The war was over, and the torch was passed from Pretzel founder Leon Cassidy to his son William, who took over full operation. Leon Cassidy was involved in various business activities through retirement. He passed away in 1969 at age 79.

Recognizing that the post-war baby boom was on the horizon, Bill Cassidy began work on establishing a line of kiddie rides such as the Whirlo and "Kiddie Circus" carousel. These were in addition to the Pretzel dark ride, always the bread-and-butter of the company. And the Pretzel ride itself, with its instantly-recognizable cars, would soon undergo its own evolution.

Pretzel started to diversify their ride lineup in the mid-'50s, advertising their "Big 3", with the Whirlo and Kiddie Circus joining the Pretzel ride.
The Whirlo is shown above being tested by local kids in a factory shot.

At left is the ride's platform and drive system assembled in the Pretzel shop.
 
 
 
  Above left: Center base used for Pretzel's "Balanced Drive" in its Whirlo and Kiddie Circus rides.

Above right: Shop superintendent Elmer Lawrence discusses motor truck with Bill Cassidy. Of Lawrence, Cassidy said: "Elmer was my right-hand man and he was a genius. He had been superintendent since 1929 and worked for us for 36 years. He never learned to read or write, but mechanically, he was a genius."

Above left: A Whirlo ride currently in operation at Sylvan Beach Amusement Park in New York.
Above right: Pretzel company label plate on Whirlo control box.

Pretzel's Kiddie Circus ride was built using the same balanced drive as the Whirlo, which had two motors powering the ride, placed at 180º opposite positions on the platform.
 
 
 
Things began to pick up speed in the late fifties as Americans became more fascinated with the automobile. Pretzel debuted its "All American ¼ Midget" (Third-generation Doug Cassidy sits behind the wheel).  As Go-Kart tracks gained in popularity, this car would be the first of several Pretzel auto rides. Gas-powered with an air-cooled engine, the car featured a combination of a welded-steel frame and a fiberglass body.