| Year | 1977 |
| Date | 06-May |
| Volume | 143 |
| Issue | 3,560 |
| Page | 494 |
| Category | Steam |
| Part | |
| Title | An Introduction to Equality in Valve Gears |
| Author | D.L.Ashton |
| Notes | Valve gear of Bulleid's "Q.1" class 0-6-0, admission, cut-offs, choice of link, equality, inequality, significance for models, references |