Stop Bobbins

Bobbins are mechanical descenders where the rope path follows the S-shaped path shown in the figure. In general the braking surface consists of two non-rotating bollards fixed to a sideplate, with a second pivoting sideplate provided to keep the rope from jumping off the other end of the bollards. A third (usually smaller) bollard may be provided. The seat maillon usually attaches to holes in extensions of the two sideplates; these holes are aligned when the sideplates pivot to the closed position.

I distinguish true bobbins from false bobbins by whether the spools (or bollards) move with respect to the frame. On true bobbins the center of the spools is fixed although the spools may rotate (on stop bobbins, the lower one usually does). On false bobbins, the center of the spools can move. I don't believe that there is necessarily any advantage of true bobbins over false bobbins or vice versa, it's merely a means of classification. Stop bobbins have a mechanism that applies additional braking force if the rappeller releases or squeezes (depending on the design) a handle on the bobbin. Sometimes the additional friction is enough to stop the rappeller, which possibly transforms the resulting injury from impact trauma to harness suspension trauma.

I find that the Petzl Stop is more likely to stop me than the Diablo, Dressler or Kong - in fact, on a clean rope, I can often rappel with these locked off. The Petzl I'D is a complex device that I've included here after trying it and seeing that the rope follows a bobbin "S" instead of the odd path shown in the instructions. The Tracson is another complex device that I've included here rather than create a new category. It combines a Jumar-type cam with a bobbin into a single rappel and ascent device. I would not like to rely on the stop feature because of the sharp cam teeth. My Tracson bent each of the first two times I tested it, so I haven't used it since. Its an interesting idea, but I think it needs more work to be practical.

ID	Device	Description	Acquired	Weight	Height	Width	Thickness	Std. volume
431	BO.VE Diablo	Bent frame, solid spools, round brake, no-stop lock, stamped gate	Repetto Sport, 1982	327	223	63	32	450
432	Dressler DAD	Bent frame, irregular cast spools, open top	Repetto Sport, 1982	247	179	51	32	292
1168	heightec-PMI Powerlock	SS Frame, Al spring-loaded upper spool, cast SS lower spool on handle /w red plastic grip	On Rope 1, 2008	737	162	184	30	878
1169	heightec-PMI Quadra	SS frame /w openings, Al upper spool, cast SS lower spool on spring-loaded plate /e spring/loaded Al handle	On Rope 1, 2008	692	185	92	30	507
522	Kong	Bent frame, solid spools, cut lower spool, top brake linked to handle, stamped gate	Inner Mountain Outfitters, 1996	397	230	65	32	478
433	Kong-Bonaiti	Bent frame pivots at top bar, solid spools, cut lower spool, top brake linked to handle, stamped gate	Speleoshoppe, 1982	400	239	60	30	430
903	Kong Indy	Bent frame, solid spools, cut lower spool reversed, top brake linked to handle, stamped gate	Inner Mountain Outfitters, 2001	476	230	64	31	456
565	Petzl I'D. Large, Version A	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate	Inner Mountain Outfitters, 2000	526	194	83	54	870
1166	Petzl I'D. Large, Version B	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate	Rescue Response Gear Inc., 2008	525	203	79	52	840
1218	Petzl I'D. Large, Version C	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate, horizontal mode button	On Rope 1, 2009	550	212	80	54	912
556	Petzl I'D, Small, Version A	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate	Inner Mountain Outfitters, 1999	536	194	83	54	870
1219	Petzl I'D, Small, Version B	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate, horizontal mode button	On Rope 1, 2009	558	212	80	54	912
435	Petzl Stop, Version A	Bent frame, solid upper (cut) & lower (/w steel brake) spools, stamped gate	Repetto Sport, 1982	289	225	61	33	453
436	Petzl Stop, Version B	Bent frame, solid upper (cut) & lower (/w steel brake) spools, stamped gate	Caves Unlimited, 1984	302	226	64	32	463
437	Petzl Stop, Version C	Stamped frame, solid upper spool (cut), cast lower spool /w stop, aux. rod, stamped gate	John E. Weinel, Inc., ~1987	327	240	63	32	484
438	Petzl Stop, Version D	Stamped frame, solid upper spool (cut), cast ribbed lower spool /w stop, aux. rod, stamped gate	Bob & Bob, 1991	322	225	62	32	446
541	Petzl Stop, Version E	Stamped frame, solid upper spool (cut), cast ribbed lower spool /w stop, aux. rod, plastic gate	TSA, 1997	325	223	68	32	485
451	Russian, Version A	Bent frame, solid upper spool (cut), solid lower, stamped gate	Theresa Williams/Maury Benamy, 1995	255	220	62	27	368
518	Russian, Version B	Bent frame, solid upper spool (cut), solid lower spool /w round stop, aux. rod, wire gate	?	246	222	55	32	391
973	Russian, Version C	Bent frame, solid upper spool (cut), solid lower, aux. rod, stamped gate	Ural Sport, 2004	286	208	74	30	459
1013	SAR Scarab, Version A	Bent frame, solid upper spool, solid lower spool (cut), lever /w round stop, stamped gate	SAR, 2006	436	195	62	35	419
1029	SAR Scarab, Version B	Bent frame, solid upper spool, solid lower spool (cut), lever /w round stop, stamped gate	SAR, 2007	430	195	62	35	419
1211	SAR SARAB	Bent frame, solid upper spool, solid lower spool (cut), spring-loaded lever /w folding handle & round stop, stamped gate	SAR, 2009	470	206	65	35	472
1215	SMC Spider	Milled body, SS cover plate, rear handle	On Rope 1, 2009	554	214	85	41	739
452	Voynett S.A.R.L. Tracson	Combination bobbin and ascender	Repetto Sport, 1982	580	192	107	50	1027

True Stop Bobbins