Capital Equipment News January 2018

Scania has standardised its in-house automated manual gear changing system named Opticruise in all its trucks, irrespective of model or applications.

types of automatic transmissions available for heavy-duty trucks: automated manual and full automatic transmissions. When it comes to an automated manual transmission, better known as AMT, Alexan- der Taftman, GM Product and Marketing at Scania South Africa, explains that the gear- box still contains a frictional clutch and pres- sure plate like the manual transmission, but this is operated/controlled by an electronic clutch actuator (ECA), which engages and disengages the clutch. “AMT refers to a transmission that is similar to stick-shift mechanical/manual transmission, except that in an AMT a com- puter performs the clutch work through elec- tromechanical clutch actuation,” explains Swanepoel. While an AMT looks very similar to a nor- mal manual stick-shift gearbox, Prince high- lights that there are a couple of modifications inside the transmission. “The big difference is that your clutch action and gear selection are no longer in the hands of the driver,” says Prince, adding that AMT is the most popular style of transmission in heavy duty long-haul trucks. He reasons that probably 90% of all extra heavy long haul trucks in South Africa are driven by automated manual transmis- sions. The same view is shared by Rodney Selesnick, senior head of Sales at Everstar Industries, the local supplier of the Powerstar range of commercial vehicles, who says the long haul truck segment’s preferred choice is the AMT, as it limits driver fatigue, driver error and improves safety of the driver, others around and transportation of merchandise. Meanwhile, a full automatic transmission is significantly different to an AMT, in both its appearance and its functions. “In a full automated system, the gearbox does not contain either a clutch or a pressure plate. Instead, a torque converter is used, which directs oil flow within the gearbox to lock the gears to certain ratios,” says Taftman. “Instead of using a clutch to convert torque to the wheels, like in manuals or AMTs, a full automatic transmission uses several key parts such as a torque converter, valve body and hydraulic pump, which are not found in manual and/or automated manual transmissions. The automatic transmission

About 90% of all extra heavy long haul trucks in South Africa are driven by automated manual transmissions

A full automatic transmission is

Full automatic transmission is a winning solution in conditions where the truck needs to pull away with big loads on steep inclines and where a high rate of acceleration is needed

unequivocally the best transmission in arduous underfoot conditions

At the time of the launch, Leslie Long, senior manager: Marketing and Demand Planning at Hino South Africa, noted a growing move towards automatic transmissions in com- mercial vehicles, and was excited to finally have a product that addressed this growing market need. Understanding transmissions Duncan Prince, manager – Specialised Heavy Trucks Western Star & MB Actros SLT at Mercedes-Benz South Africa, says a transmission is designed to transform en- gine power into a speed that is appropriate to drive axles and eventually the vehicle’s wheels. There are three major types of transmis- sions available for heavy duty trucks, name- ly conventional manual or stick-shift style transmission, automated manual transmis-

sion (AMT) and a full automatic transmis- sion, all of which are different concepts. In a manual transmission, you have a clutch which the driver engages to select the gear, before releasing it for the vehicle to start moving. “Once the vehicle starts moving, the driver accelerates to pick up speed and depresses the clutch again, which essentially interrupts the power between the engine and the wheels to allow selection of the next gear up,” explains Prince. “When the clutch is disengaged, the engine gets connected to the wheels again and the vehicle picks up speed. With a manual transmission, the gear selection and the relationship between engine speed and road speed are entirely at the discretion of the driver.” Meanwhile, although the term “automatic” is used to refer to all non-manual gearboxes, it’s important to note there are actually two

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