A method for transferring a viscous material into a syringe that has a plug dividing a syringe interior into a first sub-chamber and a second sub-chamber, where a radial clearance exists between the plug and the syringe, includes transferring the viscous material from a container into the first sub-chamber to fill the first sub-chamber while allowing air initially present within the first sub-chamber to flow into the second sub-chamber via the radial clearance, and flowing a first volume of the viscous material into but not through the radial clearance such that the viscosity of the first volume of the viscous material and the radial clearance cooperate to block a flow of a second volume of the viscous material into the radial clearance and prevent the second volume of the viscous material from leaking from the first sub-chamber into the second sub-chamber.

Disclosed is an adaptor for connecting a grease injection gun to either of a lipped or a threaded grease cartridge; the adaptor including a tubular sleeve, having an internal diameter slightly larger than the external diameter of the grease cartridge, but smaller than the lip of the lipped cartridge, for receiving the discharge end portion of the cartridge; and an adaptor head shaped and dimensioned to form a closure over the tubular sleeve, the adaptor head including an outer face configured to releasably connect with the grease injection gun, and an inner face shaped and configured to releasably connect with the tubular sleeve and the cartridge, with a flow passage extending between the outer face and the inner face, for fluid communication between the grease injection gun and the cartridge.

The invention provides an apparatus comprising a grease gun (10) having a delivery line (22), the apparatus being configured to return grease under pressure from within the delivery line (22) of the grease gun (10) back to a grease reservoir (14); the grease gun (10) comprising a dispensing head (12) fitted to reservoir (14) containing grease and including a grease inlet port (16), for receiving grease from the grease reservoir (14), a grease outlet port (20) connectable to the delivery line (22) for dispensing grease; a pressure chamber (18) wherein the grease inlet port (16) is in fluid communication with the grease outlet port (20) via the pressure chamber (18); a piston (28) operable for displacing the grease from the grease inlet port (16) to the grease outlet port (20); and a one-way flow control valve located between the pressure chamber and the grease outlet port to inhibit the reverse flow of the grease from the grease outlet port back into the pressure chamber; the dispensing head (12) further comprising a pressure return port (26), located upstream of the grease inlet port (16) and linked to the grease outlet port (20) by a pressure return passage and openable into the pressure chamber (18), for returning the grease under pressure to the pressure chamber (18) and the grease reservoir (14), in which the piston (28) acts as a valve movable between a first position where the pressure return port (26) is closed and a second position where the pressure return port (26) is open.

The invention provides an apparatus comprising a grease gun (10) having a delivery line (22), the apparatus being configured to return grease under pressure from within the delivery line (22) of the grease gun (10) back to a grease reservoir (14); the grease gun (10) comprising a dispensing head (12) fitted to reservoir (14) containing grease and including a grease inlet port (16), for receiving grease from the grease reservoir (14), a grease outlet port (20) connectable to the delivery line (22) for dispensing grease; a pressure chamber (18) wherein the grease inlet port (16) is in fluid communication with the grease outlet port (20) via the pressure chamber (18); a piston (28) operable for displacing the grease from the grease inlet port (16) to the grease outlet port (20); and a one-way flow control valve located between the pressure chamber and the grease outlet port to inhibit the reverse flow of the grease from the grease outlet port back into the pressure chamber; the dispensing head (12) further comprising a pressure return port (26), located upstream of the grease inlet port (16) and linked to the grease outlet port (20) by a pressure return passage and openable into the pressure chamber (18), for returning the grease under pressure to the pressure chamber (18) and the grease reservoir (14), in which the piston (28) acts as a valve movable between a first position where the pressure return port (26) is closed and a second position where the pressure return port (26) is open.

A grease gun cylinder walled cartridge adapted for direct attachment to any of a variety of grease gun head constructions and grease pumping systems, wherein the cartridge wall can be of any color or completely clear and see through, wherein the grease column within the cartridge is pressured toward and through an inlet port in the gun head, which port opens on the suction stroke of a piston mounted in said cylinder into a loading portion of a cylinder of the grease pumping system, and wherein the grease column pressuring means is ambient air pressure.

