541060 OEM Check Valve And Spring For CAT Pump 7500 and 7600 Unloaders (All 2SF Models) With Spring # 45924 Cat 7500S and 7600S Pressure Regulating Unloaders This unloader maintains set system pressure and goes into by-pass with the release of the trigger or an obstruction downstream. https://www.catpumps.com/sites/default/files/2020-03/7500S_C.pdf