Some call them the best of both worlds. Automated and semi-automated transmissions differ from automatic transmissions in that they’re manual gearboxes that are partially or fully electronically controlled and pneumatically or hydraulically actuated. Unlike automatics, they don’t have torque converters or planetary gearsets. The differences, say many fleet operators, can improve the bottom line.
What’s the big deal?
For several reasons, automated transmissions are more attractive than ever. Although the driver shortage may be somewhat in remission right now, the boom part of the boom/bust cycle can’t be far off. Sooner or later, the trucking industry will bounce back, and carriers will have little choice but to draw from non-traditional labor sources, recruiting drivers with little or no experience. Because properly shifting a non-synchronized, heavy-truck transmission is one of truck driving’s most demanding skills, automating it will remove a major impediment for inexperienced drivers.
In fact, a fully automated transmission behaves almost identically to an automatic transmission and is more or less transparent to a driver who’s used to an automatic. When starting from a stop, a driver presses the accelerator, and the clutch automatically engages.
From that point on, the transmission’s electronic control module (ECM) and the engine’s ECM and related sensors, read road speed, rpm and accelerator position and select the proper gear. It makes shifts while adjusting engine rpm to road speed, without disengaging the clutch, much the way an experienced driver might. The only difference from an automatic that a driver will notice is a pronounced delay between shifts.
Semi-automated transmissions are manual gearboxes that perform parts of their shifting functions automatically. There’s a clutch pedal, which typically is used only for stopping and starting out. Once the vehicle is moving, either the driver or the ECM – depending on transmission make, model and, in some cases, gear ratio – selects the gears without using the clutch.
Aside from making life easier for over-the-road drivers, automated and semi-automated transmissions use clutch plates, so torque-converter slippage – often blamed for reducing mpg in automatic transmissions – is eliminated. In severe-service and stop/go applications, however, automatics with their torque converters are generally preferred as an alternative to frequent clutch replacement.
But over the road, it’s a different story. An automated transmission can actually improve the longevity of clutches and other driveline components. The clutch is not continuously engaged and disengaged, and some or all operator error is eliminated. In addition, many automated/semi-automated transmissions have parts commonality with manual gearboxes already in service. In some, the clutch, shafts, gears and housings are interchangeable with those used in their fully manual counterparts, thus lowering manufacturing costs and reducing transmission-repair part numbers stocked at the fleet level.
Automated and semi-automated transmissions are offered by: Eaton Corp., ZF Meritor and Transmission Technologies Corp. (Spicer Transmissions). Allison Transmission is the dominant supplier of automatic transmissions for commercial vehicles.
A shift in driving
Kreilkamp Trucking of Allenton, Wis., has had five ZF Meritor FreedomLine (fully automated) transmissions in over-the-road service for the past one-and-a-half years. With 300 tractors and 800 mixed trailers, Kreilkamp hauls general commodities, metal, lumber and construction materials throughout states east of the Mississippi. Although the spin on automated transmissions is that they are better suited for less experienced drivers, Kreilkamp has found fatigue reduction for older drivers to be a bigger factor.
“Our young drivers don’t like automated transmissions very much,” says President John Kreilkamp. “They still like to shift their own gears. But drivers, say, over 40 years old, really appreciate them – especially in Chicago traffic.”
The experience of Party Time Ice in Port Huron, Mich., is more in keeping with conventional wisdom. The company has had one Transmission Technologies Corp. AMT-7, (fully automated), 7-speed transmission in service for three years and two more for one year. Party Time Ice operates Class 7 straight trucks, which deliver product within a 70-mile radius of the plants.
“Once drivers get used to it, they like it,” says Bill Rock, plant manager for Party Time. “In fact, we’ve got some young drivers who don’t even know how to drive a standard transmission.” While overall driveability is good, says Rock, an area that could use some improvement is backing. “It’s not real smooth in reverse – it jerks a bit.”
“All our drivers absolutely love them,” says Jerry Mitchell, president of Mitchell Transport. He’s referring to the Eaton AutoShift (semi-automated) transmissions his fleet started using two-and-a-half years ago.
