Structure of engine starter equipped with planetary gear speed reducer

A starter comprising:

• a casing having;
• an electric motor disposed within a motor chamber defined in said casing, said motor having an output shaft projecting from an front end thereof;
• a one-way clutch disposed frontward of said motor within said casing;
• a planetary gear train disposed between said motor and said one-way clutch within said casing, said planetary gear train working as a speed reducer to reduce a speed of rotation of the output shaft of said motor to transmit torque of the output shaft to said one-way clutch;
• a starter output shaft retained in said casing rotatably for outputting the torque of the output shaft of said motor, as transmitted through said one-way clutch;
• a partition plate extending so as to traverse an axial direction of the starter between said motor and said planetary gear train within said casing to isolate said planetary gear train from the motor chamber;
• and
• a thrust washer extending so as to traverse the axial direction of the starter between said partition plate and said planetary gear train in abutment with a front end surface of said partition plate so as to receive a thrust load, as transmitted from said planetary gear train, said thrust washer including an outer peripheral portion which is placed between a rear end surface of an internal gear of said planetary gear train and the front end surface of said partition plate and has an elastic mechanism working to elastically urge the internal gear of said planetary gear train frontward in the axial direction of the starter.