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Double-Stop Bobbins

Rope PathBobbins 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 attachedU 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.

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ID Device Description Acquired Weight Height Width Thickness Std. volume
Beal (ISC) D4 1494 Beal (ISC) D4 Al frame, SS spools, rotating handle Expé-Spelemat, 2016 681 197 82 78 1268
Camp Giant 2543 Camp Giant Forged Al front & rear plates, irregular lower bollard, control handle Rock N Rescue, 2019 546 187 92 42 730
Climbing Technology Sparrow 1432 Climbing Technology Sparrow Irregular bollard /w handle & integral clutch, swinging face plate Lior Porian, 2015 524 181 86 53 816
Climbing Technology Sparrow 200 1479 Climbing Technology Sparrow 200 Irregular bollard /w handle & integral clutch, swinging face plate Inner Mountain Outfitters, 2016 548 180 85 53 812
heightec Powerlock D32 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
heightec Powerlock D321 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
heightec Prism D31, Version A 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
heightec Prism D31, Version B 3133 heightec Prism D31, Version B Stamped frame, hollow SS upper & lower spools,  stop on handle lever extension, aux. anvil, plastic gate heightec, 2022 503 218 77 32 535
heightec Quadra 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
heightec Quadra D01 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
heightec Quadra D011 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
heightec Quadra D012 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
heightec-PMI Powerlock 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
heightec-PMI Quadra D01A 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
ISC A•B 1431 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
ISC D2 Escape Descender 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
Petzl I'D. Large, Version A 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
Petzl I'D. Large, Version B 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
Petzl I'D. Large, Version C 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
Petzl I'D. Large, Version D 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
Petzl I'D. Large, Version D 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
Petzl I'D. Large, Version D 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
Petzl I'D, Small, Version A 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
Petzl I'D, Small, Version B 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
Petzl I'D, Small, Version C 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
Petzl I'D, Small, Version C 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
Petzl I'D, Small, Version C 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
Petzl I'D Evac 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
Petzl Rig, Version A 1247 Petzl Rig, Version A Irregular bollard /w handle & integral clutch, swinging face plate On Rope 1, 2010 379 177 67 58 679
Petzl Rig, Version B 2522 Petzl Rig, Version B Irregular bollard /w handle & integral clutch, swinging face plate On Rope 1, 2019 402 179 70 54 673
Rescue Tech D5 RP885 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
>SAR A•B 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
SAR Scarab, Version A 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
SAR Scarab, Version B 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
SAR SARAB 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
SMC Spider 1215
2434
SMC Spider Milled body, SS cover plate, rear handle
  • On Rope 1, 2009
  • Bob Thrun Collection, 2017
554 214 85 41 739

Double-Stop Bobbins Near Bobbins Bobbins Bobbin Weight Distribution