Engineers Report On Lightning Fence Droppers
Report on elastic suspension fencing:
This following excerpts are taken from "Report on Elastic Suspnesion Fencing" compiled for Hi Tensile by Geoff Bailey, Bachelor of Engineering, University of Queensland.
High quality elastic suspension fencing provides an effective and cost effi cient means of stock control. Its main benefi ts are its very high capacity to elastically rebound after a stock impact, and its modest cost.
Performance of the most commonly used fence droppers and steel posts varies widely in this regard due to differences in their design and processes of manufacture.
The fence droppers:
Fence droppers are the one component in the elastic suspension fence where incorrect selection of material and material profi le most commonly occurs.
A survey of the range of metal droppers available results in the following observations:
- Rigid sheet metal droppers do not have the ability to elastically rebound after a stock impact. The sheet metal dropper stays permanently bent. This holds the fence strands bunched together—permitting stock to push under the bottom strand. Attempting to straighten rigid sheet metal droppers weakens the material and often causes breakage at the damaged spot.
- Low strength steel wire droppers create a problem as they easily bend. Again, this fl exibility means that strands remain bunched close together, allowing stock to push under the fence.
- One such low strength wire dropper is currently being imported. With a similar design to high resilient spring steel wire droppers such as the Lightning dropper, the two products can be distinguished through a basic bend test (see Test 1.1).
- High resilient spring steel wire droppers have the ability to elastically rebound. The Lightning dropper is outstanding in this regard.
Purpose of test: To distinguish between the imported wire dropper and Lightning dropper and consequently discover the superior product in terms of strength and resilience.
- Take one end of the imported wire dropper in either hand and draw the ends together to bow the dropper until both ends touch. Release the dropper slowly for safety’s sake, and notice how it stays permanently bent.
- Repeat the process for the same size of Lightning dropper. Take note of how much harder it is to bend. After carefully releasing the dropper, notice the much smaller permanent bend.
The imported dropper is easier to bend and remains bent after testing. This indicates to the tester that it is much softer than the Lighting dropper.
In fact, further investigation reveals that the imported product has only about one-quarter the resilience of the Lightning dropper.
The steel posts:
For elastic suspension fencing to be truly effective, it is essential to use the correct gauge of steel posts.
Ideally, heavy-duty (2 Kg/M) star posts should be used, in preference to medium duty (1.5 Kg /M) posts. It is also recommended that high-tensile steel posts be used, in preference to normal steel posts. High-tensile steel posts have about twice the elastic bending strength of normal steel posts, and consequently about 4 times the elastic energy absorbing capacity.
A simple comparative bending test will identify whether the post is made from high tensile steel or normal steel.
Purpose of test: To distinguish between high-tensile steel posts and normal steel posts and conclude which is more appropriate for effective elastic suspension fencing.
A heavy-duty high tensile post will support, in cantilevered bending, the weight of one person (about 85kg) at a lever arm of about 1 meter. The post must be positioned as a horizontal cantilevered bar with the long web to the top.
High-tensile posts will support approximately 85kg, therefore making them more suitable to ensure the strength of elastic suspension fencing for stock control.
The above report has been prepared and tests developed and conducted by Geoff Bailey, Bachelor of Engineering, University of Queensland, for use as a guide in the provision of high quality elastic suspension fencing. Hi Tensile invites you to conduct the quality comparison tests described above under your own conditions.
Hi Tensile is sure that you will be satisfied with the performance, durability and cost-effectiveness of their products.