Step 5: Determination of total length (L) of spring
The total spring length is equal to the 24" door travel plus 1½ diameters plus 5 diameters, as described
in Step 5 of the design procedure. Hence, L = 24 + (1.5 + 5) (1.75) = 35.4". A smaller diameter spring could be used if the track width could be increased.
6.0 STOCK NEG'ATOR SPRINGS
Dimensional and design information on stock NEG'ATOR springs, including load deflection characteristics,
can be found in this catalog.
7.0 SAFETY PRECAUTIONS
All springs store energy-caution and common sense must be observed any time a spring is being handled.
The following precautions must be observed while handling or using NEG'ATOR springs. Uncoiling or extending the spring stores energy in the extended section. If the energized spring is
released from all restraint, it will return, or try to return, to its normal free condition with considerable force
and speed. This movement may be uncontrolled in direction and/or speed. Serious injury can result from
contact with an edge, end or coiled section of the spring. In addition, on the motor form, an unrestricted
release can also result in injury from a free cable or rotating mechanical element. The NEG'ATOR Spring must not be overextended. This will pull it off its take-up drum, mounting post, or
cavity, and will create the same condition as above-free release of an energized spring. Fatigue failure of a spring in operation may be partial or complete and may result in equipment
becoming inoperative. Broken sections of a spring must be allowed, if possible, to return to their natural
state before removal. Caution should be exercised when removing spring from the equipment. The fatigue life values shown on the design charts are based on actual test data developed under
controlled conditions. These values are, at best, predictions for new applications, based on known values,
but subject to and affected by conditions beyond our control. Since spring failure may result in injury or
damage to other equipment failsafe travel-limiting devices must be built into your unit.
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