Shackles Test Results

Load Lab
Test Results - VERlocks and Gripples

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Created by Delbert L. Hall, Ph.D.
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Disclaimer: This site contains the currents results of ongoing research and is not a finished presentation of findings. The information on this site may be the results of a small sample of tests and are NOT conclusive evidence of anything – they are just my results. Take them for what they are. Any conclusions drawn from these results are yours and not are necessarily mine. Go the Load Lab Home to read the complete disclaimer.

In September 2006 I tested VERlocks (aka Gliders) and Gripples. Here are the results of those tests:

VERlocks (for 1/8" Cable)

Test #   Breaking strength (lbs) % of rated Min. breaking strength (2000 lbs)
1                1424                                        71.3%
2                1439                                        72.0%
3              1353                                        67.6%
4                1369                                        68.5%
Average       1396                                        69.8%

Gripples

I also tested Gripples (for 1/8" cable). The literature on the Gripple is a bit confusing. In one document it says that the WLL is 440 lbs (based on a 5:1 safety factor.) Since 1/8" cable has a
breaking strength of 2,000 lbs, and five times that would be 2,200 lbs, it is pretty difficult to understand how the 440 lb WLL could be. In another document, it is stated that the "Working Load Limit Range" is 180 lbs to 440 lbs (again with a 5:1 safety factor). Wow, that seems like a might big range and leaves one wondering what it will really hold? So, here is how I tested the Gripples:

Using a single piece of cable, an eye was created using the Gripple (just as shown in the Gripple Rope Clip instructions). This eye was attached to a load cell and a swaged eye made on the dead end of the cable was attached to a lever operated chain hoist. Tension was applied until the cable broke, and the force recorded. Here are the results:

Test #   Breaking strength (lbs) % of rated Min. breaking strength (2000 lbs)
1               1600                                        80.0%
2                1617                                        80.9%
3                 1651                                        82.6%
4                 1645                                        82.2%
5               1658                                        82.9%
Average      1634                                        81.7%

The Gripple is stronger than the VERlock because the Gripple has two
"channels" with locking wedges to grab the cable, whereas the VERlock
only has one channel with ball bearings that grab the cable. Based on
my results and a 5:1 design factor, the Gripple should be rated for
320 lbs WLL (not 440 lbs), assuming that you are using it as I have
described.

So where did the 180 lbs WLL come from? I have no idea, but for
giggles I tested the Gripples with two pieces of cable (using the
Gripple to join the two). The results were:

Test #   Breaking strength (lbs) % of rated Min. breaking strength (2000 lbs)
1                752                                        37.6%
2               789                                        39.5%
3               781                                        39.1%
Average      774                                        38.7%

Not surprisingly, these figure were about half (actually a little less
than half) of the results where I used the Gripple to form an eye. If
I were assigning a WLL based on this use of the Gripple it would be
150 lbs (which is close to 180 lbs).

Note: These were tensile tests and not shockload tests, so they may
not accurately reflect how the Gripple will behave in a shockload
situation. I am just reporting my results and I will leave the
interpretation of the results to each of you.

Thanks to Greg Bierly for supplying the Gripples.