Chest Jammer (Chest Ascender)
A chest jammer is a one-way device that slides up the rope but locks when you pull down. It is mounted on your chest harness and is what lets you ascend a rope by stepping up in your footloop.
What to look for
The gold standard is the Petzl Croll. It comes in small or large. We are largely apathetic about the size difference, but the large is probably worth going for. It works on ropes from 8 to 13 mm, which covers the range you will find on UK caving trips.
The Croll is simple. It has a toothed cam that grips the rope when you put weight on it and releases when you lift it. It clips into your chest harness and stays in position on your sternum.
Other brands and models are available. We would gently caution you about buying from AliExpress or Temu. Use reputable brands that have the right safety certificates and years of testing behind them.
Expect to pay about 45 to 55 pounds new.
What to get first
You need a sit harness and a chest harness first. The chest jammer attaches to your chest harness and is the main mechanical component that lets you go up the rope.
Buying Guide
- Price (New): ££
- Price (Used): £
- Buy online? Yes. The Croll is a standardised piece of equipment and buying online is fine. Just make sure you get the genuine Petzl product from a reputable retailer.
Buying Second Hand
Secondhand ascenders are a grey area. The Croll has a stainless steel cam and wear plate that can wear out over time, and it is hard to judge remaining life by eye. There are known cases of worn Crolls slipping on rope. If you know exactly what to check for, you might be OK. If you do not, buy new.
Where you can buy it
Starless River, Inglesport, Up and Under, Bernies/Earthworm, Trogg, Amazon