The S.D. Holden F7 2-4-2T Locomotives
S.D. Holden designed these small 2-4-2T locomotives in 1909 to replace the J65 0-6-0T tank engines which were in use for light passenger services. They were never a great success, and only twelve F7s were built. The J65s were actually more popular for this light branchline work. Relative to their size, the F7s had large cabs, and hence acquired the name of "Crystal Palace Tanks".
All twelve engines were fitted with Westinghouse brakes. In October 1914, No. 1311 was fitted for auto-train working using compressed air, and required a second Westinghouse pump. Nos. 1304-5, and 1309 were also converted before Grouping in 1923. In 1924, No. 8307 was fitted for mechanical auto-train working.
The F7s were used for lightweight branchline work in East Anglia, and were initially based at Saffron Walden, Ramsey, St. Ives, Stoke Ferry, Aldeburgh, Haldeigh, Braintree, and Maldon. During LNER ownership, they moved further afield and three even moved to Scotland in the early 1930s.
Although they were never very popular, the F7s were capable of hard work when required. At least one account exists of an F7 pulling a ten-coach train into Liverpool Street, after the original locomotive had failed.
Withdrawals started in 1931, but the last two survived just into Nationalisation and were withdrawn in November 1948.
Technical Details
| Cylinders (x2): | 15x22in. | |
| Motion: | Stephenson | slide valves |
| Boiler: | Max. Diameter: | 3ft 11.5in |
| Pressure: | 160psi | |
| Diagram No.: | 42 | |
| Heating Surface: | Total: | 872.9 sq.ft. |
| Firebox: | 75.7 sq.ft. | |
| Tubes: | 797.2 sq.ft. (199x 1.625in) | |
| Grate Area: | 12.2 sq.ft. | |
| Wheels: | Leading: | 3ft 6in |
| Coupled: | 4ft 10in | |
| Trailing: | 3ft 6in | |
| Tractive Effort: | 11,607lb | (@ 85% boiler pressure) |
| Total Wheelbase: | 19ft 6in | |
| Engine Weight: | 45 tons 14cwt | (full) |
| Max. Axle Load: | 14 tons 3cwt | |
| Coal Capacity: | 2 tons 0cwt | |
| Water Capacity: | 1000 gallons |
Preservation
The last F7s were withdrawn in 1948, and none survived into preservation.
Models
Finney and Smith produce a 3mm scale kit of the F7.
Alan Gibson sells a 4mm scale kit of the F7.
Connoisseur Models sell a kit of the F7 for 7mm scale (O gauge).