Tech-bits: Direct your shifts
Usually if you were was travelling from Abuja to Lokoja on the Clinton highway perhaps on high speed. You would want to consider your overtaking potential and that would mean your engine revolution response to gear change. Sadly in manual during gear change there is a lot of loss in power delivery. This is not […]
Usually if you were was travelling from Abuja to Lokoja on the Clinton highway perhaps on high speed. You would want to consider your overtaking potential and that would mean your engine revolution response to gear change. Sadly in manual during gear change there is a lot of loss in power delivery. This is not help in reducing fuel consumption. In auto transmission the difference is little. That is why engineers have been working day and night to come with the best gearing system possible for a faster gear change to reduce lose of power, improve fuel consumption plus make the car move faster. So where did the idea come from to improve the gearing system. Simple the formula one racing cars, these cars have the faster gear change you can ever think of and most idea to improve passengers come from a lot of race cars.
So the more advanced manual transmission were invent like the DSG seen in the Volkswagen, Audi and Bentley or the SMG seen in the BMW or an SMT in a Ferrari. The DSG gearbox has of course been the favourite of the two and widely produced. But how good is it? Well compared to a manual transmission it is far better and efficient. I watched a video on a comparison test of a VW Golf GTI, one with a DSG and the other with a manual transmission. The gap between the DSG model and the manual was close to two Golf cars at a quarter of a mile. So how does this technology work?
The DSG is known as the Direct Shift Gearbox (DSG) or dual-clutch transmission. It is a twin-clutch transmission automated to change gears faster than any other geared transmission.
Twin-clutch equipped cars do not have a clutch pedal; the clutch is engaged and disengaged automatically. Most twin-clutch transmissions use an automatic-style shift selector with a traditional P-R-N-D or P-R-N-D-S (Sport) shift pattern. In Drive or Sport mode, the twin-clutch transmission operates like a regular automatic. In Drive, the transmission shifts to higher gears early in order to minimize engine noise and maximize fuel economy, while Sport mode holds the lower gears longer in order to keep the engine in its powerband. Sport mode also provides more aggressive downshifts with less accelerator pedal pressure, and in some cars, including most DSG-equipped VWs and Audis, engaging Sport mode also causes the car to react more aggressively to the accelerator pedal.
Most twin-clutch transmissions have a manual mode which allows manual shifting via the shift lever or paddles mounted on the steering wheel. When driven in manual mode, the clutch is still operated automatically, but the driver controls which gears are selected and when. The transmission will follow the driver’s commands unless the selected gear would over-rev the engine (i.e. commanding first gear while driving 80 MPH).
Advantages of the twin-clutch/DSG transmission
The primary advantage of the twin-clutch/DSG is that it provides the same driving characteristics of a manual transmission (i.e. quicker throttle response and no drop in engine speed when the driver lifts off the accelerator) with the convenience of an automatic. However, the ability to perform near-instantaneous gearshifts gives the twin-clutch advantages over a manual. Volkswagen’s DSG takes about 8 milliseconds to upshift. Compare that to the SMT in the Ferrari Enzo, which takes 150 ms to upshift. Instant gear shifts mean faster acceleration: According to Audi, the A3 runs 0-60 in 6.9 seconds with a 6-speed manual and 6.7 seconds with the 6-speed DSG.
Disadvantages of the twin-clutch transmission
The main limitation of the twin-clutch/DSG is the same as all geared transmissions: Because there are a fixed number of gears, and the transmission cannot always keep the engine at its best speed for maximum power or maximum fuel economy. Because of this, twin-clutch transmissions generally cannot extract as much power or fuel economy from an engine as a continuously-variable automatic transmissions (CVTs). But because twin-clutch transmissions provide a more familiar driving experience than CVTs, most drivers prefer them. And while the twin-clutch provides superior performance compared to a manual, some drivers prefer the interaction that a manual clutch pedal and gearshift provide.
Why could it be considered worthwhile? Because it the best ever to be made in a passenger car by a far margin, beyond ordinary imagination.