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I recently bought a band brake for a home built wind turbine and was thinking of mounting it on the shaft and getting a cable from the brake to the ground so I can stop the blades in case of maintenance.

The problem is that the turbine can rotate 360° around depending on the wind direction which will break the cable. Does anyone have an idea around this?

band_brake wind turbine

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    There is a scheme used on some BMX bikes involving a sort of disk on the fork, such that pressure from the brake lever pushes on the disk (which is still free to spin around) and the disk activates the brake. These are found on even department store bikes, so you can probably look at some to see how it works. And likely you can find a scrap bike to salvage the disk from.
    – Daniel R Hicks
    Jan 13, 2020 at 13:19
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    Or just buy one of these new: universalcycles.com/shopping/…
    – Daniel R Hicks
    Jan 13, 2020 at 13:19
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    en.wikipedia.org/wiki/Detangler
    – Daniel R Hicks
    Jan 13, 2020 at 13:21
  • @DanielRHicks Good suggestion! I would make it into an answer if I were you
    – Maarten -Monica for president
    Jan 13, 2020 at 14:25

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A scheme used on many BMX bikes is a "detangler" disk on the fork. It's actually two disks, surrounding the fork shaft, arranged with flanges such that pulling up on the upper disk lifts the lower one.

Both disks are attached to cables, with the upper generally attached to two cables which lead, via a Y adapter, to the brake lever. Two cables from the lower disk lead to the two brake cantilevers.

enter image description here

These are fairly common on BMX bikes just above the cheapest ones, so you could likely view a version on bikes at a department store, and certainly any bike shop carrying BMX bikes would have some.

These are available online from several vendors as replacement parts, or you could salvage a unit from a scrapped bike.

(And I'll note that another option is to use a scheme similar to that used for the front brakes of "detangled" BMX bikes -- run the cable through the (hollow) center of the fork shaft. For your case you'd still need a small rotating cable connector at the top of the mast, but these are fairly readily available as machine components.)

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    These devices tend to work OK when new. If cared for they will continue to work OK. If they are not kept rust free and lubricated they become problematic. Left in the weather water will wash the lubricant off the bearings and flow down the bottom cables causing rust. It may be possible to use a device like this to prevent tangling but care will need to be take on installation to minimize weather related issues and frequent checks will be needed to verify functionality.
    – David D
    Jan 13, 2020 at 18:35
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    This is a great idea, and fits the design requirements. OP will probably need to make something of the same general format, but use a larger inner diameter to go around the mounting pole. The end product would benefit from a large sealed roller bearing rather than the small bearing pictured.
    – Criggie
    Jan 13, 2020 at 18:51
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    @DavidD - Actually, these things hold up fairly well to weather exposure - other brake components fail sooner, when left in the weather. And it should be possible to place the mechanism inside the "hood" shown on top of the pole.
    – Hot Licks
    Jan 13, 2020 at 19:11
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Another option might be to leave the actuation cable dangling downward from a small hole in the housing. You'll probably have a regular old bike brake lever on a short length of wooden dowel as a substitute handlebar.

As long as its not dragging on the ground it should not catch. The prevailing wind should push it backward away from the pole, minimising Clanging and Banging. You might even add a small support chain from the tailfins to hold the brake lever out of the way.

enter image description here

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    It is a good idea, didn't think of it before but since the pole is 4m high I would need at least 2m long cable which wiil bring the risk of strong wind making the cable wrap around the tale and making it unreachable. I think having the cable inside the pole would be safer so I will go with the other suggestions from daniel and hot licks. Really appreciate the help thanks.
    – mnm 180
    Jan 14, 2020 at 7:22

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