DuraDrive

DuraDrive: The quiet power that gets the job done.
NordicTrack's DuraDrive™ motors are designed with superior engineering that makes your workout quiet, durable and efficient. This dependable motor offers a smooth pace for years of exhilarating exercise. You can expect a smooth, dependable performance during even the most intense workouts.
The advantage of continuous-duty horsepower.
Treadmills with a "continuous-duty" horsepower rating mean that the motor can sustain a certain horsepower throughout your workout. Treadmills not rated as "continuous-duty" are generally a "peak" rating...meaning the treadmill may be able to reach a certain horsepower briefly, but not sustain it.
In short, this means that a 2.5 HP "continuous-duty" motor is actually more powerful than a regularly rated 2.5 HP motor. This is important to know when comparing one treadmill to another.
DuraDrive motors are included on all NordicTrack treadmills. Type and size of horsepower rating varies by model.