How does Maruti Celerio’s Auto gearbox work?

S. Muralidhar
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A common thread ties first time car buyers around the country and urban commuters who already own cars. They are both keen on being rid of the tyranny of the manual gearbox.

Just as much as many ‘self-driving’ car owners like the feel of complete control offered by a manual gearbox, the current urban driving cycle in most cities is so irritatingly slow, that a manual is quite painful to use.

But the double whammy, that is a huge price differential and less fuel-efficiency, has kept buyers at bay. And so, though there is a crying need for the convenience of an automatic, more than 96 per cent of all car buyers have stuck to manuals because they offer more value.

Now, Maruti Suzuki claims that it has the perfect solution in the Celerio, in the form of the unique low-cost automatic transmission that has been specially developed for Indian buyers.

Called ‘EZ Drive’ by Maruti this unconventional automatic is simply just the manual gearbox with an intelligent hydraulic actuator installed on top.

The brain of this actuator is the Transmission Control Unit (TCU) which is in addition to and pairs up with the electronic control unit (ECU). Information is fed to the TCU by an array of sensors including the throttle position sensor and the engine-rpm sensor, and the ECU. Based on the info, the TCU directs the hydraulic actuators to engage the clutch and shift up or down the gear range. Maruti engineers have given the Celerio an electric, drive-by-wire throttle to deliver driver inputs directly to the TCU.

So, unlike the conventional torque converter automatic or CVT (continuously variable transmission) auto gearboxes, which are entirely independent units that are married to the engine, the auto shifter in the new Maruti Celerio is just the manual gearbox and a brainy appendage sitting on top of it.

However, driving the Celerio feels like driving a conventional automatic. There is no clutch pedal and the gear knob positioned at the base of the centre stack looks and feels like a regular automatic. What is missing along the list of drive positions is a ‘Park’ or P-position, probably to avoid the additional costs of an electronic brake.

While accelerating, except for the mild shift feel as the gears change, there is no indication that it is an unconventional auto gearbox. According to Maruti engineers even if repairs are needed to the gearbox it can be done easily. But to prove its reliability Maruti has developed a long life transmission fluid, which will stay sealed for a period of 10 years or 1,60,000 kms.

From the configuration chosen it seems like the price differential for the auto variants can be kept low. To confirm that it can deliver on its promise of a fuel-efficient automatic, Maruti officials have confirmed that the ARAI-rated mileage is the same 23.1 kmpl for both the manual and the automatic variants.

(This article was published on January 30, 2014)
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