Sliding Mechanisms

The friction tester requires movement across two axes in order to accommodate sports balls of different sizes. Motion is required along the horizontal axis in order to grab the balls with the grippers. Motion along the vertical axis is what allows us to apply a normal force on the balls.

Vertical Motion

Since the vertical motion is responsible for applying the normal force, it must be stable and adjustable.

In order to achieve this, a screw system has been designed to fit in our system. The force plate will be fixed onto a plate which is attached to a threaded rod. This plate also has between 2 and 4 stationary dowel rods running through it to prevent rotation. These rods are fixed onto the base of the system, so that the turning of the screw lifts the force plate up and down.

Horizontal Motion

The horizontal motion does not need to support much force; the most important function of the horizontal motion is ease of motion and the ability to lock into place. Since it is what is used to grab differently sized balls, It must be able to lock into place or else it would not be able to hold onto the ball.

For this system, we have designed a guide rail system which allows a range of motion to accommodate a full sized basketball or anything smaller. There is a screw on top of the guide rail which is used to lock it into place.