In this video, we are going to discuss about construction and working of Parkinson gear tester used for gear inspection in gear metrology. The Parkinson gear tester is a composite method of gear inspection. It is also known as gear rolling tester. When gear is rolled with the standard gear in tight mesh, there occurs variation in center distance above the gears.
The inspection of variation in center distance is called as composite inspection of gears. The gear runout and profile variation of gear can be inspected by the method of composite gear inspection. The Parkinson gear tester is constructed using the following parts where instrument setup is placed over table and table is placed over base. There are two carriages which are placed over table among them. One is fixed carriage and other is movable carriage.
The movable carriage move with the help of rollers in horizontal direction. There is coil spring in between two carriages. The movable carriage is spring loaded towards the fixed carriage. Both the carriages carry one rotating spindle perpendicular to it. The spindle in fixed carriage carries master gear and spindle in movable carriage carries gear to be tested.
Dial indicator is attached. to base in horizontal position to keep contact with movable carriage. During the working, both the gears are maintained in mesh condition due to spring force and gear mounted on spindle are free to rotate. Due to imperfection in testing gear, the sliding carriage move in horizontal direction. The horizontal displacement of sliding carriage is sensed and indicated by dial indicator.
The plunger of tire gauge indicator which is in contact with carriage would get pressed and will show deflection. This deflection can be measured to check whether the gear must be accepted or not accepted. Nowadays there are electronic sensors used to detect motion of carriage instead of trial indicator.
These sensors record motion and gear output in form of graph. The circular graph shows gears is satisfactory whereas irregular graph shows gears has errors. A faulty gear is denoted by unsatisfactory circle.
A moderate gear is denoted by moderate circle. And perfect gear is denoted by fully satisfactory circle.