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I acquired this I'D from Inner Mountain Outfitters in 1999.
The I'D is shaped like an inverted pear (or perhaps an avocado)
with a handle on the back. There are two stamped aluminum plates
with a variety of other parts attached. The rear plate is
black anodized 3 mm. aluminum, and serves as the main frame.
The lower portion of this plate is bent forward, and a 15 by 27.6
mm slot serves as the clip-in eye.
The rear plate has several components mounted on it. Starting from the top, there is a 16 mm. thick rounded triangular anvil mounted at the upper right. Below this to the left is a 60 mm. diameter bollard. Most of the bollard's circumference is grooved to guide the rope. The upper left side of the main bollard is flattened so that the rope can run between it and the anvil. The lower portion is cut away to clear a small post. The main bollard can be rotated about 30 degrees using the handle. Rotating the bollard clockwise squeezes the rope against the anvil, stopping the descent.
The post is slightly grooved, being 12 mm. in diameter at the ends and only 10 mm. in the center. Although the rope runs over the post, its primary function is to limit the rotation of the main bollard.
There is a small toothed cam (pattern (4.3)^2(3)^2(2)) beneath the post. Petzl calls this the "anti-error catch." It does not appear to serve any useful purpose when the I'D is rigged correctly. The cam is asymmetric. Looking at the cam, the left side is parallel to the vertical rear plate, but the right side leans out about 4 mm. There is about an 8 mm. gap between the cam and front plate, so the asymmetry is not needed for clearance.
Finally, a plastic guide runs down the right side of the I'D. Its function is cosmetic.
The front plate is mounted and pivots on a small rivet attached to the lower right corner of the anvil. The fit is quite loose. This plate is stamped into a more complex form than the rear plate. The left side is bent back on itself to create a rounded edge for the rope to run against. The left side is raised so that it clears a slot that engages a rim on the main bollard pivot. A notch in the slot rests against the small bollard. A dimple in the top hits the anvil; unlike similar dimples on Petzl ascenders, this one actually makes contact. A J-notch on the lower portion of the front plate lines up with the oval hole on the rear plate. The notch admits the seat maillon, but the notch is longer so all weight is carried on the rear plate. A plastic safety catch keeps the front plate from accidentally opening, although the shape of the notch would suffice as long as the I'D was weighted.
The
normal rigging path is to bring the rope down the left side, under
the main bollard and smaller bollard, and up between the main
bollard and the anvil, then out the top and over the anvil. The
rope path is much like the classic bobbin rope path.
The main bollard is turned by the handle on the rear of the device. The handle pivots on an extension of the front post, and held on by a 40 mm. diameter aluminum fender washer. A clutch assembly controls the motion. The clutch is not visible without destroying the device. A light spring tends to turn the bollard counter-clockwise, but when used on rope the rope friction completely overpowers the spring. As a result, the behavior of the device on rope is quite different than one would expect after examining the device in the hand. The device works as follows: When viewed from the front, the normal descending position is with the handle at 9 o'clock. The rope friction is turning the bollard so that the rope is squeezed against the anvil Pulling down (counter clockwise) on the handle turns the main bollard counterclockwise, which releases the rope. If the handle is moved too far, the clutch slips and the bollard rotates back to the locking position (clockwise). Pulling the handle lower now turns the bollard clockwise, forcing the rope against the anvil and increasing friction further, much like power brakes.
Turning the handle from 9 o'clock to 1 o'clock does not affect the bollard's position. From this point, the handle moves in distinct steps. The first one (to 2 o'clock) does not rotate the bollard, but the next six steps (turning the handle to 6 o'clock) turn the bollard clockwise, again increasing friction. The distinct steps hold the handle in position. The bollard does not turn uniformly, instead, each step yields progressively less motion.
