Version A	Version B	Version C

Overview

Warning: Tom Martin (Rappelling, 1987, p. 6-36) reports, "Because Descent-Masters have been known to break during a rappel, they should be used with extreme caution."

[ Top | Version B | Version C | Return to Misc. Descenders ]

Version A
(#913)

Front View	Rear View
Left Side View	Right Side View

Technical Details

I acquired this Descent Master from Ann Dunn in 2002. It was manufactured on September 28, 1970.

The Descent-Master is made from two pieces of cast aluminum (a braking plate and a pivoting control handle), a commercial snap hook, and some minor parts. The braking plate is 178 mm. high, 12.7 mm. thick, and 49.5 mm. wide at the base (the top end is only 45.2 mm. wide). One end has a 63 mm. tall, 19.5 mm. wide slot. One side is cut out to provide a place for a cast aluminum gate. A 3.3 mm. steel (not stainless) rivet holds the gate in place. A wire spring wrapped around the rivet closes the gate. The maximum gate opening is about 13 mm. There is a post cast on the inside of the brake plate that serves two functions. First, a slot in the post guides the rope, which should be wrapped around the brake plate to the right of the slot in a right-hand helix. Tom Martin (Rappelling, 1985, p. 6-34) reports that one wrap should be used for 32-158 kg loads, and two turns for 159-181 kg. The post’s second function is to create drag by pressing a concave area against the rope when the control arm is in the upper ("stop") position. Finally, an eye on the bottom outside surface of the braking plate provides a place to attach a type 3047A snap hook with a standard 5/16-inch chain connector. The bottom of the braking plate has two cutouts to mount the control handle.

The bottom end of the control handle has two prongs that curve inward to fit into the slots at the base of the braking plate. A 4.4 mm. steel pin serves as a pivot, and two wire springs wrapped around the pivot act to raise the arm (although the action is weak - the springs will only raise the arm about 45° above the horizontal. The control handle is 204 mm. long, the bottom 40% is 35.3 mm. wide and 13.8 mm. thick, while the top 60% is 27 mm. wide and tapers to only 8 mm. thick. There are four posts on the inside of the control arm. Each one has a slot on the side to act as a rope guide. The bottom post is larger and has a flat surface that presses against the rope when the control arm is raised to the "stop" position.

There is a sticker on the outside of the control arm that reads as follows (I used red text to indicate stamped information):

Date 9-28-70 CAUTION SERIAL NO 236

1. WRAP ROPE ON SLIDER LOCK 2. INSERT ROPE IN ALL GATES ON DEVICE 3. SECURE ROPE TO STATIONARY
OBJECT 4. ATTACH DEVICE TO SAFETY BELT WITH snap hook 5. PULL TO DESCEND - RELEASE TO STOP.
DESCENT MASTER PATENT NO. 3357520

ATLAS SAFETY EQUIPMENT CO. INC.
179 N. 10th STREET, BROOKLYN, NEW YORK 11211

The snap hook has the normal U. S. Forgecraft markings: "3047A Fc TESTED." The chain connector is marked "BTC" and "5/16" on each side.

My Descent-Master came with it’s own very stiff 9.7 mm. kernmantle rope. The rope is so stiff that getting the rope in and out of the slots is difficult since the rope resists flattening. Tom Martin (Rappelling, 1985, p. 6-34) claims that old Descent-Master rope had a steel core, and that later ones used 11 mm. rope. The rope that came with mine has a 3.5 mm. steel core, then a rubber sheath that brings the diameter to 5.4 mm., then a 32-strand (eight pairs each way) nylon mantle that brings the final diameter to 9.7 mm.

Comments

First of all, I’d like to thank Adam Noble for finding this Descent-Master on eBay.com and letting me know about it. I had been looking for one since 1985 when I first saw a picture of one in Tom Martin’s book Rappelling. Needless to say, I was surprised to find one after so many years.

The Descent-Master is easy to operate - just pull the handle down to descend and move it upward to slow down or stop. The Descent-Master is designed to stop if the user lets go of the handle. I don't recommend this - I have my own my thoughts on rappel safeties.

The Descent-Master doesn't give me a smooth descent. The wrap at the top of the Descent-Master puts a twist on the rope and kinking is a problem. The device is also somewhat sensitive to rope diameter. The manufacturer used to insist that the descender must be returned to the factory if the rope wore out so that a new rope could be custom-fitted. Whether this reflected reality, a commercial ploy to sell only their own rope, or the mutterings of the company lawyer is beyond my knowledge.

This Descent-Master is one of the early models. Tom Martin (Rappelling, 1985, p. 6-36) claims that earlier models could be controlled from the ground, but neither the text nor the photos in his book explain how this was done. Don't try it. He reports that this feature was deleted from later models.

The Atlas Descent-Master is protected by U.S. Patent 3,357,520.

Warning: Tom Martin (Rappelling, 1987, p. 6-36) reports, "Because Descent-Masters have been known to break during a rappel, they should be used with extreme caution."

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Version B
(#1227)

Front View	Rear View
Left Side View	Right Side View

Technical Details

I acquired my Atlas Descent-Master, Version B from Gary Lubra in 2009. It was manufactured in October 1977.

