Hand-operated device for drilling blast-holes

A hand-operated device for drilling blast holes comprising a perforator which has an impact tool and a rotatable box which carries a rod with a drilling bit;

• a power-operated pulling winch mounted on said perforator and having a pulling element which can be secured to solid rock, said pulling winch having a shaft on which said pulling winch is fixedly mounted;
• drive means in the nature of a gear drive cooperating with said rotatable box for converting the movements of said rotatable box into movements about said shaft of said pulling winch;
• coupling means including adjusting means for selectively coupling the movements of said drive means to said pulling winch, whereby coupling of said drive means to said pulling winch causes the perforator to be fed progressively by said rotating box, said rotatable box having an external surface, and said gear drive comprising a worm thread formed on said external surface, and a gear mounted on said shaft of said pulling winch and meshed with said worm thread in an engagement zone, whereby actuation of said rotatable box translates the movements thereof to rotary movements coaxial with said shaft of said pulling winch;
• and a hollow bushing on said shaft of said pulling winch, said gear being mounted on said bushing for free rotation thereon, the rotary movements of said gear only being transmitted to said bushing when said coupling means couples said worm wheel and said bushing together.