There are several basic types of protection that you can use while climbing. The most common is passive protection like wedges and chocks. The most expensive is spring loaded camming devices (SLCD). The oldest type is the hammer-in variety like pins and pitons. Then there is fixed protection like rivets and bolts.
Spring loaded camming devices have revolutionized trad climbing. The first
commercial cams were the Forged Friends designed by Ray Jardine, based off an
attempt by Greg Lowe to make an active form of clean protection. These became
available in the mid 70s from Wild Country.
Modern Forged Friends that are very much like the originals.
The original cams had four cams mounted on a ridged stem with a finger trigger
to open and close the cams. Since that time several other companies have gotten
into the cam business and cams have evolved two axles, two and three cam configurations,
internal springs, flexible stems and other niceties, but the core design remains
fairly constant.
Modern Wild
Country Technical Friends.
The stem is fairly important on a cam and will usually come in one of three different styles, solid stem , single stainless steel cable and double stainless steel cable. The double cables are a little lighter and wider as a rule than the single cable stems on the smaller cams. The solid stems are lightest of all, but should never be placed in horizontal cracks. The U shaped double stems can be clipped directly without using the sling. This can give you couple of inches more reach in tricky aid situations. Some single stem cams have a loop formed in the bottom of the cable that will serve this same pourpose.
Cams come in all sizes and several configurations. The most common is the four cam unit (FCU) but you can also buy three cam units (TCU) and splitter makes two cam units. All of the cams on the market now days use a logarithmic curve which allows for a constant camming angle. Most cams have a camming angle of about 14 degrees. The big deal about the camming angle is that it is proportional to the holding power. The range is inverse to the holding power. In other words, the more the holding power, the smaller the range is and the larger the range is the smaller the holding power. One thing to check on the cams, is their stop. If a cam has a weak stop, then it can invert when used as a static piece. Cams that are too narrow have more of a tenancy to wobble in a crack, and cams that are too wide tend to walk worse than narrower configurations. Metolius has recently added a color bar to their cams so that it is possible to visually check if the cams are the right size for the crack.
Camming range is fairly important. Most cams ranges are limited by the camming angle. The one exception to this is the Black Diamond Cams. BD has been able to extend the range by using two axles for the opposing cams. This makes their cams heavier, but also makes them overlap more so that multiple cams will fit the same size crack. This make each cam more versatile and can result in smaller rack sizes.
Most all cams on the market come with a spectra sling attached to the bottom of the stem. This may be doubled which will allow the cam to be set deeper without another sling or draw being clipped to it. This can help reduce walking. Several cams on the market have stems that may be clipped directly without using the sling. While this is normaly considered a bad practice for clipping a rope to a cam, it can give you precious inches in aid situations. When your sling on your cam gets old and ratty, you should replace it with a tied on sling, or send it to one of the companies that repair cams.
The first and most important step in cam maintenance is inspection. Inspect your cams frequently. If you have any reason to doubt the integrity of a camming unit, (or any of your gear) heed your instincts and retire it. You should destroy retired gear to prevent any chance of future use.
Look at the teeth on your cams. If they are worn unevenly or have been flattened in a hard fall, it probably means that the cam has lost its shape and is unsafe to use.
Check for slop between the cams and the axle. There should be some free-play, but too much play indicates that the axle holes in the cams have become oval. Compare the free-play to a new cam of the same size to get an idea of how much is acceptable.
Inspect the cable body carefully. It is okay to tweak the cable to straighten it after a fall, but if any of the wire strands that make up the cable have been broken or severely kinked, the unit needs to be retired.
Look at the springs and cam stops, which can break if the unit is improperly placed and then loaded. Also take a look at the axle. It’s possible to bend the axle of a small unit in a hard fall, in which case it needs to be retired.
The most likely places to find damage to your units are the trigger wires or the sling. Straighten the trigger wires if they become bent. Try to get the wires completely straight so all the cams lobes retract at the same rate. The cam lobes should line up evenly when fully retracted or fully open. Keep an eye on the swaged joint on the trigger wire. It is the most likely place for the wire to fray. If the sling or the stitching show major signs of abrasion, or if any of the stitching is broken, the sling must be replaced.
Care of your cams is a simple process. Keep them clean and dry. If they get wet, don’t just throw them in the closet until the next trip. Dry them off and re-lube them as soon as possible.
Replace the slings if you see any signs of damage or discoloration, after a severe fall, or after five years. Even though your cam slings may show no significant signs of wear, the nylon will deteriorate with the passage of time. Store your cams in a cool, dry place away from U.V. light sources.
To clean your cams use Isopropyl alcohol. Swish the heads in it while working the trigger bar, making sure to keep the slings out of the cleaner. Use a stiff-bristled brush to clean thoroughly all around the head, especially in the springs and inside the cam lobes. If you can find an M-16 brush at an Army surplus store, it is the perfect tool. Depending upon how dirty your cams are and what lubricants you have used in the past, you might need to use a stronger solvent. Often, well-used cams will require several cleanings to work all the dirt and old lube out from the axle. Using compressed air to blow the cams can help. Rinse the unit thoroughly with hot water and then dry thoroughly. No amount of lube will restore good action to a dirty cam, so make sure your cams are cleaned thoroughly.
Now you’re ready to lube your cams and restore like-new actionuse a light oil. I use singer sewing machine oil or 3-in-one oil.
Cams are fairly easy to use, but care needs to be taken to make sure that you get safe and reliable protection from the cam. The most common mistake that beginers make is selecting the wrong size cam. The cam should be