Two improved chorded windings for 3:1 pole-changing

The paper describes two further and improved 3:1 pole-changing windings which both have only nine control leads, and in which a 60° spread has been used, instead of the 120° spread which was used in a machine previously described. A particular feature of these windings is that the coil pitch is critical, and can have only one value. Full-pitched coils cause very bad crawling effects.