SERVO ACTUATOR FOR FUEL INJECTOR

An actuator assembly (12) of a fuel injector (10) has a body (14) provided with an internal cavity (22) wherein an inner shoulder face (44) is arranged between a large bore (24) and a thinner conduit (30). A servo actuator member (32) is arranged in the cavity (22) and it has an outer shoulder face (38) provided between a large actuation portion (34) and a thinner head portion (36). The actuator assembly (12) is further provided with an integral hydraulic lash adjuster (HLA) comprising a first chamber (56) defined between the outer shoulder face (38) and the inner shoulder face (44) and, an annular first clearance (C1) arranged around the actuator member (32) filled with high viscosity fluid (F).