Front	Rear	Open for Rigging

Technical Details

I acquired this descender from Gear4Rocks in 2013. Gear4Rocks is the same company as Krok, the only difference is that the Krok trademark sells gear only inside the Ukraine, and the Gear4Rocks trademark was created to spread Ukrainian gear around the world.

The SUR is 244 mm. tall, 50 mm. wide, 37 mm. thick, and weighs 561 g.

The SUR disassembles into two pieces. The body consists of a 3.15 mm. galvanized steel plate with a 38 mm. tall, 138 mm. wide punched oval top hole and a 19.8 mm. tall, 138 mm. wide punched oval bottom hole. The top has two shallow rope notches in the sides of the plate to facilitate tie-offs. The bottom is slightly tapered. There are four aluminum bollards and two half-bollards riveted to the plate, each with two 5 mm. steel rivets. The top bollards are 33 mm. diameter and 16.2 mm. thick. Each one has a 12.7 mm. wide U-groove that gives the bollards a 21.2 mm. minor diameter. The groove is off-centered so that the edge is only 1 mm. from the back plate. The front of each bollard is cut away along horizontal chord lines so that the front height is 21.5 mm., giving room to rig the rope. The two half-bollards have similar dimensions as the top four, but are cut away on the sides and bottom, and mounted side-by-side near the edge of the plate, giving a central rope channel. The right bollard has a 3.15 mm. steel guide sharing the rivets holding it to the main plate.

The cover is a galvanized rectangular channel stamped from 1 mm. steel plate with an open rope channel in the back and four holes in front. It slides over the main assembly from the bottom. When in place, the front holes are aligned with the space between the bollards, allowing one to see how many bollards are actively rigged. A 7.7 mm. spring-loaded stainless steel pin fitting through a hole in the top bollard acts as a cover retainer. This pin has a 12 mm. head and a 5 mm. groove for the cover. It is held in place with a washer and cotter pin on the rear of the main plate. The pin engages a slot in the top of the cover. Pushing the pin in allows attaching or detaching the cover. The slot is 5.6 mm wide and terminates in an 8.3 mm. circle.

The rope guide is stamped "3506 09." The front cover is stamped with "Л," "П," "13," "123," "90," "100," "23," "12 "70," "80," "1," "2," "60," "65," "09," and "3506."

Comments

As with any enclosed device, heavy mud conditions can pose a problem.

I do not particularly like the cotter pin retaining the cover pin. The cotter pin has sharp ends that can catch on various things in my pack.

One can rig the rope around the upper bollards in various ways. The large numbers stamped on the cover represent relative friction for various rigging combinations, but he instructions did not explain these clearly. The upper number represents which slots between the bollards are used, and the bottom numbers represent the rappeller’s mass in kg. The following illustration, adapted from the Krok web site, provides more clarity:

The SUR was designed "for use by the military when landing from helicopters on rope ropes with a constant descent speed of the paratrooper without using manual braking control. That is: go down and fire at the enemy." For those of us who don't have any surviving enemies, we can consider the SUR’s possible caving and climbing applications. These are not its design purpose, and so it is of no surprise that it is not the optimal choice for either of these.