| Type | Active protection |
| Holds by | Spring-loaded expanding lobes |
| Best in | Parallel-sided cracks |
| Difficulty | Intermediate |
A cam, short for spring-loaded camming device (SLCD), is an active piece of climbing protection that a trad climber slots into a crack. Pulling a trigger retracts the spring-loaded lobes; releasing them lets the lobes expand to grip the crack walls. Cams place quickly and hold well in parallel-sided cracks where passive gear can’t.
How it works
The lobes convert a downward pull into outward force against the rock, so a fall makes a well-placed cam grip harder. This makes cams a form of active protection.
Cams vs nuts
Unlike nuts, which need a constriction, cams work in parallel cracks. See cams vs nuts.
Using them
Cams are central to a trad rack and to building gear anchors. Correct sizing — lobes mid-range, not tipped out or over-cammed — is the key skill.
Frequently asked questions
How do climbing cams work?
You pull a trigger to retract the cam's spring-loaded lobes, slot it into a crack, and release the trigger so the lobes spring outward against the walls. When a fall pulls down on the cam, the lobes try to rotate and expand harder, gripping the rock — the more force, the tighter they hold in a well-sized placement.
What's the difference between cams and nuts?
Cams are active gear with moving lobes that grip parallel-sided and flaring cracks; nuts are passive wedges that hold only where a crack pinches down. Cams place faster and protect more crack shapes, but cost more and weigh more. Most trad racks carry both.
What size cams do I need?
A starter rack usually covers finger- to hand-sized cracks (roughly 0.3 to 3 in common sizing), with sizes chosen for the rock you climb. Cams are colour-coded by size across brands, and you build the rack out as routes demand wider or thinner placements.
Sources
- Placing trad gear — American Alpine Club