Installation manual

Community S-Series - Operation and Installation Manual - Page 44
5. Wire Rope Clips
Wire rope clips, sometimes called “Crosbys” after one manufacturer, should always be of
the drop-forged type, never of malleable steel. They must always be installed in
accordance with the manufacturer’s instructions and specifications. Although specific
instructions will vary depending on the design of the clips and the diameter of the wire
rope, they will always include the number of clips, the length of the turn back, the spacing
of the clips, torque of the nuts, and the orientation of the U-bolt. Using too few clips, too
little turn back, spacing the clips improperly, over-tightening or under-tightening the nuts,
and improperly orienting the U-bolts can all cause catastrophic failure. Overlooking the
importance of re-tightening the nuts after load is applied can also lead to failure. The
prudent installer will be prepared in advance, carrying a calibrated torque wrench in the
toolbox.
As a general rule there should never be less than three wire rope clips on wire rope of 1/8”
to 1/4” in diameter, and more on larger diameters. Clips should be evenly spaced and the
U-bolts should always be oriented so that they are on the dead end of the wire rope, as
they can cause damage to the live end. Wire rope that’s properly terminated with high-
grade rope clips will result in approximately 80% of the strength of the wire rope itself.
Example: If a specific wire rope has a rated Working Load Limit of 1000 lbs., that rating will
be reduced to 800 lbs. when the wire rope is terminated with wire rope clips. Conversely,
Nicopress fittings (see below) are capable of providing terminations that are equal to the
strength of the wire rope itself.
6. Nicopress® Fittings
Like wire rope clips, Nicopress fittings are used to terminate wire rope ends. They consist
of an oval sleeve of malleable metal (typically copper, aluminum or stainless steel) that’s
pressed onto the wire rope with significant force using a specially designed tool. Nicopress
is the proprietary brand name of one manufacturer, but has become nearly a generic name
among riggers. As with wire rope clips, fittings of similar design to Nicopress are available
from multiple manufacturers of varying quality. If high grade fittings are properly installed
with the correct tool (this is a big “if”), they will form a termination that is equal in strength
to the wire rope itself. As with all rigging components, it is highly recommended that you
purchase such fittings and tools from professional supply houses, not from local hardware
stores. Genuine Nicopress tools come equipped with a calibration gauge to insure that the
tool is performing properly on every fitting over time.
7. Shackles
Only industrial grade load-rated shackles should be used to attach wire rope or fabric slings
to hang points. The use of rapid links, Quicklinks, clip locks and other non-rated hardware
items should absolutely be avoided. Shackles and other high-strength forged components
must never be dropped onto hard surfaces, such as concrete. If a shackle is dropped more
than a foot onto concrete, discard it. The impact of the fall could cause the metal to
crystallize, leading to early failure.
8. Eyebolts
Eyebolts are often used to suspend single loudspeakers, arrays, and clusters of
loudspeakers. Some of Community’s S-Series rigging accessories are designed to utilize
eyebolts. Eyebolts are available in several styles and materials. Some of the most
common are:
• Formed
steel plain eyebolts;
• Forged
steel plain eyebolts;
• Forged steel shoulder eyebolts
(sometimes called “machine eyebolts”).
For loudspeaker rigging, only rated forged steel shoulder eyebolts purchased from a
reputable manufacturer, should be utilized. Community offers this style of eyebolt at a
reasonable cost.
The SWL or WLL rating of any eyebolt is based on a straight line pull. If the load angle
varies from that of a straight line, the load rating rapidly decreases. At 45° the eyebolt has