Soviet Railways series М
The М was the heaviest passenger locomotive in the USSR when it was introduced in 1926. It had the wheel arrangement 4-8-0 and was one of the few Soviet three-cylinder locomotives. It had a high-pitched boiler and was constructed in a way that the tender carried some of the weight of the firebox. Some were fired with coal and some with oil.
Production first started at Putilov and later at Lugansk. They got the nickname “Marusya”. But soon it became evident that they didn't produce enough steam at speed and despite three cylinders, the running characteristics were not optimal. So in 1934, all were rebuilt to the two-cylinder MR by removing the inside cylinder and switching the cranked axle for a straight one. Soon they were eclipsed by the much more powerful ИС and after World War II, they were only used for suburban service.
Technical data
General
| Property | M | rebuilt MR |
|---|---|---|
| Built | 1926-1930 | 1934 |
| Manufacturers | Putilov, Luhansk | |
| Wheel arrangement | 4-8-0 (Twelve-wheeler) | |
| Gauge | 1,520 mm (Russian broad gauge) | |
Dimensions and weights
| Property | M | rebuilt MR |
|---|---|---|
| Wheelbase | 10.68 m | |
| Total wheelbase | 19.65 m | |
| Service mass | 99.5 t | |
| Adhesion mass | 72.5 t | |
| Total mass | 161.5 t | |
| Rigid wheelbase | 5.90 m | |
| Axle load | 18.2 t | |
| Water capacity | 27,000 l | |
| Fuel capacity | 8 t (coal) | |
Boiler
| Property | M | rebuilt MR |
|---|---|---|
| Grate area | 6 m² | |
| Firebox surface | 18.45 m² | |
| Tube heating surface | 241.18 m² | |
| Evaporative heating surface | 259.63 m² | |
| Superheater surface | 95.65 m² | |
| Total heating surface | 355.3 m² | |
Power plant
| Property | M | rebuilt MR |
|---|---|---|
| Driver diameter | 1,700 mm | |
| Boiler pressure | 13 bar | 14.5 bar |
| Expansion type | simple expansion | |
| Cylinders | three, 540 x 700 mm | two, 540 x 700 mm |
Power
| Property | M | rebuilt MR |
|---|---|---|
| Power source | steam | |
| Estimated power | 1,500 kW (2,039 PS) | 1,700 kW (2,311 PS) |
| Top speed | 90 km/h | |
| Starting effort | 199.0 kN | 148.0 kN |
Calculated values
| Property | M | rebuilt MR |
|---|---|---|
| Factor of adhesion | 1 : 3.57 | 1 : 4.81 |
| Optimal speed | 47 km/h | 71 km/h |
| Power-to-weight ratio | 15.1 kW/t | 17.1 kW/t |
| Heating Surface Equivalent | 543.2 m² | |
| Cylinder volume/HSE | 1 : 885.43 | 1 : 590.28 |
| Adhesive weight/Total | 1 : 1.37 | |
| Tractive force/Heating surface | 1 : 11.70 | 1 : 8.70 |
| Grate area/Heating surface | 1 : 59.21 | |
| Firebox/Tube surface | 1 : 13.07 | |
| Total/Superheater | 1 : 2.71 | |
