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 its 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 often worth having.

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

ID Device Description Acquired Weight Height Width Thickness Std. volume

1113 AML 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

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

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

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

463 Lewis Two fixed bars, movable bar on handle, bent sides, soft anodized, double rope Speleoshoppe, 1979 308 190 71 80 1079

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

555 Single Rope Technique Two Way Stop 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

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

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

1008 Troll Allp, Version A Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and painted thumbscrew on back plate David Chapman, 2006 315 132 99 34 443

1009 Troll Allp, Version B 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

1026 Troll Allp, Version C 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

1120 Troll Allp, Version D 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

1122 Troll Allp, Version E 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

584 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 591 148 92 51 694

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

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 313 132 99 39 510

ID	Device	Description	Acquired	Weight	Height	Width	Thickness	Std. volume
1113	AML	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
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
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
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
463	Lewis	Two fixed bars, movable bar on handle, bent sides, soft anodized, double rope	Speleoshoppe, 1979	308	190	71	80	1079
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
555	Single Rope Technique Two Way Stop	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
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
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
1008	Troll Allp, Version A	Two bollards on spring-loaded swinging face plate hinged at clip point, one bollard and painted thumbscrew on back plate	David Chapman, 2006	315	132	99	34	443
1009	Troll Allp, Version B	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
1026	Troll Allp, Version C	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
1120	Troll Allp, Version D	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
1122	Troll Allp, Version E	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
584	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	591	148	92	51	694
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
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	313	132	99	39	510