Most cars now have front-wheel drive. Four-wheel-drive off-road vehicles and some all-wheel-drive trucks also have driving force on the front wheels. Many people find it strange: The front wheel is responsible for steering. The two wheels swing around, while the engine and gearbox are fixed ford explorer steering knuckle. How is this power transmitted to the two wheels? How does the front wheel of a car realize both steering and driving? Let’s analyze this problem below.
Early cars were all rear-wheel drive, and the front and rear axles were rigid integral bridges. Today’s trucks still have this structure. The front wheel is responsible for steering. It is installed on the front axle through a steering kingpin (commonly known as a vertical shaft) and can swing freely from side to side. Then the car steering system drives the wheels to deflect through a series of complex steering transmission mechanisms to realize car steering; Responsible for driving, the torque from the engine is transmitted to the two rear wheels through the clutch, transmission, universal transmission, and drive axle (main reducer, differential, half shaft) to drive the car. Since the drive axle is rigid, there is no position change between the drive wheels and the drive axle, so the semi-axle is also integral. It is generally enclosed in the rear axle and cannot be seen from the outside.
With the development of automotive technology and the demand for automotive performance, four-wheel drive systems and front-wheel drive systems have gradually been developed. This requires the front axle of the car to have both steering and driving functions. This kind of axle that can realize the two functions of wheel steering and driving is called steering drive axle (generally referred to as rigid integral bridge). This kind of axle is structurally equipped with the main reducer, differential, half shaft and other parts of the general drive axle, and also has the steering knuckle, steering king pin and wheel hub that the general steering axle has. The difference is that due to the need for steering, the half shaft is divided into two sections, the inner half shaft (connected to the differential) and the outer half shaft (connected to the wheel hub), and the two are connected by a constant angular velocity universal joint; , The steering king pin is also divided into two upper and lower sections, which are respectively fixed on the ball bearing of the universal joint; the steering knuckle shaft is made hollow, and the outer half shaft passes through it. The connecting fork of the steering knuckle is a spherical shell, which can not only meet the needs of steering, but also adapt to the transmission force of the steering knuckle.
The reason why the front wheels of front-wheel drive vehicles and four-wheel drive vehicles can both steer and drive is because of the steering drive axle. The key technologies are two: one is the split-center steering king pin, which allows the half shaft to pass through and connects with the front wheels to transmit power to the front wheels; the second is the split half shaft, which allows the half shaft to pass through. The axle can automatically bend with the deflection of the front wheels, which will not interfere with the steering of the front wheels, and can ensure uninterrupted power transmission.