The 104 series trains (and their evolution from the 114 series) are Renfe's and the world's first to be specifically designed and built for high-speed mid-distance services. They are trains formed by four carriages, with the possibility of multi-wheel drive of up to three compositions and with a maximum commercial speed of 250 km/h.
104-series trains are part of the contract awarded on 25 May 2001 to the consortium comprising of Alstom and CAF, which included the construction of a batch of 20 international-gauge high-speed trains for mid-distance services.
A few years later Renfe added 13 other units from this series to its fleet, but with certain updates, so it was renamed s-114, which included traction, brake and energy efficiency improvements, as well as improved comfort and interior design, as the whole train was configured as one class.
In the interior design of both the 104 and 114 series, open spaces have been utilised to increase the comfort of passengers. In addition, they boast advanced fire safety, anti-shock and anti-slip systems.
All carriages have an indoor public address system and outdoor and indoor display monitors. Furthermore, carriages are equipped with independent air conditioning systems in the driver's cab and passenger berths; reclining and adjustable seats, four toilets, one for each carriage, one adapted to people with reduced mobility; luggage racks inside the passenger lounges, equipped with anti-theft protection, and overhead roof racks.
The 104 series trains have two Standard Class carriages, one First Class carriage and another divided into a Buffet Car and First Class. The seats, all of them reclining and adjustable according to the direction of travel, has a saloon distribution, offering a total of 237.
The First Class area is found in the end carriage, where the buffet car is located. It also has a driver's cab, toilet, luggage area, one access area and one door on each side. This carriage also has a telephone booth and a compartment for the train manager.
The remaining three carriages make up the Standard Class area. One of the intermediate carriages has a wheelchair-reserved area, as well as a toilet suitable for people with reduced mobility.
This train is based on a technology widely used by various railway companies, Pendolino, although they do not tilt, and uses very well tested components and equipment. It therefore belongs to the same family of Alaris trains that make up the 490 series, although there are differences between them.
Outside, they are similar although they have one more carriage, a fairing on the roof and two doors per carriage, with the exception of the buffet car. The technical differences can be traced to the lack of tilt, different voltage (25 kV and 50 Hz in alternating current), track gauge (1,435 mm), maximum speed (250 km/h) and higher power (4,000 kw).
Externally, S-104 trains offer a highly aerodynamic profile with which low drive resistance is achieved; inside, they are designed to ensure maximum utility and ergonomics, combined with an adequate modularisation that facilitates assembly, repair and maintenance work.
This train consists of two half-trains, with full power train and redundant equipment and systems.
Aluminium alloys have been used for the construction of the bodies, meaning it is lightweight, with a total weight at normal loads of 242.8 tons on the 104 series and 230 tons in the 114 series; this places the model in a very competitive position in terms of energy consumption compared to other trains capable of running at the same speeds.
The structure of each body consists of a flat frame, two sides, a curved roof, and two under-frame crossbars located at the ends.
It consists of four carriages, with the end carriages featuring an aerodynamic front, reducing drive resistance and behind which the driver's cabs with central control panel are located. The nose of the 114 cab is longer than that of the 104 cab, with an anti-crash system, a feature worth particular note on this train.
There are seven platforms platforms and the access doors are electrically operated with mobile footboard that is coordinated with the door. The train can run with its doors open, although when it reaches a speed of more than 5 km/h, they close automatically. It is possible to move between carriages through intercommunicating bellows and six two-sheet sliding doors that are pneumatically-electronically controlled.
The train features a fairing at the top; when combined with the contour of the front, this creates an aerodynamic profile that lowers drive resistance.
The coupling between units, with it being possible to couple up to a maximum of three, is carried out by means of an automatic Schafenberg coupling, which is rolled back when not in use; it features mechanical, pneumatic and electrical coupling, and can be mechanically and automatically coupled to 100-series trains. Semi-permanent couplings are used to couple the different carriages.
The core feature of this train is its distributed traction, which distributes traction and auxiliary equipment under the frames of all the carriages. This distributed traction is provided by 8 asynchronous and self-ventilated three-phase motors and features two transformers and four GTO thyristor converters, which provide 4,000 kW of power, significant pace and a speed of 250 km/h. Each engine, positioned perpendicular to the axle on which it operates on the carriage frame, provides power of 500 kW. This distribution of the engines in the middle of the axles offers better adhesion and acceleration.
It features collection equipment, pantographs and circuit breakers, located in the two middle carriages, four 72-volt battery packs, in direct current, and 130 A, and two auxiliary packs consisting of two 110 kVA converters and two 12 kW battery chargers. The two engines on each carriage are permanently connected in parallel to one another and powered by an electronic undulator. This means the train has four independent traction blocks, one per carriage.
The design of the auxiliary equipment is redundant. Each train consists of two half-trains with a pantograph, main transformer, two traction converters, two braking rheostats and four self-ventilated asynchronous three-phase motors with 550 kW power.
The trains are equipped with different passive safety systems, such as the absorption of low-speed impacts with progressive deformation, with fronts and comfort systems.
It boasts level 1 and 2 Ertms signalling and language translators that means it can travel with the STM-LZB and Asfa systems on lines on which the latter is installed. It also has GSM-R and conventional train-to-ground telecommunications equipment, fault diagnostic system and driving aid, continuous surveillance device (dead man), incident recording equipment and slip and anti-lock systems, tab greasing and sandbox. It also features passenger information equipment.
The train's eight bogies, with two axles each, are motorised, one axle is a motor axle and the other is a trailer axle. Each bogie weighs 7,600 kg. They are interchangeable, with the exception of the end bogies, which are equipped with the aerials for issuing and receiving information corresponding to the signalling and traffic control systems.
The primary suspension consists of steel coil springs with shock absorbers and the secondary suspension is pneumatic, with sensor systems, which warn of any problems, and anti-tilt devices. The wheels are solid, consisting of a single piece, with an "ORE S-1002" type profile. The new wheels have a diameter of 890 mm and the maximum permissible wear corresponds to a diameter of 810 mm.
Another key feature of this train is its braking capacity, thanks to an electric brake that allows it to automatically switch between the recovery system on the motor axles and the rheostatic braking system. The first type of brake takes precedence over the second, although if the grid cannot absorb the braking energy, it progressively switches to the rheostatic brake.
It also features pneumatic/electrodynamic braking with self-ventilated discs, two on the motor axles and three on the carrier axles. The service brake is a pneumatic/electrodynamic combination, the emergency brake is pneumatic with independent channel and the auxiliary brake is a pneumatic/electrodynamic combination that is pneumatically controlled. The braking equipment also features an anti-lock function, and locked axle detection separate from the anti-lock function, as well as sandboxes.
The motor axles are equipped with two self-ventilated brake discs and the trailer axles have three of the same type of discs. For the pneumatic brake, compressed air production equipment is available. The parking brake immobilises the train even on a gradient of 35-thousandths, carrying a maximum load. The braking distance, travelling at 250 km/h, is about 2,800 metres.