A rotary drill bit, comprising: a body having an inlet and three cutting arms (106, 107, 108), each with a journal extending therefrom and a rotary cutter (109, 110, 111) mounted on the journal by means of a plurality of bearings (120, 125, 130) such that a clearance is defined between the rotary cutter (109, 110, 111) and a base surface of the cutting arm (106, 107, 108) from which the journal extends; and an isolated lubrication system corresponding to each cutting arm (106, 107, 108), each including: a reservoir in the body to contain a fluid lubricant, the fluid lubricant being isolated from communication outside the body, a plurality of conduits (145, 150, 155) in the body having direct or indirect communication with the reservoir and with respect to each other such that the plurality of conduits (145, 150, 155) facilitate lubrication between the journal and the rotary cutter (109, 110, 111) and to the bearings (120, 125, 130) by means of at least one of a gravitational force and a centrifugal force acting on the fluid lubricant, and a sealing system including: a sealing cap provided to the reservoir in the body to isolate the reservoir from communication outside the body, the sealing cap having an orifice and a retractable component provided in the orifice for the supply of fluid lubricant to the reservoir, a seal provided between the journal and the rotary cutter (109, 110, 111) in the clearance, and a stepped passageway extending from the seal to an opening in the clearance, wherein a suction conduit is provided between the body inlet and each reservoir to facilitate suction of air from the reservoirs and a plug with a suction seal is provided in each of the suction conduits to isolate the reservoirs from communication outside the body after the vacuum is created. a body having an inlet and three cutting arms (106, 107, 108), each with a journal extending therefrom and a rotary cutter (109, 110, 111) mounted on the journal by means of a plurality of bearings (120, 125, 130) such that a clearance is defined between the rotary cutter (109, 110, 111) and a base surface of the cutting arm (106, 107, 108) from which the journal extends; and an isolated lubrication system corresponding to each cutting arm (106, 107, 108), each including: a reservoir in the body to contain a fluid lubricant, the fluid lubricant being isolated from communication outside the body, a plurality of conduits (145, 150, 155) in the body having direct or indirect communication with the reservoir and with respect to each other such that the plurality of conduits (145, 150, 155) facilitate lubrication between the journal and the rotary cutter (109, 110, 111) and to the bearings (120, 125, 130) by means of at least one of a gravitational force and a centrifugal force acting on the fluid lubricant, and a sealing system including: a sealing cap provided to the reservoir in the body to isolate the reservoir from communication outside the body, the sealing cap having an orifice and a retractable component provided in the orifice for the supply of fluid lubricant to the reservoir, a seal provided between the journal and the rotary cutter (109, 110, 111) in the clearance, and a stepped passageway extending from the seal to an opening in the clearance, wherein a suction conduit is provided between the body inlet and each reservoir to facilitate suction of air from the reservoirs and a plug with a suction seal is provided in each of the suction conduits to isolate the reservoirs from communication outside the body after the vacuum is created. a reservoir in the body to contain a fluid lubricant, the fluid lubricant being isolated from communication outside the body, a plurality of conduits (145, 150, 155) in the body having direct or indirect communication with the reservoir and with respect to each other such that the plurality of conduits (145, 150, 155) facilitate lubrication between the journal and the rotary cutter (109, 110, 111) and to the bearings (120, 125, 130) by means of at least one of a gravitational force and a centrifugal force acting on the fluid lubricant, and a sealing system including: a sealing cap provided to the reservoir in the body to isolate the reservoir from communication outside the body, the sealing cap having an orifice and a retractable component provided in the orifice for the supply of fluid lubricant to the reservoir, a seal provided between the journal and the rotary cutter (109, 110, 111) in the clearance, and a stepped passageway extending from the seal to an opening in the clearance, wherein a suction conduit is provided between the body inlet and each reservoir to facilitate suction of air from the reservoirs and a plug with a suction seal is provided in each of the suction conduits to isolate the reservoirs from communication outside the body after the vacuum is created. a sealing cap provided to the reservoir in the body to isolate the reservoir from communication outside the body, the sealing cap having an orifice and a retractable component provided in the orifice for the supply of fluid lubricant to the reservoir, a seal provided between the journal and the rotary cutter (109, 110, 111) in the clearance, and a stepped passageway extending from the seal to an opening in the clearance, wherein a suction conduit is provided between the body inlet and each reservoir to facilitate suction of air from the reservoirs and a plug with a suction seal is provided in each of the suction conduits to isolate the reservoirs from communication outside the body after the vacuum is created.