RENFE Class 333.1

{{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 = Initial series: 1974–1976
333.1: 1994–1995
333.2: 1997–1998
333.3: 2002–2003
333.4: 2003–2004 | totalproduction = 333 (initial): 93
333.1: 8
333.2: 4
333.3, 333.4: 92 | uicclass = Co′Co′ | gauge = Iberian gauge | bogies = General Motors 'flexicoil' type | length = Initial:
333.3/333.4: | width = Initial:
333.3/333.4: | height = Initial:
333.3/333.4: | axleload = | locoweight = | fueltype = Diesel | fuelcap = Initial:
333.3: (?) | primemover = General Motors GM 16-645-E-3A | enginetype = Two-stroke engine Diesel engine | cylindercount = V16 engine | alternator = General Motors AR-10 / D-14 | transmission = Diesel-electric transmission | tractionmotors = Initial: 6 of GM D-77
RENFE 333.3 and 333.4: 6 of D-78 | maxspeed = 333 (initial):
333.1:
333.2:
333.3:
333.4: | poweroutput = Initial: (nominal at rail) | tractiveeffort = Initial
starting: at μ=0.28
Continuous: at
Top speed: at
Rebuilt (333.3 and 333.4)
Starting:
Continuous: at |} The Renfe Series 333 represent a class of powerful six-axle diesel-electric locomotives introduced during the 1970s, standing as Spain’s most potent non-electrified locomotives at that time.

Following more than three decades of operation, these locomotives underwent significant modernization using Alstom technology to prolong their service life, giving rise to subseries 333.3 and 333.4, which include enhanced components and upgraded performance features tailored to contemporary Spanish rail requirements.

Background

During the early 1970s, Renfe embarked on a dieselization initiative that replaced steam engines for medium-powered duties with classes such as 316 (previously 1600), 318 (previously 1800), and subsequently the more numerous 319 (previously 1900) and 321 (previously 2100). Concurrently, the diesel-hydraulic class 340 (formerly 4000), inspired by the German V 200, was intended for express services on unelectrified routes like Madrid-Barcelona but encountered reliability challenges due to inadequate maintenance and utilization in slower freight roles. This prompted Renfe to seek a new diesel locomotive capable of efficiently hauling both express passenger and heavy freight trains across Spain at speeds up to approximately 62 mph.

The successful performance of the Class 319, manufactured by Macosa in collaboration with General Motors, influenced the decision to adopt a General Motors GT26-type locomotive (). Rather than selecting the standard single-cab GM design, Renfe chose a twin-cab configuration modeled on the Scandinavian producer NOHAB’s JT26 featuring the Nohab bi-cabin body style (similar to that used in the DSB class MZ), as operated by Danske Statsbaner (DSB).

Renfe ultimately opted for the MZ1 variant delivering close to output and incorporated electrical train heating—a pioneering feature in Spain.

Technical

These locomotives incorporate engines, generators, traction motors, and electrical components manufactured by General Motors. The diesel engines are two-stroke V16 units with a 45-degree offset (EMD 645), featuring a compression ratio of 14.5:1 and a total displacement of 10,320 cubic inches (169.12 liters).

Traction power output stands at 2,514 horsepower at 600 V AC, which is converted to DC through silicon diode rectifiers. This power is delivered to six nose-suspended traction motors that drive the wheels via pinion gears with a gear ratio of 59:18.

The maximum operational speed is rated at , although certain locomotives have reached higher speeds following specific modifications. The bogies utilize the 'flexicoil' suspension system.

For safety, these locomotives are equipped with ASFA, a Spanish train protection mechanism (refer to Train protection system).

Service history and operators

A total of 93 units were initially commissioned from Macosa for Renfe and were delivered between 1974 and 1976. These locomotives were first stationed at the Madrid Atocha depot and progressively replaced the class 340 on routes such as Madrid-Burgos. Despite enhancements, class 340 maintained a faster schedule by approximately 13 minutes on the 329-mile Madrid to Móra la Nova route.

Class 333 locomotives were responsible for hauling prominent services including the express train connecting Barcelona to A Coruña/Vigo via stops like Roda de Barà, la Plana-Picamoixons, and Miranda de Ebro. They also managed rapid services between Madrid and Canfranc, as well as the Madrid to Vigo Pendular service until the lines were electrified.

Their operational range extended to routes such as Ourense to Medina del Campo, transporting coal from Samper de Calanda to power plants in Andorra, and working in pairs to haul ore from Ojos Negros to steel production facilities in Sagunto.

Following the deregulation on 1 January 2005, which ended Renfe’s exclusive rights, private operators entered Spain’s rail freight market. Consequently, companies like "Continental Rail" (part of ACS) and "Acciona Rail" acquired Class 333.3 locomotives for freight operations.

Variants and rebuilds

Throughout the 1990s and early 2000s, several units underwent upgrades or complete rebuilds to adapt to changing operational requirements, resulting in modifications from their original 'Viking' design. None of the initial models remain active today.

Subclass 333.0

This group consists of the original batch of 93 locomotives that were neither rebuilt nor upgraded, numbered from 333.001 to 333.093.

Subclass 333.1

In the early 1990s, eight units received new bogies capable of supporting speeds up to 160 km/h, creating subclass 333.1 (numbers 333.101 to 333.108). These were primarily designated for passenger transport.

Subclass 333.2

During the same decade, four locomotives intended for mixed traffic duties were enhanced with updated bogies and gearing allowing operation at speeds up to 140 km/h, forming subclass 333.2 (numbered 333.201 to 333.204).

Subclass 333.3

Between 2000 and 2005, Renfe constructed 92 locomotives utilizing some components from the original series; however, only the prime mover, generators, and ASFA safety system were preserved. The remainder was redesigned in collaboration with Alstom, incorporating modernized control electronics that replaced traditional relays with microprocessor-controlled power systems. Traction motors were upgraded from D-77 to D-78 models, while fuel capacity was increased from 4,500 to 7,200 liters.

Designed mainly for freight service, these locomotives achieve a maximum speed of 120 km/h and benefit from an estimated 8–10% gain in tractive effort due to advanced power electronics technology. Notably, locomotive number 333.304 (previously numbered 333.050) was lost in the Chinchilla de Montearagón accident in 2003.

Subclass 333.4

Between 2003 and 2004, eight units originally classified as 333.3 were modified for passenger operations, achieving a maximum velocity of 140 km/h and subsequently redesignated as subclass 333.4.

See also

• Renfe Class 334, a comparable reconstructed model featuring a distinct GM-EMD engine.
• Stadler Euro, locomotives manufactured at the same facility in Valencia, which may include Class 334 variants.