MÁV Class 601

The MÁV class 601 (nicknamed as "The Giant" or "Big boy" ) is a class of Hungarian four cylinder Mallet -type locomotives, which was designed to haul long and very heavy cargo on very steep railway tracks.[1] With their 22.5 meter length and 2200 KW power,[2] they were the largest and most powerful steam locomotives which have ever built before (and during) the First World War in Europe.[3]

MÁV class 601
MÁV 601.jpg
MÁV 601
Type and origin
Power typeSteam
Build date1914–1921
Total produced60
 • Whyte2-6-6-0
 • UIC(1′C)C
Gauge1,435 mm (4 ft 8+12 in) standard gauge
Leading dia.950 mm (37+38 in)
Driver dia.1,440 mm (56+34 in)
Axle load15.78 tonnes (15.53 long tons; 17.39 short tons)
Loco weightEmpty Engine: 99.8 tonnes (98.2 long tons; 110.0 short tons) (without water and coal)
Tender weight53.1 tonnes (52.3 long tons; 58.5 short tons)
Total weightin driving condition: 163.32 tonnes (160.74 long tons; 180.03 short tons)
Fuel typeCoal
Fuel capacity8 tonnes (7.9 long tons; 8.8 short tons)
Water cap.26 m3 (5,700 imp gal)
 • Firegrate area
5.24 m2 (56.4 sq ft)
Boiler pressure15.5 kg/cm2 (1.52 MPa; 220 psi)
Heating surface252 m2 (2,710 sq ft)
 • Heating area87.3 m2 (940 sq ft)
CylindersFour, compound, outside
High-pressure cylinder520 mm × 660 mm (20+12 in × 26 in)
Low-pressure cylinder800 mm × 660 mm (31+12 in × 26 in)
Performance figures
Power outputMost Efficient: 1,550 hp (1,160 kW) Maximal: 2,950 hp (2,200 kW)
Tractive effort218.76 kN (49,179.20 lbf)

Based on the good operating experience with the series 651 more powerful locomotives arose at the MÁVAG in Budapest from 1914 on, which were especially provided for the line from Karlstadt (today: Karlovac, Croatia) to Fiume (today: Rijeka). By utilisation of the permitted axial load of 16,5t a locomotive was developed, which alone could move freighttrains uphill even on the steep line in the croatian karst without a banking engine.

 Allowed train loads of Class 601 engines 

 Angle of elevation 
 15 km/h (9.3 mph)   20 km/h (12 mph)   25 km/h (16 mph)   30 km/h (19 mph)   40 km/h (25 mph)   45 km/h (28 mph)   50 km/h (31 mph)   60 km/h (37 mph) 
 0‰ 5,950 tonnes (5,860 long tons; 6,560 short tons) 5,550 tonnes (5,460 long tons; 6,120 short tons) 5,057 tonnes (4,977 long tons; 5,574 short tons) 4,650 tonnes (4,580 long tons; 5,130 short tons) 3,770 tonnes (3,710 long tons; 4,160 short tons) 3,160 tonnes (3,110 long tons; 3,480 short tons) 2,610 tonnes (2,570 long tons; 2,880 short tons) 1,825 tonnes (1,796 long tons; 2,012 short tons)
 5‰ 1,860 tonnes (1,830 long tons; 2,050 short tons) 1,817 tonnes (1,788 long tons; 2,003 short tons) 1,760 tonnes (1,730 long tons; 1,940 short tons) 1,697 tonnes (1,670 long tons; 1,871 short tons) 1,550 tonnes (1,530 long tons; 1,710 short tons) 1,370 tonnes (1,350 long tons; 1,510 short tons) 1,187 tonnes (1,168 long tons; 1,308 short tons) 910 tonnes (900 long tons; 1,000 short tons)
10‰ 1,052 tonnes (1,035 long tons; 1,160 short tons) 1,035 tonnes (1,019 long tons; 1,141 short tons) 1,013 tonnes (997 long tons; 1,117 short tons) 990 tonnes (970 long tons; 1,090 short tons) 930 tonnes (920 long tons; 1,030 short tons) 833 tonnes (820 long tons; 918 short tons) 730 tonnes (720 long tons; 800 short tons) 570 tonnes (560 long tons; 630 short tons)
16‰ 657 tonnes (647 long tons; 724 short tons) 650 tonnes (640 long tons; 720 short tons) 640 tonnes (630 long tons; 710 short tons) 628 tonnes (618 long tons; 692 short tons) 600 tonnes (590 long tons; 660 short tons) 538 tonnes (530 long tons; 593 short tons) 471 tonnes (464 long tons; 519 short tons) 369 tonnes (363 long tons; 407 short tons)
20‰ 511 tonnes (503 long tons; 563 short tons) 506 tonnes (498 long tons; 558 short tons) 500 tonnes (490 long tons; 550 short tons) 491 tonnes (483 long tons; 541 short tons) 472 tonnes (465 long tons; 520 short tons) 423 tonnes (416 long tons; 466 short tons) 369 tonnes (363 long tons; 407 short tons) 287 tonnes (282 long tons; 316 short tons)
25‰ 389 tonnes (383 long tons; 429 short tons) 385 tonnes (379 long tons; 424 short tons) 381 tonnes (375 long tons; 420 short tons) 375 tonnes (369 long tons; 413 short tons) 362 tonnes (356 long tons; 399 short tons) 323 tonnes (318 long tons; 356 short tons) 280 tonnes (280 long tons; 310 short tons) 215 tonnes (212 long tons; 237 short tons)