The Tampa, Fla.-based refrigerated carrier, which operates throughout states east of the Rockies, now has 72 automated units, which require clutching for starting and stopping only. “No one wants to go back to a manual transmission,” Mitchell insists. “Man is like electricity – he’ll take the path of least resistance. And let’s face it, shifting is work. We’ve only got eight manuals left.”
In a fully automated transmission, such as TTC’s medium-duty AMT-7, the transmission’s electronic control module (ECM) – and the engine’s related sensors – read road speed, rpm and accelerator position and select the proper gear. The ECM makes shifts while adjusting engine rpm to road speed, without disengaging the clutch, much the way an experienced driver might.
Kreilkamp Trucking has found that the automated transmissions “are actually delivering better fuel economy than our manual transmissions,” Kreilkamp says. “And we’ve had no hard-parts failures. We were beta testing the transmissions early on, and the folks from ZF Meritor had to come out and make some adjustments to the software. But since then, they’ve gotten it right.”
It’s too early to tell when, but, “I think the fuel savings alone will pay for the upcharge [for the automated boxes],” concludes Kreilkamp. “They’re the transmissions of the future.”
While Mitchell didn’t notice any great increase in mpg when the fleet started using the AutoShifts, “We saw no decrease at all – even with newer, lower-emitting engines.
“What I really like is that these transmissions sort of level-out our fuel-economy graphs,” Mitchell says. “We don’t see hills and valleys, depending on drivers. Used to be, when mpg was low for a particular truck, it wasn’t easy to tell whether it was the engine or non-fuel-efficient shifting techniques. This pretty much takes the driver out of the mpg picture.”
Party Time Ice hasn’t noticed any change in fuel economy with the automated transmissions, says Rock, who admits, however, that that doesn’t mean much. “We run kind of heavy, the routes vary, and there’s a mix of city and highway driving. It’s hard for us to get a good handle on fuel economy to begin with.”
Party Time Ice has found the AMT-7 transmissions to be generally reliable, but, “Like any computerized device, when it’s down, it’s down,” says Rock. “Most problems have been software-related. The guys from TTC usually just come out with their PCs and take care of the problem. They definitely stand behind the product.”
Mitchell acknowledges a few problems in maintenance. “But, as with any new technology, you’ve got to expect that. Most were software related, and the Eaton guys were great about taking care of them.”
Some problems resulted from failing to train drivers on the proper use of the transmissions, Mitchell says. “I mean, this isn’t your father’s Oldsmobile – you don’t just toss a driver the keys and send him off.”
The future is now
“We’ll definitely buy more of them,” Rock says. “But I think we need a little more power to get the most out of them [they currently run 190-hp Cats]. Next time, I think we’ll go with 230-250 hp.
“I think there’s a payback here,” Rock concludes. “If the reduction in clutch and drivetrain wear and tear prevents premature component failure, it’s definitely worth the cost.”
Mitchell plans to keep spec’ing automated transmissions. “They’re the wave of the future.”
Allison Transmission’s new 1000/2000 Series, fully automatic, electronically controlled, 5-speed transmissions are ideal for severe-service, stop/go applications for Class 3 through 7 trucks.
The automatic option
As attractive as automated transmissions are for over-the-road applications, there are high-clutch-wear vocations where an automatic, with its torque converter, is a more practical choice. Refuse service, with its constant stopping and starting, is one of them.
The Essex City Department of Public Works, Cedar Grove, N.J., has about 130 Allison automatic-equipped refuse trucks in service and, according to John Dolce, director of fleet management, that’s definitely the way to go.
“There’s less opportunity for driver error,” notes Dolce. “There’s no clutch to replace and, in a situation with multiple drivers, automatics are more forgiving of varying driving techniques. Meanwhile, the driver has much better control at creeping speeds.”
Automatics are actually easier to maintain than manuals, Dolce says. “Just change the fluid and make sure the coolers are doing their job. The most important consideration with an automatic is to prevent the fluid from overheating.”