Ball Cage Universal Shaft: The Most Efficient Cardan Shaft-Jiangsu Sitong Cardan Shaft Co.,Ltd
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Ball Cage Universal Shaft: The Most Efficient Cardan Shaft

Views:4     Author:Cardan Shaft Manufacturer     Publish Time: 2004-06-16      Origin:Sitong Cardan Shaft Co.,Ltd

The ball cage universal shaft is a coupling that uses sliding transmission for high-speed transmission. The ball cage universal shaft is connected to the main shaft and the driven shaft through the outer ring of the ball cage and the inner ring of the star, the center of the power transmission steel ball is located in the plane passing through the center of the coupling, and is mounted on the outer ring of the ball In the raceway composed of the outer spherical groove of the star inner ring, the center of the two spherical surfaces coincides with the center of the universal coupling. In order to ensure that the center of all steel balls is on the bisector of the angle between the axes of the two shafts, the steel ball It is installed in the ball cage to ensure that when the angle between the main shaft and the driven shaft of the coupling changes, the force transmission point can always be located on the bisector of the angle. Therefore, the main and follower of the ball cage type universal coupling The transmission speed between the moving shafts can be kept synchronized.

 

The ball joint plunger type universal coupling is a new type universal coupling. It is composed of a power transmission arm pair and a connecting plate. The connecting plate has two pieces, and there are several Or groove, used to connect the power transmission arm pair and the bearing and other components. Between the two connecting plates, more than three same power transmission arm pairs are connected, and they are evenly distributed on the same radius of the connecting plate. Each power transmission arm pair is telescopic, and is adjusted and positioned by the stopper 8. The power transmission arm pair includes a ball arm 5 and a power transmission arm 2. The power transmission arm bolt 1 is installed in the hole or groove of one receiving plate, and the ball arm is installed in the hole or groove of the other receiving plate. The ball arm and the power transmission arm are connected by a ball head and a socket. A mortar-shaped gland 4 is positioned outside the acetabular seat.



Characteristics of ball cage universal shaft



The transmission mode of the ball cage universal shaft can be sliding transmission or rolling transmission. When sliding transmission is adopted, in order to buffer and reduce vibration, a polymer buffer sleeve is installed on the ball arm and the power transmission arm. When rolling transmission is adopted, the original buffer sleeve is converted into a rolling element on the ball arm and the transmission arm. At the same time, the original buffer pad is also changed into a rolling element between the ball head and the socket. Adapt to the needs of rigid transmission.

 

1.Compared with the cross shaft universal shaft, the ball joint plunger universal coupling has the following characteristics:

 

2.With cushioning and vibration reduction performance, it can reduce noise and automatically circulate lubrication;

 

3.Under the same rotation diameter and inclination angle, it can increase the load capacity by 0.5 to 1 times;

 

4.Good synchronization, even single ball hinge plunger type universal coupling can guarantee synchronization;

 

5.The axial x and radial y initial compensations are large, especially the axial x can be achieved without external splines;

 

6.Novel structure, light quality, good manufacturability, easy mass production and lower cost;

 

7.Reliable work, easy assembly and disassembly, easy maintenance, long service life, not only low-speed heavy-load and normal speed working conditions

 


Type of Ball Cage Universal Joints




Ball cage universal joints can be divided into ball cage type bowl universal joints, ball cage type double-compensation universal joints and ball cage telescopic universal joints according to their inner and outer raceway structures.

 

(1) Ball cage bowl-shaped universal joint

 

The ball-cage bowl-shaped universal joint is also called fixed type ball-cage constant velocity universal joint, or RF joint for short. It is mainly composed of star sleeve, ball cage, spherical shell and steel ball. The star sleeve 7 is connected to the middle half shaft through an internal spline, and is axially limited by a snap ring, a spacer sleeve and a disc spring. The outer surface of the star sleeve has 6 curved grooves, forming an inner raceway. The spherical shell is integrated with the outer half shaft with splines, and the corresponding 6 curved grooves are formed on the inner surface to form an outer raceway. There are six window holes in the cage. After assembling, the six steel balls are respectively installed in six grooves and kept in a plane with a ball cage.

 

The ball-cage bowl-shaped universal joint can transmit torque under the condition that the maximum intersection angle of the two axes is 42°, regardless of the transmission direction, all 6 steel balls transmit force. Compared with the ball and fork type universal joint, under the same outer size, it has strong bearing capacity, long service life, compact structure, and easy disassembly and assembly. Therefore, it is more and more widely used. Bridges use this type of universal joint.

 

(2) Ball cage type double-compensated universal joint.

