In the area on the short side of the instrument’s base, you will find a circular gadget similar to a watch dial. As the instrument moves, you will see the moving liquid inside, and there is a bubble in the liquid.
Yes, this is an universal bubble level. In addition, you can also find 4 screws at the four corners of the black base. These parts are to help you adjust the level of this vertical rebound resilience tester.
When you place the instrument on the bench in the laboratory, if the bubble is in the middle of the disc, it means that the instrument is level.
If you find that the bubble is not at the center, it means that the instrument is not in a horizontal state.
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 are required 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).