Equipment World Digital Magazine
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bar equals about 14.5 psi.) Compared to unit injectors, those in common rail systems may have more or fewer holes and may have more or fewer individual pulses of fuel per injection sequence. Likewise, years of improvements to variable rate turbochargers have created turbos that deliver smooth performance at a wide range of engine speeds, with minimal turbo lag during acceleration. But turbos have been limited to one strategy: to increase air volume over what's available in a naturally-aspirated engine. Turbo compounding adds a second benefit by me- chanically coupling the turbo to the crankshaft (or to a generator) while still delivering higher air volumes. The result is a slight bump in power output with no additional fuel usage. Transmissions Automated manuals are becoming the most popular option for heavy trucks. They mate well with modern engines, reduce driver fatigue and are more accom- modating of less-experienced drivers. AMTs also do a better job of keeping an engine in its sweet spot for given condi- tions, whether maxi- mum torque or peak fuel efficiency. OEMs are mak- ing improvements to AMTs for construction and vocational appli- cations. Components are ruggedized and ratios optimized; many now include one or two low-reduction ratios to boost perfor- mance in tough condi- tions and allow for low-speed operation, such as curb pouring. These "crawler" gears also allow the use of higher-ratio differentials, perhaps a 3.08 or 3.21 instead of a 3.73 or 3.90, to reduce fuel consumption with no loss of performance at launch, at low-speeds, or on grades. In the early days of electronic control modules, the engine was the arbiter of performance. Now, it's the transmission calling the shots. Overall there's better integration of drivetrain components, and OEMs are making it easier for engines, transmissions and even cruise control systems to chat among themselves. All of this is transparent to the driver other than obvious improvements in performance and fuel efficiency. November 2016 | EquipmentWorld.com 28 machine matters | continued Freightliner's 114SD vocational truck platform is avail- able with the Detroit DD13 diesel engine featuring Detroit Connect Virtual Technician onboard diagnostics. Peterbilt offers the Bendix Wingman Fusion advanced driv- er safety system on its 579 and 567 (shown) models. Features of the system include lane departure warning, in-lane object recognition and enhanced collision mitigation. The latter is an awareness of potentially dangerous situations using input from multiple sensors. I n August, the Environmental Protection Agency (EPA) and the National Traffic Safety Administration (NHTSA) issued final Phase 2 new emissions and fuel economy standards for medium- and heavy-duty vehicles, (with 8,500 pounds of gross vehicle weight or more.) Phase 2 of the greenhouse gas (GHG) and fuel efficiency standards will go into effect after model year (MY) 2018, but will not be fully implement- ed until model year MY 2027. The primary GHGs of concern from transportation sources are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and hydrofluorocarbons (HFC). Primary emphasis is on CO2 and fuel consumption. EPA has fact sheets for Phase 1 (through MY 2018) and Phase 2 (MY 2019-2027) standards. Information in this article covers OEMs' efforts to meet the 2017 regulations, known as GHG17. EPA issues Phase 2 of greenhouse gases rule Mack offers creeper gears in their mDRIVE HD automated manual transmissions. The 13-speed unit is available in direct or overdrive configuration, with one low reduc- tion gear. The 14-speed AMT is overdrive only and has a second, ultra-low-speed gear. Both offer up to four reverse gear ratios.