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Unknown #1
(#881)

Front Rear
Front Rear
 
Side Open for Rigging
Side Open for Rigging

Technical Details

Mike Moser gave me this rope grab during the 2007 NSS Convention. There are no markings on this rope grab to indicate who manufactured it.

This rope grab operates on the same principle as a Type 1 Lever Cam Ascender. The shell is a U-shaped steel stamping with two tabs on each side that are bent outward and back, then welded to form top and bottom channels for a hinge pin. A U-shaped steel stamping forms the central section of the left-hand hinge. The cam axle passes through this channel where it is secured by a flat washer and an acorn nut. Inside the channel is a spring-loaded arm. The spring forces the arm downwards where it pushes on a pin attached to the cam, causing the cam to close. The arm has a small rectangular hole that can fit over a tab near the top of the channel, defeating the spring action. The left-hand hinge pin is bent inward at the top, where it supports a steel roller. The lower end is fixed held by an acorn nut.

The cam is made from five pieces of steel sheet riveted together. One rivet is the pin mentioned earlier, the other a countersunk rivet near the toe of the cam face. The two outer and central sheet are cut to form seven z-shaped teeth on each, while the second and fourth sheets are smooth at the cam face. The outer sheets are thicker than the center three. The outer sheets bend outward to form a channel for a spring-loaded pivoting eye, also made from stamped steel. The eye is riveted in place.

The cam axle has an eye on the left side that engages the right-hand hinge pin. This pin is U-shaped and spring-loaded, and moves downward to open the device. A spring-loaded plate on the other rend of the U-pin acts as a safety lock. Finally, another stamping riveted loosely to the right side pivots downward so that a notch captures a head on the U-pin, locking it in the closed position.

The left side lever is stamped with a down-pointing arrow and the word "LOCK." The left side channel is stamped with "Mfg. date 1996-12" on the inside and "NO. 26890" on the outside. The right side of the main channel is stamped with "UP" near the top, "|| OPEN" under the spring-loaded plate (where it is well-hidden from view), opposing right and left-pointing triangles and "LOCK" just above the plate, and "MAIN LINE Ø16" near the pivoting latch. The spring loaded side plate is stamped with "PULL," ad down-pointing arrow, and "PUSH."

Comments

To open the device, lock the lever on the left, open the side latch on the right, and then simultaneously hold the cam in the open position, press the spring-loaded side plate where it says "PUSH," and slide it downward. If you can do all of this at once while fighting the spring, the cam will now swing open. To close the device, simply reverse the complex process.