Air, Light and Efficiency Showing Influence of Sash Types and Building Design . Idler and power ends of Pond OperatingDevice. Upper and lower rods are continuallvunder tcnsiun and the work of operating the sashi^ equally divided berween them. See photo-graphs on next page. The worm and gear are cutfrom steel and run in oil in a dust-proof case. at their far ends to a chain running over an idler. To these rods areattached compound le\-er arms exerting a thrust against the lowermember of the sash. This thrust is angular at hrst but increasinglydirect as the sash is raised, hence the lifting effo
Air, Light and Efficiency Showing Influence of Sash Types and Building Design . Idler and power ends of Pond OperatingDevice. Upper and lower rods are continuallvunder tcnsiun and the work of operating the sashi^ equally divided berween them. See photo-graphs on next page. The worm and gear are cutfrom steel and run in oil in a dust-proof case. at their far ends to a chain running over an idler. To these rods areattached compound le\-er arms exerting a thrust against the lowermember of the sash. This thrust is angular at hrst but increasinglydirect as the sash is raised, hence the lifting effort is most effectivewhen the greatest weight is overcome. The rods are always in tension, and the load is divided equallybetween them as shown in the three views showing the sash from shutto open. This principle of tension transmission, with balancedthrust against the sash, largely accounts for the extremely lowfriction of the de\-ice. 42 The modern idea—long lines of weather proof sash i [1 DAVID L U P T 0 N S SONS COMPANY The worm and gear areaccurately cut from steel an
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectr, booksubjectwindows
