According to elasticity, drive shafts can be classified in different ways based on their key component-the universal joint. If classified by whether the universal joint has significant elasticity in the direction of torsion, they can be divided into rigid universal joint drive shafts and flexible universal joint drive shafts.
1. Rigid universal joint: Transmits power through a hinge-like connection of parts.
2. Flexible universal joint: Transmits power through elastic parts and also has a buffering and vibration damping effect.
According to angular rate, rigid universal joints can be further divided into non-constant velocity universal joints (such as cross-type universal joints), quasi-constant velocity universal joints (such as double-joint universal joints and three-pin universal joints), and constant velocity universal joints (such as ball cage universal joints and ball fork universal joints). Constant and non-constant velocity refer to whether the rotational angular rates of the driven shaft and the driving shaft are equal when they rotate together. Of course, the average rotational speeds of the driving shaft and the driven shaft are equal.
1. Constant velocity universal joint: A universal joint in which the angular velocities of the driving and driven shafts remain equal when the angle between the two shafts changes is called a constant velocity universal joint or constant angular velocity universal joint. They are mainly used in the wheel transmission devices of steering drive axles, disconnected drive axles, etc., and are mainly used for power transmission in cars.
2. Non-constant velocity universal joint: A universal joint in which the angular velocities of the driving and driven shafts are not equal when the angle between the two shafts changes is called a non-constant velocity universal joint, also called a cross-type universal joint. Cross-type rigid universal joint drive shafts are the most widely used and have the longest history in automotive transmission systems. When a car is rear-wheel drive, a cross-type universal joint drive shaft is often used. For some high-end cars, constant velocity ball joints are also used. When a car is front-wheel drive, a constant velocity universal joint is often used. A constant velocity universal joint is also a type of drive shaft, just with a different name. The drive shaft usually referred to is the cross-type rigid universal joint drive shaft. The cross-shaft rigid universal joint is mainly used to transmit changes in angle. It generally consists of a flange fork, a cross-shaft assembly with needle roller bearings, a universal joint fork or sliding fork, an intermediate connecting fork or spline shaft fork, and axial fixing components for the needle roller bearings. The flange fork is a fork-shaped part with a flange, generally made of forgings from medium carbon steel or medium carbon alloy steel, but also sometimes made of sand castings from ductile iron or precision castings from medium carbon steel or medium carbon high-quality alloy steel. The flange fork usually has a flat flange, but some also have a trapezoidal toothed flange. The cross-shaft assembly with needle roller bearings generally includes four needle roller bearings, a cross-shaft, and a grease nipple. The needle roller bearings generally consist of several needle rollers, a bearing cup, and a multi-edge rubber oil seal (some with a skeleton). In some needle roller bearings, there is also a circular gasket with an oil groove, made of nylon, copper, or other materials, mainly used to reduce the axial clearance of the universal joint and improve the dynamic balance of the drive shaft. A universal joint fork is a fork-shaped part, generally made of forgings from medium carbon steel or medium carbon alloy steel, but sometimes precision castings from medium carbon steel are also used. The axial fixing components of needle roller bearings are generally elastic retaining rings (internal and external snap-fit) in the hole (or shaft), or bearing pressure plates, locking plates, bolts, etc.
