Heavy Duty Trucking, September 2018

HDT SEPTEMBER 2018 78 WWW TRUCKINGINFO COM TRANSMISSIONS the other OEMs continue to offer both Usually direct drive is great says John Moore product marketing manager powertrain for Volvo Trucks North America If youre running 65 mph or less super direct drivelines are providing efficiency at even faster speeds But overdrives give you a wider range at higher speeds Overdrives also offer a wider range of ratios with heavier axles If a truck has a 52000 pound rear axle for example it would be difficult to find a direct drive ratio for that weight In this case a fleet would be forced into an overdrive transmission Rear axles are starting to catch up says Barraclough Manufacturers are coming out with ratios in the mid to lower two ratios like a 247 228 or even down to a 215 to 1 Those ratios allow you to work with the direct drive transmissions operating at higher road speeds of 65 to 70 mph while keeping the engine running efficiently 2 Manual or automated Fleets have a choice of three types of transmissions Manual automated manual AMT and automatic Manual transmissions are often preferred due to their simplicity reliability and low acquisition cost However a shortage of skilled drivers has led fleets to shift from manual transmissions to automatics and AMTs And Eaton Cummins and Paccar call their new transmissions simply automated rather than automated manual noting that they were designed from the ground up as automated models Automatic and automated transmissions benefit fleets in many ways New drivers catch on quickly because driving a truck with an automated transmission is a lot like driving a car you put it into gear and go It keeps their eyes on the road reduces distractions and lessens the fatigue associated with manual transmissions says DTNAs Daniels Automated and automatic transmissions also can save a fleet money in the long run by offering consistent performance fuel economy and reliability across duty cycles and driver skill levels With automation drivers no longer need to think about gear they are in or the proper shift on a grade Automated manuals work well in downspeeding applications You cant use a manual in those situations because the engine speeds are too low the driver would be shifting too much and in some cases not shifting fast enough Moore says An automated manual knows when to downshift and it does it quickly so the driver doesnt need to be concerned about it The fuel savings in this situation could easily be 10 when comparing extreme downspeeding with AMTs to older conventional drivelines with manuals he adds Nevertheless Christian Fieldhaus senior project manager of sales for ZF reports there is still a case for manual transmissions He notes trucking remains a very price sensitive market so some companies may not want to invest in a pricier automated or automatic transmission DeVito agrees Fleets still spec manual transmissions when trying to save money when they have an experienced driver pool or when they have a technically challenging application such as a heavy haul or wrecker service where the driver needs to be in complete control Though there are niche applications where manual transmissions work best Barraclough says Those applications are starting to dwindle Automated or automated manual transmissions such as the Mack mDrive can now work with a split box transmission on a pump or vacuum truck We could not put the mDrive on this application until this year So while there are still heavy haul applications where a manual is still needed I suspect its only a matter of time before these situations are solved 3 Shifter developments Fleets have three shifter options for automated and automatic transmissions A physical shifter between the seats a dash mounted push button shifter and a column mounted shifter Detroit has put its shifters on the steering column and incorporates engine brake controls into them Drivers no longer must locate a separate gear shifter brake controller and brake actuator while driving Paccar also offers a column mounted shifter which Hergart says provides an intuitive handshake between the driver and the powertrain with easy access to engine brake shifting and transmission WAREHOUSELATEXNITRILEDYNEEMA TOUGH GLOVESπSHIPPING SUPPLY SPECIALISTSORDER BY 6 PM FOR SAME DAY SHIPPING COMPLETE CATALOG 1 800 295 5510