Manual Transmission

Manual Transmission

Two French engineers, Louis-Rene Panhard and Emile Levassor first introduced the transmission in 1894. The two gave a demonstration of their new invention, but while during the demonstration their gasoline powered engine failed to run, so they had to give their presentation in a lecture. Many people believed that this invention would not work, until a British automotive pioneer, F. W. Lanchester said that there is one belt-driven high gear for speed and one belt-driven low gear to climb over objects. One year after Lanchester said this, the two Frenchmen had designed a car with a 3-speed sliding gear transmission that the press could test-drive. This changed the minds of people who believed that the transmission would not work. This invention was revolutionary to the automotive world; the transmission wasn't the only new thing, but the whole drivetrain layout was changed. Panhard and Levassor's manual transmission had been adopted by most carmakers by 1904. This transmission has been used until recent times, but with many improvements. The most significant improvement has been the synchronizing system. This system allows for the gears to mesh with each other smoothly. The first synch system was introduced by Cedilla in 1928. Since then Porsche as added gears to the 3-speed manual to make a 6-speed manual. Today the 5-speed transmission is the most common manual transmission in vehicles.

The purpose of having a transmission in a car is to limit the vehicle's torque. Transmissions effectively "smooth out" the torque curve of the engine to allow the car to start off, accelerate at a desired level and then to cruise on level ground at the highest speed with the engine running at its most efficient range. Torque is what makes the car move. The car's weight, inclination of the road surface and engine characteristics all combine to dictate the amount of torque necessary to smoothly drive along. Since we don't run our engines at constant speeds, the transmission is needed to mechanically multiply torque to allow the smoothest possible operation.

The transmission is connected to the engine through the clutch; the input shaft of the transmission therefore turns at the same rpm as the engine. The basic manual transmission consists of a lay shaft, gears, drive shaft, collar, and gear fork. The crankshaft is always spinning when the car is moving unless of course you decide to stall your car. The shaft coming from the clutch spins the lay shaft. The lay shaft then spins the gears, which are on bearings. The bearings allow the gears to spin on their own when they are not engaged, this way they will not affect anything. The collar is directly connected to the drive shaft, that means which ever gear it connects to it directly links the two together, that is the gear and the driveshaft. When the teeth on the collar move into one of the gears by the gear fork, it makes the drive shaft turn. When the drive shaft turns the tires will turn and propel the vehicle.

The transmission uses gears to allow the power from the engine to be used in different ways. For example, while traveling up a hill you want more power to go to your wheels for every revolution. By putting it in a low gear it will allow your car to climb the hill easier. To be in a low gear means that the transmission uses a small gear on the engine out put shaft and large one on the drive shaft. This will allow the engine to apply more power per revolution of the drive train. When traveling on a highway, you wouldn't need as much power and you also want the wheels to move faster then the engine. That means that you would want a larger gear on the engine output shaft and a smaller gear on your drive shaft. That would allow the tires to move faster then the engine. Usually the ratio of the 6th gear in a 6-speed is around 1.0, so for every one revolution of the crank shaft there is one revolution of the driveshaft.

After driving a manual transmission for the first time, I was surprised at how much control and precision is needed to drive the car. I was having difficulty moving the car without stalling. I had to practice letting off the clutch slightly and right then applying the gas. It took me a long time but I got the hang of it; I was going from first gear to second and then to a complete stop. Although I was able to go from first to second, the shifts weren't smooth and the ride was uncomfortable. I need to work on letting off the clutch