Key takeaways
- A cam (SLCD) is removable protection with spring-loaded lobes that grip a crack.
- Pulling the trigger retracts the lobes to place it; releasing expands them to grip.
- A downward load makes the lobes press outward on the rock, holding the fall.
- Cams excel in parallel-sided cracks (where passive nuts struggle); each cam fits a size range.
From 'camming' — the mechanical action of the lobes.
What a cam is
A cam — spring-loaded camming device (SLCD) — is a piece of removable trad-climbing protection with spring-loaded lobes on a stem. Pull the trigger and the lobes retract so you can slot it into a crack; release the trigger and they spring out to grip the rock. It’s the workhorse of modern trad protection.
How it grips
The clever part is the mechanics: when a fall loads the cam downward, that force is converted into outward pressure of the lobes against the crack walls — so the harder it’s pulled, the harder it grips. This lets a cam hold big falls while remaining fully removable afterward.
Leading a parallel-sided crack where a nut would just slide out, a climber pulls the cam’s trigger, slots it so the lobes sit around the middle of their range in solid rock, releases the trigger, gives it a tug to seat it, and clips the rope — protected by a placement only a cam could make.
Cams vs nuts
Cams excel in parallel cracks and place fast, but cost more and weigh more; passive nuts are cheaper and lighter and shine in tapering constrictions. Trad climbers carry both. See cams vs nuts, and use a nut tool to free stuck pieces.
The bottom line
The cam is the workhorse of modern trad climbing: pull the trigger, slot it in a crack, and its spring-loaded lobes grip the rock — converting a fall's downward pull into outward holding force, all while staying removable. Cams shine in parallel cracks where nuts can't, and trad climbers carry both, picking the right protection for each placement.
Frequently asked questions
What is a cam in climbing?
A cam, or spring-loaded camming device (SLCD), is a piece of removable trad-climbing protection. It has spring-loaded lobes on a stem; you pull a trigger to retract the lobes, place the device in a crack, and release the trigger so the lobes spring out and grip the rock. A pulled rope (a fall) presses the lobes harder against the crack walls, holding the fall.
How do you place a cam?
Pull the trigger to retract the lobes, slide the cam into a suitable crack, and release the trigger so the lobes expand against the walls. Aim for the lobes to be retracted to roughly the middle of their range (not fully open or fully closed), placed in solid rock with the stem pointing in the likely direction of load. Then give it a gentle tug to seat it.
Cams or nuts — which is better?
They complement each other. Cams handle parallel-sided cracks and place quickly, but are expensive and heavier; passive nuts are cheaper, lighter, and excellent in tapering constrictions, but don't work in parallel cracks. Trad climbers carry both and choose the right tool for each placement. See our cams vs nuts comparison.
Sources
- Protection & trad gear — American Alpine Club
- Climbing protection standards — UIAA