A grievance or dispute between an employer and his employees may be submitted to a local board of arbitrators, consisting of three persons, for hearing and settlement. When the employees concerned are members in good standing of a labor organization, one arbitrator may be appointed by such organization and one by the employer. The two so designated shall appoint a third, who shall be chairman of the board. If such employees are not members of a labor organization, a majority thereof at a meeting duly called for that purpose may designate one arbitrator for such board.