Accounting for lost motion
Backlash and deflection are critical factors when designing mechanical control cables.
In pull-pull controls, cable cores generate more friction than solid-wire cores. Most cable controls use 1 X 19 cable because it has a relatively smooth OD and is more flexible than solid-wire cores. For applications requiring more flexibility, specify 7 X 7 cable. However, with 7 X 7 cable, higher loads reduce efficiency and can subject the liner to undue wear and damage.
Proper alignment and mounting also help increase efficiency and cycle life and reduce working loads. In cases where a lever arm moves, mount the control to minimize angular deflection of the core. If possible, specify a fitting or assembly that rotates at the mounting point.
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Conduit and core selection All conduit and core combinations should include a reasonable clearance between the conduit ID and core OD. For most light and medium-duty pull-pull applications, a 0.015 to 0.025-in. clearance is recommended. Note that decreasing the clearance to minimize the effects of lost motion can dramatically increase operating forces. |
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Cable Manufacturing and Assembly Co., cmacable.com
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