Ball cage type double compensation universal joint is also called ball cage sliding universal joint. The outer ball seat is cylindrical, and the inner and outer raceways are linear grooves parallel to the axis, that is, cylindrical. When transmitting torque, the inner ball seat and the outer ball seat can move relatively axially. The inner and outer spherical surfaces of the ball cage are eccentric in the axial direction, and the center of the inner spherical surface and the center of the outer spherical surface are located on both sides of the center of the universal joint to ensure the constant speed transmission of the universal joint. The structure is simplified, and the axial displacement is achieved by the rolling of the steel ball along the inner and outer raceways. The rolling resistance is small, the wear is light, and the life is long. Therefore, it is most suitable for disconnected drive axles.

 

(3) Ball cage telescopic universal joint.

Ball cage telescopic universal joint, referred to as VL type universal joint. The inner and outer raceways are cylindrical, but the centerline of the cylinder is not parallel to the axis, but inclined at the same angle relative to the axis. Moreover, the inclination directions of two adjacent raceways on the same part are opposite, that is, a "V" shape. After assembly, at the same circumferential position, the inclination directions of the inner and outer raceways are exactly opposite, that is, symmetrically cross, and the steel ball is at the intersection of the inner and outer raceways. When the inner half shaft and the middle half shaft intersect at any angle, due to the control effect of the inner and outer raceways and the ball cage, all the transmission steel balls are located on the bisector of the intersection angle between the shafts, thereby achieving constant angular speed transmission.

 

Because the inner and outer raceways of the universal joint are arranged in a "V" shape along the circumferential direction, and during the transmission of power, the inner and outer star wheels can move axially, so that the axial length of the front wheel is compensated when it jumps. So it is called VL type universal joint. It allows a maximum included angle of 22° between the shafts and an axial expansion and contraction of up to 45mm. The intersection angle range of the VL type universal joint is 20°-25°, which is larger than the cross angle of the two adjacent shafts of the cross joint rigid universal joint, but smaller than the ball fork and RF joints. The VL type universal joints are all arranged on the side of the main reducer in the steering axle of the automobile, while the fixed type ball cage type universal joints that are not telescopic in the axial direction are arranged near the wheel side.


Determination of Ball Cage Universal Shaft Type





The structure of the Ball cage bowl-shaped universal joint is similar to the general ball cage type, only the outer raceway is a straight groove. When transmitting torque, the star sleeve and the cylindrical shell can move relatively in the axial direction, so the sliding splines of other universal transmission devices can be omitted. This is not only simple in structure, but also because the axial relative movement is achieved by the steel ball rolling along the inner and outer raceways, so compared with the sliding Huajian, its rolling resistance is small and the transmission efficiency is high. This universal joint allows a maximum working angle of 20° and is widely used in heavy industrial equipment.

 

Ball cage type double-compensated universal joints are mainly used in steering drive axles, which are rarely used at present. Birfield type ball joints and telescopic ball joints are widely used in steering axles with independent suspensions. Birfield type joints are used on the side near the steering wheel, close to the differential. The side uses a telescopic ball cage type universal joint. Telescopic universal joints are also widely used in disconnected drive axles.

 

The Ball cage telescopic universal joint is a constant velocity universal joint. Its working feature is that all force transmission points are always located on the bisector of the angle between the two axes, so that the angular velocity of the two axes connected by the universal joint is Always equal. Constant-speed universal joints are widely used in wheel transmissions such as steering axles and disconnected axles. The structure of a telescopic ball cage type constant velocity universal joint used in a light vehicle is shown in Figure 1. Since the ball cage type universal joint carries six gasoline balls at the same time, it has strong bearing capacity and impact resistance, high transmission efficiency, compact structure, easy installation, and large working angle. Suitable for applications on light vehicles.


Causes of Ball cage universal shaft failure

Although Cage joints very precise manufacturing process, but each year nearly 2% of the vehicles in a certain number of years, the side of the axle or CV joint failure.

 

Overloading shorten the life of Cage joints. When atmospheric temperature too high or too low, the rubber or thermoplastic material  suffers and a premature failure of the boot occur which leads the joint to be exposed to the external environment, lose grease and consequently deteriorate very quickly.

 

Similarly the use of the vehicle in saline (salty) environments has effects to increase the rate of corrosion that occurs naturally in the presence of normal weathering. This phenomenon often leads to premature degradation of the splines and threads, it is necessary to replace the joint.

 

On the other side, road conditions are firmly effect the drive shaft.

 

Rough road have more dirt and dust particles, Which results abrasion of Cage joints and joint may fail before time.

 

Generally it seems that 80 % of the problems in Cage joints are caused by a change in the working distance of the side shaft, 8 % by faults or negligence during installation. 8 % come from cracked axle boots which lead to a loss of lubricant, resulting in soiling of the joint.

 

Taking relatively simple measures, as mention, will greatly improve component reliability without affecting manufacturing costs and prolong the life of components.






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