Article by: Bhushan Mhapralkar

Story by : Bhushan Mhapralkar

Automated Manual Transmission (AMT) is set to make life easier for an Indian commercial vehicle driver.

There’s is little doubt that an AMT will make life easier for an Indian commercial vehicle driver. It already is, though the penetration of AMT is not high yet. With an ability to replace manual transmission as well as an automatic transmission, AMTs are catching up. As mentioned earlier, they are however limited to a few commercial vehicles at the moment. Manual transmissions may be enjoying greater accepetance over AMTs, but the situation is set to change. Market leader in buses, Ashok Leyland is already offering an AMT on its buses. It has also developed an AMT for its ICV range of vehicles. Market leader Tata Motors is also investing in AMT technology. It is said to be relying upon its G750, G1150 and G550 gearbox as candidates for AMTs.


AMTs are catching up

Oerlikon sources may term the Indian commercial vehicle market as already overcrowded for an AMT specialist like it to venture into, it was mid-last year that Wabco unveiled its Optidrive AMT technology in India. The company highlighted the technology by explaining that it combines the ease of driving (that an automatic transmission offers) with the efficiency of a manual transmission. Wabco sources emphasised a good deal on the AMT’s ability to save fuel. Terming Optidrive as a modular system, made up of three key components – a cabin mounted shift lever unit including the system’s electronic control unit; a shift actuator mounted on the gearbox, and a clutch actuator, the sources explained that the transmission was capable of changing gears in full automatic mode, or as initiated by the driver. Thus, apart from optimising the gear shifting process, Optidrive, explained sources, takes upon itself the task to enhance a vehicle’s ability to ply in the most efficient manner.


Ashok Leyland chose Optidrive

Ashok Leyland’s Leymatic AMT employs Wabco’s Optidrive. One may need to travel to Kolkata to find out how it is fairing. Over 1100 Ashok Leyland low-floor Janbus there feature the Leymatic AMT. Based on a 6-speed automated manual transmission, the Leymatic AMT, according to Alok Saraogi, Vice President – Brand Marketing & Corporate Communications at Ashok Leyland Ltd., was found to provide consistent fuel economy and superior driver comfort. Opining that AMT could improve the operating economics and help towards driver retention, Alok explains that his company chose Wabco because of their experience in AMTs. “An existing synchromesh transmission was chosen,” he says. Industry experts claim that the two (manual) transmissions chosen for AMT include the ZF-based S6 36 synchromesh ODGB 6-speed unit (for bus application) and a ZF-based 6S 850 6-speed unit (for lighter truck application). They also claim that a modular approach was employed, and with the intention to develop AMTs across the entire platform. While work is said to be on, to convert a 9-speed manual transmission into an AMT, the two AMTs developed until now have been customised to meet the Indian operation conditions, including abuse and overloading. They come with economy mode and rocking mode, and carry a high level of local content.


Europe is at the forefront of AMT

The move to AMTs started in Europe. Europe continues to be at the forefront of AMT technology. According to Jacques Esculier, Chairman & CEO of Brussels-based Wabco Holding Inc., “Close to 80 per cent of the trucks in Europe use AMT.” He explains that an AMT consists of an electronic system that can be put on the top of the manual system, and leads to five per cent fuel saving apart from saving the driver the effort to shift gears. An interesting example of an AMT on a premium luxury segment bus is the Volvo ‘I-Shift’ AMT. Also found on the Volvo FMX deep mining tipper, I-Shift was recently introduced in India. In the European market it has been around for quite some time. Its birth can in fact be traced to the 80s when a group of young Volvo engineers thought about ways to automate a manual transmission. This led to the emergence of the first Geartronic transmission in the early 90s. It was built on a manual transmission with the addition of a gear shift system and automated clutch control. The second generation Geartronic appeared in 1999, and included more integration and protection for the valves and electrical components, The I-Shift AMT emerged in 2001, built from scratch as an automated mechanical transmission. In the US, it was introduced in 2007. What has come to India is the fourth generation iteration of the I-Shift.


I-Shift improves driveability

With a torque rating of up to 2,500 lb-ft., I-Shift aids in getting the right ratio for the right speed, and at the right time. Using electronics to continuously monitor grade, speed, weight and engine load, I-Shift swaps cogs when necessary. At other times, it holds a gear to ensure fuel efficiency. At the core of the I-Shift is a 12-speed electronically controlled splitter and range change transmission, installed with advanced software optimised for deep mining operations. Offering 12-forward and 4-reverse gears, the I-Shift, communicates with the engine via standard CAN topologies. If this signals the use of mechatronics, the I-Shift is made up of a transmission control system (including the control unit and valves among other bits), electronic gear shifting lever, sensors, shifting cylinders, clutch control system and counter shaft brake.

