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Petzl Double-rope Bobbins

Version A Version B Version C
Version A Version B Version C

Overview


Version A
(#1207)

Front View Rear View Side View
Front View Rear View Side View
 
Front View: Open for Rigging Rear View: Open for Rigging
Front View: Open for Rigging Rear View: Open for Rigging

Technical Details

I acquired my Petzl double rope Version A used on eBay from Albéric Sibille in 2009. It is the oldest bobbin on this page.

Version A is 197 mm. tall, 45 mm. wide, 41 mm. thick, and weighs 305 g. The side plates and bollards are much like those on Version B. Like Version C, Version A has a quick-attachment feature. The attachment point on the fixed side plate is a 24 mm. high by 14 mm. wide (worn) hole located 3 mm. off center. A similar hole on the pivoting side plate has been cut open on the narrow side, so the side plate resembles a hook. The opening of the hook is covered by a spring loaded, stamped steel, sheet metal gate riveted to the side plate.

The pivoting side plate is stamped with has "F. PETZL" inside an oval and "FRANCE." The fixed side plate is stamped "2652." The bolt heads have "U V" and "A 2" in raised letters.

Comments

The gate is crudely made and the spring is quite weak, although this might be related to its age. The large tab makes the gate rather easy to operate, but also makes it easy to open by accident. Some people believe that this contributed to my friend's death. I don't know for sure, but I prefer a more secure gate.

Albéric sent me a spare set of bollards that fit this bobbin. The lower one id substantially the same as the one on the bobbin, but the upper one had U-shaped rope grooves. The bolts in the spare bollards were unmarked, rusted, and had heads that were only 2.8 mm. tall. These might be the original bolts.

I suspect that the "2652" was a previous owner's identifying mark.


Version B
(#439, 1232)

Front View Rear View Side View
Front View Rear View Side View
 
Front View: Open for Rigging Rear View: Open for Rigging
Front View: Open for Rigging Rear View: Open for Rigging

Technical Details

Al Fincham acquired this descender for me from Rocksport in Somerset, U. K. in 1981. I acquired a second one used (but in like-new condition) on eBay from Susan Wooly in 2009. I acquired another in 2017 as part of Bob Thrun's collection.

My Petzl, double rope Version B is 194 mm. tall, 45 mm. wide, 41 mm. thick, and weighs 311 g.

As in the single rope bobbin Version B, there is a fixed and a pivoting side plate made of 32 by 3.3 mm. aluminum. The upper end of the fixed side plate is bent inwards in a quarter circle, while the upper end of the pivoting side plate is bent into an 11.4 mm. I.D. inverted U-shaped channel. The end of the side plate is cut so that when closed, approximately 2/3 of the width of the side plate is in contact with the upper bobbin,. The remainder is cut away to allow clearance for opening the bobbin. When the bobbin is in use the side plates keep the rope on the top bollard, and the end of the top side plate keeps the rope from jumping between the two grooves in the top bollard. The lower ends of the side plates are bent to converge at the attachment point, which consists of a 13 mm. hole in each side plate. These holes are beveled on both sides. The bollards are turned aluminum with a milled slot to keep them from rotating on the fixed side plate The lower bollard has a single wide rope groove, while the upper bollard has independent grooves for the two ropes. The bollards are bolted to the fixed side plate with 7 mm. A2 bolts. The pivoting side plate pivots on the lower bolt and has a slot to allow clearing the upper bolt. The lower U-groove bollard is mounted through a hole in its center, but the upper V-groove bollard uses an off-centered arrangement to allow a smaller clearance slot in the upper side plate.

The pivoting side plate is stamped "PETZL," and "FRANCE." The bolt heads are marked "UV" and "A2."

Comments

This bobbin is substantially larger than its single rope equivalent, and so one may be inclined to choose the smaller version on weight considerations alone. The disadvantage of this choice is that single rope bobbins effectively can not be used on double rope rappels, and hence can not be relied on when conditions are not known with absolute certainty in advance. My experience suggests that one will eventually encounter situations where a double rope rappel is needed. Single rope bobbin users will not be able to deal with these situations unless they have a second rappel device available. This is a small argument against using bobbins as opposed to other devices. Double rope bobbins do not have this disadvantage, and can be used on single ropes as well.


Version C
(#440)

Front View Rear View Side View
Front View Rear View Side View
 
Front View: Open for Rigging Rear View: Open for Rigging
Front View: Open for Rigging Rear View: Open for Rigging

Technical Details

Al Fincham acquired this descender for me from Rocksport in Somerset, U. K. in 1981 (at the same time as Version B).

My Version C is 191 mm. tall, 45 mm. wide, 41 mm. thick, and weighs 324 g.

This version differs from Version B in two ways. First, it has a quick-attachment feature similar to that on the single rope Petzl bobbin Version C. Second, the lower bollard has a U-groove for each rope rather than a large common one. The bolts are about 1 mm. too short to completely extend through the nuts.

The pivoting side plate is stamped with an icon illustrating how the descender is threaded, but anyone who needs this assistance shouldn't be using a bobbin anyhow. It is also stamped "PETZL," "MAXI 1500 KG," and "FRANCE." The bolt heads are unmarked.

Comments

All of the comments on the single rope Version C quick attachment feature apply here as well. The lower bollard design is substantially different than that of double rope Version B, but I find very little difference in the performance characteristics of the two, since they are both too fast for my taste. Lighter cavers might notice a difference. When a double rope bobbin is rigged for extra friction during a single rope rappel, the two groove design has the advantage of keeping the rope paths separated on the lower bollard, where the directions of rope motion may be opposite.