[1] At 22.5 m (73 ft 10 in) long and outputting 2,200 kW (3,000 hp),[2] they were the largest and most powerful steam locomotives built in Europe before and during World War I.
The suspension of the driven wheels, which were riveted together from 28 mm thick solid iron plates and embedded in an internally arranged frame, was connected by dowels.
The front frame section could pivot laterally around the Mallet pin, and the straightening and 'anti-snaking' was provided by plate springs.
Wheel arrangement (Jelleg): (1'C)'C–h4v Service mass with tender : 163.32 / 162.5 metric tons Total wheelbase with tender : 19,182 mm The rear frame wheels were driven by high-pressure cylinders and the front by low-pressure cylinders.
From the transfer hose, the steam was discharged into the piston chambers of the low pressure cylinders.
The steam cylinders were equipped with wide, flexible, self-tensioning cylindrical pushrods with internal inlet, controlled by counter-cranking Heusinger-Walschaert-type camshafts.
The main spar was also connected to the rear control units by separate tie rods on either side.
This latter solution was necessary because the large standing boiler prevented the main beam from being positioned at the rear control units.
Due to the height restrictions of the locomotive, the so-called front head consisted of two parallel cylinders, into which the 70 Brotan 85/95 mm pipes, which formed the side of the firebox, ran.
The American system spark arrestor and the superheater cabinet were installed in the 2892 mm long fume cupboard.
The superheating was controlled by means of a superheater protection cabinet and dampers mounted on it, which were moved by a small steam cylinder (the so-called servomotor or automatic).
The boiler was also fitted with three 4″ MÁV-style[4] direct spring-loaded safety valves and a so-called smoke evacuator.
The boiler was fed with water bytwo Friedmann class SZ non-intake, 11 mm orifice, so-called "restarting" fresh steam guns.
Type of stationary boiler: Brotan–Deffner system, water-tube firebox Height of boiler longitudinal axis above rail crown: 3120 mm Steam pressure: 15 bar Fire Tubes Number: 188 / 176 Inner/outer diameter: 46.5 mm / 52 mm Length: 5600 mm Flue Tubes Number: 52 / 36 Heating Surfaces Grate area: 5.09 / 5.24 m² Radiant heating surface: 23 / 25.7 m² Tube heating surface: 252 / 221 m² Superheater area: 66 / 87.3 m² Performance Effective steam production capacity: 12,750 kg/h The dome-shaped sandbox was placed on the locomotive's smoke box, behind the chimney.
To ensure safe running on high gradients, the locomotive was also equipped with a Le Chatelier-type back-steam device.
The locomotives were also equipped with an acetylene generator and a Bavarian system of high-pressure steam heating.
By the end of the war, 57 units of this type had been produced by the MÁVAG Company for the MÁV (Hungarian State Railways).
In 1918, three such locomotives were built for the Chemins de fer Orientaux (CO) in Turkey, where they were assigned road numbers 601–603.
MÁV stationed the majority of the Class 601 locomotives in Zagreb and a smaller number in Miskolc.
Consequently, the piston valves of the Class 601 locomotives were redesigned to a narrow-ring type with reduced friction.
This modification was integrated by MÁV with the standardization of piston valve dimensions across its superheated locomotives.
As part of this process, the piston valve diameters and overlap values of the Class 601 locomotives remained unchanged.
Following the loss in World War I, all previously built Class 601 locomotives ended up beyond Hungary's borders due to the redistribution of railway vehicles.
These included locomotives stranded in severed territories, those seized during the Romanian occupation after the fall of the Hungarian Soviet Republic, and those assigned to successor states under the Treaty of Trianon.
MÁV’s locomotive fleet, including the Class 601, expanded significantly after the Vienna Awards.
By the 1950s, these locomotives were rarely used, mostly sidelined as reserve units or relegated to boiler heating duty until their certificates expired.
Államvasútak 1–C+C jellegű, 601. sorozatú, kompaund, túlhevítős, Mallet-rendszerű mozdonya [The Compound, Superheated, Mallet-System Class 601 1–C+C Steam Locomotives of the Royal Hungarian State Railways], A gőzmozdony [The Steam Locomotive], 1914, Vol.
Lányi Ernő, Lovász István, Mohay László, Szontagh Gáspár, Villányi György (eds.