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Poly-Bollards

OK, I'll admit that this is a bizarre name, but it makes some sense because its all I can think of right now. I used to just lump these as miscellaneous descenders, but there are enough of them made to justify giving them their own category.

These devices have three or more bollards that the rope snakes between. At least one of the bollards moves with respect to the others (or else I call it a fixed multibar device), and I specifically exclude stop bobbins with their characteristic S-bend.

We all know that when a rope passes around a post, friction provides a braking action according to the snubbing formula. Poly-bollards may have many posts, but three of them are arranged as shown in the figure. The tension on the rope tends to pull the center bollard into the upper and lower ones, wedging the rope and exaggerating the friction beyond what normal snubbing provides (the mathematics describing this is rather interesting). To move, there must be some means of moving the center bollard away from the others as shown by the arrow. Normally this is done by some form of lever arrangement. One of the important design goals is to provide the proper lever arrangement so that the user can easily control their rappel. Some poly-bollards use a screw instead of a lever to move the center bollard. These do not have an auto-stop capability, but the user can set the screw so that the bollards are pulled together, providing a relatively secure stop position. The autostop feature is viewed as a safety advantage by some. I tend to disagree that it is a safety advantage for a variety of reasons, but I do consider it to be a convenience that is occasionally worth having.

These devices keep the rope running in a plane, so they do not introduce any significant spin.

