A continuous chain saw lubricating system employed in a tree delimbing and topping machine having a plurality of lubricant conduits connected to a piston cylinder which is divided into co-functioning and alternating receiving and discharge chambers by a piston. The designation of the chambers is dependent upon the direction of axial movement of the piston. The discharge chamber is defined by a pressure increase and the receiving chamber is defined by a pressure decrease. The pressure variations are such as to allow lubricant to be either drawn into the receiving chamber or discharged from the discharge chamber through a series of check valves connected to the piston cylinder. The piston is reciprocated by the tree delimbing and topping machine causing lubricant to be continuously supplied to the reciprocating chain saw during its cutting and retraction strokes.