vacuum brake


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vacuum brake

[′vak·yəm ‚brāk]
(mechanical engineering)
A form of air brake which operates by maintaining low pressure in the actuating cylinder; braking action is produced by opening one side of the cylinder to the atmosphere so that atmospheric pressure, aided in some designs by gravity, applies the brake.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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Vacuum brakes posed a serious threat to Westinghouse.(87) The Massachusetts Railroad Commission, headed by Charles Francis Adams, Jr., conducted a comparative trial of the two systems on the Eastern Railroad in April 1873.(88) The vacuum system apparently impressed many New England roads, for in November 1874 Wootten heard from Isaac Hinckley, president of the Philadelphia, Wilmington, and Baltimore Railroad, that "the Boston and Maine, the Boston and Albany, and the Grand Trunk ...
It was later that the system was modified to apply the vacuum brake as well.
The 45% glass-reinforced PPA reduced both the weight [by 60%] and the wall thickness of the "power piston" of Delphi's new vacuum brake boosters when compared to traditional thermosets.
The vacuum brake booster has become redundant, while the brake pedal and master brake cylinder become a single operating mechanism that is hydraulically uncoupled from the rest of the system by valves, and serves only to record the brake request.
But as soon as the vacuum brakes were repaired the train began moving forward.
"As these are the subject of both a change in the manufacturing method and design in order to accommodate air brakes and steam-driven air pumps instead of the vacuum brakes fitted onto the originals, design justification that the original design worked satisfactorily is not enough," says Allatt.
He designed several locomotives; however, his greatest legacy was the introduction of vacuum brakes to Ireland, a trend which continued in Britain.