RAMs Vibrate To Stay Smooth While Saving Fuel. Here’s Why

Did you know that our RAM 1500 DT models use small modules that send vibrations into their frame to make it quieter? Why you ask? To save fuel! Okay, that sounds very complicated, but it’s actually pretty clever – let’s explain.

With a growing niche in the European market and the all-time best-selling vehicle category in the US, millions of full-size pickup trucks are driving around. For obvious reasons, it’s crucial to save fuel as much as possible. To accomplish this, our RAM 1500 trucks use all kinds of clever solutions to improve aerodynamics and consume less valuable energy in general. Most of our AEC vehicles are also converted to accept LPG or E85 as a more economical and ecological type of fuel, which makes driving them even more sensible.

One of those party tricks is the Multi-Displacement-System (MDS). Of course, it can’t really change the size of the engine, but it can shut down four of RAM’s eight cylinders in situations where not as much power is needed. Instead of 5.7 liters of displacement, only 2.85 liters spread over different cylinders are consuming fuel. The driver can’t feel any of this magic except for the lower consumption, thanks to another ingenious solution: the Active Tuned Mass Module (ATMM).

Wow, this is getting complicated! Don’t worry; the explanation is easy. A V8 engine has a firing order, where there is always one piston, compensating the ignition stroke of the other. A movement in one direction is balanced by a simultaneous motion in the opposite direction. The result is a totally smooth-running engine that’s almost free of any vibrations. If MDS takes away one or more of these counter-balancing strokes, this sends the motor into a very slight disharmony – it does not run just as smoothly and would send some of those vibrations into the passenger compartment, creating an unpleasant noise or feeling of vibration.

Copyright by AEC, 2021; ATMM on one of our RAM 1500 DTs

Much like noise-canceling headphones, these Active Tuned Mass Modules create a tiny vibration that counteracts those disharmonies, making the result as smooth as ever. They are fixed to various points on the truck’s frame, utilizing small electric motors that turn an unbalanced weight shaft. Their basic functionality is just the same as the vibration module in your phone. Still not clear enough? Take out your keys and twist a keyring around your finger. Feel that imbalance? This is what keeps our trucks smooth. Of course, the input of those modules is finely tuned by an electronic signal. While this system is not crucial for using the car, it still makes for a much better ride. There even is an entire category in vehicle R&D dedicated to the sensation of possible disruptions. It’s called NVH, which stands for noise, vibrations, and harshness.

That’s one of the secrets why RAM drives so smooth and quiet.