Five-speed gearbox

Pic. 12.3. Manual Transmission (iB5), which is equipped with all car models from 1996 release

Fiesta cars are equipped with a five-speed gearbox (pic. 12.3). All forward gears are fully synchronized, with the first three gears even being double synchronized. Depending on the engine model, gearboxes with different gear ratios are installed. Only the automatic transmission operates steplessly, choosing the required gear ratios between two pairs of bevel gears of different diameters. As practice shows, gearboxes of Fiesta cars are reliable in operation and rarely fail. If you encounter an exception to the rule, have the transmission repaired by an auto repair shop or service center. It is possible to carry out repairs on your own only if you have the necessary tools and certain knowledge and experience. Even auto repair shops take overhauled gearboxes to their manufacturer or change the gearbox to another one.



TECHNICAL DICTIONARY


Transmission operation

Torque from the crankshaft of the engine through the clutch is transmitted to the input shaft of the gearbox. Five helical gears and a reverse gear are mounted on the input shaft, which are in constant mesh with the gears on the output shaft. The gears on the output shaft are mounted on needle bearings and rotate freely on the shaft until a certain gear is engaged in the gear change mechanism.

Gears and shafts

When a gear is engaged, the corresponding gear is locked with the output shaft of the gearbox. The ratio of the number of teeth of the included pair of gears ultimately provides the appropriate transmission. When shifting gears, no connection is made between the gears - the connection is made between the gear and the shaft. The gear lever acts on the fork, which through the clutch provides a rigid kinematic connection of the gears. To align the rotational speeds of the shaft and gear, synchronizers are used, consisting of several elements. The faster rotating shaft is braked by friction until the connection with torque transmission is made at a uniform speed. Since it takes a little time to synchronize the speeds, it is not recommended to press hard on the gear lever, especially with a cold engine and thick gear oil.

Forward and reverse gears

The speed of the first three gears of the Fiesta is less than the speed of the engine crankshaft. In fourth gear, the gear ratio is 0.95:1 and the driven gears rotate at a higher speed than the engine crankshaft. Experts talk about «long» transmission that maintains the optimum power characteristics of Ford engines. In fifth gear (gear ratio 0.76:1) «scissors» - the difference between the frequencies of rotation of the crankshaft of the engine and the drive is even greater, which saves the engine and reduces fuel consumption, mainly at long distances. When shifting all forward gears, two gears are involved. Only three gears are used for reverse gear. The third gear, also called the idler gear, is located on a separate shaft and is only activated when the driveshaft needs to change direction to reverse the vehicle.