| Powertype: | Steam |
| GWR 3100 Class | |
| Designer: | Churchward (rebuilt by Collett) |
| Builder: | GWR Swindon Works |
| Ordernumber: | Lot 319 |
| Builddate: | 1906 |
| Rebuilddate: | 1938 |
| Numberrebuilt: | 5 |
| Whytetype: | 2-6-2T |
| Uicclass: | 1'C1 h2t |
| Leadingdiameter: | 3feet |
| Driverdiameter: | 5feet |
| Trailingdiameter: | 3feet |
| Minimumcurve: | 6chain normal, 5chain slow |
| Length: | 41feet over buffers |
| Width: | 8feet |
| Height: | 13feet |
| Axleload: | (19LT) full |
| Weightondrivers: | (57LT) full |
| Locoweight: | (81LT) full |
| Fueltype: | Coal |
| Watercap: | 2000impgal |
| Boiler: | GWR Standard No. 4 |
| Boilerpressure: | 225lbf/in2 |
| Firearea: | 20.56square feet |
| Tubearea: | 1349square feet |
| Fireboxarea: | 128.72square feet |
| Superheatertype: | 4-element or 6-element |
| Superheaterarea: | 4-element: 136.64square feet, 6-element: 181.1square feet |
| Cylindercount: | Two, outside |
| Cylindersize: | 18.5x |
| Tractiveeffort: | 31170lbf |
| Operator: | GWR » BR |
| Operatorclass: | 3100 |
| Fleetnumbers: | 3100–3104 |
| Powerclass: | GWR: D, BR: 4MT |
| Axleloadclass: | GWR: Red |
| Withdrawndate: | 1957–1960 |
| Disposition: | All scrapped |
The Great Western Railway (GWR) 3100 Class was a class of 2-6-2T side tank steam locomotive.
This class of large prairie was created in 1938 when Collett rebuilt some of Churchward's 3150 Class with a view to using them as bankers, particularly from Severn Tunnel Junction shed. These engines used the standard class 4 boiler again, but pressed to 225psi. and using smaller coupled wheels of 5inchesft3inchesin (ftin) diameter, and NaNinches increase in cylinder diameter, nominal tractive effort rose to . Almost impossible to pick out was a 21NaN1 reduction in pony truck wheel diameter to 3feet. Only five engines were ever modified, namely 3173, 3156, 3181, 3155 and 3179 which were rebuilt as 3100 to 3104 respectively. None of these were preserved.