Transmissions

ATREX – integrated hybrid propulsion and Drive-by-Wire for increased mission ability

The ATREX transmission marks a milestone in military vehicle drivetrain technology, merging RENK's established mechanical transmission expertise with Magnet Motor's military grade electric drives and electronics. This integration creates a robust and reliable system, enhancing hybrid propulsion and enabling drive-by-wire functionalities.

Designed for tracked vehicles weighing up to 70 tons and reaching speeds of 70 km/h, the ATREX transmission system supports a combined power output of up to 1,500 kW, of which 300 kW can be provided by electric drives. This configuration not only ensures superior propulsion performance but also broadens mission capabilities and operational range through unparalleled fuel efficiency.

Features

Enable flexible driver stations, reduction of work load on crew, reduction of needed crew
Enable remote controlled / autonomous driving
Electrical power generation by PTO functionality to supply electronic systems and charge battery.
Silent watch enables to shift to surveillance mode with just using the low profile battery energy instead of main engine.
Silent maneuvering utilizes the electric drives to cover shorter distances without using the main engine.

Enables Silent Watch operation mode with minimal heat, vibration and noise profile.
Escape Boost enables crew to leave critical area with electric drives while main engine has not started.
Sprint Boost adds electric drive power to combustion engine for maximum speed to pass dangerous areas.
Silent maneuvering with reduced noise and also lower emissions in workshops etc.

Proven and state of the art technology (high TRL)
Increase maneuvering reliability due to redundant design (steer and brake)
Operation in all conditions (climate, terrain)
Reduced wear by lowering short-term diesel engine usage

Driving with enhanced speed, tractive effort and acceleration
Fast pivot and smooth, variable steering
Proven and high force braking with additional recuperation option. Max slope, max deceleration, continuous slope.
Increased operating range due to hybrid system with recuperation

High power / weight ratio means low space demand in the vehicle
Less effort and space demand for installation due to x-by-wire
Lower lifecycle costs due to reduced wear (thus less maintenance costs) and reduced fuel consumption

Short development times as technology and components are known and proven in use.
Modular approach means standardized products which benefits platform vehicles.
Extensive know-how for conventional and hybrid solutions from design, manufacturing to testing.

Advantages

Extended silent watch, silent maneuvering and wider operation range

ATREX is an integrated hybrid propulsion transmission system designed to enhance military vehicle operations through advanced electric drive capabilities. This system allows for immediate vehicle mobilization via electric power, facilitating silent maneuvering and rapid deployment from or into high-risk areas without the need to start the main engine. Such capabilities are particularly advantageous for reconnaissance and stealth missions, where operational discretion is paramount.

Key features like silent watch and silent maneuvering, coupled with energy recuperation during braking, contribute to significant reductions in fuel consumption.

Consequently, vehicles equipped with the ATREX system benefit from extended operational range and reduced emissions, aligning with modern military objectives for efficiency and sustainability in field operations.

Features for superior mission abilities:

With a sufficiently large battery pack, a tank equipped with a ATREX transmission can operate independently of the main engine and conduct reconnaissance missions.

In case a critical situation occurs during the silent the "Escape Boost" feature allows the vehicles to move swiftly on electric power while the main diesel engine powers up. Only due to this "Escape Boost" a silent watch with disengaged main engine is possible in potential combat areas as the powering up of the main engine takes too long.

When the battery is depleted, the ATREX can use the steering and propulsion drives as generators, providing up to 350kW for rapid recharging. As a result, the main engine can be shut down much earlier.

Vehicles can be driven or positioned with minimal noise and heat signature, facilitating covert movements and reducing detection risk.

Beyond tactical benefits, this capability allows for engine-off operations in sensitive environments, such as indoor spaces or during transportation, reducing wear on the engine and mitigating environmental impact.

With the hybrid technology the inefficient idle runtime of the diesel engine can be dramatically reduced. And for short distance driving the electric drive can be used instead of starting the main engine. This will have a significant reduction of fuel consumption and thus increase the miles of movement for the tank.

Another major advantage of the ATREX is its advanced recuperation system, which recharges the battery during braking maneuvers. This continuous reuse of energy can further improve the operating range.

Smooth, redundant electric steering with 4-level braking system for efficient maneuvering

ATREX is utilizing the battle-proven hydromechanical technology to offer highest reliability. But with the two generators and the redundant design of the electronics and drives, even higher reliability is achieved and an increase in maneuverability.

ATREX features an advanced Electric Steer Drive (ESD) that guarantees smooth steering and seamless gear transitions through its superimposed and redundant design. This drive-by-wire solution streamlines vehicle integration and enables remote operation, enhancing maneuverability and control.

The electric propulsion and steering capabilities of the ATREX system facilitate improved and precise maneuvering in tight spaces, such as workshop, train, camp, etc. For movements without heavy steering (e.g. pivot) or steep inclines the electric drives can be used without starting the main engine. Thus conserving energy and minimizing wear.

The battle proven hydromechanical transmissions from RENK are the basis for ATREX and thus mechanical friction and gear box brake are used for precise braking maneuvers and stopping on slopes. Naturally, the retarder is another proven and vital component for handling the major share of the forces. Using the electric drives of the ATREX for recuperation, the tank will not only be slowed down, but electric energy will be gained, which leads to increased efficiency and operating range of the vehicle.

Unlike purely electric systems, the hybrid ATREX manages the intense forces of emergency stops with its blend of energy recovery, friction brake and a mechanical retarder. In lower speed driving situation also the gear box brake and recuperation is available, which supports the steering capability and recuperates energy. This 4 -level braking system maximizes the reliability and efficiency of tracked vehicle mobility systems.

