Work requiring disconnection and removal commenced on a mud mixing pump assembly without completing a Permit to Work, Lock/Tag/Try or reviewing the JSA. During the work scope, a Motorman passing by was asked to operate the chain fall assembly by pulling the control chain to raise the motor. While pulling on this chain, it is thought that the loose fall of the operating chain contacted the on/off switch for the electric pump. This switch was about three foot above the motor and in direct line of the chain fall assembly. (See attached photos) This energized the 100 horsepower motor and caused it to go out of control. It swung outward then upward, striking the motorman who was seriously injured and received a fracture of the upper arm and severe bruising to the side of his body, neck and face.