gear backlash of roots blower

 In mechanical engineering, backlash, sometimes called lash, play, or slop, is a clearance or lost motion in a mechanism caused by gaps between the parts. It can be defined as "the maximum distance or angle through which any part of a mechanical system may be moved in one direction without applying appreciable force or motion to the next part in mechanical sequence. An example, in the context of gears and gear trains, is the amount of clearance between mated gear teeth. It can be seen when the direction of movement is reversed and the slack or lost motion is taken up before the reversal of motion is complete.

The gear pair of the Roots blower is generally supported by 45 steel. The three-blade Roots blower gear pair is not only a pair of transmission gears, but also a pair of synchronizing gears. Only when the rotation angles of the two gears are consistent, the two impellers of the blower can operate normally. Otherwise, the two impellers will collide and destroy the normal operation of the blower, and even cause equipment accidents.

Most of the gear pairs on the driven shaft of the three-blade Roots blower are made into a gear ring and a gear hub assembly. The clearance between the impellers can be achieved by adjusting the driven gear ring. When adjusting, it is only necessary to remove the positioning pin and rotate the screw, that is, to rotate the moving gear ring to achieve the purpose of adjusting the impeller clearance. After the clearance is adjusted, tighten the fastening screws, re-drill the locating pin holes, and attach new locating pins.

When designing the gear backlash, care should be taken not to be greater than or equal to the tooth engagement clearance of the two impellers. Practice has proved that when the gear backlash is greater than two-thirds of the impeller clearance, the two impellers will collide during operation. In this case, the two-toothed gear needs to be updated or readjusted.

The gear and the shaft adopt a high-precision transition fit, and the key used for fixing the gear adopts a special tolerance fit to prevent the gear key from loosening, so that the gear can be tightly fixed on the shaft, so as to avoid the increase of the backlash of the gear once the gear is loosened. The two impellers will collide.