Long® Active and Passive Warm-Up Products


Dana’s active and passive warm-up technologies enhance the efficiency of commercial vehicles with thermal bypass valves and integrated heat exchangers. By quickly increasing and maintaining vehicle operating temperatures, fleet managers can expect lower fuel consumption and reduced emissions.


A quantity of fuel must be consumed to overcome friction in powertrain components, such as the transmission, engine, and axle. We use two techniques to maintain optimum hot oil temperatures. First, the thermal energy generated inside each component is captured. Second, external thermal energy from the vehicle cooling and exhaust systems is introduced to warm the engine.

Active Warm-Up (AWU)

In most vehicle applications in the northern hemisphere, heat generated internally is not sufficient to bring oils to optimum temperature quickly enough to reduce friction or parasitic losses. AWU uses excess thermal energies to warm these oils, such as heat lost through cooling systems or engine exhaust, providing a thermal-management innovation beyond what can be achieved through thermal bypass valves (TBVs) alone.

Passive Warm-Up

The thermal bypass valve (TBV) prevents cold or partially warmed oils from leaving powertrain components such as the transmission. Internal circulation of vehicle oils keeps thermal energy from dissipating, which improves efficiency.

Vehicle Integration

Combining these two thermal management technologies creates an integrated system that reduces complexity and increases the system’s response time. This thermal-management technology provides a significant reduction of fuel consumption and emissions, to the benefit of commercial-vehicle OEMs, fleet managers, and dealers.


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