Hungarian State Railways IIIu
Hungarian State Railways class 324, Czechoslovak State Railways class 344.4, Polish State Railways Ol 103, Yugoslav Railway class 22, and Italian State Railway class 683
The MÁV series IIIu is among the most successful 2-6-2 tender locomotives. Despite a driver diameter of only 1,440 mm and a top speed of 75 km/h, it was also used in express service. Production started at MÁVAG in 1909 and the first 355 locomotives were built as saturated two-cylinder compounds with a boiler pressure of 15 bars.
540 more were built as superheated simples with a pressure of only 12 bars. The 397 last of them had received a Brotan firebox due to World War I. Additionally, the 95 last of these also had a feedwater heater and cleaner of the Pecz-Rejtő system. After World War I, many came to Czechoslovakia, Yugoslavia, Poland and Italy. After World War II, one each even had been operated in Western and Eastern Germany.
Technical data
General
| Property | compound | superheated |
|---|---|---|
| Built | 1909-1923 | |
| Manufacturers | MÁVAG | |
| Wheel arrangement | 2-6-2 (Prairie) | |
| Gauge | 1,435 mm (Standard gauge) | |
Dimensions and weights
| Property | compound | superheated |
|---|---|---|
| Length | 17.53 m | |
| Length loco | 10.97 m | |
| Wheelbase | 8.31 m | |
| Total wheelbase | 14.24 m | |
| Empty mass | 51.7 t | 53.9 t |
| Service mass | 58.1 t | 60.1 t |
| Adhesion mass | 41.7 t | 42.3 t |
| Rigid wheelbase | 3.50 m | |
| Axle load | 13.9 t | 14.1 t |
Boiler
| Property | compound | superheated |
|---|---|---|
| Grate area | 3.148 m² | 3.15 m² |
| Firebox surface | 11 m² | 11.24 m² |
| Tube heating surface | 202.6 m² | 160.37 m² |
| Evaporative heating surface | 213.6 m² | 171.61 m² |
| Total heating surface | 213.6 m² | 208.3 m² |
| Superheater surface | 36.7 m² |
Power plant
| Property | compound | superheated |
|---|---|---|
| Driver diameter | 1,440 mm | |
| Boiler pressure | 15 bar | 12 bar |
| Expansion type | compound | simple expansion |
| Cylinders | two, HP: 460 x 650 mm and LP: 690 x 650 mm | two, 510 x 650 mm |
Power
| Property | compound | superheated |
|---|---|---|
| Power source | steam | |
| Estimated power | 780 kW (1,061 PS) | 820 kW (1,115 PS) |
| Starting effort | 84.3 kN | 119.8 kN |
| Starting effort simple | 101.2 kN | |
Calculated values
| Property | compound | superheated |
|---|---|---|
| Factor of adhesion | 1 : 4.85 | 1 : 3.46 |
| Optimal speed | 56 km/h | 42 km/h |
| Power-to-weight ratio | 13.4 kW/t | 13.6 kW/t |
| Heating Surface Equivalent | 268.6 m² | 301.2 m² |
| Cylinder volume/HSE | 1 : 854.62 | 1 : 881.67 |
| Adhesive weight/Total | 1 : 1.39 | 1 : 1.42 |
| Tractive force/Heating surface | 1 : 8.24 | 1 : 12.01 |
| Grate area/Heating surface | 1 : 67.85 | 1 : 66.13 |
| Firebox/Tube surface | 1 : 18.42 | 1 : 14.27 |
| Total/Superheater | 1 : 4.68 |
