Application and function of speed reducer reducer in the family of reducer, planetary reducer, with its small size, high transmission efficiency, wide scope of speed, precision higher advantages, is widely used in servo, stepper, dc transmission system. Its function is to ensure the precision transmission, mainly used to reduce the speed increase torque and reduce the load/motor rotation inertia ratio. In order to better help the masses of users with good planetary reducer, reducer and drive motor shaft, this paper analyzed the cause of, and introduces in detail how to correct installation machine of decelerate of planet of a different heart broken shaft problems Some users in the equipment operation after a few months drive motor output shaft is broken. In the areas of need to match the speed reducer and equipment mainly include the following: 1, like aviation, satellite, medical, military science and technology, equipment, wafer robot and other automation equipment to moving load and required precision positioning when there is need, the purpose is to improve the accuracy. 2. The torque needs to be improved, and the cost of the control system will be needed. 3. You can increase your efficiency without additional costs. 4. Because of the large load inertia, the optimal equivalent load inertia can be used to obtain the optimal control response and improve the performance of the product. 5. Increase the service life of the equipment: the planetary reducer can also effectively solve the attenuation of the motor's low-speed control characteristics. Due to the control of the servo motor can be reduced to a because of the speed, resulting in a certain degree of attenuation, especially in the low speed signal extraction and stability of the current control, especially easy to see. Therefore, the deceleration function is used to speed up the motor. 6, to reduce the cost of equipment: from a cost point of view, assuming that 0.4 KW AC servo motor drive collocation, take a unit equipment costs, match with 5 KW AC servo motor driver must take 15 unit costs, but if use 0.4 KW servo motors and drives, match a set of reducer is able to achieve the foregoing cost 15 unit cost to complete, the operating cost saving more than 50% of the gear speed reducer role mainly include: 1) slow down at the same time to improve the output torque, torque output ratio according to the motor output by reduction ratio, but can't exceed the speed reducer rated torque. 2) reduce the inertia of the load at the same time, and reduce the inertia to the square of deceleration ratio. You can see that the general motors have a inertia value. The gear reducer is a kind of power transmission mechanism, which USES the gear speed converter to decelerate the rotary number of the motor (motor) to the desired rotation number and obtain the large torque mechanism. The speed reducer is widely used in the current mechanism for transmission of power and motion. In almost all kinds of mechanical transmission system can see traces of it, from the transport ships, automobiles, locomotives, construction of heavy machinery, processing machinery and automated production equipment used in the machinery industry, to the daily life of common household appliances, clocks and watches, and so on. Its application in power transmission work, to the small load, the Angle of the accurate transmission can meet the application of speed reducer, and in industrial applications, deceleration machine has to slow down and increase torque function. Therefore, it is widely used in the conversion equipment of speed and torque.