Its English name is CARABINER, which is called “hook ring” in the domestic mountaineering industry.

The hook rings used in early mountain climbing were made of steel or iron. Steel is characterized by its durability and high endurance (some can withstand 4000-5000 kg of tension). The disadvantage is that it is heavy, increases the load of climbers, and can not be carried in large quantities. Later, this kind of clasp was gradually replaced by aluminium alloy clasp. The aluminium alloy clasp is light and strong. At present, some manufacturers are better than titanium alloy clasp of aluminium alloy. Hook rings are the most widely used and indispensable and substituted equipment in climbing equipment. The main purpose of hook rings is to connect climbing rope with middle fulcrum.

Hook rings can replace many complex and cumbersome knots in climbing. For example, the combination and use of many climbing equipments, such as safety sling, riser and descender, depend on hook and loop.

The hook-and-loop is the guarantee of safety in the course of river-tracing exploration and climbing rock wall. It is also called safety buckle.

When climbing, make sure that the main rope is connected to the middle fulcrum through a hook-and-loop. Any hook-and-loop must be strong enough to withstand the impact and pull of the sudden fall of the climber.

But how is it strong enough? According to the falling test of UIAA, the climbing rope can bear at least 1200 kg of pulling force. Because the rope brakes on the hook ring, the load of the hook ring should be 1.33 times of that of the rope in the falling test of UIAA. Therefore, the hook ring should bear at least 1500 kg of impact pulling force. That is to say, in order to achieve maximum safety in a serious fall, the hook ring can at least withstand such a load.

The normal pulling force of aluminium alloy hooks and rings is generally 2000-3000 kg to ensure the safety of climbers.

Hook rings are generally divided into 0 type, D type and modified D type.

Type 0 hook-ring has the advantages of small friction, wide application range, better activity of fastening on rocks and blocks than type D hook-ring. In climbing, type 0 hook-ring is generally used to connect lifters, pulleys and other equipment. Under normal conditions, it does not withstand impact pulling force, and does not stuck on sharp angles, change direction or suddenly move. Its disadvantage is that the impact tension is small, and its load is shared equally by both sides of the hook and ring, which can generally bear 1500-1800 kg of tension.

D-type hook ring is a kind of more used hook ring. It is stronger than 0-type hook ring. Almost all the load is borne by the long side opposite the opening, so it bears large impact tension and high safety factor. Now it has been improved, with a large opening like a cashew nut, which is easy for climbers to operate with one hand.

In addition, the hook rings with safety locks, mostly large triangle or large D type, are used for the complex connection of equipment. The most common use is to ensure the connection of main rope and safety sling. Therefore, we also call this kind of hook rings as safety hook rings.

There are two basic states of the hook ring, opening and closing. When the hook ring is closed, it can bear three times as much tension as when it is opened.

Special attention should be paid to the use of the hook ring: after hanging the hook ring, the opening should be turned downward and outward, or downward towards the climber, in order to prevent entanglement and twist. Check whether there are cracks or cracks before use. Opening and closing of the opening should be smooth (because its internal structure is based on springs and can be removed by dropping kerosene, solvent or lubricant into the cracks. In order to alleviate rope friction, double hook rings can also be used.

Finally, when choosing the hook ring, we should choose it according to the actual needs. The pulling force, weight and price of different kinds of hook rings are different because of different uses and loads. I believe that when you think about what kind of hook you like, you also include your trust and safety in the reference. In short, it is a very easy to realize but difficult to explain the feeling.