Contents: Conversion of traction force ↳ During gear shifting, the engine is… ↳ Torque converter - transmits torque… ↳ The last link before the drive… ↳
This chapter explains how the Focus engine transmits its power to the drive axle. The transmission consists of the gearbox, clutch and final drive. To ensure that all the elements interact perfectly, they are connected by a precisely harmonised system of joints, shafts, bearings and gears. How much power is actually transmitted to the wheels depends primarily on the engine and the accelerator pedal. But the accelerator pedal will be of little help if the engine speed does not match the current speed - every internal combustion engine only develops power over a limited range of speeds. To help you understand your engine better, we have provided various power curves in the chapter "Engines".
If you want to drive economically, accelerate smoothly and always try to coordinate your speed with a gear that brings 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. In combination with the 1.6-liter Zetec-SE engine, Ford offers an electronically controlled four-speed automatic with overdrive and a bypass clutch (4F27E) as an alternative.
Conversion of traction force
In order to be able to accelerate smoothly from a standstill, the drive wheels need a lot of torque. But as you will see from the power curves, below 1500 rpm, at least for petrol engines, the torque is still insufficient: the slow-running gear of first gear therefore facilitates a smooth increase in engine speed and the Focus's movement. In fourth and fifth gear, the opposite happens: in both gears, the conversion to acceleration becomes effective. Compared to the speed of the drive wheels, the engine turns more slowly in the upshifting gears. In other words: the gearbox matches the engine speed to the desired speed of the drive wheels.
During gear shifting, the engine is disconnected from the gearbox - the clutch
Each time you start moving or change gears, the power flow between the engine and gearbox is briefly interrupted. In cars with a manual gearbox, this is done by the clutch. It allows you to move off smoothly and change gears without jerking by equalizing the different rotation speeds of the crankshaft and the gearbox drive shaft. The relationship between the planetary gears of an automatic gearbox is more complex: in this case, each shift is carried out without interrupting the traction force.
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 electromagnetic valves that control the automatic transmission from a common housing. The torque converter not only works extremely comfortably, but also without mechanical wear.
Torque converter with bypass clutch of the torque converter: 1 - converter housing and pump wheel; 2 - turbine wheel; 3 - guide wheel; 4 - clutch with bypass of the torque converter; 5 - gearbox input shaft.
The last link before the drive wheels is the main gear
On its way to the drive wheels, the engine torque passes the last link - the main transmission. Its task is to slow down the rotation frequency coming from the gearbox, i.e. to increase the torque and distribute it evenly to the drive wheels.
The original version can be found on the website: FORDBOOK.ru