Active climbing cam
From DDL Wiki
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The climbing cam is a mechanical device composed of 12 different parts. | The climbing cam is a mechanical device composed of 12 different parts. | ||
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- | ! Part No. !! Name !! Weight (g) !! Qty. !! Function !! Manufacture method !! Picture | + | ! Part No. !! Name !! Weight (g) !! Qty. !! Function !! Manufacture method !! Picture |
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| 1 || spring || 0.5 || 2 || Creates force that pushes the lobes against the crack walls to maintain position until loaded in a fall or removed by climber | | 1 || spring || 0.5 || 2 || Creates force that pushes the lobes against the crack walls to maintain position until loaded in a fall or removed by climber | ||
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! Part number !! Parts!! DFMA !! FMEA !! DFE | ! Part number !! Parts!! DFMA !! FMEA !! DFE |
Revision as of 10:15, 7 February 2007
Contents |
Pre-Dissasembly Phase
User interaction
Inputs
- retraction force from hand
- friction force from rock
- reaction force from rock
Outputs
- force on climbing rope
- force on rock
Function
Spring Loaded Camming Devices
- protect against falls in free or aid climbing
- build removable anchors in rock
- secure a belayer
- mountaineering uses
- mountain rescue
- passive climbing protection
Method of Use
- locate crack
- Identify appropriate size cam unit
- remove cam from harness/chest sling
- grip cam securely
- retract the trigger
- insert in crack, pocket or flake
- find secure placement
- orient the cam with expected direction of force
- retract trigger and remove
- removed either on rappel or by 2nd climber
- replace back on harness or chest sling
Stakeholders
- climber
- rescue workers (mountain rescue)
- insurance companies (health, life & company insurance)
- tourism
- manufacturers
- hospitals
- environment
- retail services
- distributors
Issues associated with use
- having proper size for each type of placement
- dropping the device while climbing
- "walking" in cracks (when device gets stuck in a rock and you cannot remove it)
- with many devices the extra weight is evident
Watch a demonstration video on using a climbing cam that we did in the lab
Part analysis
Manufacture of parts
The climbing cam is a mechanical device composed of 12 different parts.
Part number | Parts | DFMA | FMEA | DFE |
---|---|---|---|---|
1 | spring | cell 1,2 | failure of all 3 springs would result in complete failure of the cam in normal usage. cam could still be partially functional with one or two failed springs but should not be used for climbing. cam could still function as passive protection without springs. | spring may be made leaner, metal can be recycled |
2 | cam lobes | cell 2,2 | failure of one cam lobe by serious deformation would reduce the friction provided by the cam it would also interfere with how the other lobes engaged within the rock. | casting instead of machining to reduce waste metal, recycle metal |
3 | main cable | cell 2,2 | a severed cable would result in the cam no longer supporting the weight of a falling climber. ecessively worn or severly bent cables should be used with extreme caution. | increase durability to maximize first life, recycle material |
4 | thin plastic tubes | cell 2,2 | failure of tubing would excellerate the deterioration of the main cable, thus reducing the lifespan of the product. Failure would also increase force needed to retract trigger. | make plastic tube shorter, recycle plastic |
5 | sling; plastic tube (orange) | cell 2,2 | Failure of tubing would result in faster wearing of main cable and also wearing on nylon slings often looped onto cam and clipped to rope. | less thick plastic, recycle plastic |
6 | trigger | cell 2,2 | Failure of trigger would release trigger cables and make placement and retrieval of cam very difficult yet still possible | use less material, recycle material |
7 | axle | cell 2,2 | Failure of axle by complete fracture would result in a complete failure of the cam yielding it unsafe for use in climbing | use material efficiently, casting instead of machining, recycle metal |
8 | axle ends | cell 2,2 | failure of axel ends would result in a detachment of the axle from the main cable. If both ends were to fail the cam would not support the weight of a falling climber. Failure of one end would result in an unbalanced force on the cam and the lobes would probably be spun free form the rock | use less material to weld, use a lower emission production like join/bend |
9 | finger support | cell 2,2 | Complete fracture of finger support would make retrieval and placement of cam difficult but still safe for climbing | reduce mass, casting instead of machining the holes, recycle material |
10 | spring pin | cell 2,2 | failure of a spring pin would have the same effects as failure of the spring | use less metal, recycle material |
11 | trigger wire | cell 2,2 | failure of all trigger wires would make placement and retrieval of cam extremely difficult, if not impossible in normal climbing situations. Pratial failure of wires would make placement and retrieval difficult. | increase durability to maximize first life, recycle material |
12 | copper connector | cell 2,2 | Failure of the connectors would be very similar to failure of the trigger wires, making it difficult to place and remove the product | use lighter material, recycle less material |
Functionality
On its initial position, the camming device starts with the three lobes aligned horizontally. The trigger is pulled towards the sling using the index and middle finger. This movement slides the trigger down pulling the trigger wires, which are attached to the trigger on one end, and to the lobes on the other end. The tension on the cables causes the lobes to rotate around the axle; the trigger must be pulled until the lobes are completely aligned vertically. During the triggering process, the springs come into action, creating an opposite force that causes the lobes to resist to rotation (and at the same time trying to bring the lobes back to their initial position); the fingers in the trigger must therefore apply resistance to keep the lobes aligned vertically. At this time is when the cam is inserted in the crack. Once the cam is in place, the trigger must be released, causing the lobes to return to their normal position. Now, the springs are in charge of pushing the lobes against the rock walls inside the crack.
Failure analysis
The climbing cam relies mostly on the correct functionality of the lobes, which are the parts in contact with the rock while the device is in place. The lobes rest on the axle and the springs give them the force keeping them against the rock walls. The camming device's main cable is also crucial, since it is attached to the axle and it is the part holding the weight.
Additionally, during climbing more than one cam is used. In case of any single one cam failing, the remaining cams will support the climber(s) from falling.
Customer Needs/Product Requirements
-reliable in a fall
-light weight
-easy and versatile placement
-low cost for user group
-durable and long lasting, able to withstand use in the mountains
-easy to handle
-diverse functionality
-compatible with sizes of older models
-accomdates variety of hand sizes
-intuitive for new users
-easy to retrieve from rock
-fast placement and removal