Great Western Railway class 4575 “Small Prairie”
From 1927, the then chief engineer of the GWR, Charles Collett, procured 100 pieces of an improved version of the Class 4500 developed by Churchward. The most important difference concerned larger water tanks, which could be visually recognized by the sloping top at the front. Since the company numbers of the first series followed the 75 units of class 4500 without gaps, they became class 4575. The total of 100 units were initially assigned numbers up to 4599 and finally from 5500 to 5574.
Although these locomotives were built later than their predecessors, they remained in service little longer. Their retirement began in April 1956 and was completed in December 1964. A total of eleven pieces still exist today. The number 5521 even came to Poland from 2007 to take part in the annual parade of the museum in Wolsztyn. After that it spent some time in Hungary to pull the Orient Express and after another stay in Poland to come back to England.
Technical data
General
- Built
- 1927-1929
- Manufacturers
- Swindon
- Wheel arrangement
- 2-6-2T (Prairie)
- Gauge
- 1,435 mm (Standard gauge)
Dimensions and weights
- Length
- 11.09 m
- Wheelbase
- 8.18 m
- Service mass
- 62 t
- Adhesion mass
- 47 t
- Rigid wheelbase
- 3.53 m
- Axle load
- 15.8 t
- Water capacity
- 4,921 l
- Fuel capacity
- 3.8 t (coal)
Boiler
- Grate area
- 1.533 m²
- Firebox surface
- 8.733 m²
- Tube heating surface
- 92.206 m²
- Evaporative heating surface
- 100.939 m²
- Superheater surface
- 6.503 m²
- Total heating surface
- 107.4 m²
Power plant
- Driver diameter
- 1,410 mm
- Boiler pressure
- 13.8 bar
- Expansion type
- simple expansion
- Cylinders
- two, 432 x 610 mm
Power
- Power source
- steam
- Estimated power
- 634 kW (862 PS)
- Starting effort
- 94.5 kN
Calculated values
- Factor of adhesion
- 1 : 4.88
- Optimal speed
- 42 km/h
- Power-to-weight ratio
- 10.2 kW/t
- Heating Surface Equivalent
- 157.6 m²
- Cylinder volume/HSE
- 1 : 1,132.78
- Adhesive weight/Total
- 1 : 1.32
- Tractive force/Heating surface
- 1 : 18.37
- Grate area/Heating surface
- 1 : 70.09
- Firebox/Tube surface
- 1 : 10.56
- Total/Superheater
- 1 : 15.52