vane-type pump, PC Suction and pressure effect via reduction or enlargement of the chambers. Centrifugal force causes apex seal to fit against housing. function of the pressure relief valve. function of the V-ribbed belt drive. description ordernumber 1151 see also: Demand-driven oil pump with suction stage (V8) high-pressure pump for engines with direct petrol injection (GDI) case model, valves nozzle holder set with 4 injection nozzles