Frame and chassisEdit

The required traction power required a very large boiler, so an additional running wheel was placed in front of the six coupled bikes. The coupled bikes were therefore mounted in triplicate in a separate frame in accordance with the Mallet system, while the running wheel was mounted in the front frame as an Adams-Webb type axle with a lateral offset of 42–42 mm. In addition, the rear (driving) wheel of the front frame (i.e. the locomotive's fourth wheel) was turned thinner, and the front (locomotive's fifth) wheel of the rear frame was allowed to move laterally by 12–12 mm. The driven axles were made of 3% nickel steel, while the coupled and running axles were made of liquid steel. The axles of driven and coupled bicycles were completely drilled along the axle line. 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 first, second and fifth wheels were also fitted with tyre lubricators. The two parts of the frame were connected by the so-called Mallet pin. The complete boiler was mounted on the rear frame - the rear frame extended forward over the front frame to support the front of the boiler - and the cab (in the parlance of the time, the 'locomotive galley'). The extension of the rear frame section rested on the front frame section via a sliding plate. The front frame section could pivot laterally around the Mallet pin, and the straightening and 'anti-snaking' was provided by plate springs.


The rear frame wheels were driven by high-pressure cylinders and the front by low-pressure cylinders. The steam from the high-pressure cylinders was discharged through the cross-flow tube into the common flow tube, which also served as a receiver, and was fitted with a ball joint at the rear. From the transfer hose, the steam was discharged into the piston chambers of the low pressure cylinders. In each frame, the rear of the nickel-steel rims was the actuator. The right-hand cranks were wedged 90° forward on the wheel axle compared to the left-hand cranks. The piston rod was not a through rod on the rear, only on the front. The piston rod sleeves at the rear of each machine had a Schmidt-type metal seal, while the front of the front machine had a closed bushing. The crossheads were two-wire. The drive and coupling rods were of I-shaped cross-section.

