Portable battery-powered grease gun

A portable grease gun for dispensing grease from a replaceable cartridge, said grease gun comprising:

• a main body having forward and rearward ends and side walls defining a cartridge chamber for receiving the cartridge;
• a plunger sealingly engageable inside the cartridge and moveable from the rearward end toward the forward end of the cartridge chamber;
• the forward end of the cartridge chamber having an opening therein;
• means biasing the plunger toward the forward end of the cartridge;
• a discharge chamber having a discharge opening combined with the forward end of the gun for receiving grease from the cartridge through the opening in said forward end;
• a check valve between the discharge opening in the forward end of the chamber and the discharge chamber;
• a piston moveable toward and away from the discharge chamber to force grease in the discharge chamber through the discharge opening whenever the piston moves toward the discharge chamber;
• a check valve in the discharge opening to allow grease to be forced from the discharge chamber only out through the discharge opening;
• user-controlled battery-operated power means operatively connected to the piston for moving the piston;
• and a battery chamber located near the battery-operated power means, the power means and battery chamber are both being located below the cartridge chamber.