If you enjoy trad climbing and mountaineering, no doubt you'll have a selection of camming devices as part of your rack. But do you ever check them for damage or wear and tear? If not, then maybe you should, as we find out in this report from the experts at the BMC Technical Committee.
In the early 1970s Ray Jardine conceptualised a spring-loaded camming device as a means of protecting rock climbs; within the same decade Mark Vallance formed Wild Country and with Jardine’s input they took the prototype ‘camming device’ they affectionately named the ‘Friend’ into production. Other manufacturers soon caught on and began producing a range of camming devices with subtle differences but essentially the same primary function. These innovative pieces of equipment revolutionised the way we protect ourselves whilst climbing and the versatile camming device (often abbreviated to cam) is now commonplace on climbing racks around the globe!
Since their introduction, the design has been continually tweaked; culminating in an ever lighter and stronger product. Where the worlds of strong and light collide, they do so with compromise. Innovation has taken this compromise to a level where camming devices are the lightest and strongest they have ever been, allowing a pleasurable climbing experience for most and for those at the forefront to continue pushing the boundaries of what is possible!
On occasions, equipment fails. Even the high quality precisely engineered camming devices on the market today are prone to degradation and eventual failure. It is the aim of this article to investigate one aspect of camming device failure and to draw a number of key learning points along the way.
In 2012, two camming devices were returned to the manufacturer after they failed the owner’s routine inspection. The manufacturers kindly forwarded the remains of the devices to the BMC Technical Committee for a further independent analysis and the dissemination of this information to BMC members.
During the devices use and subsequent further inspection the owner noticed a crunching sound whilst operating the triggers – worrying! Closer visual inspection revealed that individual strands of the flexible stem were snapping with each trigger operation – more worrying! The owner then proceeded to flex the head of the device back and forth until eventually the rigid stem detached from the flexible stem – alarming! (See figure 2).
In case it is not clear – damage from repeated bending may occur where the flexible stem enters the rigid stem (See figures 2&3) and if any strands of the flexible stem are found to be broken then it is very definitely time to retire the camming device!
Figure 2: Camming device flexible stem and rigid stem separated after flexing
Figure 3: Onset of failure where the flexible stem enters the rigid stem
The camming devices inspected are old; but how old is old? Raise your hands if you know the age of each piece of equipment on your climbing rack…. If you are uncertain about the age of a piece of equipment then you can check this with the manufacturer in most cases. There is a link to one manufacturers online camming device age guide at the end of this article. Manufacturers largely offer a conservative estimate of 10 years from first usage for metal components. One of the devices inspected was manufactured in 1996 and as such was operating on borrowed time; the other was manufactured in 2003 and should therefore have been approaching a well-earned and comfortable retirement.
How can a device fail before the manufacturers recommend obsolescence date? We very carefully enter the realm of ‘wear and tear’ (See figure 4).
Figure 4: Camming device Lobe Wear - Yellow 1.0 Camming device (L) High Wear, Red 0.5 Camming device (R) Very High Wear,
The owner of the inspected devices states that they were not strained more than others owned and whilst they have seen much use in both Summer and Winter they have not held many falls. A fair assessment of usage which I guess most climbers would offer something similar when describing the use of their own kit. Figure 4 shows lobe wear on the devices; the Yellow device on the left exhibiting ‘high’ levels of wear and the Red device on the right exhibiting ‘very high’ wear. How do your camming devices look in comparison?
Figures 4 ,5 and 6 are included as an illustration of the level of general wear on the various components of the devices examined; they are not offered as criterion for equipment retirement. It is hoped that these images will act as a comparative with readers own equipment and foster the notion to check for damage where the flexible stem enters the rigid stem as highlighted in figures 2 & 3.
Figure 5 shows wear on the sling, again included for comparative purposes.
Figure 5: Sling Wear – Yellow 1.0 Camming device
Generally speaking, both devices have been heavily used and have probably shared many quality days out on the crags and mountains with their owner! The age of the devices, amount of wear and the owner’s confirmation that the devices have seen much use suggest that the flexible stems of the devices have undergone a very large number of bending cycles. The significant abrasion of the flexible stem shown in Figure 6 further substantiates this.
Figure 6: Camming device flexible stem abrasion
Both devices inspected both failed at the point where the flexible stem enters the rigid stem (Circled in red in figures 2 & 3). Where the flexible stem and rigid stem meet the cable is forced to bend around a very small radius formed by the outer edge of the rigid stem. This increases the bending stress in the cable at this location. Repeated bending i.e. repeated bending stress accelerates fatigue and eventual failure in cables (See figure 7).
Figure 7: Looking into the rigid stem showing the snapped strands of the flexible stem.
Although there have previously been examples of similar camming device failure, these failures are by no means commonly reported to the BMC. Other cases of stem failure that have been investigated, involved devices from a range of manufacturers, though it is important to state that they have each involved devices with a single flexible stem.
What can we learn from this?
• Even the precisely engineered camming devices of today are subject to failure through wear and bending fatigue; this is concentrated at the point where the flexible stem joins the rigid stem.
• On modern flexible camming devices the potential break point is often covered by a protective plastic sheath, in some cases this sheath can be moved slightly to allow inspection.
• Manufacturers – consider revising the sheath design or make transparent to allow owner inspection.
• Thorough inspection of camming devices at the start of the climbing season coupled with inspection before or after each use is strongly recommended.
• Users should also be aware that if equipment is used heavily, it may not last as long as the manufacturer’s estimated life span. Bear this in mind….
• Even if the camming device has seen only moderate use, adhere to the manufacturers guidelines for retiring camming devices
The camming devices inspected were retired after the owner inspected them and found fault. It is much preferred to retire equipment in this manner than to have it fail in use and find out whilst at the sharp end…
Personal equipment inspection is paramount and if there is any doubt in your mind then there is no doubt that retiring and replacing the equipment is by far the best option!
By Paul Knowles (PK)
As well as volunteering for the BMC Technical Committee, PK is Senior Lecturer in Outdoor Studies, Manchester Metropolitan University as well as offering rock climbing and mountaineering instruction through his company Peak Outdoor
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