Views:242 Author:Site Editor Publish Time: 2020-02-10 Origin:Site
Pulleys, which belong to disc hubs, are generally relatively large in size and manufactured by casting and forging. They are pulleys are mainly used for long-distance transmission, such as the output of small diesel engines, agriculture machine, tractors, automobiles, mining machinery, machining equipment, textile machinery, packaging machinery, lathes, forging machines, some small horsepower motorcycles, air compressor, reducer, generator, gin, and so on.
The transmission advantages of tractor pulley are: it can reduce the load impact. It runs smoothly, with low noise and low vibration. Its structure is simple and easy to adjust. The manufacturing and installation accuracy of the pulley transmission is not as strict as the meshing transmission. It has the function of overload protection, the adjustment range of the center distance between the two shafts is large.
The disadvantages of the pulley transmission are: it has elastic sliding and slipping, the transmission efficiency is low and the accurate transmission ratio cannot be maintained, when the pulley drive transmits the same large circumferential force, the contour size and the pressure on the shaft are greater than the meshing drive. The pulley drive belt has a shorter life. The diameter and other dimensions of the pulleys of various types of machinery and equipment are matched according to the reduction ratio, and they are designed according to the working speed and the speed of the motor.
Working speed / motor speed = driving wheel diameter / driven wheel diameter * 0.98 (slip coefficient). If a steel pulley is used, the linear speed should be no higher than 40m / s. If using a cast iron material, the linear speed should be no higher 35m / s, motor speed and pulley diameter conversion ratio, speed ratio = output speed: input speed = load pulley pitch circle diameter: motor pulley pitch circle diameter. The pitch circle diameter is the same as the reference diameter, diameter-2h = pitch circle diameter, h is the groove depth on the reference line, and different models of V-belt h are different, YZABCDE, the groove depth on the reference line is h = 1.6 2 2.75 3.5 4.8 8.1 9.6. The diameter of the pitch circle of the pulley is the theoretical diameter of the pitch line of the pulley. It is a bit like the diameter of an index circle of a gear. It is generally expressed by PD, and the outer circle is generally expressed by OD. Different groove pitch circles and outer circles have different conversion formulas. It is relatively easy to measure the outer circle of the pulley, and calculate the pitch circle according to the formula. SPZ: OD = PD + 4; SPA: OD = PD + 5.5; SPB: OD = PD + 7; SPC: OD = PD + 9.6. The minimum outer diameter of the pulley of A or SPA is 80mm. If it is smaller than that, especially at high speed, the belt is prone to delamination and cracks at the bottom.
1) Gasoline must be used for the last cleaning before assembly to ensure that all parts are clean and dry, to ensure that the mating surfaces are tightly fitted, and have sufficient friction.
2) Hexagon socket bolts should also be washed and dried with gasoline before assembly. Do not apply lubricating oil or grease to bolts or screw holes to ensure sufficient friction and self-locking ability after bolts are tightened.
3) When the three hexagon socket bolts are about to be installed, they need to be tightened in turn to ensure that the tapered sleeve receives uniform axial force and that the coaxial positioning of the pulley and the tapered sleeve is good.
4) Check and measure the length of the hexagon socket bolts for assembly before installation to ensure that the assembly bolts can bear against the bottom end of the blind hole of the tapered sleeve after tightening, to ensure that the tapered surface fits tightly, and to ensure that the bolt is subject to the reverse thrust of the bottom end of the blind hole.
5) After the pulley is tightened, check and adjust the relative positions of the master and driven pulleys to ensure that the two pulleys are on the same plane and the belt tension is moderate.
6) The pulley cover should be intact and securely installed to prevent that the belt breaks or the pulley is loose during the operation from causing a major safety accident.
7) The taper sleeve is a wearing part. After a long period of operation, the inner hole and the chain groove may be damaged. It should be checked before each assembly. If defects are found, the spare parts should be replaced in time