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I acquired
this descender from Repetto Sport in Genova, Italy in 1982.
The fixed sideplate is an elongated piece of 4 mm. aluminum bent inwards in a dogleg at the lower end. Two beveled 13 mm. holes below the dogleg serve as attachment points. The upper bollard is an aluminum casting bolted to the fixed sideplate with two 6 mm. bolts. This bollard is not circular, but more airfoil shaped with the concavity in the lower surface provided to work in conjunction with the autostop role of the lower bollard. The lower bollard is a spiral shaped aluminum casting bolted to the pivoting sideplate. This sideplate extends upwards only to the bottom of the upper bollard, with a sub-millimeter clearance provided. The lower end of the pivoting sideplate doglegs inwards and has one 13 mm. beveled attachment hole aligned with the upper hole on the fixed sideplate. A projection extending below this hole limits rotation of the pivoting sideplate if a carabiner or maillon is in the fixed sideplate's lower hole. The lower bollard and pivoting sideplate rotate on an 8 mm. bolt through the fixed sideplate. A 6 mm. bolt keeps the lower bollard from rotating with respect to the pivoting sideplate. Finally, a 10 mm. diameter by 14 mm. cylinder is riveted to the inside of the fixed sideplate below the lower bollard. This pin is necessary to keep small ropes in the device when the lower bollard and pivoting sideplate are rotated to the fully engaged position.
The pivoting sideplate is stamped "DAD" and "BREVETE". The bolt heads are marked with "A2" and an "L" inside a diamond.
The DAD departs from traditional bobbin design in several ways.
By using castings, the manufacturer is able to use more complex
shapes for the bollards at the probable sacrifice of some superfluous
strength. This gives the designer more control over the characteristics
of the device. The airfoil shape to the upper bollard reduced
the height of the descender by several centimeters. The autostop
feature on the DAD is more secure than on the Diablo, but is easily
disengaged by accidentally bumping the pivoting sideplate. The
autostop feature is easily overridden by rigging into the upper,
rather than lower attachment hole. My biggest objection to the
DAD is the lack of any means to keep the rope running over the
top of the upper bollard. I find that stiff ropes, such as PMI
standard, are particularly willing to leave their appointed path.
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I acquired this descender (#1227) from Repetto Sport in Genova, Italy in 1982.
The two sideplates are made of 33 by 3.0 mm. aluminum. The sideplates are very similar to the Petzl Version B design, and a quick attachment feature nearly identical to Petzl's is provided. The attachment points are not beveled. The upper bollard is very similar to Petzl's, complete with off-center mounting and provision of a threaded 7 mm. hole for reversing the bollard. The lower bollard is part of an autostop device. The bollard has a 15 mm. diameter toothed cylinder attached at the 10 o'clock position . The cylinder is screwed onto a 5 mm. connecting pin which is then pinned to the bollard with a 1 mm. roll pin. A handle is attached to the bollard with two 3.5 mm. screws. The fixed sideplate prevents these screws from backing out.The lower bollard and attached handle assembly house a bronze bushing and pivot on the lower 7 mm. bolt. Friction from the main rope's passage tends to turn the lower bollard and force the toothed cylinder towards the upper bollard, thus locking the rope and ideally arresting the descent. The rappeler uses the handle to keep the autostop feature disengaged.
The handle assembly has two other features. Plastic plates are riveted to the two sides of the handle to increase its thickness, mainly for comfort and aesthetic reasons. In addition, there is a small lever attached to the back of the fixed sideplate with a 3 mm. countersunk head machine screw. A turned pin riveted to this lever extends through an arcuate slot in the fixed sideplate and can engage a slot in the handle when the autostop feature is disengaged, thus holding the descender in this position.
The pivoting sideplate is stamped "diablo" and "brevettato". The lower bolt head is marked "RS" and "A2", the upper "C" and "A2".
In general this is a well made descender. The manufacturer paid attention to minor details, such as center punching the bolts so the nuts would not loosen. The use of a bronze bushing rather than the tempting omission is another commendable practice. The one oversight I noticed is that the roll rivet on the attachment point guard is barely expanded and had a very sharp end on the inside near the rope path, but probably far enough away to be of no concern.
Unfortunately, I find the autostop feature is rather insecure.
In fact, I have used this descender for normal rappeling with
the autostop fully engaged, and find the friction provided to
be preferable to the normal amount. The lever provided for disengaging
the autostop feature works, but it appears to be rather weak,
so I do not use it.
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©2007, Gary D. Storrick