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Lewis Descender

Version A Version B
Version A Version B

Overview


Version A
(#1332)

Front View Rear View
Front View Rear View
 
Left Side View Right Side View
Left Side View Right Side View

Technical Details

I acquired my Lewis, Version A from John Marshall in 2012.

My Lewis, Version A is 187 mm. tall, 74 mm. wide, 79 mm. thick, and weighs 305 g.

Version A is identical to Version B except that the side plates and rollers are not anodized.

The left side plate is stamped with "LEWIS" and the right with "PAT.APP.No" and "28672778." Each bolt head has "M", "A2", and "NS" in raised letters.

Comments

The Lewis is a British descender.


Version B
(#463, 2410)

Front View Rear View
Front View Rear View
 
Left Side View Right Side View
Left Side View Right Side View

Technical Details

I acquired my Lewis, Version B from Speleoshoppe in 1979. I acquired another in 2017 as part of Bob Thrun's collection.

My Lewis, Version B is 190 mm. tall, 71 mm. wide, 80 mm. thick, and weighs 308 g.

The Lewis descender is a double-rope device. Except for the bolts and nuts, it is bilaterally symmetrical.

The Lewis Descender consists of two fixed bollards mounted between fixed aluminum side plates, and a moving bollard mounted on a lever pivoting from the upper bollard. The side plates are 3.5 mm. anodized aluminum. One is stamped "LEWIS" and the other "PAT.APP.No 28672778." The side plates are drilled to receive the bollard mounting bolts, and have a 13 mm attachment hole drilled at the bottom. The attachment holes on the two plates are about 1.2 mm. out of line with each other. A large, rounded notch in each side plate provides clearance for the moving bollard.

The top fixed bollard is 25.5 mm. in diameter It is split into two with the lever pivoting between the two halves. Each half is 15 mm. long, limiting the device to ropes smaller than this. The lower fixed bollard is 19 mm. in diameter and 33 mm. long.

The moving bollard is in two pieces, each 19.4 mm. in diameter and 31.3 mm. long, and bolted on each side of a 5 mm. subtriangular aluminum plate. There is a beveled 13 mm. hole in the plate, and a handle made out of 12 mm. tubing is riveted to the plate. Depressing the handle pivots the moving bollard away from the fixed bollards, reducing friction.

The left side plate is stamped with "PAT.APP.No" and "28672778." The right side plate is stamped with " "LEWIS."The head of the top bolt has a raised "M," the head of the lower bolt has "INKOBA" and "A_2," and the head of the bolt holding the moving bollard has "M," "A4," a logo, and "88."

Comments

The Lewis descender can be used on single or double rope. A bight is taken in each rope, and pushed through the device from the lever side, and looped over the moving bollard. If you did the math, you'll recognize that the moving bollard extends about 14 mm. beyond the side plates, so the rope does not tend to come off accidentally.

I have vivid memories of this being the worst device in my collection, but the conditions I used it under (goldline in a rainstorm) were perhaps not a fair test. Still, I don't like this descender because I feel that it is too sensitive. Under the conditions just mentioned, a 5 mm. movement at the tip of the handle made the difference between solidly stopped and near free-fall. On drier kernmantle ropes, it might perform better.

The offset eyes are not intentional, and make for a tight fit for some carabiners (in fact, some modern carabiners won't fit at all). Use a maillon instead, they're safer anyhow.