Patent ID: 7775503

Claim:
A pressure relief valve for a lubrication system, the pressure relief valve comprising a housing having a bore, first and second ends, an inlet port and an outlet port for, respectively, admitting lubricant from a high pressure side of the lubrication system into the bore and expelling it therefrom, a pilot pressure inlet port at its first end for admitting lubricant taken from a point remote from said high pressure side, and a biasing member and a piston assembly located within the bore, the piston assembly comprising a second piston biased against the first end of the housing by the biasing member and the second piston connected to a first piston and having a smaller diameter than the first piston, wherein a face of the first piston is exposed to pressure from lubricant entering the bore through the inlet port and a face of the second piston is exposed to pressure from lubricant entering the bore through the pilot pressure inlet port, said first piston opening said outlet port when pressure from said inlet port overcomes said biasing member.