The three photos shown here demonstrate the lengths that the Ford Motor Company had to go to in the late 1930s because of Henry Ford’s stubborn-ness. He was insistent that the Ford car stay with mechanical brakes, long after most all other firms had changed over to hydraulic brakes. Even his son Edsel Ford could not sway him until finally the 1939 model year, when the change was finally made.
The scheme you see above was probably cooked up to convince the public the brakes on a 1937 Ford could still do the job. The reality of this stunt is probably that most any car with all four brakes locked up, no matter what the type would be able to preform the same PR stunt.
Shown (above) on the left is a 1938 Ford Standard Model and on the right a 1938 Ford Deluxe. Both are shown on brake testing machines installed on the production line to enable the line workers to adjust the brakes. The machine appears to spin each of the four wheels by separate drives and a load gauge of some sort allows the worker to adjust each brake for even operation.