Construction and operation of the gearbox three- and four-speed (gradual).
Three-speed and four-speed mechanical gearboxes are most often used in passenger cars. These boxes, thanks to the use of different gear ratios, allow driving forwards z 3 the 4 speeds and going backward at one speed. Very heavy cars and special-purpose cars have gearboxes with a higher number of gears.
The gearbox housing is attached to the clutch housing, as its extension and most often forms together with it and the engine a common block mounted in the car.
The three-speed gearbox consists of a housing, the clutch shaft (propelling), main roller (driven), intermediate shaft, gear wheels, axis (fight) with rear gear and gearshift gear.
The principle of operation of a three-speed gearbox. The clutch shaft of the gearbox is mounted at its rear end in the wall of the gearbox housing, it ends with a toothed wheel with spur gear teeth. The main shaft is mounted in the extension of the clutch shaft, which transmits the motion towards the driving wheels. This shaft is mounted at one end in the clutch shaft, and the other end in the wall of the case housing. The main shaft is longitudinally grooved (equipped with multi-bodies), on which two sliding gears of different diameter are slid. These wheels are equipped with flanges, with which they can be moved along the shaft. They have free translational movement along the shaft, and turning around, cause the shaft to rotate. The smaller toothed wheel is equipped with spur toothing, whose canines correspond to the teeth on the clutch shaft. This is called. claw clutch.
Below both rollers, end-mounted in the walls of the gearbox housing, there is an intermediate shaft, equipped with stationary gears of various diameters. The intermediate shaft with its largest gear is permanently meshed with the gear of the clutch shaft.
The fourth shaft is located on the side of the lay shaft at the rear of the box (axle with a gear wheel) - reverse gear. It has a gear in constant mesh with the corresponding idler shaft gear.
Idle - neutral. The drive from the clutch shaft goes to the intermediate shaft, but the rotation from the lay shaft is not transmitted to the primary shaft, because no gear on the main shaft engages with the idler shaft wheels.
First run. Due to the meshing of the larger gear on the main shaft with the small gear on the intermediate shaft, the movement from the input shaft via the intermediate shaft is transferred to the main shaft. Because of the biggest difference in wheel diameters, this is a gear (the slowest, and at the same time the strongest.
Second gear. When we slide the smaller gear along the main shaft and engage it with the corresponding gear on the intermediate shaft, then we will get the second gear - faster. In this case, the second gear sprocket on the main shaft has a smaller diameter than the idler sprocket on the intermediate shaft., hence it rotates faster than the idler shaft, but not yet as fast as the engine's crankshaft, as the transmission of rotation involves a constant deceleration gear between the clutch shaft and the lay shaft. So we get faster driving speed, but at the same time less force on the driving wheels of the vehicle.
Third gear - direct. In this case, the second gear gear on the main shaft is meshed with its inner teeth (fangs) with the drive shaft gear, that is, the gearbox main shaft and the clutch shaft are directly connected, and the intermediate shaft, even though it rotates, it is not involved in the power transmission. Due to the direct connection, the gearbox main shaft rotates at the same speed as the engine crankshaft. As a result, the highest driving speed is achieved, but at the same time the smallest force on the driving wheels of the vehicle.
Rear gear. When the gear on the main shaft is moved yes, that we will mesh them with the rear gear shaft pinion, then we introduce an intermediate gear between the gear on the intermediate shaft and the gear on the main shaft. We will then rotate the main shaft in the opposite direction to engine rotation. As a result, this causes the car's wheels to rotate and allows the car to run in reverse.
The four-speed gearbox in operation does not differ from the three-speed gearbox. By increasing the number of gears, it is possible to use four forward gears with different speeds.