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Lancashire & Yorkshire class 7 “High-Flyers”

Great Britain 1899 40 produced
flickr/Historical Railway Images PD

Also known as “High-Flyers”, the Lancashire & Yorkshire class 7 locomotives were among the first Atlantics in Britain. Their nickname came from the high-pitched boiler that lay above the 7 ft 3 in high driving wheels. Aspinall had developed them to get a more powerful replacement for the existing 4-4-0 and 4-2-2 locomotives. As with Ivatt, this wheel arrangement was chosen to accommodate a larger, albeit narrow, firebox. 

At the time of their introduction, they had the largest boiler of any British steam locomotive and reached high average speeds with the relatively light trains. While No. 1417's alleged speed of 117 mph is highly questionable, No. 1392 likely actually reached 100 mph with a five-car train on a trial run in 1899.

After one of the locos was the first in Britain to be fitted with an early superheater, five others were also fitted with it, but this was later removed. After the grouping, they were the only 4-4-2 tender locomotives on the LMS and were grouped into power class 2P. The withdrawals took place between 1926 and 1934.

Technical data

General

Built
1899-1902
Manufacturers
Horwich
Wheel arrangement
4-4-2 (Atlantic)
Gauge
1,435 mm (Standard gauge)

Dimensions and weights

Wheelbase
8.46 m
Service mass
59.7 t
Adhesion mass
35.6 t
Total mass
90.8 t
Rigid wheelbase
2.22 m
Axle load
17.8 t
Water capacity
12,503 l
Fuel capacity
5.3 t (coal)

Boiler

Grate area
2.42 m²
Firebox surface
16.332 m²
Tube heating surface
174.398 m²
Evaporative heating surface
190.73 m²
Total heating surface
190.7 m²

Power plant

Driver diameter
2,210 mm
Boiler pressure
12.4 bar
Expansion type
simple expansion
Cylinders
two, 483 x 660 mm

Power

Power source
steam
Estimated power
708 kW (963 PS)
Starting effort
73.4 kN

Calculated values

Factor of adhesion
1 : 4.75
Optimal speed
60 km/h
Power-to-weight ratio
11.9 kW/t
Heating Surface Equivalent
272.4 m²
Cylinder volume/HSE
1 : 886.97
Adhesive weight/Total
1 : 1.68
Tractive force/Heating surface
1 : 8.04
Grate area/Heating surface
1 : 78.81
Firebox/Tube surface
1 : 10.68
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