To reduce the idling work (resistance) of the steam cylinders, an openable pressure compensating switch connecting the front and rear piston areas of the cylinders and, in the first examples, a Ricour valve on the inlet were fitted, and in later examples air valves were fitted to the piston boxes of the high-pressure cylinders. A compression valve was also fitted to all four cylinders to prevent water hammer. The crossheads were two-wire. In order to facilitate starting, the locomotives were also fitted with a starter, identical in principle to the Borries starter but without a non-return valve, to supply fresh steam to all four 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 high-pressure pistons had a 354 mm diameter, 40 mm internal overlap and 7 mm negative external overlap, while the low-pressure pistons had a 430 mm diameter, 39 mm internal overlap and 4 mm negative external overlap. The counter crank was located nearly 90° ahead of the crank in the forward stroke, in other words, it was wedged as a leading edge in relation to the crank. In accordance with this and the internal inlet, the swinging arch stone was positioned on the upper part of the swinging arch (coulisse) in the forward direction. This arrangement, common on domestic locomotives of the period, is not an advantageous solution for locomotives running predominantly in forward gear, as it causes faster wear of the swinging arch bedding. The steering drawbar, which moved forward when the locomotive was moving forward, was connected to the main spar behind the high-pressure cylinders via the steering lever. Also connected to this strut, by means of an intermediate connecting rod, was the front control linkage trailing arm. 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.


The locomotive's boiler, based on the experience with the types already mentioned, was built with a Brotan-Deffner type water tube boiler and, in keeping with the times, a Schmidt type superheater. The relatively small diameter of the wheels and the high position of the longitudinal boiler made it possible to have a wide standing boiler and thus a wide grate. 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. At the time of its construction, the steam boilers of MÁV's 601 series locomotives were the largest Brotan boilers in Europe in terms of size and power. The grate consisted of three parts, the first part was hinged. The longitudinal boiler consisted of three belts, the steam dome being located on the first belt and the Pecz-Rejtő feedwater purifiers on the second: two six-cell cylindrical units arranged in parallel under a common casing. The steam dome houses the water separator and the double flat-piston steam regulator with a vertical pusher. The control rod of the structure was routed inside the boiler. The third boiler belt was tapered to connect to the preheaters and the stationary boiler. The boiler was fitted with 188 continuous flues of 46,5/52 mm diameter and a total of 36 continuous flues of 119/127 mm diameter in four rows. The smoke tubes were fitted with superheater elements consisting of 27/34 mm diameter tubes. 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). On the first locomotive, the boiler shell was tightly fitted over the Brotan tubes and the front end, so that after the tapered longitudinal boiler tube there was a break in the outer line of the boiler. In later examples, the standing boiler shell was already fitted to the upper arc of the longitudinal boiler and later the first locomotive was also so designed. The boiler was also fitted with 3 4″ MÁV-style[4] direct spring-loaded safety valves and a so-called smoke evacuator. The boiler was fed with water by 2 Friedmann class SZ non-intake, 11 mm orifice, so-called "restarting" fresh steam guns.

Supporting equipmentEdit

The dome-shaped sandbox was placed on the locomotive's smoke box, behind the chimney. The sanding device delivered sand in front of the second, third and fourth wheels.

The locomotive was fitted with one Westinghouse-type brake cylinder per frame and was also fitted with a direct-acting regulating brake for use on longer gradients. The brake shoes braked the locomotive's driven wheels from the front, while the running wheels were unbraked as was usual on MÁV locomotives. The brake shoe pressure was almost equal to the traction weight. To ensure safe running on high gradients, the locomotive was also equipped with a Le Chatelier-type back-steam device. The parts in the steam were lubricated by a 10-slot Friedmann LD piston hot parts lubrication pump per frame. In unfavourable adhesion conditions, a compressed air sand blaster was used to apply sand to the coupled rims of the front frame. For sanding the rear wheel set, a second, smaller sand tank was installed at the driver's position. The locomotives were also equipped with an acetylene generator and a Bavarian system of high-pressure steam heating.


  1. ^ Wolfgang Lübsen: Die Orientbahn und ihre Lokomotiven. in: Lok-Magazin 57, Dezember 1972, S. 448–452
  2. ^ http://vasutgepeszet.hu/wp-content/uploads/2014/12/201404_03-06_vegl.pdf[bare URL PDF]
  3. ^ (Béla Czére, Ákos Vaszkó): Nagyvasúti Vontatójármüvek Magyarországon, Közlekedési Můzeum, Közlekedési Dokumentációs Vállalat, Budapest, 1985, ISBN 9635521618