Front	Rear

Left	Right	Front: Open for Rigging	Rear: Open for Rigging

Technical Details

I acquired my One-armed Amigo from Krok in 2021.

My One-armed Amigo is 161 mm. tall, 108 mm. wide, 27 mm. thick, and weighs 471 g.

The Amigo Consists of two fixed and one pivoting bollard between a fixed rear and opening front plate. The pivoting bollard has an attached handle assembly with a rope channel and a secondary pivoting handle with attached rope brake.

The front and rear plates, main handle, and rope channel are made from 2 mm. steel, while the secondary handle is 2.9 mm. aluminum.

The front and rear plates are127 mm. tall, 50 mm. wide irregular shapes. Each has a nonfunctional 7.8 mm. hole near the gap between the two main bollards and a 13 mm. attachment hole near the base. The plates are 16.7 mm. apart at the top, but each has a dog-leg inward bend near the bottom so they nearly touch at the attachment hole. The front plate pivots on the upper bollard rivet, allowing one to open the Amigo for rigging. Notches on the right side engage mushroom heads on one of the upper bollard rivets and on the lower bollard axle.

The topmost bollard is a 16 mm. long, 10 mm. steel rod. The second bollard is a 28 mm. diameter, 16 mm. disc with a flattened bottom. The curved upper surface has a turned 8.5 mm. wide, 1.8 mm. deep V-shaped rope groove. Two rivets attach the bollard to the rear plate. The top rivet has a mushroom extension to engage a slot in the front plate.

The lower bollard is milled from steel. It pivots on a stainless- steel axle riveted to the fixed plate. The axle has a mushroom extension to engage a slot in the front plate. This bollard is subtriangular with a curved lower surface. This surface has a 7 mm. wide, 1.6 mm. deep U-shaped rope groove. The bollard is part of an autostop assembly, and its nose acts as a brake. Friction from the main rope’s passage tends to turn the lower bollard and force the nose towards the upper bollard, thus locking the rope and ideally arresting the descent.

A steel control handle is riveted to the fixed side plate side of the lower bollard. The rappeller uses the handle to keep the autostop feature disengaged. A U-shaped rope channel is riveted to the handle. The channel doubles as a hand grip, allowing the user to lift he handle to reduce friction for descent. The secondary handle pivots on a stainless steel axle riveted to the main channel near the top of the rope channel. Two brake blocks saddle the secondary handle. The secondary handle is 121 mm. long and has an 87 mm. long, 27 mm. wide, and 15 mm. thick rubber handgrip with three shallow finger grooves. Squeezing the secondary handle and rope channel/handgrip together forces the brake blocks against the rope, providing additional friction for descent.

Most of the metal parts are painted.

The pivoting printed is printed "Однорукий Амиго" (One-armed Amigo), "MBS 15 kN," "20.09.04.04," the Krok logo, and a book-with-an-"i" icon. The rear is printed with a rigging illustration for a normal bobbin (the illustration does not show the handles or how they are used), "EN 12841-2014/B," "Max 400 кг Ø 10÷11," "Max 500 кг Ø 11÷12," "EAC," "TP TC 019/2011," and the Ukrainian Conformity Mark.

Comments

Krok worked with my friend Konstantin Serafimov to develop the Amigo. Konstantin was concerned by most people’s instinctive reaction to grip things tightly when falling. Knowing that this is why conventional safeties, such as the prusik backup, do not work reliably, he sought to capitalize on this reflex to develop devices where gripping tighter would slow one’s descent. The One-armed Amigo came from those efforts.

As a result of Konstantin’s design goals, the Amigo does not work like most stop bobbins. To descend, one needs to lift the handle and loosen one’s grip, while most stop bobbins use squeeze-to-descend. After many years using the standard design, I find the Amigo to be counter-intuitive. I would need to unlearn decades of experience before I could feel comfortable with the Amigo, but for someone with no experience, learning the Amigo’s control motions should not be difficult.

I weigh 90 kg, and I found that the Amigo would not hold my body weight. When I tried it on 9 mm. rope - smaller than recommended - it would not hold my body weight even when I squeezed the anti-panic handle. Do not use the Amigo on small-diameter rope.

The handle layout on the Amigo is not streamlined for packing.

There is no gate or cutout to allow opening the Amigo without removing it from the harness, which makes it inconvenient to pass rebelays.

I dislike painted finishes on my descenders. I also prefer aluminum to steel, for both corrosion resistance (steel rusts), and for its lighter weight. Aluminum can also be anodized, eliminating the need for paint.