General information about the gearbox

This chapter talks about that. how the Focus engine transfers its power to the drive axle. The transmission includes a gearbox, clutch and final drive. In order for all elements to interact flawlessly, they are connected by a precisely harmonized system of hinges, shafts, bearings and gears. How much power is actually transmitted to the wheels depends primarily on the engine and the gas pedal. But the accelerator pedal is of little help if the engine RPM does not match the speed at the moment - each internal combustion engine develops power only in a limited range of RPM. In order to better understand your engine, in chapter «Engines» we have given various power curves.

If you want to drive economically, increase your speed slowly and always try to coordinate your speed with a gear that brings the engine speed close to maximum torque. In order to be able to combine torque and speed as smoothly as possible, the Focus uses a fully synchronized five-speed gearbox. Combined with the 1.6L Zetec-SE engine, Ford offers an electronically controlled four-speed automatic with overdrive and torque converter bypass clutch as an alternative (4F27E).

Traction conversion

To be able to easily increase speed from a standstill, the drive wheels need a lot of torque. But as you'll see from the power curves, below 1500 rpm, at least with petrol engines, there's still not enough torque: so using the 1st gear sluggish gear makes it easier to rev the engine smoothly and drive the Focus. When the fourth and fifth gears are engaged, the opposite happens: in both gears, the conversion to acceleration becomes effective. Compared to the speed of the drive wheels, the engine rotates slower in overdrive gears. In other words: the gearbox adjusts the engine speed to the desired speed of the drive wheels.

During a gear shift, the engine is disconnected from the gearbox - clutch

Every time you start driving or changing gears, the power flow between the engine and gearbox is interrupted for a short time. In manual transmission vehicles, the clutch does this. It allows you to gently move off and change gears without jerks by equalizing the different speeds of the crankshaft and the drive shaft of the gearbox. The interconnection of the planetary gears of an automatic transmission functions more complexly: in this case, each shift is carried out without interruption in traction.

Torque converter - transmits torque to the gearbox hydraulically

In an automatic transmission, instead of a conventional friction clutch, the start of movement and gear changes are coordinated by a hydraulic torque converter. In the Focus, this is done by adjusting six solenoid valves that control the automatic transmission from a common housing. The torque converter not only works extremely comfortably, but also without mechanical wear.

The last link before the drive wheels is the final drive

On the way to the drive wheels, the engine torque passes the last link - the final drive. Its task is to slow down the speed coming from the gearbox, i.e. increase the torque and evenly distribute it to the drive wheels.