a lubrication conduit 6 are disclosed by fig4 and 5 6 and 7 8 and 9 and 10 and 11 respectively the lubricant conduit 6 fluidly connects to the pump 5 and serves to supply pressurized lubricant to a device in need of lubrication e g a motor the lubricant conduit 6 of each embodiment can be protected from damage caused by excessive pressure by providing a pressure relief valve 14 in the embodiment of fig4 a conduit or pipe leads from the annular conduit 12 to two input ports u201c a u201d of respective 3 port 2 position valves i e directional control valves 15 the valve ports u201c b u201d in fig4 5 are each in fluid communication with a reservoir t e g reservoir 2 of fig1 valve ports u201c c u201d are each in fluid communication with a pump outlet a p and b r respectively the other pump ports are the pressure gauge ports ma and mt a measuring port m and a vent e thus in fig4 and 5 a two line central lubrication system includes two directional control valves 15 in the form of two 3 port 2 position valves 18 19 respectively which operate as follows if the valve 18 is switched to the first position lubricant is supplied through outlet a p and if valve 18 is switched to the second position lubricant is supplied to the reservoir t unpressurized.