Switchable ratchet blocks -These blocks have a ratchet mechanism that can easily be switched on or off even under load and the swivel head can be locked in a fixed position.
The wave ratchet offers 20 to 40%* more grip without adding any additional wear to the rope.
The most effective way to increase friction is to add sharp edges to the ratchet sheave, but this quickly deteriorates and wears away the rope. So, after working alongside leading rope manufacturers the Allen design team came up with a simple solution which improves grip without chewing away at your expensive rope.
The Wave Ratchet sheave has an offset V style grip, made from a hard-wearing recycled plastic nylon, which does not have sharp edges that will eat into the rope. Instead, by adjusting the V formation in the sheave to be slightly offset, the ratchet now grips the rope at additional points around the sheave, resulting in more grip. However, the new Wave Ratchet not only improves grip but as a result of the design it also allows for a less jumpy feel when easing the sheets.
*Depends on the type of rope in use with the sheave.