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Single Rope Technique Ascenders

A1 Explorer A1 EXP 6 Explorer
A1 Explorer A1 EXP 6 Explorer
 
Caver 8-11 mm Caver 8-15 mm Climber
Caver 8-11 mm Caver 8-15 mm Climber

Overview


A1 Explorer
(#54, 2213)

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

Technical Details

I acquired this pair of ascenders from Inner Mountain Outfitters at the 1994 Speleofest. I acquired another pair in 2017 as part of Bob Thrun's collection.

The Single Rope Technique A1 Explorer is 206 mm. tall, 86 mm. wide, 31 mm. thick, and weighs 314 g.

The shell is milled from the same extrusion as the Caver 8-11 mm. Like the caver, the extrusion direction is oriented parallel to the vertical axis of the ascender, and contains two opposing channels. One channel is rounded and becomes the rope channel, the other is square and holds the cam. The rope channel is 14 mm. wide. The construction is a refinement of the Caver construction. The ascender has a more rounded shape, and the handgrip is angled. A soft plastic grip with aluminum insets is riveted to the frame. There are two holes at the bottom of the frame. The larger hole has an aluminum inset that provides a larger radius for slings to run over. The inside diameter of the inset is 17 mm. The smaller hole is located farther from the main line, and is only 12.8 mm. in diameter. The top of the frame has a 16 mm. hole drilled through both sides of the rope channel, and a 12.8 mm. hole above the cam pivot. The rope channel does no protrude as far from the ascender body as on the Caver.

The cam is a plated skeletonized, reinforced stainless steel casting with a (4.3)^5(4) conical tooth count. The tooth axes are perpendicular to the cam face. The cam radius increases from 46 to 62 mm. over an angle of 37°, giving a 25° cam angle. The cam, cam spring, and a cam housing are mounted on a 6.4 mm. semi-tubular rivet. The cam housing is a piece of thin sheet metal bent to cover the top of the cam channel and serve as a spacer along the sides of the cam. The top of the housing is indented; this limits cam closing so that the teeth do not hit the inside of the rope channel. The cam safety is a U-shaped piece of stainless steel mounted on a 3 mm. stainless steel rivet placed through two tabs on the base of the cam. A small thumb knob is staked to the safety. The knob is turned to give a contoured grip. The safety is placed so that it does not interfere with one's hand in the handle.

The back of the frame is stamped with "AUSTRALIA," the SRT logo, and "PATENTED." An arrow, "UP," and "SRT" are cast on each side of the cam. The aluminum inset on the front side of the grip is marked with the SRT logo and "EXPLORER." The rear inset is marked "Ø 11mm AT CAM MAX 900kg."

Comments

The Explorer series is S.R.T's premier line. One expects quality form S.R.T., and once again they deliver. The sling attachment holes are not beveled, but the aluminum inset in the main attachment point provides adequate sling protection. The sling attachment holes could theoretically have the same safety problem described for the Clog ascender, so I don't recommend using carabiners in them. There is one more upper sling attachment hole than C.M.I. provides. Unfortunately, the upper frame is still more difficult to grasp from above than either the Jumar or the small C.M.I. UltrAscender. This latter point is more important than the number of attachment holes available.

The cam is very well made, reminiscent of Jumar's. I suspect that it is also quite strong. The comments provided for the Caver apply here as well.

The ascender cam can be opened by either hand. The cam safety can easily be operated with the thumb of the normal hand (right hand for right-hand ascender), and the cam opened in one smooth motion. Opening with the opposite hand is more difficult, but can be done with the index finger. The safety is solid and much better made than the one on the I.S.C. Big Wall. The safety can be hooked over the cam channel to hold the cam completely open. There is no partial cam hold open feature, nor is one needed.

In general, this is a very well made, rugged ascender which is suitable for a wide variety of uses.


A1 EXP 6 Explorer
(#147)

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

Technical Details

I acquired this pair of ascenders from Single Rope Technique Equipment in 2000.

