The term prime mover refers to the diesel engine that is found in each locomotive. Tsunami2 is available with the most common prime movers found on many diesel locomotives. Although different locomotive designs may have the same prime mover, they may produce slightly different sounds. These differences are due to how the prime mover is mounted and how the exhaust manifold is set up. To accommodate this, Tsunami2 has a 7-band equalizer that can be adjusted to make each locomotive have its own unique timbre.

Locomotives also differ in their gear ratio design. Some were designed with very low ratios for yard switching, while others had higher ratios for high-speed passenger train operations. Tsunami2 allows you to set the top speed and adjust how fast it reaches its highest notch through a user-adjustable speed curve and momentum CVs. Some locomotives contain two of the same prime movers. For example, the ALCO DH-643 has two 244 prime movers. To better accommodate this sound, you should consider adding a second speaker and boosting the equalizer's low-frequency volume.

Below is a list of prime movers and the product line to which they correspond. Select a prime mover from one of the charts below to see a list of specific locomotives that use that engine. Note that Econami Digital Sound Decoders have a more limited selection of prime movers than Tsunami2 does. If you cannot find your locomotive in the Econami selection consider Tsunami2 instead.

The most distinctive sound heard on a diesel locomotive is the airhorn. Railroads used airhorns to warn vehicles and pedestrians, as well as to communicate to other trains, yard personnel and trainmen.

One of the great features of Digital Sound Decoders and DCC is the ability to incorporate prototypical horn signals, just like the real thing! Tsunami2 and Econami decoders have functions for both a long horn blast and a short horn toot, making crisp and accurate signals possible. Both decoders also come with the ability to set up automatic signals such as forward, reverse, a public grade-crossing, and brakes applied.

To make your selection easier and more fun, each diesel Tsunami2 Digital Sound Decoder comes with 42 airhorns that were most commonly heard for the era and prototype. Each Econami Digital Sound Decoder comes pre-loaded with 16 of the most common airhorn choices used with the prime mover options in the decoder. Many railroads used more than one type of airhorn. Since Tsunami2 and Econami offer so many different airhorns in each decoder, you don’t have to permanently commit to any one. Remember this is your railroad -- so don’t hesitate to select the horn you enjoy hearing the most. If you are interested in sticking closely to prototype practice, you can read more information on which airhorn is appropriate for a specific road using the Locomotive Airhorn Usage page.