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Smooth ride in tough truck

You know you’re old if you remember when a pickup truck rode — well, like a truck.

You know you’re old if you remember when a pickup truck rode — well, like a truck. Today’s buyers want a more comfortable ride, but they also need the work capability that comes with a strong, solid frame. Dodge has tackled the problem with a new fluid-filled hydro body mount that’s exclusive to the company.

It’s used on the 2010 Ram 2500 and 3500 heavy-duty Crew and Quad Cab trucks, soaking up vibration where the back corners of the cab bolt to the frame.

“Frames like to flex,” says Kevin Mets, an engineer responsible for Ram heavy-duty trucks.

“We used tools like computer-aided engineering to look at solutions to improve the overall ride. It wasn’t a clean sheet of paper. We had to look at the current, proven chassis frame and body, and figure out how to improve the ride.”

Vibrations from road imperfections affect the vehicle’s suspension, axles and body. The researchers were looking for “coupling,” where these vibrations meet and create a shaking sensation — in this case, at the cab mounting point.

“You have to let the frame do what it wants to do,” Mets says. “It wants to flex. So you isolate the cab, and ultimately, the occupant.”

The solution was the hydro mount, which goes between the body and the frame. While it looks similar to a conventional rubber body mount, it contains two fluid-filled chambers separated by a spiral track. Fluid flows through the track between the chambers, creating a damping effect similar to that of a shock absorber, and soaking up the frame flex before it can enter the passenger compartment. Thanks to the mounts, driving the big truck feels as smooth as piloting a sedan.

It’s used only on the four-door Crew and Mega Cab models, since the shorter, two-door regular cab mounts ahead of the flex point and isn’t affected by the frame’s vibrations the way the longer cabs are.

Just adding the mount wasn’t enough; it then had to be “tuned” to get it right, Mets says, starting with the computer design that assessed the body flex and how best to counteract it with the hydro mount.

“You can change the rubber from soft to hockey-puck hard. There are different viscosities of fluid. Most important are the upper and lower sections of the hydro mount itself, and the ‘racetrack’ spiral design. You go from the computer analysis, and then create some prototype parts. The engineers use real trucks and real parts to tune in that final recipe.”

 
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