Version B is 206 mm. tall, 50 mm. wide, 92 mm. thick, and weighs 807 g. Version B is similar to Version A, although there are minor differences in the casting, the main one being the visible steps in the posts on the braking plate. These seem to be cope & drag parting lines in the sand casting. The main functional improvement in Version B is the addition of a 2 mm. wire safety pin attached to the braking plate with a jack chain and machine screw.

There is a sticker on the outside of the control arm that reads as follows (I used red text to indicate stamped information):

Date 10-77 CAUTION Serial No. 312

1. Use only rope supplied with the unit 2. At least one turn on slider lock is
essential 3. Insert rope in all gates on device 4. Secure rope to stationary
object 5. Attach device to safety belt with snap hook 6. Pull to descend
7. Release to stop
Descent Master Pat No. 3357520

There is a second sticker on the inside of the back plate. It reads as follows:

CAUTION
1 - AT LEAST
ONE TURN ON SLIDER LOCK
IS
ESSENTIAL
2 - TO STOP
RELEASE HANDLE

The snap hook is stamped "ATLAS" and "403-A." The chain connector is marked "BTC" and "5/16" on each side.

Comments

The Descent-Master is easy to operate - just pull the handle down to descend and move it upward to slow down or stop. The Descent-Master is designed to stop if the user lets go of the handle. I don't recommend this - I have my own my thoughts on rappel safeties.

The Descent-Master doesn't give me a smooth descent. The wrap at the top of the Descent-Master puts a twist on the rope and kinking is a problem. The device is also somewhat sensitive to rope diameter. The manufacturer used to insist that the descender must be returned to the factory if the rope wore out so that a new rope could be custom-fitted. Whether this reflected reality, a commercial ploy to sell only their own rope, or the mutterings of the company lawyer is beyond my knowledge.

Warning: Tom Martin (Rappelling, 1987, p. 6-36) reports, "Because Descent-Masters have been known to break during a rappel, they should be used with extreme caution."

[ Top | Version A | Version B | Return to Misc. Descenders ]

Version C
(#960)

Front View	Rear View
Left Side View	Right Side View

Technical Details

I acquired this Descent Master from John Klewicki in 2004. It was manufactured in October 1984.

The Descent-Master is made from two pieces of cast aluminum (a braking plate and a pivoting control handle), a commercial snap hook, and some minor parts. The braking plate is 181 mm. high, 13 mm. thick (20.5 at the axle), and 52 mm. wide (at the base, the top end is only 46.5 mm. wide). One end has a 63 mm. tall, 18 to 19.5 mm. wide slot. One side is cut out to provide a place for a cast aluminum gate. A 3.3 mm. steel (not stainless) rivet holds the gate in place. A wire spring wrapped around the rivet closes the gate. The maximum gate opening is about 13 mm. There is a post cast on the inside of the brake plate that serves the same functions as in Version A. Finally, an eye on the bottom outside surface of the braking plate provides a place to attach an Atlas type 403-A (U. S. Forgecraft type 3031) snap hook with an 8 mm. maillon. The bottom of the braking plate has two cutouts to mount the control handle.

The bottom end of the control handle has two prongs that curve inward to fit into the slots at the base of the braking plate. A 5 mm steel pin serves as a pivot, and two wire springs wrapped around the pivot act to raise the arm (although the action is weak - the springs will only raise the arm about 30° above the horizontal. The control handle is 210 mm. long, the bottom 40% is 35.8 mm. wide and 14.2 mm. thick, while the top 60% is 31.5 mm. wide and tapers to only 7.5 mm. thick. There are four posts on the inside of the control arm. Each one has a slot on the side to act as a rope guide. The bottom post is larger and has a flat surface that presses against the rope when the control arm is raised to the "stop" position. The top gate has holes that allow inserting a 2 mm. wire safety. The safety is attached to the braking plate with a short jack chain.

There is a sticker on the outside of the control arm that reads as follows (I used red text to indicate stamped information):

Date 10-84 CAUTION Serial No. 723

1.Use only rope supplied with the unit 2. At least one turn on slider lock is
essential 3. Insert rope in all gates on device 4. Secure rope to stationary
object 5. Attach device to safety belt with snap hook 6. Pull to descend
7. Release to stop
ATLAS SAFETY EQUIPMENT CO. INC.
1 JOHNSON AVENUE, MATAWAN, N.J. 07747
Descent Master Pat No. 3357520

There is a second sticker on the inside of the back plate. It reads as follows:

CAUTION
1 - AT LEAST
ONE TURN ON SLIDER LOCK
IS
ESSENTIAL
2 - TO STOP
RELEASE HANDLE

The snap hook has "ATLAS 403-A" stamped in the gate and normal U. S. Forgecraft markings "30431 Fc 84" stamped on the body. The maillon has no markings.

Comments

Version C is somewhat beefier than Version A, but not finished as nicely. The hinge area between the back plate and control handle is significantly stronger than in Version A. Much of the surface is a rough, sand-cast finish. The wire safety is rather flimsy-looking, but probably adequate.

I note that Version A (made in September 1970) was serial number 236, Version B (made in October 1977) is serial number 312, and Version C (made in October 1984) is serial number 723. If the serial numbers are consecutive (as they appear to be), this would indicate that few Descent Masters were made and sold. Of course, they could have restarted the numbering at any time.

Warning: Tom Martin (Rappelling, 1987, p. 6-36) reports, "Because Descent-Masters have been known to break during a rappel, they should be used with extreme caution."

[ Top | Version A | Version B | Version C ]