This rebound resilience test has strict requirements for the perpendicularity of the plunger guide to the base. If you do not put the instrument horizontally during the test, it will cause the plunger to increase friction with the plunger guide during the process of falling and bouncing.
The increase of friction will intensify the resistance of plunger movement, resulting in the measured value of the plunger’s rebound height being smaller than the actual value, which will affect the accuracy of test results.
In order to solve this problem, an omnidirectional bubble level is installed on the base of this instrument. With the aid of 4 leveling screws located in the four corners, you can easily adjust this instrument to a horizontal state.
The method is simple. After placing the instrument on the test bench, you first observe the position of the bubble. If it is in the middle position, it means that the instrument is already in a horizontal state, so there is no need to adjust it.
If it is not at the center, you need to manually turn one or more of the four leveling screws to adjust the height of the base in different directions until the bubble runs to the center of the disc (You need to observe the position of the bubble when adjusting, generally in which direction the bubble is, You find the screw that corresponds to this direction, and then slowly rotate the screw to increase the height).