Mechanical transmission is divided into gear transmission, turbine scroll rod transmission, belt transmission, chain transmission and gear train.
1. Gear transmission
Gear transmission is the most widely used transmission form in mechanical transmission. Its transmission is more accurate, high efficiency, compact structure, reliable work, long life. Gear transmission can be divided into many different types according to different standards.
Advantage:
Compact structure, suitable for short distance transmission; suitable for a wide range of circumferential speed and power; accurate transmission ratio, stability, high efficiency; high reliability, long service life; can realize the transmission between parallel shaft, any angle intersection shaft and any angle staggered shaft.
Disadvantages:
It is not suitable for long distance transmission between two shafts and has no overload protection.
2. Turbine scroll rod drive
It is applicable to the motion and dynamic force between two vertical and disjoint axes in space.
Advantage:
Large transmission ratio and compact structure.
Disadvantages:
Large axial force, easy to heat, low efficiency, only one-way transmission.
The main parameters of turbine worm rod drive are: modulus; pressure angle; worm gear indexing circle; worm indexing circle; lead; number of worm gear teeth; number of worm head; transmission ratio, etc.
3. Belt drive
Belt drive is a kind of mechanical transmission which uses the flexible belt tensioned on the pulley to carry out movement or power transmission. Belt drive is usually composed of driving wheel, driven wheel and annular belt tensioned on two wheels.
1) The concept of opening motion, center distance and wrap angle is used when two axes are parallel and the rotation direction is the same.
2) According to the cross-sectional shape, the belt can be divided into three types: flat belt, V-belt and special belt.
3) The key points of application are: the calculation of transmission ratio; the stress analysis and calculation of belt; the allowable power of single V-belt.
Advantage:
It is suitable for the transmission with large center distance between two shafts. The belt has good flexibility, which can ease the impact and absorb vibration. It can slip when overload and prevent damage to other parts. It has simple structure and low cost.
Disadvantages:
The results show that the overall size of the transmission is large, the tension device is needed, the constant transmission ratio can not be guaranteed due to slipping, the service life of the belt is short, and the transmission efficiency is low.
4. Chain drive
Chain transmission is a kind of transmission mode which transfers the motion and power of the driving sprocket with special tooth shape to the driven sprocket with special tooth shape through the chain. Including driving chain, driven chain, ring chain.
Advantage:
Compared with belt drive, chain drive has many advantages, such as no elastic sliding and slipping phenomenon, accurate average transmission ratio, reliable operation and high efficiency; large transmission power, strong overload capacity, small transmission size under the same working condition; small tension required, small pressure acting on the shaft; can work in high temperature, humidity, dust, pollution and other harsh environment.
Compared with gear drive, chain drive requires lower manufacturing and installation accuracy; when the center distance is larger, its transmission structure is simple; the instantaneous chain speed and instantaneous transmission ratio are not constant, and the transmission stability is poor.
Disadvantages:
The main disadvantages of chain drive are: it can only be used for the transmission between two parallel shafts; high cost, easy to wear, easy to extend, poor transmission stability, additional dynamic load, vibration, impact and noise during operation, so it is not suitable for rapid reverse transmission.
5. Gear train
Transmission consisting of more than two gears is called wheel train. According to whether there is axial movement in the gear train, gear transmission can be divided into common gear transmission and planetary gear transmission. The gear with axis movement in the gear system is called planetary gear.
The main features of the wheel train are: it is suitable for the transmission between two shafts which are far away; it can be used as transmission to realize transmission; it can obtain a large transmission ratio; realize the synthesis and decomposition of motion.
Post time: Jul-06-2021