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Drop tests on DB Tree Rope Saver

Richard Tregoweth - Saturday, November 14, 2009



Testing of climbing equipment in New Zealand is limited to the static load tests provided by DM Standen  and the like. These tests put hydraulic load on rope, splices or slings to ascertain their breaking strength. An advantage of these static tests is the precise measurement of the load at breaking point. However this style of test does not show how equipment might perform in the work environment where a fall puts shock load on the system.

The Treemagineers in the UK are experimenting with a soft eye rope saver similar to the DB Tree Rope Saver and they have the luxury of a CE rated 'shock load' testing system. Chris Cowell from the Treemagineers contacted Drew Dristow with concerns regarding the testing of the DB Tree Rope Saver. Chris felt the equipment should be shock tested, in addition to the static test, but as Drew pointed out no such testing facilities are available in New Zealand. So, collectively they decided the next best thing was to shock load the DB Tree Rope Saver by using weights (similar to Morgan Thompson's drop test for the Unicender) dropped from a specific height over multiple tests - preferably at least 5 drops of one meter with a 80 kg weight off the same DB Tree Rope Saver.

Those tests were carried out in the Auckland Domain on November 12, 2009. The DB Tree Rope Saver passed the initial series of tests without any issues so progressively longer drops and heavier weights were added (up to 100 kg) to stress the system. No elements in the DB Tree Rope Saver system failed; rope, splices, pulley or webbing slings throughout the entire series of 'shock load' tests.

There has been some debate regarding the New Zealand made 22 kN Aspiring webbing sling used in the DB Tree Rope Saver System. Various critics have claimed the Aspiring slings are prone to failure after 6 months due the effects of UV rays on the dyneema material. To settle the issue once-and-for-all the DB Tree Team tested a 9 month old sling to the extreme - without failure. (As predicted by Lindsay Main from Aspiring Enterprises).

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