Renfe Class 333

Renfe Class 333
	File:RN333-024.JPG Renfe Class 333 locomotive
Company type	Diesel-electric locomotive
Industry	Rail transport
Founded	1974
Headquarters	Spain
Products	Diesel-electric locomotives

{{Infobox locomotive | name = Renfe Class 333 | powertype = Diesel-electric | image = RN333-024.JPG | caption = Renfe Class 333 | designer = Macosa, General Motors, NOHAB
Refurbishment : Alstom | builddate = Original series: 1974–1976
333.1: 1994–1995
333.2: 1997–1998
333.3: 2002–2003
333.4: 2003–2004 | totalproduction = 93 (original)
8 (333.1)
4 (333.2)
92 (333.3 and 333.4) | uicclass = Co′Co′ | gauge = Iberian gauge | bogies = General Motors 'flexicoil' type | length = Original:
333.3/333.4: | width = Original:
333.3/333.4: | height = Original:
333.3/333.4: | axleload = | locoweight = | fueltype = Diesel | fuelcap = Original:
333.3: | primemover = General Motors EMD 645#GM 16-645-E-3A GM 16-645-E-3A, | enginetype = Two-stroke Diesel engine | cylindercount = V16 | alternator = General Motors AR-10 / D-14 | transmission = Diesel-electric transmission | tractionmotors = Original: 6 GM D-77
333.3 and 333.4: 6 D-78 | maxspeed = Original:
333.1:
333.2:
333.3:
333.4: | poweroutput = Original: nominal at rail | tractiveeffort = Original starting: at μ=0.28
Continuous: at
Top speed: at
Rebuilt (333.3 and 333.4) starting: , continuous: at | locobrakes = Pneumatic and rheostatic | operator = Renfe |} The Renfe Series 333 are robust six-axle diesel-electric locomotives introduced during the 1970s, recognized as Spain’s most powerful non-electrified engines of their era.

Three decades after their debut, these locomotives underwent modernization featuring Alstom technology, which prolonged their service life and led to the creation of subseries 333.3 and 333.4, equipped with upgraded systems and enhanced operational capabilities tailored to contemporary Spanish rail requirements.

Background

During the early 1970s, Renfe advanced its dieselization efforts by introducing classes such as 316, 318, 319, and 321, which effectively replaced steam traction for medium-power duties. In contrast, the diesel-hydraulic class 340, inspired by the German V 200, suffered from maintenance shortcomings and was poorly matched to slow freight services, resulting in reliability problems. This situation prompted Renfe to pursue a new diesel locomotive capable of efficiently handling both express passenger and heavy freight operations across the country at speeds up to approximately 100 km/h (62 mph).

The proven performance of the Class 319, developed collaboratively by Macosa and General Motors, influenced the decision to adopt a General Motors GT26-type locomotive (). Rather than selecting the conventional single-cab GM design, Renfe chose a two-cab configuration modeled on Scandinavian manufacturer NOHAB, which produced GM-powered locomotives under license. The final choice was based on the JT26 platform featuring the Nohab bi-cabin body style—similar to the DSB class MZ operated by Danske Statsbaner—and was designated MZ1, delivering nearly of power and introducing electric train heating for the first time in Spain.

Technical

These locomotives were equipped with General Motors components, including engines, generators, traction motors, and electrical systems. The diesel engines are two-stroke, 16-cylinder V-type units set at a 45-degree angle (EMD 645), featuring a compression ratio of 14.5:1 and a total displacement of 10,320 cubic inches (169.12 liters).

Their traction power is rated at 2,514 horsepower, produced at 600 V AC and converted to DC through silicon diode rectifiers. Power is delivered to six nose-suspended traction motors that drive the wheels via a pinion gear ratio of 59:18. The maximum operational speed is , with some locomotives capable of reaching after undergoing modifications. These units utilize 'flexicoil' bogies and are fitted with ASFA, the Spanish train safety system.

Service history and operators

A total of 93 units were initially commissioned from Macosa for Renfe and were delivered between 1974 and 1976. They were first assigned to the Madrid Atocha depot and progressively replaced class 340 locomotives on the Madrid-Burgos route as well as other lines. Despite this, class 340 still maintained a faster schedule by approximately 13 minutes over the 329-mile Madrid to Móra la Nova route.

Class 333 locomotives were responsible for hauling prominent services such as the express trains running from Barcelona to A Coruña/Vigo, passing through stops like Roda de Barà, la Plana-Picamoixons, and Miranda de Ebro. They also operated high-speed routes between Madrid and Canfranc, in addition to pulling the Madrid to Vigo Pendular trains prior to electrification.

Their service extended to routes like Ourense to Medina del Campo, coal transportation from Samper de Calanda to thermal power plants in Andorra, and paired operations hauling ore from Ojos Negros to steel production facilities at Sagunto.

Following the deregulation of Spain’s railway sector on 1 January 2005, which ended Renfe's exclusive control, private operators such as "Continental Rail" (part of ACS) and "Acciona Rail" acquired Class 333.3 locomotives for freight services.

Variants and rebuilds

Throughout the 1990s and early 2000s, multiple units underwent upgrades or complete rebuilds to adapt to changing operational requirements; none of the original models remain active today.

Subclass 333.0

This category comprises the original locomotives that have not been rebuilt, numbered from 333.001 to 333.093.

Subclass 333.1

In the early 1990s, eight locomotives were modified with new bogies enabling operation at speeds up to 160 km/h. These were designated subclass 333.1 and numbered between 333.101 and 333.108, primarily intended for passenger service.

Subclass 333.2

During the same decade, four locomotives designed for mixed traffic received upgrades including new bogies and gearing adjustments allowing speeds up to 140 km/h, forming subclass 333.2 (units numbered from 333.201 to 333.204).

Subclass 333.3

Between 2000 and 2005, Renfe produced a series of 92 locomotives incorporating some original parts; however, only the prime mover, generators, and ASFA safety system were retained from earlier models. The remainder of the locomotive was redesigned with collaboration from Alstom. Control systems transitioned from relay-based technology to microprocessor-controlled power electronics. Traction motors were upgraded from D-77 to D-78 types, while fuel tank capacity increased from 4,500 liters to 7,200 liters.

These locomotives are optimized for freight transport with a maximum speed of 120 km/h and deliver an increase in tractive effort by approximately 8–10% due to enhanced power electronics.

Unit number 333.304 (previously numbered 333.050) was destroyed in the Chinchilla de Montearagón accident in 2003.

Subclass 333.4

Between 2003 and 2004, eight locomotives originally classified as subclass 333.3 underwent modifications to serve passenger operations, achieving a maximum speed of 140 km/h, and were subsequently re-designated as subclass 333.4.