초록 ▼

A pneumatic spear gun (11) comprising a barrel (27) having an open end (33) through which a shaft (15) of a spear (13) can be received. A first piston (35) is slidingly and sealingly received in the barrel (27) for movement towards and away from a retracted position. A retaining means (41) is provid

A pneumatic spear gun (11) comprising a barrel (27) having an open end (33) through which a shaft (15) of a spear (13) can be received. A first piston (35) is slidingly and sealingly received in the barrel (27) for movement towards and away from a retracted position. A retaining means (41) is provided for releasably retaining the piston (35) in the retracted position. A source of compressible fluid such as air is contained in a reservoir (59) and is arranged to undergo compression upon movement of the piston (35) into the retracted position and to propel the piston along the barrel (27) from the retracted position upon release of the piston thereby to propel the spear (13). A control means is provided for selectively increasing the pressure of the compressible fluid for varying the propulsive force applied to the piston (35). The control means includes a cylinder (43) forming part of the resevoir (59) and having a second piston (45) slidingly and sealingly mounted therein. One side of the second piston (45) is exposed to the compressible fluid whereby movement of the second piston (45) along the cylinder (43) effects a volume reduction of the reservoir (59) to thereby an increase in the pressure of the propulsive fluid.

대표청구항 ▼

[ What is claimed is:] [1.] A method of changing the propulsive force of a projectile of a spear gun comprising the steps of:providing a compressible fluid in a compressible fluid reservoir in the spear gun, wherein the compressible fluid produces a propulsive force to propel the projectile from the

[ What is claimed is:] [1.] A method of changing the propulsive force of a projectile of a spear gun comprising the steps of:providing a compressible fluid in a compressible fluid reservoir in the spear gun, wherein the compressible fluid produces a propulsive force to propel the projectile from the spear gun;inserting the projectile into the spear gun until a piston for receiving the projectile reaches a fully retracted position; andmoving a movable wall in the spear gun in order to change the volume of the reservoir, wherein the change in the volume of the reservoir changes the propulsive force on the projectile by changing the pressure of the compressible fluid inside the reservoir.