Patent ID: 7249695
Filing Date: 2007-07-31
Classification: F16N

Abstract:
1. A grease gun for use in enhancing the pressure applied to a blocked grease fitting, the grease gun comprising: a housing including a handle portion and a head portion, the head portion having a bore forming a pump cylinder and an inlet passage and an outlet passage extending from the exterior of the head portion and opening into the bore, the outlet passage opening into the bore at a point axially spaced in a first direction from the opening of the inlet passage into the bore; a grease supply cylinder sealingly secured to the head portion so that the bore is in fluid communication with the grease in the supply cylinder; a discharge hose in fluid communication with the outlet passage for delivering grease to the grease fitting; an electric motor disposed within the housing, the motor including a shaft; a battery; a circuit interconnecting the battery and the motor, the circuit including a switch operable by a user holding the fluid dispensing dispenser in his hand for manually activating the motor when the switch is actuated, and a thermal protector for breaking the circuit at a predetermined temperature; a transmission disposed within the housing and operably connected to the motor, the transmission comprising a planetary gear assembly including an output gear, and a drive gear meshing with the output gear, the drive gear including a drive pin eccentrically mounted on a face of drive gear and projecting outwardly from the face of the drive gear; a yoke having a cam slot for receiving the drive pin for reciprocation of the yoke by the drive pin upon rotation of the drive gear; and a piston fastened to the yoke at one end and the other end of the piston slidably disposed in the bore for reciprocal movement relative to the housing between a first position axially spaced in a second direction from the opening of the inlet passage into the bore and a second position past the inlet passage opening in the first direction, the piston moving toward the outlet passage opening in the first direction through a pumping stroke for forcing the grease in the bore out through the outlet passage opening and into the discharge hose, and away from the outlet passage and past the inlet passage opening in the second direction through a return stroke for priming the bore, wherein, when the switch is continuously actuated, the thermal protector cycles between an open circuit condition and a closed circuit condition when the discharge hose is connected to a blocked grease fitting, the pressure in the bore and discharge hose increasing each time the thermal protector resets to the open circuit condition up to a maximum pressure.