With that hybrid approach, the demands of next generation military vehicles are taken into account.

Increased steering and braking with electric drives

Increased protection to safeguard crew, vehicle and mission

The Escape Boost and Sprint Boost feature allow for immediate acceleration, granting vehicles and their crews the capability to swiftly vacate hazardous zones. This rapid response capability is vital for evading threats and repositioning to strategic advantage, significantly enhancing the vehicle's protective measures and crew safety.

In addition to rapid evasion capabilities, the ATREX transmission system offers significant advantages in stealth operations through its Silent Drive and Silent Maneuvering features. By minimizing the vehicle’s acoustic, thermal, and vibrational signatures, the system reduces the likelihood of detection by enemy forces.

Furthermore, the reduction in mental stress from decreased vibration and noise during silent watch mode enhances crew endurance and focus. This improvement in operational environment is crucial, increasing the likelihood of making timely and correct decisions that are vital for the safety of the crew, the integrity of the vehicle, and the success of the mission.

Electric drives can kick-in to boost the tank

Fail-safe steering by redundant electronics and drives

Redundant steering systems for even higher reliability

Unlike some traditional mechanical transmissions, which lack a backup in case of steering failure, the ATREX hybrid system incorporates a redundant steering drive. This system features two independent drives within a single package, ensuring that steering remains responsive and accurate, even if one drive fails. Additionally, the electronic components and cabling are also designed redundantly, providing an extra layer of security and operational confidence.

Beyond steering, the ATREX system enhances vehicle dependability through redundant designs in all critical systems. Components as pumps and oil systems or brakes are equipped with backups, ensuring continuous operation without interruption.

By integrating multiple backup systems across steering, propulsion, and safety-critical components, the ATREX hybrid transmission not only boosts vehicle reliability and performance but also ensures that operational security is maintained at all times, under all conditions.

Higher fuel efficiency for the tactical advantage with lower emissions

The fuel efficiency of a military vehicle can significantly increase range, reduce logistical burden, lower emissions and reduce costs, thereby improving overall military readiness and capability. Significant fuel savings can be achieved through the ATREX and the advanced hybrid technology it incorporates.

With the silent watch and silent maneuvering, the reduced usage of the combustion engine is a major leverage for an increased fuel efficiency and lower emissions.

Another major advantage is the ability to recapture and use the tremendous braking energy to recharge the battery and use that energy instead for propulsion or electronic systems.

Higher operation range due to hybrid advantages

In alert situation and a classic powerpack, the main engine is running in idle, which demands a significant fuel amount per hour. Equipped with a ATREX and the hybrid setup with the alert boost feature, the main engine can be switched off. Thus not only the equivalent fuel and emissions can be saved, but also the stress by vibrations for the vehicle and crew is reducing the mechanical and mental wear. The U.S. Army has found that its medium tactical vehicles spend nearly 80% of their time in idle mode, burning a large amount of fuel without even moving. With hybrid technology, this can be greatly reduced.

The mentioned silent maneuvering - driving limited distances on electric power – works without starting the engine and thus conserves a fair amount of fuel. In addition, the lower usage of the main engine for short distances reduces the wear and service intervals.

Another major advantage of the ATREX is its advanced recuperation system, which recharges the battery during braking maneuvers. This continuous reuse of energy can significantly improve the operating range.

In military vehicle operations, particularly tanks, full-speed scenarios constitute less than 10% of their operational lifespan. Traditional drivetrains, designed for peak performance, result in the main engine running at around 70-80% capacity for the majority of their movement time, often outside its efficiency optimum.

Hybrid propulsion systems address this inefficiency by optimizing the combustion engine for average operational demands rather than peak requirements. This optimization allows the engine to operate closer to its efficiency peak, enhancing fuel consumption rates. For high-demand scenarios, the system leverages an electric drive to provide additional power, ensuring that peak performance is met without compromising the combustion engine's efficiency.

Key technical benefits include:

Engine Optimization: The combustion engine is sized and calibrated for typical operational modes, operating more frequently within its efficiency peak.
Operational Efficiency: By maintaining the combustion engine within its optimal efficiency range and using electric drive for peak demands, the system achieves higher overall fuel efficiency.
Weight Reduction: A smaller combustion engine contributes to overall vehicle weight reduction, potentially enhancing mobility and further improving fuel efficiency. In fairness: The weight decrease will be eaten up by the weight of the battery pack and generators, but those also add various advantages as shown above and below.

The setup

Smart concept with highest redundancy

Equipped with an electric steering drive, the system enables precise vehicle handling through electronic control, providing a responsive and accurate steering mechanism. The traction drive component is optimized for efficiency, delivering power directly to the drivetrain with minimal energy loss.

Electric Steer Drive (ESD)

Electric drive with 150kW for steering. The system is fully redundant and can (in addition to the EPD) charge the battery in case the tank is in idle mode.

Electric Propulsion Drive (EPD)

In drive mode can add power to the transmission for increased acceleration and speed.
In generator mode can provide power to steer drive and battery.

ESD Power Electronics

Military grade electronics with redundant design and build to control the Electric Steering Drive and shift between generator and drive mode.

ATREX Control System

Military grade electronics to manage the operation of the transmission and the rugged electrical drive electronics.

EPD Power Electronic

Military grade electronics with redundant setup to manage the power distribution and drive/generator mode for the Electric Propulsion Drive.