This subchapter shall be administered by the Railroad Retirement Board established by the Railroad Retirement Act of 1937 [
45 U.S.C.
228a et seq.] as an independent agency in the executive branch of the Government and composed of three members appointed by the President, by and with the advice and consent of the Senate. Each member shall hold office for a term of five years, except that any member appointed to fill a vacancy occurring prior to the expiration of the term for which his predecessor was appointed shall be appointed for the remainder of the term and any member holding office pursuant to appointment under the Railroad Retirement Act of 1937 when this subchapter becomes effective shall hold office until the term for which he was appointed under such Railroad Retirement Act of 1937 expires. One member shall be appointed from recommendations made by representatives of the employees and one member shall be appointed from recommendations made by representatives of employers as defined in paragraph (i) of section
231
(a)(1) of this title, in both cases as the President shall direct, so as to provide representation on the Board satisfactory to the largest number, respectively, of employees and employers concerned. One member, who shall be the chairman of the Board, shall be appointed without recommendation by either employers or employees and shall not be in the employment of or be pecuniarily or otherwise interested in any employer or organization of employees. Vacancies in the Board shall not impair the powers or affect the duties of the Board or of the remaining members of the Board, of whom a majority of those in office shall constitute a quorum for the transaction of business. Upon the expiration of his term of office a member shall continue to serve until his successor is appointed and shall have qualified.