in North America have increased from about 70 percent to 95 percent in the past 10 years. “Th e trend toward automation in medium duty markets is a function of vehicles being ‘a tool’ used to perform a task,” Th omas says. “In contrast to Class 8 operations, where the vehicle tends to be the business, and driving the vehicle is the operator’s primary responsibility, medium duty truck drivers wear more hats and act as drivers, salespeople, order takers, shelf stockers and more.” PERFORMANCE AND MAINTENANCE CONSIDERATIONS Both manual and automatic transmissions require a clutch pedal to connect to the vehicle’s engine. During gear changes, engine torque is interrupted and the vehicle begins to lose speed. As a result, more fuel is consumed for the vehicle to maintain a certain speed. When speed is lost at each gear change, it translates into a lower average speed for the vehicle over the course of a workday. Performance is negatively aff ected, as is the fl eet’s bottom line. Also, the clutch of a manual transmission or automated manual transmission (AMT) is a wear item that requires regular inspection, maintenance and replacement at certain intervals. Maintenance of the clutch can be quite frequent due to the potential abuse it takes from inexperienced vehicle operators. Furthermore, driver fatigue from constant use of the clutch pedal and gear shift er is a signifi cant and unwelcomed byproduct of operating manualequipped vehicles. “Manuals remain a proven, cost-eff ective option for fl eets with skilled drivers,” Th omas of Eaton says. “Automatic transmissions off er a more comfortable driving experience, particularly for less skilled drivers.” SPEC’ING When spec’ing vehicles, medium duty fl eets need to ask a number of questions related to automatic and manual transmissions, says Allison’s Love. Th ese include: • Does my fl eet value reliability and durability, performance or fuel economy, and to what degree? • Does my fl eet value driver comfort and driver retention, or seek a higher level of safety? • What type of fuel will my fl eet use, and what is the appropriate transmission choice to maximize vehicle performance for that fuel choice? Eaton’s Th omas also points to four key factors for medium duty fl eets to consider when evaluating vehicles equipped with manual transmissions versus vehicles equipped with automatic transmissions: • Application — Primarily whether or not a vehicle will require a power take-off (PTO). Many medium duty fl eets will spec a transmission with a PTO purely for the enhanced residual value of the vehicle. • Terrain — Th e geography where a medium duty vehicle will be used can infl uence a truck’s torque and horsepower requirements. Characteristics of medium duty transmissions • The North American market is dominated by automatic transmissions in the Class 6 and 7 markets. • Medium duty transmissions typically have 5 to 7 forward speeds. • Torque ratings range from 520 ft/lbs to 660 ft/lbs. • Engine horsepower ratings are typically 220hp to 300hp Information provided by Eaton FLEETS ARE FINDING automatic transmissions are easier to maintain. Vehicles that are used in hilly or mountainous areas oft en require higher ratings. • Fleet preferences for acceleration performance, balanced against the preference for fuel economy. • How long does the fl eet intend to keep the vehicle? — Many lease fl eets turn vehicles over every fi ve years or so, with the goal of maintaining “nice” and new vehicles that are more consumer-friendly. Conversely, small businesses may keep trucks for 15 to 20 years or longer, or at least up until repairs become costly enough to warrant replacing them. School busses have an average life of 12 to 15 years, and some states require them to be retired upon reaching a designated vehicle age. Medium Duty | ADDITIONAL CONSIDERATIONS Th e quest for improved fuel economy and the emergence of alternative fuels have been key drivers for medium duty fl eets as they transition toward vehicles equipped with automatic transitions. Now, the focused should be on vehicle performance and how transmissions aff ect this. “We’ve seen the vast majority of the medium duty market convert to automatic transmissions, leaving only a handful of manual or automated manual transmissions,” says Love of Allison. “Th is trend is particularly evidenced in school bus applications, which have seen a signifi cant shift toward the use of propane engines in recent years,” adds Th omas of Eaton. “Much of the shift toward alternative fuels is attributed to the increasing cost and complexity of diesel emissions technology, such as diesel particulate fi lter systems.” Examples of transmission technology designed to improve fuel economy include “smart shift ” schedule adjustments, deeper and enhanced engine/transmission optimization and integration, as well as vehicle acceleration management. TRENDING TOWARD AUTOMATION Every medium duty fl eet is diff erent. So when spec’ing vehicles, these fl eets need to keep a number of considerations in mind when deciding between vehicles equipped with manual transmissions or vehicles equipped with automatic transmissions. However, a combination of factors – including the ever-shrinking pool of experienced drivers, resources and capital available for training – as well as a concerted eff ort to improve fuel economy, have led many medium duty fl eets to lean toward automation. “Initial cost is lower for the manual over the automatic, however, when total lifetime costs of training, maintenance, fuel consumption and productivity are factored in, the automatic is the lower overall cost choice,” Love says. Every medium duty fl eet is different. So when spec’ing vehicles, these fl eets need to keep a number of considerations in mind when deciding between vehicles equipped with manual transmissions or vehicles equipped with automatic transmissions. Photo couresty of GMC VehicleServicePros.com ❚ OCTOBER 2016 ❚ FLEET MAINTENANCE 29
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