Drive mechanism, pump assembly and lubrication system

A pump assembly for pumping a fluid lubricant, the pump assembly comprising:

• a pump mechanism having a fluid lubricant inlet,
• a fluid lubricant outlet, and
• a pumping shaft configured to pump the fluid lubricant from the fluid lubricant inlet to the fluid lubricant outlet by means of a reciprocating motion, wherein
• the pump assembly further comprises a drive mechanism having;
• a pneumatic cylinder housing defining a cylinder volume that is configured to house a gas,
• a piston arranged in the pneumatic cylinder housing, separating the cylinder volume in a first chamber and a second chamber, and being displaceable back and forth in the pneumatic cylinder housing between a first dead center and a second dead center,
• a valve unit having a first state and a second state,
• a gas inlet configured to be connected to a pressure source,
• a gas outlet configured to be connected to a pressure sink, wherein
• the gas inlet is in fluid communication with the first chamber of the cylinder volume, and the second chamber of the cylinder volume is in fluid communication with the gas outlet, when the valve unit is in the first state, wherein
• the gas inlet is in fluid communication with the second chamber of the cylinder volume, and the first chamber of the cylinder volume is in fluid communication with the gas outlet, when the valve unit is in the second state, wherein
• the drive mechanism further comprises:
• a valve unit actuator having a magnet that is located adjacent the valve unit and that is configured to alternately shift the state of the valve unit between the first state and the second state, wherein
• the piston at the first dead center is arranged to mechanically displace the valve unit actuator from a second position to a first position, the magnet shifting the valve unit from the second state to the first state, and wherein
• the piston at the second dead center is arranged to mechanically displace the valve unit actuator from the first position to the second position, the magnet shifting the valve unit from the first state to the second state, and
• wherein the valve unit is shifted in a direction perpendicular to the movement of the valve unit actuator.