Front	Rear	Top

Front: Handle Extended	Front: Open for Rigging

Technical Details

I acquired my SUM from Devonshire Imports in 2006.

The SUM consists of three major forged aluminum pieces: back, rotating block, and cover plate. The back is shaped like a teardrop turned horizontal, with a 15x19 mm. eye at the narrow end. A steel pin near the eye engages a slot in the cover plate. A cylindrical boss centered on the large end provides an axle for the rotating block. This axle is about 33 mm. in diameter, and without tearing the SUM apart, I'm not exactly sure how it was assembled. Obviously there is a lip of some sort. Anyhow, two projections from the boss form the central segment of a rope channel, and a steel pin lines the one wear point on this channel.

The pivoting block rotates around the boss. The outer diameter of the block is about 64.5 mm. A plastic handle snaps into a handle extension on one side of the block. The handle lies above the eye on the rear frame. There are two slots in the perimeter of the rotating block. With the handle closed against the eye, the slots align with the slot in the center to let the rope run freely. When block pivots counter-clockwise, the slots lose their alignment and pinch the rope at the circle of separation. Two steel pins on the rotating block protect the major wear areas.

The cover rotates on a pin at the end of the rear block opposite the eye.

The rear of the back piece has "SUM" and "FadeRS" cast into it, as does the front of the cover. The cover also has a number of printed marks: a climber icon near the rope exit point, a hand-holding-a-rope icon near the rope entry point, "WARNING: Training and check needed before use," "International Patent Pend -Made in Spain-EEC," a Reading-Is-Dangerous icon, "UIAA," a "1" in a circle, "ROPE Ø 9.1-10.5," "105," and "CE-120." The pivoting block has a bas-relief casting showing a climber and braking hand on a rope, indicating the proper rigging.

Comments

The workmanship on the SUM is excellent, and it functions well. It is a bit large and heavy for me to lug around for my routine trad climbing, but it might make a good climbing gym device. I might justify carrying it on wall climbs. Basically, the SUM seems to be a good choice in the same situations that one might use a Petzl Grigri or a Trango Cinch, but the SUM is the heaviest of the three.

My greatest complaint with the SUM is that it is relatively sensitive to rope diameter, and the old-school norm of an 11 mm rope falls outside the range specified for the SUM. The SUM does not work well on oversized ropes, since it cannot open enough to let them feed well.

The instructions state that the belayer must let go of the SUM to catch a fall. Read this carefully, since they do NOT say to let go with the braking hand. Although the SUM may still catch, one should always keep the braking hand on the rope. Since the SUM doesn't work the same as most common belay devices, practice with it before depending on it for safety.

One can also rappel with the SUM. The SUM provides a stop feature, so the user has to depress the handle to descent. I don't care for autostop descenders for a variety of reasons, but some people prefer them. Squeezing the handle on the SUM requires more force than I prefer, and my hand could get tired on long descents. Faders recognized this, and their instructions presented some sort of contorted shoulder position that allows one to "lean" on the lever. "More of the force for lowering comes from ’leaning’ then ’squeezing,’" they say. It feels a bit strange but it may help. Of course, there is no convenient way to rappel doubled ropes on the SUM, a point to remember before finding that you need to descent a lead and haul line while on a wall climb.

Devonshire Imports provided the following advertising information:

The SUM is a belay/descender device of a new generation to be used with a UIAA single ropes from 10.5 to 9.1mm in diameter, which makes it unique in the market. Its exclusive and innovative blocking concept, not only catches the thinnest ropes, but also achieves a dynamic braking. Even for the most severe fall, the SUM performs blocking firmly and also with a reduced shock load. Both the climber and the belay system and anchors benefit from this impact reduction, increasing the security and useful life of the whole belay system. This device can be used to belay while trad climbing, it gives an automatic dynamic belay! Thanks to its ergonomic and lightweight design, the SUM is a belay device, not only robust and secure, but also easy to use. As an innovative product, the SUM by FADERS has been worldwide patented. Visit www.faders.es