THE RIGHT SCREW
It's all about achieving the best possible pull-out resistance. This is achieved by the maximum embedment depth of the main screw. The problem with the supplied standard screws is that they are usually too short. There can be many reasons for this, but in particular the thickness of the ATW, foot straps and deck pads differ, so that the screw is embedded more or less deeply depending on the make selected. The pull-out resistance can be reduced by up to 25% if the screws are too short!
What is different about the TRS-35?
The TRS-35 are 35mm long and each comes with 3 pieces of approx. 1.6mm thick polyamide washers. The length of the screw can be adjusted between 30-35mm. The picture below shows a perfectly adjusted screw length (without washers).
Screws that are too short: Increased risk of overtightening/tearing out of the inserts
Screws that are too long: The tip of the screw hits the bottom. If you continue to turn, the insert or the screw can be overtightened!
Always choose the perfect screw length!
How do I set the correct screw length?
1. Measure the hole depth of the inserts
The holes must be free of sand, dirt or other contaminants! Impurities in the insert hole reduce the possible insertion depth of the screw and can result in the screw being overtightened!
Standard inserts are approx. 20mm deep. Measure on your own responsibility!
2. Trial tightening
Use your standard bolts, these should be approximately 28-32mm long or use the TRS-35 with all 3-polyamide washers and install one side of the footstrap. Then measure the overhang between the pin (ATW) and the upper edge (CAP) as shown in the image below.
3. Determine the embedment depth
Take another ATW with a cover cap and the same screw and adjust the protrusion measured previously. Now measure the overhang from the tip of the screw to the lower edge of the ATW.
Formula: measured protrusion + compressed deck pad - safety distance = Embedment depth
Example: 15mm (measured) + 2mm (deck pad) - 2mm (safety) = 15mm (embedment depth)
4. Determine the maximum screw length
Formula: insert depth - embedment depth + screw length = max. screw length
E.g.: 20 mm (insert) - 15 mm (embedment depth) + 30mm (screw length) = 35 mm (max. screw length)
If there are foreign objects in the insert hole, this reduces the insert depth. This can lead to overtightening of the screws or inserts! The same applies to screws that are set too long. If the screws are too short, there is a risk that the insert hole will be overtightened or the screw will tear out!