Simondjuk
Well-Known Member
paulieraw,
The top fitting is really quite crude, but there is a bearing (probably not worth of the title though) between the foil and the fitting. The hard rubber/plastic ferrule, down the centre of the bearing assembly, is to assist with grip from the clamping grub screws and protect the forestay from them. If you didn't tighten these up sufficiently, and the top bearing became at all draggy, the bearing housing would rotate with the rest of the foil. I suppose, eventually, wearing away the rubber insert until the aluminium of the bearing carrier itself would be running directly against the forestay.
When you look at the arrangement, it seems remarkable that sufficient grip is provided to prevent slippage. Having nipped the grub screws on mine up only modestly (not wanting to punish the wire within) and the bearing subsequently having seized, I can assure that they do grip pretty well, so obviously do their job. To put that in quantifiable terms, since the foil and bearing are effectively one item on my furler at present due the the seized bearing in between, if I try to rotate the whole lot from the bottom, I can't due to the level of grip against the forestay at the top. Well, I probably could if I was prepared to put significant twisting loads into the couple of inches of wire between the bearing and top wire terminal, but I'm not.
The top fitting is really quite crude, but there is a bearing (probably not worth of the title though) between the foil and the fitting. The hard rubber/plastic ferrule, down the centre of the bearing assembly, is to assist with grip from the clamping grub screws and protect the forestay from them. If you didn't tighten these up sufficiently, and the top bearing became at all draggy, the bearing housing would rotate with the rest of the foil. I suppose, eventually, wearing away the rubber insert until the aluminium of the bearing carrier itself would be running directly against the forestay.
When you look at the arrangement, it seems remarkable that sufficient grip is provided to prevent slippage. Having nipped the grub screws on mine up only modestly (not wanting to punish the wire within) and the bearing subsequently having seized, I can assure that they do grip pretty well, so obviously do their job. To put that in quantifiable terms, since the foil and bearing are effectively one item on my furler at present due the the seized bearing in between, if I try to rotate the whole lot from the bottom, I can't due to the level of grip against the forestay at the top. Well, I probably could if I was prepared to put significant twisting loads into the couple of inches of wire between the bearing and top wire terminal, but I'm not.
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