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| Rung Fastener
The rung fastener has ¼"-20 threads and a hex head
that is sized to fit any standard 3/8" wrench or socket. The washer head has been
designed to allow the fastener to be torqued to high values (18 ft/lbs.) without stripping
the threads. When properly installed, this fastener is resistant to the effects of
vibration.
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| Rung
An "I"-Beam shaped rung provides a great strength-to-weight ratio. The hole at
the center of the rung is where the rung fastener is attached. The fastener hole is
designed to provide maximum grip for the fastener threads.
Patented
5,580,014 U.S.
2,137,879 Canada
2,285,343 UK
Other patents pending.
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| Testing the Connection
 Extensive vibration testing was conducted on
Redi-Rail cable tray to verify that exposure to severe vibration would not adversely
affect the integrity of the rung fastener connection. The tray was attached to a test
frame with trapeze hangers, while a running motor with an offset weight caused vibration.
The motor speed was set to maintain the desired vibration frequency. The vibration
frequency for each test was set so that the empty tray would shake violently (a much worse
case than would be tolerated in any tray installation). The tray was tested empty because
it was the worst case – cables would dampen the vibration. The total time that the
tray was subjected to a particular vibration frequency was monitored.
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| Round 1 –
Compare Redi-Rail to Welded Tray
The Setup
Round 1 of vibration testing was conducted to compare the response of Redi-Rail with
traditional welded tray. One 36" wide, Redi-Rail straight section and one 36"
wide, welded straight section were attached to the test frame. All Redi-Rail rung
fasteners and trapeze hardware were  first numbered and then scribed to determine if they were loosening
under vibration. All welds were numbered while the trapeze hardware for the welded tray
was numbered and scribed. The vibration frequency was set so that both Redi-Rail and the
welded tray were experiencing vertical movement of 3/16". Double click on the video
clip to the right to see the tray vibration.
Test Results
Each weld and fastener was monitored throughout the test. On the welded tray,
one weld developed a superficial crack while Redi-Rail remained unaffected. The test was
run for over 370 hrs. without failure.
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| Round 2 –
Redi-Rail at its
Natural Frequency
The Setup
Round 2 of vibration testing was conducted to test Redi-Rail at its natural (or resonant)
frequency. Natural frequency would be considered "worst case" since this is the
frequency where the tray would experience its largest amplitude (vertical movement). The
same 36" wide, Redi-Rail straight section was used that was tested during Round 1-
the rung fasteners and trapeze hardware also retained their assigned numbers. The
vibration frequency was set so that the tray experienced a vertical movement of 5/16".
Test Results
Each fastener was monitored throughout the test. The Redi-Rail rung fasteners
and trapeze hardware remained unaffected. The test was run for over 321 hrs.
without failure. At this stage, the Redi-Rail straight section had been subjected to
691 total hrs. of vibration.
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| Round 3 –
Redi-Rail with a
Mid-Span Splice
The Setup
 Round
3 of vibration testing was conducted to determine how Redi-Rail would respond when
spliced. The same 36" wide, Redi-Rail straight section was used that was tested
during both Rounds 1 and 2. The tray was cut into two pieces at its center and a pair of
straight splice plates was added. The rung fasteners and trapeze hardware retained their
assigned numbers while the splice hardware was given new numbers (since they had just been
added). The vibration frequency was set to the natural frequency of the spliced tray
section, which caused the tray to experience a vertical movement of 3/16".
Round
3 of vibration testing was conducted to determine how Redi-Rail would respond when
spliced. The same 36" wide, Redi-Rail straight section was used that was tested
during both Rounds 1 and 2. The tray was cut into two pieces at its center and a pair of
straight splice plates was added. The rung fasteners and trapeze hardware retained their
assigned numbers while the splice hardware was given new numbers (since they had just been
added). The vibration frequency was set to the natural frequency of the spliced tray
section, which caused the tray to experience a vertical movement of 3/16".
The blue coloring shown on the tray and splice was used to make it easier to scribe the
fasteners for monitoring purposes.
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Test Results
Each fastener has been monitored throughout the testing process. To date, the Redi-Rail
rung fasteners, splice hardware, and trapeze hardware remain unaffected. Currently (as of
1/5/99), the splice test has been running for 3449 hrs. without failure.
The Redi-Rail straight section has been subjected to a total of 4140 hrs.
of vibration testing and still counting . . .
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| Conclusions
Redi-Rail cable tray is resistive to vibration.
The integrity of the rung fastener connection was not compromised even when subjected to
vibration much more severe than would be tolerated in any "real world" cable
tray installation. Even when splice plates were added, the tray was not affected. |
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Review
Redi-Rail Rung to Side Rail Resistance Test Results in Relation to
Electrical Continuity of Connections
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