| Year | 1930 |
| Date | 16-Oct |
| Volume | 63 |
| Issue | 1,536 |
| Page | 382 |
| Category | Locomotive |
| Part | |
| Title | Walschaerts Valve Gear Difficulties |
| Author | Henry Greenly |
| Notes | Modified Zenner diagram showing necessary proportions of lap and port opening for various full-gear cut-off points |