The Cowan D39 (GNSR Class C) 4-4-0 Locomotives

D39 No. 6803 at Elgin in August 1925

The Great North of Scotland Railway (GNSR) ordered twelve locomotives in 1877 based on Cowan's earlier GNSR Class L (LNER D47/1) locomotives but with larger diameter cylinders (17.5in compared to 17in). The design followed the traditional GNSR outside cylinder 4-4-0 pattern. Nine were fitted with 5ft 7in driving wheels and became GNSR Class M (LNER D45). The remaining three were fitted with 6ft 1in driving wheels and became GNSR Class C (LNER D39). All twelve engines were built by Neilson & Co, and the three D39s were delivered between December 1878 and January 1879. These were the last GNSR engines built to a Cowan design before his resignation in 1883.

Pickersgill fitted new boilers to all three D39s between February 1897 and February 1898. Nos. 1 & 3 had their boilers fitted at Kittybrewster, but No. 2 had its new boiler fitted at Inverurie. The new boilers were of the same type designed by Manson to re-boiler the GNSR Class K (LNER D47/2) locomotives. They were also used on the GNSR Class L (LNER D47/1) and GNSR Class M (LNER D45) classes. The new boilers were slightly wider with a diameter of 4ft 6in compared to 4ft 4.25in. The original boilers were fitted with Salter spring-balance safety valves, and had their domes mounted on a raised firebox. In contrast, the new boilers had Ramsbottom safety valves, and their domes were located on the barrel, flush with the firebox.

Roscoe and Furness lubricators were originally fitted, and these were retained after the Pickersgill re-boilerings. Sight-feed lubricators were eventually fitted shortly before Grouping (1923).

The D39s were built as express locomotives, and they were initially used on the Elgin-Keith-Aberdeen services. They continued to work some main line duties after the introduction of later 4-4-0s, and they eventually moved to the Deeside line. By Grouping (1923), the D39s were relegated to branch and local duties. No. 1 was allocated to Kittybrewster, operating as a spare engine or as the Inverurie pilot. It was withdrawn in August 1925, and never bore its LNER number of '6801'. During LNER ownership, No. 6802 (GNSR No. 2) operated branch line services from Keith, and was withdrawn in June 1926. At this time, No. 6803 (GNSR No. 3) also operated branch line services, but it was allocated to Elgin. No. 6803 was withdrawn in February 1927, and class D39 became extinct.

Technical Details

Cylinders (x2): (outside) 17.5x26in.
Motion: Stephenson
Valves: slide
Boiler: Max. Diameter: 4ft 6in
Pressure: 150psi
Heating Surface: Total: 1118.5 sq.ft.
Firebox: 100 sq.ft.
Tubes: 1018.5 sq.ft. (215x 1.75in)
Grate Area: 15.64 sq.ft.
Wheels: Leading: 3ft 0.5in
Coupled: 6ft 1in
Tender: 3ft 7.5in
Tractive Effort: (@ 85% boiler pressure) 13,907lb
Wheelbase: Total: 39ft 1.5in
Engine: 20ft 6in
Tender: 11ft 0in
Weight (full): Total: 71 tons 0cwt
Engine: 42 tons 0cwt
Tender: 29 tons 0cwt
Max. Axle Load: 14 tons


The last D39 was withdrawn in 1927, and none have survived into preservation.


I am not aware of any models of the D39 in any scale.