No46.  Multicender  Rope Runner Pro

 

Rope Runner, Rope Runner Pro, Unicender, Rope Wrench, Chicane/ZigZag, Akimbo, Hitch Hiker.
(https://www.works-odsk.com/srt-by)

 

 I will analyze two aspects of work at height positioning systems, fluidity and safety, from aJapanese and European perspective, and contextualise this in regard available SRS belay devices.
 

Ascent - hitch (rope), mechanical hitch, mechanical device,
Descent - double hitch, hitch + wrench, mechanical hitch + Wrench, mechanical device
Diagonal descent / jumps - low pressure release of belay, gentle deceleration
Shock load - Slipping motion at 6kN

 

Ascent
The belay device should change to a neutral mode on ascent and become close to frictionless as the foot and knee ascender take charge.  
Any belay device should function to lock closed on the rope when the climber decides to put their weight into it, and so a hitch by itself is not an unsafe way to climb, but it should be remembered that descent is difficult and could be dangerous.  When paired with a separate friction tool a hitch is manageable but still not advisable as better tools are readily available. The ZigZag (Petzl) is the same, in their instruction ascent is allowed, weighting the rope is allowed, but descent prohibited unless a separate friction tool is used, exactly the same as a hitch. When attempting to release a hitch on a Stationary Rope System the climber will at first experience an intense tightening and thus need to use an over abundance of force. This burst of released energy will induce a fast and uncontrolled descent, melting the hitch, rope and skin, bringing the climber to a sudden stop with possible dangerous peak loading at the anchor.
SRS devices can change from neutral ascent, to lock and then descent, it is taken as granted that this three way mechanism is available in a variety of devices. It should be noted that there is a lexicon of tools and techniques that preceded the SRS ‘Multicender’ and in gaining simplicity modern climbers have lost a number of very interesting techniques.

 

Descent
There are some devices that have been used by Rescue and other Work at Height disciplines for many years that typically are not used by modern SRS climbers. Petzl’s I’d and RIG, ISC’s D4 are well known and there are many other ‘box cam lever’ devices from lesser known companies. The box cam device is simple in design and function and allows a lot of pressure to be applied to the rope in a small area. This pressure is released by opening out and then pulling a lever. These devices are popular with rock climbers too, Trango’s Cinch is one that found a loving home on the Arborists side lanyard.
The box cam lever is usually operated with one hand on the lever and a braking hand on the rope next to ones hip, this is a typical descent technique. Climbers that operate in an up and down environment can usually afford to give up both hands for descent. Recommended descent speeds relate to the heating up of materials, TAZ clearly state a maximum descent speed in their literature for the Lov2.


It is possible to use two hitches, stacked one above the other, this spreads the loading over a larger area of rope. Climbing is cumbersome but this is an interesting technique to have in your toolbox.
Kevin Bingham created the Rope Wrench and paired to a single hitch can be used. Petzl’s mechanical hitch (ZigZag) can also be paired with the Wrench (Chicane) and finally there are bonafide mechanical devices. In conception order, Unicender, Rope Runner, Bulldog Bone, Akimbo and most recently the Rope Runner Pro. All these mechanical devices share some similarities and differences in design. The Unicender has a small lever action which relates directly to the difficulty of one handed operation, fortunately there are two modes of operation, wrapping rope around the body of the Unicender allows easy descent operation. Rope Runner, Bulldog Bone and Akimbo all use a lever action but it is the Runner that has the smoothest action due to it using three points of contact and the longest lever. Between the top and middle friction point of the Runner there is a unique and complex motion that allows instant reaction and manipulation of pressure and speed. Like the Bulldog Bone, Akimbo, Hitch/Wrench and ZigZag, the Runner can be operated with a single pulling motion for descent but novel to it the Runner can be released at the top friction point (opened) and pushed (closed) at the second friction point. It is a complex yet
easy to use mechanism that allows greater control.

 

Diagonal Descents
A person stands on one side of a river wanting cross to the other side. They have two options, walk 10M’s along the bank, 5M’s across a bridge and then 10M’s back. Or take a running jump to cross directly. Tree climbers have the same options, either descend to the crotch of the lower branch and then climb upwards and outwards along it. Or use energy contained in the pendulum to jump diagonally downwards. It is not for me to say which one is best or safest but ‘jumping’ becomes a natural movement and is best achieved with one hand operating the belay and one hand outstretched to the incoming target. Swinging on the pendulum and releasing the belay is a dynamic and exciting action but in truth the movement of the belay device covers no more distance than 3M, and usually much less, so that materials at the contact points do not heat up dramatically.
(There is much more heating with a prolonged vertical descent.)
All of the Multiscenders listed at the top of the article allow two aspects, a clear vertical channel for the rope to run through and low pressure release response when descending and while ‘one handed jumps’ are not typically taught to beginners, it is a key technique for Arborists and will build naturally into ones movement vocabulary.

 

Shock Load
It is said that 6kN is a breaking point for the human body in a Sit harness, any loads above this cause serious internal damage. Parachute harnesses allow much higher peak loads but it is from the bottom up that we may find use with the mechanical device through tailoring the friction efficiency to loads well below 6kN. Tests run at ODSK show slippage as low as 2.5kN for some devices. In fact, anybody that has experienced the Runner and Bulldog Bone will understand that a fast descent never stops immediately but brakes slowly. If it were a car one would want this mechanism rather than emergency style stoppage and of course one can easily imagine the lower peak loads at the anchor point.

 

To say this clearly, a mechanical device offers less resistance than a rope, can decelerate slowly and have in built slippage if the climber slips off a branch.
 

Rope Runner Pro
Did you watch Kevin Bingham climb in the RRP advertisement video? Kevin is a very talented climber, look at how simple his set up is, no foot ascender or rope rocket, he footlocked about twenty meters and simply floated around that huge tree.
There has been some changes to the device that has refined it, most strikingly is the softness of the edges and if we look a little closer at it we see three slick pins. It has been designed to open and close without the parts separating, so when transferring at height there are no droppable parts. The karabiner attachment and pulley mechanism is similar but has been constructed in a clever way. There is a centralized point for attaching a chest harness and above this there are markings 1,2,3,4,5 for noting adjustment settings for different ropes. The tolerance of the bollard adjustment means that these markings are general at best. What I see as the biggest change is the addition of a plastic block next to the upper spine which stops the head from lowering past a specific point when moving upwards and creates a near frictionless tool for ascent and other upward movement in the
crown. A shocking thing is its amazing ability to tend slack, even in difficult positions with flat rope angles. The Runner is known for its ability to tend slack when climbing vertically but I was taken aback to see it tend slack by itself with a flat diagonal rope angle. The friction points are not flat but concave so there is no ‘breaking in’ period, it is fast slick and smooth from the start.
I am a TRT climber but have been so impressed with the RRP that I decided to use SRS for a while again. I positively recommend this device as an upgrade from the original or for a climber new to mechanical tools.