Double-Stop Bobbins

Bobbins are mechanical descenders where the rope path follows the S-shaped path shown in the figure. The braking surface typically consists of two non-rotating bollards fixed to a side plate, with a second pivoting side plate 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 side plates; these holes are aligned when the side plates pivot to the closed position.

Some bobbins have a mechanism that applies additional braking force if the rappeller releases or squeezes (depending on the design) a handle on the bobbin. Plain bobbins, have no such mechanism. I divide the bobbins with such mechanisms into these groups:

1. Stop Bobbins, where the main upper bollard is fixed to the rear plate, the main lower bollard is fixed to a rotating lever that moves in one direction to stop and the other for descending,

2. Double-Stop Bobbins, the subject of this page, where the main upper bollard is fixed to the rear plate, the main lower bollard is fixed to a rotating lever that moves in either direction to stop and to the center for descending, and

3. Near Bobbins, where the two main bollards are attached to a rotating lever. These may have a double stop feature, and attachments to provide for a double stop are available for most of those that do not.

As much as I dislike auto-stop descenders (for a variety of reasons), I dislike double-stop descenders even more. It is very difficult to design a simple double-stop descender that is not strongly affected by rope diameter. Some of these have so little tolerance for rope variations that they are effectively unusable in caving and climbing environments; others have enough slop that I question their effectiveness.

