The first three pictures show the jointer, the tendon machine and the mortise machine. Note in the second picture the wheel at the bottom right of the picture. The wheel has a chain wrapped around it with a weight hanging from it. The purpose was to put tension on the belt which ran this particular machine. The only way to turn the unit off quickly was to kick the weight to remove the pressure on the belt.
Today there is an electric safety switch.
The final three pictures give a better idea of how the tools are powered. The first picture shows the power belt coming from the main ceiling shaft down to the floor transfer unit. Here the power is channeled, by a shaft, pulley, and another belt to the jointer. It is important to remember that certain woodworking machines require certain amounts of Rpm's. Pulleys must be sized properly in order to attain the best possible speeds.