Gas supply pump for ship dual fuel engine

A gas supply pump for a ship dual fuel engine, the gas supply pump comprising:

• a rotatable camshaft;
• a plurality of cam noses arranged at regular intervals along a lengthwise direction of the camshaft, wherein the cam noses are eccentric from a center of the camshaft;
• a cam roller in close contact with each cam nose;
• a drive shaft and a piston adjacent to each other on one side of the cam roller;
• a liquefied gas compression device to compress and discharge liquefied gas by a linear reciprocating motion of the piston;
• a coupling case at a coupled part of the drive shaft and the piston;
• a rack member connected to the drive shaft, or connected and fixed to both the drive shaft and the piston in an internal space of the coupling case;
• and
• a pinion engaged with a teeth-shaped rack on an outer surface of the rack member,
• wherein, as the camshaft rotates, when the cam nose moves in a compression direction of the piston, the piston is compressed, and when the cam nose moves in a decompression direction of the piston, the piston is decompressed,
• wherein the cam roller is selectively spaced apart from the cam nose, and when the cam roller and the cam nose are spaced apart from each other, a rotational driving force of the cam nose is not transmitted to the piston, and
• wherein the cam nose and the cam roller are spaced apart from each other by a movement of the rack member and the pinion which are engaged with each other.