ID	Device ↓	Description	Acquired	Weight ↓	Height ↓	Width ↓	Thickness ↓	Std. volume ↓
2484	Asol	Bent frame, solid spools, cut lower spool, top brake linked to handle, plastic gate	Liao Kangin, 2018	375	227	59	31	404
1494	Beal (ISC) D4	Al frame, SS spools, rotating handle	Expé-Spelemat, 2016	681	197	82	78	1268
2528	Camnal Down	Bent frame, solid spools, cut lower spool, dual top brake linked to handle, stamped gate	Duoqiao Technology (sporting_mall), 2019	352	232	63	31	452
2543	Camp Giant	Forged Al front & rear plates, irregular lower bollard, control handle	Rock N Rescue, 2019	546	187	92	42	730
3068	Chinese	Bent frame, solid spools, cut lower spool, dual top brake linked to handle, stamped gate	hea1985, 2021	349	233	63	31	456
1432	Climbing Technology Sparrow	Irregular bollard /w handle & integral clutch, swinging face plate	Lior Porian, 2015	524	181	86	53	816
1479	Climbing Technology Sparrow 200	Irregular bollard /w handle & integral clutch, swinging face plate	Inner Mountain Outfitters, 2016	548	180	85	53	812
3112	heightec Powerlock D32	SS Frame, Al spring-loaded upper spool, cast SS lower spool on handle /w red plastic grip	Janine Campanile, 2021	732	162	184	30	883
3134	heightec Powerlock D321	Anodized Al Frame, cast SS spring-loaded upper spool, cast SS lower spool on handle /w plastic grip, plastic gate	heightec, 2022	519	206	175	32	1150
1496	heightec Prism D31, Version A	Stamped frame, solid pivoting upper spool (cut), cast hollow lower spool, stop on handle lever extension, aux. anvil, plastic gate	American Alpine Club Store, 2017	510	239	78	31	570
3219	heightec Prism D31, Version B	Stamped frame, hollow SS upper & lower spools, stop on handle lever extension, aux. anvil, plastic gate	Sam Johnson, 2022	495	217	77	32	532
3133	heightec Prism D31, Version C	Stamped frame, hollow SS upper & lower spools, stop on handle lever extension, aux. anvil, plastic gate	heightec, 2022	503	218	77	32	535
3150	heightec Quadra	SS frame /w openings, Al upper spool, cast SS lower spool on spring-loaded plate /w spring/loaded Al handle, plastic grip	break k, 2022	618	200	76	29	447
3148	heightec Quadra D01	SS frame /w openings, spring-loaded hollow cast SS upper spool, cast SS lower spool, spring-loaded metal handle	heightec, 2022	729	185	89	31	516
3135	heightec Quadra D011	Anodized Al frame /w openings, Al spring-loaded hollow upper spool, cast SS lower spool, plastic handle	heightec, 2022	524	210	89	31	572
3149	heightec Quadra D012	Anodized Al frame /w openings, spring-loaded hollow cast SS upper spool, cast SS lower spool, spring-loaded plastic handle & gate	heightec, 2022	527	211	89	32	596
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 D01A	SS frame /w openings, Al upper spool, cast SS lower spool on spring-loaded plate /w spring/loaded Al handle	On Rope 1, 2008	692	185	92	30	507
1431	International Safety Components (ISC) A•B	Bent frame, solid upper spool, solid lower spool (cut), spring-loadedlever /w folding handle & round stop, stamped gate	Jon Edelman, 2015	454	206	65	35	468
1398	International Safety Components (ISC) D2 Escape Descender	Closed Al frame, cast spools, rotating handle, for 7-8 mm rope	Rescue Technology, 2013	290	143	70	61	603
2530	Ito-Rocky	Bent frame, solid spools, cut lower spool, dual top brake linked to handle, stamped gate	Andy Garcia, 2019	372	224	59	30	403
903 2436	Kong Indy	Bent frame, solid spools, cut lower spool reversed, top brake linked to handle, stamped gate	Inner Mountain Outfitters, 2001 Bob Thrun Collection, 2017	476	230	64	31	456
1395	Kong Indy EVO NFPA	Bent frame, cast ribbed spools, top brake linked to handle	On Rope 1, 2013	455	216	62	33	444
3069	Kong Indy Evo Plus	Bent frame, cast ribbed spools, top brake linked to folding handle	TradeInn / Amazon.com, 2021	491	201	57	44	503
1342	Krok Anti-Panic Aluminum, Version A	Bent frame, solid spools, high handle, push-button twist catch, no gate, painted	Gear4Rocks, 2012	345	195	120	33	780
1361	Krok Anti-Panic Aluminum, Version B	Bent frame, solid spools, high handle, push-button twist catch, no gate, painted	Krok (Alex Dniprovsky & Alex Kostromitinov), 2012	408	208	118	33	816
1343	Krok Anti-Panic Steel	Bent frame, solid spools, high handle	Gear4Rocks, 2012	528	194	121	29	689
3016	Krok One-armed Amigo 6061.36 (Однорукий Амиго)	Stamped frame, milled bollards, rotating arm with rope channel, brake handle on arm	Krok, 2021	471	161	108	27	474
1352	Krok Stopor-Desant	Bent frame, solid spools, high handle	Gear4Rocks, 2012	476	150	121	31	560
3187	NewDoar	Bent frame, solid spools, cut lower spool, dual top brake linked to handle, stamped gate	Meituo / Amazon.com, 2022	375	231	58	32	427
565 2432	Petzl I’D. Large, Version A	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate	Inner Mountain Outfitters, 2000 Bob Thrun Collection, 2017	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
2524	Petzl I’D. Large, Version D	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate	On Rope 1, 2019	588	200	83	56	933
2592 +2587	Petzl I’D. Large, Version D with additional closed brake	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate /w closed brake added	I’D: Lisa Seifert, 2021 Brake: KS Rescue, 2021	608	205	81	71	1188
2589 +2588	Petzl I’D. Large, Version D with additional open brake	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate /w open brake added	I’D: Mo Money Pawn, 2021 Brake: Gear Express, 2021	611	205	81	73	1199
556 2433	Petzl I’D, Small, Version A	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate	Inner Mountain Outfitters, 1999 Bob Thrun Collection, 2017	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
2523	Petzl I’D, Small, Version C	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate	On Rope 1, 2019	593	202	82	59	972
2565 +2548	Petzl I’D, Small, Version C with additional closed brake	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate /w closed brake added	I’D: Nicholas Harris, 2020 Brake: Rock N Rescue, 2019	616	202	82	72	1200
2569 +2542	Petzl I’D, Small, Version C with additional open brake	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate /w open brake added	I’D: Angie Beck, 2020 Brake: Amazon.com, 2019	617	202	82	73	1207
2525	Petzl I’D Evac	Irregular bollard /w handle & integral clutch, anti-error catch, swinging face plate /w hook	The Safe Path - Amazon.com, 2019	616	203	83	73	1221
1247	Petzl Rig, Version A	Irregular bollard /w handle & integral clutch, swinging face plate	On Rope 1, 2010	379	177	67	58	679
2522	Petzl Rig, Version B	Irregular bollard /w handle & integral clutch, swinging face plate	On Rope 1, 2019	402	179	70	54	673
3038	Rescue Tech D5 RP885	Closed Al frame, cast spools, rotating handle, for 12.5-13 mm rope	Paul A. Wood, 2021	769	193	97	76	1411
3268	S.E.Peak SE-218	Bent frame, solid upper spools, cut forged lower spool, forged dual top brake linked to handle, stamped gate	Amazon.com, 2023	425	230	60	32	446
3202	SAR A•B	Bent frame, solid upper spool, solid lower spool (cut), spring-loadedlever /w folding handle & round stop, stamped gate	Legit Kit, 2022	455	202	61	36	439
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
3244	Singing Rock / Kong Indy Evo Plus	Bent frame, cast ribbed spools, top brake linked to folding handle	Ondřej Belica / Climbing CZ sro, 2022	485	201	57	44	503
1215 2434	SMC Spider	Milled body, SS cover plate, rear handle	On Rope 1, 2009 Bob Thrun Collection, 2017	554	214	85	41	739
3062	SOB	Bent frame, solid spools, cut lower spool, dual top brake linked to handle, stamped gate	Xinqiang Yu 新强余 (tdcq888), 2021	349	235	63	31	460
2460	SUT	Bent frame, solid spools, cut lower spool, dual top brake linked to handle, stamped gate	Kangjin Liao, 2017	474	232	66	31	479
2539	Vento	Bent frame, solid spools, cut lower spool, dual top brake linked to handle, stamped gate	Artyom Babin (Артём Бабин), 2019	463	232	62	32	456
3366	Vento Crow (Ворон)	Irregular bollard /w handle & integral clutch, swinging face plate	Artyom Babin (Артём Бабин), 2023	559	178	91	53	854
2531	Z&W	Bent frame, solid spools, cut lower spool, dual top brake linked to handle, stamped gate	Duoqiao Technology (sporting_mall), 2019	376	228	58	30	399