Cams – the quest for the ultimate protection

Cams – the quest for the ultimate protection

Following the invention of the karabiner and the dynamic rope in the first half of the 20th century, the next greatest development in climbing technology must have been the arrival of the Spring Loaded Camming Device (SLCD). The first SLCD’s were developed by Ray Jardine ( see http://en.wikipedia.org/wiki/Ray_Jardine ) in answer to the challenges faced by climbers in Yosemite during the Golden Age of Climbing – the late 1970’s and 80’s. Ray was the genius who worked out the magic angle of 13.75° which allows the cam to exert more force upon the crack sides, the harder the cam’s stem is pulled. Ray sold his invention to a British climbing company on which they built a world class reputation – the Wild Country “Friend” emerged as a the generic name of choice.

The arrival of the SLCD was a big deal because, for the first time, climbers had a piece of protection which could :
• Fit parallel sided cracks
• Where a single unit fitted a range of crack sizes
• Which could be placed quickly with one hand – of particular importance as any climber, who has led trad. routes close to their limit, will tell you.

The SLCD allowed for vast tracks of previously unconsidered rock face to be explored with much greater confidence. Not every one welcomed them, however. Some resistance was voiced by the previous generation of climbers who considered the units “cheating”. The resistance didn’t last long – soon Friends where pretty much the central part of the modern climbing rack.
The original friend had a rigid stem and four cams. While this design worked well, it had a number of inherent problems – like the fact that the rigid stem could would not work in shallow horizontal cracks. The leverage generated by a serious leader fall could bend or break the stem.
Numerous other designs followed; various companies worked on their own styles – HB, Metolius, Faders, Rock Pillars and Kong to name just a few. The arrival of the flexible stem was a significant improvement, and three cam units allowed SLDC’s to be placed in narrower pockets & slots. However the most significant design modification was introduced by Black Diamond. They introduced their Camalots with a double axle – a design which has numerous advantages :

• The dual axle allows a much greater opening & closing range – the average Camelot will cover the range of approximately two single axle equivalents. This translates into two clear advantages :

o When choosing an SLCD to fit a given crack, one is far more likely to get the selection right the first time around when using Camelots
o When choosing to carry a lighter, more compact rack for climbing longer, easier routes, one doesn’t necessarily have to sacrifice as many crack sizes when carrying Camelots as one Camelot will fit more crack sizes.

• The dual axle design is also stronger; for a couple of reasons :

o The impact force from any fall is spread over two axels rather than one – each axle beign much the same thickness as that used on most single axel designs
o The axel design prevents the cams from rotating backwards into a position where they no longer make positive contact with the rock – there by allowing the SLCD to pull out. This was a serious flaw in the original design, which was later counteracted by cam stops. However the very nature of the dual axel design mitigates this possibility – and indeed, Camalots can actually be safely used in a fully “open” format as one would use passive protection like nuts or hexes in V shaped cracks.

• These built in “cam-limiters” also prevents the cam from being compressed too tightly or over-camming – which, in turn, prevents Camalots from getting stuck. Table Mountain itself attests to the truth of this statement as there are numerous stuck single axle SLCD’s dotted along the popular routes on the Ledge – but not a single Camelot.

Initially the Camelots had a dual U stem design, which made them more inclined to walk into cracks, and they were considerably heavier than Friends. These two disadvantages together with their higher cost, made them less popular initially. However a design make over about 6 years ago produced single stem units of about the same weight as many single axel designs and the devaluation of the US dollar relative to the GB pound also made them more competitive – to the point that they have become the design of choice and have dominated SLCD sales in recent years.

The greatest accolade for the design occurred this year when – 20 years after the first Camelots arrived – the patent on dual axel technology expired and no less than three manufacturers launched dual axel designs with immediate effect – including the leading British manufacturer’s DMM – who own Wild Country ! In fact DMM – who are known for their superb engineering – found it virtually impossible to improve on the Black Diamond design, so their new Dragons are almost exactly the same as Camalots but for their clip-in sling.
Some general pointers :

My years as instructor at Cape Town School of Mountaineering allowed me to refine my thinking about SLCD use while teaching others to use them and the following pointers may be useful :

• A successful SLCD placement requires that all four cams make solid contact with the rock.
• In vertical placements, always make sure that the sling of the SLCD points vertically downward – in the same direction as the force that might be exerted during a fall. Diagonally oriented SLCD’s can be ripped into a vertical orientation, thus dislodging the cam’s and increasing the chance of failure.
• In horizontal cracks, place the SLCD with the wider cams down (i.e. on the floor of the crack) which will enhance the stability of the unit and minimise the tendency to “walk” deeper into the crack
• SLCD’s exert much greater forces than “passive” protection (nuts or hexes) and so one needs to me that much more cautious of friable rock
• When encountering a difficult-to-remove (“stuck”) SLCD, the most successful strategy is to get your belayer to take your weight in a position that allows you to get both hands and yours eyes to the unit with ease. Alternatively put in another piece at the same level and hang on that while you work. Get a finger on each trigger and both thumbs on the back of the stem. Pulling both fingers together, push very slightly forward in to the crack at first. This usually releases the cams and allows you to get the unit move outwards.
It is often useful to move the unit sideways into a broader part of the crack while keeping the stem perpendicular to the edge of the crack (i.e. don’t rotate it sideways which often allows the cams to move in different ways which can contribute to more difficulty).
In cases where the SLCD is really stuck , one can use a nut tool to move one cam at a time, and thereby gradually move the unit into a wider area. In these cases, it is very important to be able to see the “lie of the land” within the crack so as to choose which way to move it.
Finally, if you are a novice to this removal process, it is often more prudent to leave the “stuck” SLCD (especially the single axel varieties) alone and climb up to your leader. Tell him about the stuck unit and allow him to go down and fetch it. An experienced hand can often get these units out surprisingly easily.

For more on the history of SLCD development check out : http://http://www.needlesports.com/NeedleSports/nutsmuseum/camsstory.htm

For more on the mathematics and engineering behind the SLCD – check out :
http://http://en.wikipedia.org/wiki/Spring-loaded_camming_device

For more in depth info check out these gear reviews :
http://http://www.supertopo.com/review/Black-Diamond-Camalot-C4

http://http://www.alpineexposures.com/pages/black-diamond-c4-camalot-review