| Year | 1947 |
| Date | 24-Apr |
| Volume | 96 |
| Issue | 2,396 |
| Page | 530 |
| Category | Railway |
| Part | 11 |
| Title | Railway Interlocking Frames. (a) Evans O'Donnell Type. (b) Great Central Type. (c) McKenzie and Holland's "Cam and Tappet" Type |
| Author | O.S.Nock |
| Notes | The "Direct Lever", the inclined trough, G.C.R. type of locking frame, two movements, the "cam and tappet" type |