All vehicles require a transmission of some type, the vehicle’s engine speed & torque must be transmitted to the wheels with the ability to vary the ratio of speed & torque being applied, along with a mechanism to disconnect & reconnect the engines power.
Time Travel – from an automatic transmissions perspective;
1950’s Cast Iron, two-speed, very simple, very heavy, really forgiving. However, a cars average age on the road was three years & once you reached 50,000 miles your transmission was “worn-out”.
1970’s Mix of aluminum & cast iron transmissions on the market, some were now three-speed models, lighter in weight, they would handle much more horsepower, however they were retaining heat a lot longer now that they started to be made of aluminum. A cars average age on the road had risen to five & half years, but the transmissions where only lasting until about 75,000 miles before they are worn-out.
1980’s No more cast iron, mainly the transmission are now four-speed and starting to use lock-up torque converters. This was the decade that the front wheel drive trans-axle became very popular. But now transmissions are starting to get electronic switches internally and many cars are using fuel injection. It’s the decade where electronics are becoming common place. A cars average age on the road is now up to seven & half years and the transmissions are starting to last about 90,000 miles before they are worn-out.
1990’s Four-speed automatic transmissions are now the “norm”, electronic controls and monitoring of oil pressures, shift speed & even shift feel. Electronics are also controlling the torque converter lock-up clutch and transmissions utilize pulse width modulated oil pressure & clutch controls. Everything is about what electronics can monitor and adjust for, so input & output speeds, clutch engagement time, torque converter slippage, transmission range/gear and temperatures are all under electronic controls. During this time almost 90% of our cars have become front wheel drive vehicles, with rear wheel drives being relegated to pick-up trucks & full size SUV’s. Americans are also pulling more “toys” down the highway, using these pickup trucks; SUV’s & even their mini-vans. A cars average age on the road has risen again to approximately eight & half years and mileage has risen to over 100,000 miles before major transmission wear has occurred.
2000 Future; We are now already driving five & six-speed transmissions and with the ever increasing need for significantly improved fuel economy, we see eight & ten-speed transmissions being developed for the very near future. Constant Velocity Transmissions (or constantly variable ratio transmissions) CVT’s & dual-clutch electronic controlled and electro-mechanical clutch & manual transmissions will all be used to help increase the car & truck fuel efficiency. Transmission are already sealed for life, with no dipsticks in many cases, all electronic control systems and vehicle computer networks, mean that our cars are often as complex as any standard business computer networks. A cars average age on the road today has peaked over ten years and the standard mileage that a transmission can operate over with out any major repairs has climbed significantly in this current decade.