Characterised by a fast gear changing system featuring minimum interruption in torque delivery during gear changing, I-Shift is easy to operate according to sources at Volvo Trucks India. Options on the gear lever enables the driver to select between economy and performance modes. Manual up-shift and down-shift is also possible. It requires the use of shift button on the handle. With more than 33,000 I-Shifts sold the world over since 2001, the highlight of this AMT is its ability to down-shift and up-shift in smaller, optimal steps. This helps to improve driveability. Weighing 70 kgs less than the manual transmission, at 280 kgs (without oil), I-Shift is programmed to know the engine’s efficiency map for each engine rating. Offering two shifter control styles – basic and premium, I-Shift could be had with an integrated engine brake interface, and driver information display interface too. Employing a single dry clutch, the transmission is priced 8 to 10 per cent higher than that of manual transmission. The splitter and range gears in the I-Shift AMT are synchronised, while the base unit has no mechanical synchromesh. Speed synchronisation takes place electronically with the help of the engine and transmission control units, after which the gear is changed.


BharatBenz 3143 features G330 AMT

The AMT G330 12-speed transmission on BharatBenz 3143 deep mining tipper is a constant mesh unit. With a peak torque handling capacity of 3300 Nm, the gearbox is equipped with a dual plate 400mm diameter clutch. Termed as Powershift, the G330-12 is based on an internally developed and produced, light-alloy basic transmission with three non-synchronised forward gears and one reverse gear. A total of 12 forward and four reverse gears are made possible by synchronised range-change and splitter boxes with automatic gearshifts in both the main transmission and upstream and downstream units. The omission of heavy synchromesh packages, which are replaced by a so-called lay shaft brake, considerably reduces the moving masses. In conjunction with the latest control technology acting in tandem with extremely sensitive actuators, makes rapid yet smooth ratio changes possible. Unlike the Actros or the Axor, which are known to have an armrest located paddle-shift like action-lever, the 3143 has a multifunction steering column mounted stalk to facilitate gear changes manually. An ‘auto’ or ‘manual’ selection button is on the centre console. Activating it to manual mode, and pushing the stalk up, engages the gear. Similar procedure leads to higher gears. To downshift, the stalk has to be pushed down. Pushing it towards the driver engages the exhaust brake, and pushing it in the other direction releases the same.

Instead of the traditional, separate display of whole and half ratios, the 3143 has an alphanumerical display on the dash. It displays if the transmission is in the ‘A’ (Auto) mode or ‘M” (manual) mode apart from the cog it is in. If it is in the first gear, second gear, third gear, etc. Stemming from the fact that 12 gears are as good as 16 gears found on earlier heavy-duty truck transmissions, the gear changes take place more quickly. A simple overdrive is said to differentiate the G 330-12 transmission installed in construction vehicles like the 3143 deep mining tipper. Suspended from mounts that are made of steel rather than aluminium, the G330 is claimed to be capable of handling a total combined road-train weight of up to 250 tonnes.


Scania Metrolink features GRS 875 Opticruise AMT

The 8-speed GRS 875 Opticruise AMT on Scania Metrolink buses benefits drivers, passengers and operators in several ways. Tracing its origin to Scania’s CAG semi-automatic system, Opticruise improves comfort and eliminates the need to watch revs and change gears, enabling the driver to devote more attention to handle the vehicle, and to other traffic. Familiarisation is quick and safe, and economical driving is easy and consistent. Wear and tear is reduced on the clutch and other powertrain components, increasing service life. Refined over the years, the concept of a standard mechanical gearbox remains, but with modified and improved mechanical components, and an entirely new software. The clutch pedal used to start and stop no longer exists. Neither on the 8-speed Opticruise AMT, nor on the 12-speed Opticruise GRSO 925 AMT that is found on the P410 deep mining tipper.

AMTs may be limited to a certain class of commercial vehicles as of current. Their applicability to set to grow. As a cost effective alternative to automatic transmissions, they are set to grow. However, rather than competiting with automatic transmissions, AMTs will complement them. As transporters seek more comfort, efficiency and safety, AMTs and automatic transmission will find more takers in India. The casualty will be the manual transmission.


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