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I acquired my Two Way Stop from Single Rope Technique in October, 1999.
The Two Way Stop uses many of the same pieces as the Belay Stop. I've used gray text for the parts of the description that apply to both devices.
The Two Way Stop consists of three bollards. The top and bottom bollard are mounted between two fixed plates, while the third is mounted on swinging plate. The pivot that serves as an attachment post. A lever mounted between the fixed plates controls the position of the swinging plate, and hence the friction.
Each fixed plate is an irregular piece of gold anodized 4 mm. aluminum. The plates are 167 mm. high with curved top and sides. The top half of each plate is about 67 mm wide at the top, increases to 79 mm. about 50 mm. down, then the plates taper to join a 17 mm. diameter circular arc at the bottom. Both plates have a shallow notch at the top right (facing the front of the device) to help hold the rope while tying off. The rear plate has two smaller plates attached to house a spring-loaded catch. The fixed plates are attached to a 13 mm. diameter steel attachment post at the center of the bottom circular arc. The fixed plates are rigidly riveted to the post. The top and bottom rope bollards are also riveted between the fixed plates. A lever made of three layers of 4 mm. aluminum pivots on a rod at the level of the top bollard. This lever moves the swinging plate as described later. A threaded rod on the lever fits into a semicircular arc cut from the front plate. A disarming key on this rod can be tightened to hold the lever in any desired position. A green aluminum stamping folds out from the end of the lever to extend its length.
An irregular swinging plate is hinged to the attachment post. The middle bollard is mounted on this plate. The rivet is extended on the rear side of the swinging plate so that the spring-loaded catch can engage and keep the device closed. The end of the catch spring tends to open the swinging plate. Each end of this rivet has a washer that extends over the sides of the corresponding notches in the fixed plates. A steel plate is riveted to the swinging plate. A roller on the control lever presses against this plate. When the lever is up, the swinging gate can close. Pulling the lever down cams the swinging plate open, decreasing the friction provided by the bollards. This continues until the lever is in the intermediate position. Pulling it further causes the roller to engage the inside of a notch in the swinging plate, which pulls the plate closed, increasing friction substantially.
The bollards are made of stainless steel. The bollards are riveted to the appropriate plate and pinned so they can not rotate. Each rope bollard has a groove that fits into a corresponding notch in the appropriate plate (i.e., the fixed bollards have a notch to clear the swinging plate and vice versa). The bollards are 16 mm. wide, excluding the notch. All three bollards appear to be identical. The bollard diameter is 28 mm. in the center, and widens to 32 mm. about 1 mm. from the edge, then remains constant. The three bollards are mounted 112 mm, 72 mm. and 47 mm. from the center of the pivot point. When the rope is inserted, this asymmetrical arrangement ensures that the rope is pinched between the center and bottom bollards only.
The front piece is covered with stampings, including
The safety catch has an arrow and the word "OPEN" to assist the intellectually challenged.
Like all Single Rope Technique Equipment, the Two Way Stop is well made, rugged, strong, and a bit heavy.
The green lever extension indicates that my Two Way Stop was designed for ropes greater than 12 mm. in diameter. There is a red version for smaller ropes. I assume that there is some more significant difference than the color of the extension (perhaps the steel cam race), although I don't see any immediate reason why mine wouldn't work on smaller rope. I haven't had the chance to thoroughly test the Two Way Stop, so I can't say how it performs with different ropes and under various conditions of mud and water. What I have tested is its performance on clean, dry 11 mm. PMI pit rope, a rather stiff caving rope, on short drops. In these limited tests it has performed very well, despite the fact that I was using a rope that the manufacturer said the device was not suited for. Your mileage may vary, so don't do this. The stop function worked in both directions.
The Two-way stop is designed for the traditional right-handed user who brakes with their right hand at the right hip. Although I'm right-handed, I prefer to brake left-handed, so I'd rather have a mirror-image version, although this hardly is significant enough to be worth worrying about.
One should understand that part of the friction is obtained by squeezing the rope between the center and bottom bollard. As one turns the rod counter-clockwise, it forces the swinging plate in the direction that separates the center and lower bollard, reducing the rope squeezing action. The friction decreases accordingly. This process only continues until there is no more squeezing. After that, there is very little change in friction. This is rather obvious, because there is no large change in the snubbing angle once the bollards are separated. The Two Way Stop addresses the problem of the brain-dead not releasing the stop handle while flying out of control, because pulling and pushing will both stop the Darwin Candidate. The corporate lawyers will love this but for trained users, this feature is less important. Note that Single Rope Technique has provided a disarming key to hold the lever in a desired postion. Skilled users will appreciate this, Darwin Candidates will use it to improve the gene pool.
I don't understand why the Two Way Stop can't do everything the Belay Stop can. They cost the same, so I'd choose the Two Way because of the faster control provided by the lever.
The Belay Stop and the SRT Two Way Stop are both protected by U.S. Patent 6,029,777.
PolyBollard555.html/070318
©2007, Gary D. Storrick
