More secrets of slip-forming revealed in this detail drawing of a jack and the ‘typical deck layout’

The viewer can take his or her own meaning from the drawing, but allow us to point out the inset illustration labeled “Overhead Deck Cable.” It shows 4-10 neoprene-covered wire with power outlets and “lites” rendered in such charming style. (Neoprene was invented by Dupont in 1930.)

Traces of Double J Manufacturing Co., Inc.–which opened in 1949–turn up in a web search. Double J is characterized as a producer of industrial and commercial machinery and equipment. There’s even a phone number, but dialing 913.342.4400 yields, “We’re sorry, you have reached a number that has been disconnected or is no longer in service.”

Nevertheless, this excellent drawing commemorates the company.

7 comments on “More secrets of slip-forming revealed in this detail drawing of a jack and the ‘typical deck layout’

  1. Chandler Thomas says:

    Double J jacks were an electric means to raise a slip form. They were used by many contractors into the 1970’s. Other powered raising systems included compressed air and hydraulic. Double J jacks were introduced after WWII. Their first systems used an electric motor, coupled to a gear reducer for the landing gear of WWII bombers. This system powered a connecting arm to an eccentric which “pinched” the jack rod. As the eccentric rotated, it lifted the form. These jacks had advantages and disadvantages. Advantages included double action meaning they could raise or lower, constant speed, use of a water level system with “brain box” that controlled all jacks and kept the form level at all times. To begin raising the form, the deck foreman or jack man would raise the brain box on a rod and the rest of the jacks would begin to rise to reach level. Disadvantages included 1 speed which was slower than air or hydraulic, ultra heavy wood jack yokes, no means for raising the form in the event of loss of electricity, use of solid jack rods exclusively which were considerably more expensive than hollow rods. I completed several slips using these jacks.

  2. Suzassippi says:

    Very interesting, both the drawing and the description from Chandler Thomas. I could not find anything in the newspaper archives about the company, but the Official Gazette of the US Patent Office, vol. 658, 1958, listed them as granted a patent for “Apparatus for raising and leveling forms for walls of concrete structures” May 13, 1952.

  3. rjanetwalraven says:

    Before we had a television, my mother would drive us out to watch “the pour.” As a young child, I was fascinated with watching the elevator “grow.” There were bright lights, men pushing wheelbarrows, the “buggy” going up and down carrying concrete to the levels being jacked up… so much activity all at once. My dad, Bill Walraven, was quite particular about the concrete pour being perfect, especially when the temperature dropped. He took great pride in “his” grain elevators having no freeze lines. To this day, I love driving through Kansas, Oklahoma, the Pandhandle of Texas, admiring all those prairie skyscrapers.

    • Suzassippi says:

      I will be in Oklahoma in June–I will be sure to look for them all along the way!

      • rjanetwalraven says:

        Wonderful! My dad, superintendent for Chalmers & Borton, built grain elevators in Enid and Ponca City. During WWII, he also built the barracks out at Vance Air Force Base, Enid. EnJOY your trip!

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