Data from "Passenger Tank Locomotives, Nigerian Ry", Locomotive Magazine, Volume XXXIV [34], No. 427 (15 March 1928), pp. 69-70; and Nasmyth Wilson advertisement, Railway Gazette (18 September 1931), p. 47 (supplement page xvii). (Thanks to Teemu Koivumaki for his 19 August 2024 email supplying key information for several Nigerian Railways classes. His 29 August email provided 1949 NR diagrams of this and other locomotives.) Nasmyth Wilson works numbers were 1493-1496 in 1928. Robert Stephenson & Company works numbers were 4017-4021 in 1930.
Locobase 20161 shows the 401 class of Ten-wheelers that may have served as the baseline for these "Baltic" tanks. The long Belpaire firebox, identical cylinder volume and driver diameter suggest as much. Neither the LM report nor NR's 1949 diagram show either tube or flue counts and diameters. The only significant difference between the two builders was added in ink to the diagram. Nasmyth Wilson installed a Lockyer 4" (102 mm) regulator while RS&C used an Owen regulator.
The design suited the passenger traffic over the 119 1/2 miles between Lagos's Iddo terminus and Ibadan, which was laid with 80 lb/yard (40 kg/m) rail. Maximum curve radius for this design was 14 degrees.
"These engines have now been in traffic for several months", reported LM in March 1928, " and are giving every satisfaction."
| Principal Dimensions by Steve Llanso of Middle Run Media | |
|---|---|
| Class | 451 |
| Locobase ID | 21195 |
| Railroad | Nigerian Railways |
| Country | Nigeria |
| Whyte | 4-6-4T |
| Number in Class | 9 |
| Road Numbers | 451-459 |
| Gauge | 3'6" |
| Number Built | 9 |
| Builder | several |
| Year | 1927 |
| Valve Gear | Walschaert |
| Locomotive Length and Weight | |
| Driver Wheelbase (ft / m) | 11 / 3.35 |
| Engine Wheelbase (ft / m) | 34.75 / 10.59 |
| Ratio of driving wheelbase to overall engine wheelbase | 0.32 |
| Overall Wheelbase (engine & tender) (ft / m) | 34.75 / 10.59 |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 28,000 / 12,701 |
| Weight on Drivers (lbs / kg) | 81,984 / 37,187 |
| Engine Weight (lbs / kg) | 160,720 / 72,901 |
| Tender Loaded Weight (lbs / kg) | |
| Total Engine and Tender Weight (lbs / kg) | |
| Tender Water Capacity (gals / ML) | 4200 / 15.91 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 3.85 / 3.50 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 46 / 23 |
| Geometry Relating to Tractive Effort | |
| Driver Diameter (in / mm) | 54 / 1372 |
| Boiler Pressure (psi / kPa) | 160 / 1100 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 18" x 22" / 457x559 |
| Tractive Effort (lbs / kg) | 17,952 / 8142.90 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 4.57 |
| Heating Ability | |
| Tubes (number - dia) (in / mm) | / 51 |
| Flues (number - dia) (in / mm) | |
| Flue/Tube length (ft / m) | 10.42 / 3.18 |
| Firebox Area (sq ft / m2) | 151 / 14.03 |
| Grate Area (sq ft / m2) | 18 / 1.67 |
| Evaporative Heating Surface (sq ft / m2) | 952 / 88.44 |
| Superheating Surface (sq ft / m2) | 178 / 16.54 |
| Combined Heating Surface (sq ft / m2) | 1130 / 104.98 |
| Evaporative Heating Surface/Cylinder Volume | 146.92 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 2880 |
| Same as above plus superheater percentage | 3341 |
| Same as above but substitute firebox area for grate area | 28,026 |
| Power L1 | 7354 |
| Power MT | 593.27 |