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True 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.

Bobbins are quite popular among European cavers, but then again, they all seem to use almost exactly the same system. This has advantages, but stifles creativity. I've used bobbins as my short-drop device, but they really don't have enough friction for my weight (I'm 1.91 m, 88 kg), especially when I'm carrying a heavy load. They should work better for a 50 to 60 kg lightweight.


Gallery

Image ID Device Description Acquired Weight Height Width Thickness Std. volume
Austrian 430 Austrian Rod frame, solid spools, lower spool cut & pivots on frame, noncommercial Peter Ludwig, 1991 195 143 45 40 257
John Woods 1471 John Woods Bent frame, unfinished, 2 groove Petzl spools, sheet metal  gate John Woods, 2015 269 207 47 36 351
Keychain Bobbin 2416 Key Chain Bobbin Bent frame, solid spools.
UNSAFE! Decorative use only.
Bob Thrun Collection, 2017 17 56 13 12 9
Kong-Bonaiti Doble 434
2421
Kong-Bonaiti Doble Bent frame, solid spools, plastic gate
  • Inner Mountain Outfitters, 1994
  • Bob Thrun Collection, 2017
269 193 55 32 340
Kong Banana 951 Kong Banana Curved bent frame, solid spools, aux bar, stamped gate Inner Mountain Outfitters, 2004 233 193 55 30 316
Orcus 1465 Orcus Bent frame, unfinished, solid spools Ondřej Belica, 2015 248 187 46 37 318
Petzl, double rope, Version A 1207 Petzl, double rope, Version A Bent frame, unfinished, 2 groove upper spool, 1-groove lower spool, stamped gate Albéric Sibille, 2009 305 197 45 41 359
Petzl, double rope, Version B 439
1232
2418
Petzl, double rope, Version B Bent frame, unfinished, 2 groove upper spool, 1-groove lower spool
  • Al Fincham, 1981
  • Susan Wooly, 2009
  • Bob Thrun Collection, 2017
311 194 45 41 358
Petzl, double rope, Version C 440 Petzl, double rope, Version C Bent frame, unfinished, 2 groove spools, stamped gate Al Fincham, 1981 324 191 45 41 352
Petzl, single rope, Version A 1206 Petzl Simple, Version A Bent frame, unfinished, solid spools, stamped gate Albéric Sibille, 2009 214 193 44 31 258
Petzl, single rope, Version B 1220 Petzl Simple, Version B Bent frame, unfinished, solid spools, stamped gate Mariana Oliveira, 2009 214 193 45 26 226
Petzl, single rope, Version B 2317 Petzl Simple, Version C Bent frame, unfinished, solid spools Bob Thrun Collection, 2017 233 192 45 31 266
Petzl, single rope, Version C 441 Petzl Simple, Version D Bent frame, unfinished, solid spools Speleoshoppe, 1979 220 187 45 31 261
Petzl, single rope, Version D 442,
1185
Petzl Simple, Version E Bent frame, unfinished, solid spools, stamped gate
  • Speleoshoppe, 1979
  • Hawill's Ltd., 2008
240 182 45 31 254
Petzl, single rope, Version E 1242 Petzl Simple, Version F Bent frame, soft anodized solid spools, stamped gate Francois Gelinas, 2009 236 189 45 31 261
Petzl, single rope, Version F 444 Petzl Simple, Version G Bent frame, solid spools, aux. bar, stamped gate John E. Weinel, Inc., ~1987 248 195 45 32 281
Petzl, single rope, Version G 443
2419
Petzl Simple, Version H Stamped frame, solid spools, aux. bar, stamped gate
  • 1990
  • Bob Thrun Collection, 2017
248 195 45 32 281
Petzl, single rope, Version H 1010 Petzl Simple, Version I Stamped frame, solid spools, aux. bar, plastic gate Inner Mountain Outfitters, 2006 237 197 42 32 267
Repetto (C.T.) Bis-Bang 1160 Repetto (C.T.) Bis-Bang Stamped frame, large Al & small steel solid spools, aux. bar, stamped gate, double rope Expé-Spelemat, 2008 247 177 56 41 407
RB 1469 RB Bent frame, unfinished, 2 groove upper spool, 1-groove lower spool Olivier Peron Caillet, 2015 313 199 45 43 383
Repetto Spider 929 Repetto Spider Bent frame, solid spools, aux. bar, stamped gate Inner Mountain Outfitters, 2003 251 197 52 29 297
Repetto Spider 2415 Rocksport Buggery Box Fixed Al Plate & bent Al cover, bronze bollards Bob Thrun Collection, 2017 314 155 49 30 233
Russian 450 Russian Bent frame, solid spools, aux. bar, wire gate 1994 353 195 45 32 281
Unknown "S" 1163 Unknown "S" Bent frame, solid cylindrical spools, noncommercial Bill Boehle, 2008 245 203 38 38 298

Stop Bobbins False Bobbins Bobbin Weight Distribution