Mack has added two versions of its mDRIVE HD automated manual transmission (AMT) to offer low-speed reduction gear options for MP series engines, adding versatility to the Pinnacle, Granite and Titan trucks.
Announced Wednewsday at the Work Truck Show in Indianapolis, the two versions include a 13-speed option designed for easier starting on steep grades and under heavy load, and a 14-speed ultra-low-speed reduction gear designed for paving operations and maneuvering under heavy hauls.
Both models offer three low-speed and one fast-speed reverse gear ratios and will be available for order in August.
“We’ve added on a front extension on the transmission between the bell housing and the main case of the transmission and with that we’ve added extra gears,” says Stu Russoli. highway and powertrain product manager.
The extension adds 4.75 inches to the length of the transmission and about 90 pounds to the weight. However the unit remains lighter than any of Mack’s competition in the vocational heavy-duty market, Russoli adds.
The versatility the transmission adds is the key point for the mDRIVE HD options.
“You can run your highway truck, run your construction truck in the heavy duty on the highway, get the reduction and still have your highway speeds,” Russoli explains. “What we found was when people go into a pit or on a jobsite they were actually gearing their rear axle ratio a little bit lower so they could do the work at the job site. So how do we fix that?
“That’s where the 13-speed comes in. Now we’ve added a 17:1 bottom gear, so after you hit first gear you go down to a crawler gear, which gives you a 17:1 ratio. Now I can work in the pit and still have my faster rear axle ratio, where I can go faster, get to my highway speeds, keep the RPMs down and get really good fuel economy, but still be able to do the work in my off-road situations.”
The 14-speed option adds two lower gears, which allows an operator to shift down to a crawler two and then down to a crawler one.
“You have a one through 12 where you have your normal gears that are working great for everybody today, and we’ve added on a 19:1 ratio for the crawler two,” Russoli adds. “Then you can go down to a crawler one which is a 32:1 ratio, so that brings you into your curb-pouring applications or your paving applications where you need to go at a walking speed, that half-mile an hour or in that range.”
Prior to the 14-speed option, Russoli says operators had to press on the brake all the time, which leads to overheating the clutch.
“We’ve actually changed the rules on the whole thing where you can use the mDRIVE in almost every construction application that’s out there,” he said. “So we really broadened the scope of our transmission.”
Mack also is extending its warranty coverage on all its mDRIVE and mDRIVE HD transmissions and clutches to 36 months and unlimited miles for heavy-duty applications; to 12 months and unlimited miles for severe-duty applications on the mDRIVE; and to 24 months and unlimited miles for the mDRIVE HD.