Gallery

Image ID Device Description Acquired Weight Height Width Thickness Std. volume
Aircraft Materials Ltd., Version A 1113 Aircraft Materials Ltd., Version A Anodized Al frame /w two fixed bollards and side strap, swinging anodized handle /w plastic gip, larger moving bollard on hand lever Paul Hugill, 2007 531 233 97 35 785
Aircraft Materials Ltd., Version B 1262 Aircraft Materials Ltd., Version B Anodized Al frame /w two fixed bollards and opening side strap, swinging anodized handle /w plastic gip, larger moving bollard on hand lever Ron Boomsma, 2010 551 204 99 41 837
Aircraft Materials Ltd., Version C 1201 Aircraft Materials Ltd., Version C Anodized Al frame /w two fixed bollards and opening side strap, swinging anodized handle /w plastic gip, larger moving bollard on hand lever Daniel Griffin, 2009 599 210 97 51 1043
Aircraft Materials Ltd., Version D 1263 Aircraft Materials Ltd., Version D Anodized Al frame /w 4 fixed bollards and opening side strap, swinging anodized handle, larger moving bollard on hand lever Ron Boomsma, 2010 481 191 95 43 784
Fallright Auto Stop DAS 1003 Fallright Auto Stop DAS Anodized Al frame /w two fixed bollards and side strap, swinging anodized handle /w plastic gip, larger moving bollard on hand lever, stop bollard on frame. Fallright International, 2006 722 245 95 40 942
Fallright Controlled Rate Descender Mk. 2 1004 Fallright Controlled Rate Descender Mk. 2 Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and thumbscrew on back plate Steven Ward, 2006 349 132 123 34 549
Fallright Controlled Rate Descender, P/N 071-1 2467 Fallright Controlled Rate Descender, P/N 071-1 Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and thumbscrew on back plate, opening lock Doug Schmitt, 2017 590 148 125 38 690
Gemini Rescue Equip. Gemlok 459 Gemini Rescue Equip. Gemlok Bent anodized Al frame /w four fixed bollards, swinging anodized side plate, larger moving bollard on hand lever. Speleoshoppe, 1994 420 230 67 39 601
Krok Fedya Mirror 1347 Krok Fedya Mirror Steel frame /w  fixed bollards and side strap, swinging steel handle /w plastic gip, larger moving bollard on hand lever, stop bollard on frame. Gear4Rocks, 2012 394 173 67 25 293
Krok Fedya Standard 1346 Krok Fedya Standard Steel frame /w  fixed bollards and side strap, swinging steel handle /w plastic gip, larger moving bollard on hand lever, stop bollard on frame. Gear4Rocks, 2012 369 174 68 26 304
Krok Snail 1363
1393
Krok Snail Stamped rear & pivoting front plate, round handle-actuated cam, two bollards, spring catch.
  • Krok (Alex Dniprovsky & Alex Kostromitinov), 2012
  • Gear4Rocks, 2013
332 87 185 46 739
Lewis, Version A 1335 Lewis, Version A Two fixed bars, movable bar on handle, bent sides, soft anodized, double rope John Marshall, 2012 305 187 74 79 1087
Lewis, Version B 463
2410
Lewis, Version B Two fixed bars, movable bar on handle,bent sides, soft anodized, double rope
  • Speleoshoppe, 1979
  • Bob Thrun Collection, 201
308 190 71 80 1079
Single Rope Technique Belay Stop 554 Single Rope Technique Belay Stop Two fixed bollards on closed frame, one bollard and thumbscrew on spring-loaded swinging plate hinged at clip point, spring-loaded safety pin. Single Rope Technique, 1999 781 167 129 46 991
Single Rope Technique Two Way Stop, Version A 555 Single Rope Technique Two Way Stop, Version A Two fixed bollards and spring-loaded control lever on closed frame, one bollard on spring-loaded swinging plate hinged at clip point, spring-loaded safety pin, disarming nut. Single Rope Technique, 1999 821 213 106 55 1242
Single Rope Technique Two Way Stop, Version B 1401 Single Rope Technique Two Way Stop, Version B One fixed bollard and spring-loaded control lever on closed frame, three bollards on spring-loaded swinging plate hinged at clip point, spring-loaded safety. Jai Andrews, 2013 825 213 105 53 1191
Stab Descender 1150 Stab Descender Stamped frame, handle moves bollard #5, hinged frame Steven Messer, 2008 960 234 91 69 1468
Storrick Double Allp, Version A 1087 Storrick Double Allp, Version A Two double-rope bollards on swinging face plate hinged at clip point, one double-rope bollard and thumbscrew on back plate Dr. Gary D. Storrick, 2007 428 138 108 49 729
Storrick Double Allp, Version B 1121 Storrick Double Allp, Version B Two double-rope bollards on fixed side plates, one double-rope bollard and thumbscrew on swinging central plate hinged at clip point Dr. Gary D. Storrick, 2007 525 139 118 63 1026
Troll Allp, Version A 1120 Troll Allp, Version A Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and painted thumbscrew on back plate Jansen Cardy, 2007 293 135 103 30 424
Troll Allp, Version B 1008
1306
Troll Allp, Version B Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and painted thumbscrew on back plate
  • David Chapman, 2006
  • Speedy-Marquee, 2011
315 132 99 34 443
Troll Allp, Version C 1009 Troll Allp, Version C Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and thumbscrew on back plate Chris Pund, 2006 295 133 100 32 428
Troll Allp, Version D 1122 Troll Allp, Version D Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and thumbscrew on back plate, screw-type safety pin John Sales, 2007 316 134 98 34 447
Troll Allp, Version E 1026 Troll Allp, Version E Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and thumbscrew on back plate, spring-loaded safety pin John Charles, 2007 322 133 103 34 458
Troll Allp, Version F 1147 Troll Allp, Version F Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and thumbscrew on back plate, spring-loaded safety pin Steve Chamberlain, 2008 326 134 102 34 458
Troll Allp, Version G 1309 Troll Allp, Version G Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and thumbscrew on back plate, spring-loaded safety pin proacsafety, 2011 320 134 98 34 439
Troll Pro Allp Tech 584
1112
Troll Pro Allp Tech
Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and thumbscrew on back plate, spring-loaded safety pin
  • Dalloz Fall Protection, 2000
  • Speedy-Marquee, 2011
591 148 92 51 694
Troll (USA) Alp, Version A 1096 Troll (USA) Alp, Version A Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and thumbscrew on back plate Ron Erickson, 2007 305 134 102 31 426
Troll (USA) Alp, Version B 553 Troll (USA) Alp, Version B Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and thumbscrew on back plate, spring-loaded safety pin
  • Troll USA, 1999
  • Paul Hugill, 2007
313 132 99 39 510

Polybollard Weight Chart