| Year | 1931 |
| Date | 07-May |
| Volume | 64 |
| Issue | 1,565 |
| Page | 447 |
| Category | Electrical Work |
| Part | 1 |
| Title | How Commutators are Built |
| Author | A.H.A. |
| Notes | Two-part commutator made from tube, improved segment securing method, best form, disc type, with round stud segments |