For Cat Model 66DX35G1l , 3CP Or 5 CP
(Except Models 5CP4120, 5CP6120, 5CP6180CSS and 5CP6190)
OEM Check Valve Kit For CAT Pump 7860, 7850 and 7730 Unloaders
Pressure Regulating Unloaders
Parts List link : https://www.catpumps.com/sites/default/files/2020-08/67DX39G1I_H.pdf
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/products/pdfs/7850_C.pdf