Image courtsey of Plateway Press
The Metropolitan Water Board put out to tender many of items required for the railway’s construction and operation including rails, wagons, and most significantly the locomotives. Despite outsourcing the building of many key components, the MWB was keen to design all aspects of the railway to ensure it met their detailed requirements. This included the locomotives which were designed in house and the tender to construct them awarded to Kerr Stuart & Co Ltd in 1913.
The above drawing shows the MWB’s concept for the locomotives which differs slightly from the as built locos. The design demonstrates how the MWB was not content with off the shelf locomotives. Shortly after this drawing was produced, Kerr Stuart & Co Ltd responded with a modified proposed locomotive using some of Kerr Stuart's already in production parts including many components of the motion. Content with the designs, the MWB placed the order on the 29th of May 1914 at a cost of £678. This sum would increase, finally costing £729 each.
The locomotive’s works numbers were 2366, 2367 & 2368 and were named Hampton, Kempton & Sunbury accordingly. Between the 15th September 1914 and the 2nd March 1915, some 87 separate drawings were produced for these engines.
The locomotives had outside cylinders and used Walschaerts valve gear which had the benefit of having exceptional large wearing surfaces. The coupled wheels had steel centres with rolled steel tyres. The trailing wheels were millers chilled with side motion controlled by spiral springs to eliminate hunting in use. A large dome was bolted to a seating on top of the boiler barrel which provided easy access to the regulator for repairs. The large dome and high regulator also helped to reduce priming on the very steep and rapid changing gradients on the railway. A mud drum was fitted beneath the boiler to collect the sediment aiding the boiler wash-out process. Water was fed into the boiler through an axle driven pump when in motion and an injector for when stationary. Cylinder lubrication was fed from two displacement lubricators mounted on the sides of the smoke box. These lubricators were later replaced by a mechanical lubricator on the right hand side of the locomotive. The engines only featured a handbrake and not any continuous braking system as they only ever hauled coal wagons.
Driving wheel diameter 24''
Fixed wheelbase 36''
Cylinders 8.5'' x 12'' stroke
Length over buffers 15' - 3''
Height 8' - 3''
Working pressure 150 lbs inch
Boiler barrel 0.375'' steel plate
Grate area 3.9 sq ft
Heating surface firebox 22 sq ft
Water tanks 170 gallon capacity
Weight empty 9 tons 6 cwt
Brakes Hand, on coupled wheels only
Fire door Sliding type
Trailing wheel diameter 16.5''
Total Wheelbase 84''
Driving axles 3.25'' Dia journels 5.5'' Long
Width of footplate 6'
Safety Valves 1.25'' ramsbottom
Tractive effort 4,480 lbs
Boiler tubes 49 tubes 0.75'' dia
Firebox Copper, 0.5'' thick
Heating surface tubes 127.5 sq ft
Injector No. 4 automatic self starting simple type
Weight working 10 tons 15 cwt
Sanding 4 boxes, all controlled from footplate
Image courtsey of London Museum of Water and Steam