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ratchet block pulleys/speed bar lines kit

Updated the Wednesday 7 January 2015

With the continuing evolution of performance wings cross country and competition pilots accelerate more and more often during transitions.
What’s more, for a greater degree of precision and in order to facilitate the transfer from one bar to another, pilots often accelerate using one leg at a time.
The effort required can be substantial and can last long enough to induce muscle fatigue.
The use of ratchet block pulleys is therefore perfectly justified. The principle of this type of pulley is simple. If load is applied to the line in one direction the pulley turns freely but if it is applied in the opposite direction the pulley locks. The hub of the pulley is not smooth and is designed in such a way as to induce friction in one direction but not the other, when the pulley locks this friction reduces the effort required to hold the line in place. But this friction quickly wears out the speedbar lines.
So the use of ratchet pulleys necessitates the use of a compatible type of cord in order to avoid the failure of speedbar lines, otherwise frequent inspection and replacement is required.
The problem is not a simple one, certain types of cord resist wear extremely well, but they do so because they induce little friction and thus are not compatible for use with ratchet pulleys as they generate little or no braking effect.

During the 2009 competition season Kortel Design therefore tested not only the different types of ratchet pulley suitable for paragliding but also an array of types of cord and the compatibility of their various combinations.

There are two types of ratchet pulley, standard and automatic. For the latter the pulley turns freely in both directions under light loads and the ratchet mechanism automatically engages when the load increases (for certain models the level of load necessary to trigger the ratchet is adjustable).
On paper the operation of the automatic type of pulley seems ideal for releasing the speedbar without causing wear on the speedbar line. But in reality even the slightest load induced by releasing the speedbar is sufficient to engage the ratchet, in order to allow the pulley to turn freely once more the pilot is obliged to push the speedbar which is incompatible with conventional speedbar usage.

So ultimately for our requirements the behaviour of the automatic type of pulley is identical to that of the standard type, we therefore eliminated it.

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poulie_ronstan

Following these tests Kortel Design has selected the following combination:
Ratchet block Harken + dyneema line with dyneema sheath.
The line supplied with the kit is ready for use with an attachment loop and regular markings which facilitate the symmetrical adjustment of the speedbar.

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harken + cordelette

These pulleys are larger than traditional models thus their use can change the equilibrium of your harness when accelerating. The line runs further forward of the centre of gravity compared to normal pulleys, it is therefore possible that your feet rise skywards when you accelerate.
It is for this reason that our Kanibal II and Kanibal Race harnesses are now equipped with specific attachment points for these pulleys, positioned further to the rear, they allow the line to run through the correct point.

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attache poulie multiple

So jump on your accelerators and as the saying goes: ‘If you touch your brakes you’re a coward!

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