20/26 H.P.

W/n 7033 (D. Hall)

 The 20/26 H.P. is one of the models commonly known as the plate frame type due to its frame being made from steel plate as opposed to the channel section of most of the older models. It was available as 2 and 3-ton variants.

 The 20/26 H.P. type was fitted with the Dorman 2JOR petrol engine, similar to the engine fitted to earlier 20 H.P. types. In contrast to the 2JO, the 2JOR had a detachable “Ricardo” cylinder head. Many of these plate-framed locos were actually listed as 20 H.P. in works records but all are referred to here as 20/26 H.P. to avoid confusion.

 One easy way to tell a 20/26 H.P. apart from the very similar looking plate framed 20/28 H.P. diesel is the exhaust. On a 20/26 H.P. this ends in a large silencer next to the radiator, whereas on a diesel loco it usually ends just under the engine cover on the opposite side and has an exhaust operated whistle on the end. The petrol locos had the whistle screwed directly into the cylinder head and this worked off the engine compression. Of course, many 20/26 H.P. locos were rebuilt with diesel engines later in their lives, both by their owners and MR, thus effectively making them 20/28s. These rebuilds have the tell-tale sign of a hole in the front cross member where the radiator outlet pipe formerly passed through to the engine. The 20/28s built new did not have this feature.

 Number Series (built between 1934 and 1941)

  4701-4728, 4801-4815, 7021-7023, 7025-7098, 9101-9104.

 Note: The following locos are known to have been reconditioned by MR in 1952. They were fitted with Dorman 2DWD diesel engines, given new works numbers, and sold as new 20/28 H.P. locos:

                           Old Number               New Number

                          7032                             9539

                          7080-7081                   9540-9541

                          7083-7087                   9660-9664