun.

대표청구항 ▼

[ I claim:] [1.] A method of production of a gas discharge cartridge generally of the shotgun kind which cartridge is suitable for use with an impulse generating tool for breaking up rock, boulders, concrete in mining and general construction, the method of production being such as to render said ca

[ I claim:] [1.] A method of production of a gas discharge cartridge generally of the shotgun kind which cartridge is suitable for use with an impulse generating tool for breaking up rock, boulders, concrete in mining and general construction, the method of production being such as to render said cartridge incapable of being fired from conventional shotguns all having centre fire firing mechanisms, and such as to render said cartridge capable of being fired from said impulse generating tool suitable to house a cartridge generally of the shotgun kind in a cartridge chamber thereof and including a rim fire firing pin offset by a predetermined amount of at least more than 2 mm from an axis of said cartridge chamber, the method including:providing a cartridge casing of a size and shape suitable to be housed in a cartridge chamber of a conventional shotgun, the cartridge casing containing a gas producing propellant and including a rear wall having a concentrically positioned aperture through said rear wall;mounting a percussion cap in said aperture, the percussion cap being of the rim fire kind which has a rear end and a closed hollow body which projects forwardly from said rear end and which closed hollow body contains a priming or initiating composition, said rear end including, along a concentric peripheral band thereof at a radius corresponding to said offset of said predetermined amount, structure which contains of said priming or initiating composition, and which structure is adapted, when struck by said rim fire firing pin in use, to produce heat and pressure to ignite said priming or initiating composition contained in said structure, said rear end being vacant of structure capable of igniting priming or initiating composition when struck by a firing pin of a centre fire firing mechanism in use in a central concentric region having a diameter of at most 4 mm.