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heightec-PMI
Rescue Compact D41A/
D44 Rope Grab/
D44A

(#255, 2128)

Front View: Closed Rear View: Closed
Front View: Closed Rear View: Closed
 
Front View: Open for Rigging Rear View: Open for Rigging
Front View: Open for Rigging Rear View: Open for Rigging

Confused?

What should I call this? There are several obvious options, as follows

  1. The box that it came in calls it a "RESCUE COMPACT - D44 ROPE GRAB" and has an upside-down picture of the device.
  2. The instruction sheet calls it a "RESCUE COMPACT Stainless SteelRope [sic] ascender D41A and has a right-side-up picture of the device. The instructions give instructions for use as an ascender and as a device for hoisting casualties; but they also say, "WARNING- NOT FOR FALL ARREST," which means that this is NOT a rope grab.
  3. The device itself is marked "D44A."
  4. The 2008 PMI catalog, page 65 calls this a "RESCUE COMPACT" and states that it is"slid down to the subject for a secure connection in a variety of situations," indicating that it is neither a rope grab nor an ascender.

Since the instructions warn me not to use this as a rope grab, heightec-PMI has another device numbered D41A, and that device is an ascender with an aluminum shell (shaped somewhat differently), I'm going to use the number on the box and call this one a D44 (assuming that an A stands for aluminum), and call it an ascender.


Technical Details

I acquired my D44 from On Rope 1 at the 2008 Old Timers' Reunion. I acquired another in 2017 as part of Bob Thrun's collection.

This ascender is 113 mm. tall, 80 mm. wide, 25 mm. thick, and weighs 300 g.

The D44 is right-handed. The ascender shell is subtriangular red anodized shape bent from 2.9 mm. stainless steel sheet. The rope channel is formed by bending the left side of the ascender into a U. The rope channel is 15.8 mm. in diameter. The main sling attachment point is a 14.9 mm. hole located below the cam and to the right of the rope channel. A second lower attachment point of the same size lies right and slightly below the first. The right side of the shell is bent on an inclined axis to form another U. A hole drilled through both sides of the U accepts a roll rivet. The cam and cam spring are mounted on this rivet. The head of the rivet is on the front of the shell. The pivot is centered 51 mm. from the inside of the rope groove. There is a 4.9 mm. high, 7.9 mm. cam stop pin riveted to the shell.

The cam is a plated skeletonized steel casting. The cam radius, measured from the pivot, increases from 38 to 52 mm. over an angle of 37°, giving a 26° cam angle. The cam has number of small conical teeth, all of which have their axes approximately perpendicular to the cam face. The tooth pattern is (1.2^3)^2(1.2)^2(B). The B stands for a small bar. A spring-loaded manual safety is mounted mounted on an axle riveted to the bottom center of the cam. The normal action of the spring holds the safety against the cam. The safety has a 12.8 mm. tall, 6 mm. diameter pin mounted on it for the fingers. When the cam is opened, the shell interferes with the safety, thus preventing cam opening. At full open the safety can be released and the spring will hold the tab against the back of the shell, locking the cam open.

The rear of the ascender is etched with "heightec-PMI," "D44A," a book-with-an-"i" icon, "O Ø" "10.5-13," and "0708."

Comments

The D44 is similar to the heightec-PMI Compact D41A, but there are some differences in the shell shape (and material) and the shape of the cam safety. The larger shell adds some unnecessary bulk, and the longer cam safety adds some security to the hold-open feature (security means little when it used is to prevent gripping) at the expense of making the safety harder to operate.

The heightec-PMI is solidly made. All sharp edges have been removed. It is too heavy for regular caving or climbing use, but the extra weight might allow it to be "slid down to the subject for a secure connection in a variety of situations" as the catalog suggests. Extra weight even might please the "bigger-is-better" crowd. The attachment points are simply holes in the shell, and although rounded they should have been beveled more; even so, I would consider their small radius too sharp for directly attaching rope slings.

The cam and its teeth are very well made. I'm not sure what purpose the bar serves - several people have sent me emails telling me that the analogous bars on the Lucky AB-20 and VauDe AB-20 Bloquer keep the cam from closing and touching the shell (so what?), but the bar does not do touch the shell on the D41A. Perhaps it is there to keep the ascender from gripping small cord??