PRIMARY SYSTEM: ONE ASCENDER ON THE BELAY ROPE.

SECONDARY SYSTEM: ONE ASCENDER ON THE BACKUP ROPE.

Advantages:

- Redundancy principle also followed for the belay rope

- Comfortable, allows wearing only a seat harness without shoulder straps

- Facilitates changing between ascent and descent modes

- The system slides along the rope, without pulling

Disadvantages:

- Rope installation is more complex

Risks in case of primary ascender malfunction:

- Fall height twice the length of the secondary ascender's attachment lanyard

INSTALLATION ON THE HARNESS WITH TWO ASCENDERS:

THE PRIMARY ASCENDER IS CONNECTED TO THE HARNESS BELAY LOOP WITH AN OK CARABINER.

A RESCUCENDER is placed on the other rope as a backup. It is connected to the harness tie-in points with a quick link (PRESTO or GO), a 17 cm EXPRESS sling and an OK TRIACT-LOCK carabiner. After installation, verify that each ascender slides correctly on the rope in the up direction, and locks instantly in the down direction.

Before climbing, verify that all connectors are locked.

GEAR NECESSARY FOR THE SELF-BELAY SYSTEM:

- two EN 892 dynamic single ropes or two EN 1891 low stretch kernmantel ropes of 10 mm minimum diameter

- a primary ascender (ASCENSION, MICRO TRAXION, BASIC, MINI TRAXION), and its OK connector

- a secondary ascender: RESCUCENDER and its OK TRIACT-LOCK connector

- a 17 cm EXPRESS sling

- A PRESTO or GO quick link, tightened with a wrench

【轉(zhuǎn)自：https://www.petzl.com/US/en/Sport/Setting-up-a-self-belay-system-on-two-ropes-with-two-ascenders?ActivityName=Rock-climbing】