An ascender is any device designed for moving up a rope. They work by allowing the rope to move freely when they are moved upwards, but by locking into position when weighted so they cannot move down the rope under load. In general this involves a cam with thin teeth which bite into the rope to fully lock the ascender in place. These teeth are designed to pass between the fibres of the rope sheath and so do not damage the rope.
Single Rope Technique
For ascending a rope you will need two ascenders. One (the hand jammer) loosely attached to the harness to prevent it being dropped but not restrict movement, with a footloop attached. Standing in the footloop allows a second jammer attached between the sit and chest harnesses on the caver's chest (the chest jammer or croll) to move up the rope. Sitting back in the harness and weighting the croll allows the hand jammer to be moved up the rope and so on.
Other devices and their uses
The basic devices used in SRT are the croll and either the basic or the ascension. They are also usful in hauling and rescues as progress capture devices. In this section we also have the petzl pantin foot jammer, the tibloc emergency ascender and the shunt abseil backup device.
Lightweight chest ascender at only 80 gramsRecommended for Sport: ActivitiesMountaineering, Climbing, Caving Professional: Work activitiesRope Access, Sailboats Professional: Rescue activitiesMountain rescue, Firebrigades and civil protection For ropes 8 to 12 mm