The front plate is stamped with the Petzl Logo, "I'D", "MADE IN FRANCE","PATENTED", a "reading is dangerous" icon, and an illustration of the device in use. The outside of the rear plate is stamped "99176C", "CE0197", "EN 341 TYPE A", and "MAX 150 Kg /200m." The inside has symbols that I believe are intended to show how the device is rigged. One symbol looks like a shepherd's crook, the other shows a hand holding a rope. The main bollard has "Rope" and "10<Ø<11.5" cast into it.
I haven't finished testing the I'D yet, but here's my preliminary report:
First, The I'D is stamped ""MAX 150 Kg /200m." which clearly indicates that the I'D is not suitable for large persons carrying heavy loads, nor is it suitable for long drops. Although it is common for manufacturers to stamp strength figures into their equipment, one generally does not see a depth limit. I have to commend Petzl for mentioning this. Certainly this is not a device for large persons and heavy loads, such as one finds in expedition caving, big wall climbing, or some industrial settings. It is also not a device for long drops.
I'm not
a fan of control handles, and the one on the I'D doesn't impress
me. The light plastic handle does not inspire confidence. When
the handle is in the normal rappelling position (9 o'clock) one
can stop by pushing the handle down, but I find it easier to brake
as one does with more traditional devices. Locking off involves
moving the handle toward 3 o'clock (or farther), but if you need
your hands free I recommend either tying off or clipping an ascender
on as a backup
Rappelling with the I'D was a surprise since the handle didn't work as I had expected it to; instead, the I'D was locked off most of the time. I tried the I'D on 12 mm. PMI, which is about the largest rope that will fit into the small I'D (there is a larger version of the I'D for the "bigger is better" crowd). The I'D was completely locked for all handle positions between 9 and 3 o'clock. Locking the handle at 3 o'clock and then knocking it loose did not cause me to fall to my death. This is one stop descender that I can not rappel on in the locked position, at least not on this rope. The only way I could descend was to put the handle at 9 o'clock and then pull down on it with my left hand. Building up speed was difficult since pulling too far (and not very far at that) caused the clutch to slip and the I'D would lock off. After a while (about 2 feet) this began to annoy me, but with a little practice and a reserve of patience, I was able to obtain a sustained descent.
The rope leaving the top of the I'D tends to run over the anvil and remain in the plane of the bollard, tracing the traditional bobbin "S" shape. At times it would slide out and run over the edge of the front plate. At no time did it tend to run over the rounded portion of the front plate as indicated by the stamping on the plate.
The eye slot is not large enough or shaped properly for using redundant seat carabiners instead of the safer maillon rapide links.
When rigging the I'D, be careful to rig it high. I found that if the I'D is rigged low, it is difficult to slide it up because the anti-error catch will engage. The catch serves no useful purpose that I know of except for interfering with the natural deselection of those who can't follow the cryptic rigging directions stamped inside the device. Perhaps clearer icons (like an arrow) might eliminate the need for the catch. In my case, most ropes that I use hang vertically and exhibit cylindrical symmetry so the asymmetry of the cam is of no real advantage.
The
ID can also be rigged for lowering. When doing so, use a second
carabiner to guide the braking end of the rope so that it follows
the complet S-shaped path .
The Petzl I'D is protected by U.S. Patents #5,360,083 and #5,577,576. These are worth reading if you are interested in how the internal mechanism works.
Despite my first impressions, the I'D really isn't a bad device.
It apparently isn't strong enough for rescue or industrial use,
and I wouldn't want to expose the clutch to abrasive cave mud,
but it performs much better than I expected and it does provide
a relatively secure stop position. I'm still no fan of stop descenders
for a variety of reasons,
but this one is fun to play with.
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I acquired this I'D from Inner Mountain Outfitters in 1999.
The large Petzl I'D is designed for 11.5 to 13 mm. rope. The external dimensions are identical to the small I'D, and the only easy ways to tell them apart are color (the large one is gray) or by reading the cam casting. It appears that only the main bollard is different (except for the color). It is smaller than the bollard on the small I'D, providing more clearance for larger rope. The main bollard has "Rope" and "11.5<Ø<13" cast into it.
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©2007, Gary D. Storrick