Car Transmission

An automatic transmission (often informally shortened to auto, and abbreviated to AT) is a motor vehicle transmission that can automatically change gear ratiosas the vehicle moves, freeing the driver from having to shift gears manually. Similar but larger devices are also used for heavy-duty commercial and industrial vehicles and equipment.

Most automatic transmissions have a defined set of gear ranges, often with a parking pawl feature that locks the output shaft of the transmission. Continuously variable transmissions (CVTs), which are very different to conventional automatic transmissions, can change their ‘ratios’ over a wider ’stepless’ range, rather than between a set of fixed gear ratios. CVTs have been used for decades in two-wheeled scooters; but have only seen use in a few automobile models. Recently, however, CVT technology has gained greater acceptance among manufacturers and customers, especially in Audi and Nissan automobiles, and gas-electric hybrid vehicles. (more…)

The transmission in the Mercedes 126 is a very robust design, as one would expect. In its day, it was one of the best units available, which led Porsche to use it in the legendary 928. But as with all other systems on these cars, we should not let the reputation for longevity stop us from performing frequent services.

As a general rule of thumb, transmission fluid should be changed every 30,000 miles. Unlike modern cars, where the trend is to do away with service access ports altogether, these Mercedes transmissions allow us to drain not just the pan but also the torque converter. In other words, we can remove almost the entire fluid charge without resorting to such gimmicks as power flushes.

Whereas engine oil should be changed hot, transmission fluid is best changed when merely warm to protect the mechanic from a very real risk of scalding. (more…)