A grease gun cylinder walled cartridge adapted for direct attachment to any of a variety of grease gun head constructions and grease pumping systems, wherein the cartridge wall can be of any color or completely clear and see through, wherein the grease column within the cartridge is pressured toward and through an inlet port in the gun head, which port opens on the suction stroke of a piston mounted in said cylinder into a loading portion of a cylinder of the grease pumping system, and wherein the grease column pressuring means is ambient air pressure.

The invention provides an apparatus comprising a grease gun (10) having a delivery line (22), the apparatus being configured to return grease under pressure from within the delivery line (22) of the grease gun (10) back to a grease reservoir (14); the grease gun (10) comprising a dispensing head (12) fitted to reservoir (14) containing grease and including a grease inlet port (16), for receiving grease from the grease reservoir (14), a grease outlet port (20) connectable to the delivery line (22) for dispensing grease; a pressure chamber (18) wherein the grease inlet port (16) is in fluid communication with the grease outlet port (20) via the pressure chamber (18); a piston (28) operable for displacing the grease from the grease inlet port (16) to the grease outlet port (20); and a one-way flow control valve located between the pressure chamber and the grease outlet port to inhibit the reverse flow of the grease from the grease outlet port back into the pressure chamber; the dispensing head (12) further comprising a pressure return port (26), located upstream of the grease inlet port (16) and linked to the grease outlet port (20) by a pressure return passage and openable into the pressure chamber (18), for returning the grease under pressure to the pressure chamber (18) and the grease reservoir (14), in which the piston (28) acts as a valve movable between a first position where the pressure return port (26) is closed and a second position where the pressure return port (26) is open.

The invention provides an apparatus comprising a grease gun (10) having a delivery line (22), the apparatus being configured to return grease under pressure from within the delivery line (22) of the grease gun (10) back to a grease reservoir (14); the grease gun (10) comprising a dispensing head (12) fitted to reservoir (14) containing grease and including a grease inlet port (16), for receiving grease from the grease reservoir (14), a grease outlet port (20) connectable to the delivery line (22) for dispensing grease; a pressure chamber (18) wherein the grease inlet port (16) is in fluid communication with the grease outlet port (20) via the pressure chamber (18); a piston (28) operable for displacing the grease from the grease inlet port (16) to the grease outlet port (20); and a one-way flow control valve located between the pressure chamber and the grease outlet port to inhibit the reverse flow of the grease from the grease outlet port back into the pressure chamber; the dispensing head (12) further comprising a pressure return port (26), located upstream of the grease inlet port (16) and linked to the grease outlet port (20) by a pressure return passage and openable into the pressure chamber (18), for returning the grease under pressure to the pressure chamber (18) and the grease reservoir (14), in which the piston (28) acts as a valve movable between a first position where the pressure return port (26) is closed and a second position where the pressure return port (26) is open.

Disclosed is an adaptor for connecting a grease injection gun to either of a lipped or a threaded grease cartridge; the adaptor including a tubular sleeve, having an internal diameter slightly larger than the external diameter of the grease cartridge, but smaller than the lip of the lipped cartridge, for receiving the discharge end portion of the cartridge; and an adaptor head shaped and dimensioned to form a closure over the tubular sleeve, the adaptor head including an outer face configured to releasably connect with the grease injection gun, and an inner face shaped and configured to releasably connect with the tubular sleeve and the cartridge, with a flow passage extending between the outer face and the inner face, for fluid communication between the grease injection gun and the cartridge.

A method for transferring a viscous material from a container into a dispensing syringe having first and second ends, the second end being a discharge port smaller than the inner diameter of the main body portion, includes inserting into the syringe a plug configured to permit gas flow in only one direction to divide a chamber within the syringe into a first sub-chamber in communication with the discharge port and a second sub-chamber in communication with the first open end of the syringe. Then, a rod is inserted into the syringe from the first open end of the syringe to engage the plug, and the viscous material is extruded from the container and through the discharge port into the first sub-chamber of the syringe. While the first sub-chamber is being filled with the viscous material, the plug and the rod are moving away from the discharge port.