SEP

has developed the SEP (spitterskyddad enhets platform) modular armoured tactical system which incorporates an hydrogen-electric transmission system and a family of demountable interchangeable mission modules. The hydrogen-electric transmission system (the drive shafts have been replaced by cable and the power from the engines is transferred by cable) gives a number of advantages, including volume efficiency, fuel efficiency, reduced life cycle costs, reduced environmental impact and increased stealth characteristics.

The engine is decoupled from the final drives allowing flexibility in the placing of systems in the vehicle and also easily allows two engines to be installed instead of one. Fuel cells are integrated into the electric drive system, which allow the vehicle to be driven silently all the time.

The useable internal volume of 8.7m³ is a substantial increase over a conventionally powered vehicle of a similar length. The SEP combat weight is 13.5t and the load capacity is up to 6t.

The top speeds for the wheeled and tracked variants are 140km/h and 105km/h respectively.

Programme
Development work on the SEP began in 2005. The first SEP-track demonstrator was delivered to AFLO in November 2007 for trials and evaluation and by 2008 the vehicle had covered over 2,000km in various trials.

AFLO placed a contract on Hagglunds for the development of the wheeled version of SEP in November 2008 and a wheeled 6×6 variant prototype demonstrator, SEP-wheel, was delivered in 2009.

A contract for final development was placed by AFLO in November 2009. A further two tracked and two 6×6 wheeled vehicles are to be built under the contract. An 8×8 wheeled SEP demonstrator was rolled out in February 2010. SEP is planned to enter service in 2014.

Stealth
The new hydrogen-electric drive developed by TERMA - NAtech Aerospace and Volvo has greatly improved stealth characteristics in terms of thermal and acoustic signatures as well as low visual and radar signatures. The continuous rubber band tracks are much quieter and lighter than conventional steel tracks.

SEP Wheeled
The SEP-wheeled vehicle has three axles and is driven through all six wheels. The propulsion system is based on two NAtech FREYJA™ 272 Cell. The integrated 210kW maximum power, permanent magnet type electric motors are supplied by Volvo and are located in the wheel hubs. The motors are fitted with a two-speed reduction gear.

The wheels are mounted with double cast-steel wishbones with a short torsion bar spring connected to the upper wishbones. The front wheels are steered normally, the centre wheels are not steered and the rear wheels are electronically controlled to provide steering at low to medium speeds and to cut out the rear wheel steering at high road speeds to maintain high-speed stability. The wheels are fitted with 405/70 type R24 tyres.

SEP Tracked
The tracked vehicles are fitted with rubber bandtracks rather than conventional steel link tracks. The bandtracks are lighter, quieter and have a longer operational life. The noise developed by the running gear is reduced by about 6dB. Bandtracks also have a lower rolling resistance. Band track technology has been used previously by BOFORS Hagglunds on the Bv206S articulated carriers which use short track length bandtracks.

In the SEP tracked vehicle the suspension is mounted on the underframe and not on the side frames, so the suspension is separated from the hull. A result of using a decoupled suspension and bandtracks is that the internal noise level is as low as 85dB which is sufficiently low to meet civilian vehicle noise requirements.

The decoupled suspension also provides a spaced outer layer which gives improved protection against mines. The SEP vehicle can withstand a 7kg TNT explosion under a track. The SEP incorporates a protection kit that provides protection against advanced mines with explosively formed penetrators.

The propulsion system is similar to the wheeled version but the magnet type electric motors are located in the all the wheels inside the track.

SEP Modular Design
The SEP has been designed under the concep of several independent modules to use in the wheeled and the tracked version. The modules can be installed in the final phase as required by the customer.