The Single Rope Technique A1 EXP 6 Large Explorer is 209 mm. tall, 88 mm. wide, 32 mm. thick, and weighs 352 g. The rope channel is 18 mm. wide. The cam radius increases from 41 to 61 mm. over an angle of 41°, giving a 29° cam angle. The tooth pattern is (3.4)^2(5.4)^2(3.4)^2(F), where the F is a flat spot below the teeth.

Comments

This is a large Version of the A1 Explorer (now numbered the A1 EXP) that can handle ropes ranging from 8 mm. to 16 mm diameter. This ascender is well-made, and ought to please to the "bigger is better" crowd, but I prefer the smaller version.


Single Rope Technique/Rollgliss/DBI Sala
A1 EXP 6L & 6R
(#2217, 2218)

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

Technical Details

I acquired two pairs of Single Rope Technique/Rollgliss/DBI Sala A1 EXP 6L & 6R in 2017 as part of Bob Thrun's collection.

The Single Rope Technique/Rollgliss/DBI Sala A1 EXP 6L & 6R is 212 mm. tall, 88 mm. wide, 31 mm. thick, and weighs 386 g. The rope channel is 18 mm. wide. The cam radius increases from 41 to 59 mm. over an angle of 40°, giving a 28° cam angle. The tooth pattern is (3.4)^2(5.4)^2(3.4)^2(F), where the F is a flat spot below the teeth.

The rear is screened with "CAPITAL SAFETY GROUP," the DBI-SALA logo, "www.capitalsafety.com," "Rollgliss®," "8700524," the SRTE logo, "Made under a quality scheme certified by SAI GLOBAL Lic SMKH25365," "MBS AT CAM 800kg," "Rope ¥ 10.5≤ Ø ≤ 13mm, the SAI GLobal certified product icon, a danger icon, "WARNING," "PROPER TRAINING IS ESSENTIAL," a book-with-an-"i" icon, "Lic SMKH25365," "CE 2056," "EN 12278," "AS/NZS 4488," "MEETS NFPA 1983 (2012 ED)T," "D.O.M. Sep 2012," AND "SERIAL # 201071-3." The cam has "SRT,", "UP," and an up-pointing arrow cast in raised characters.

Comments

The Single Rope Technique/Rollgliss/DBI Sala A1 EXP 6L & 6R is essentially the same as the A1 EXP 6 Explorer, differing only in the color and markings. The rear is printed with enough literature to keep your mind occupied while climbing the hawser anchoring your battleship.


Caver 8-11 mm
(#51, 2214)

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

Technical Details

I acquired this pair of ascenders from K.H.S. Sales at the 1988 Old Timers Reunion. I acquired another pair in 2017 as part of Bob Thrun's collection.

The Single Rope Technique Caver, 8-11 mm. is 185 mm. tall, 76 mm. wide, 25 mm. thick, and weighs 251 g.

The shell is milled from a custom aluminum extrusion which appears to be a direct copy of the C.M.I. 5000 extrusion. Like the C.M.I., the extrusion direction is oriented parallel to the vertical axis of the ascender, and contains two opposing channels. One channel is rounded and becomes the rope channel, the other is square and holds the cam. The rope channel is 14 mm. wide. The manufacturing process is similar to C.M.I.'s, but the shape of the final ascender varies somewhat. The hand hole is nearly rectangular rather than sloped at the top, and the top of the frame is not sloped like the C.M.I. 5000 . Two 15.6 mm. holes are drilled at the bottom and a two more are drilled at the top of the frame. The hand hole is made a little wider than on the C.M.I. 5000 , so the rope channel does no protrude as far from the ascender body as on the C.M.I. 5000.

The cam is a plated skeletonized, reinforced stainless steel casting with a (4.5)^3(4.3)^3 conical tooth count. The tooth axes are perpendicular to the cam face. The cam radius increases from 40 to 58 mm. over an angle of 44°, giving a 26° cam angle. The cam, cam spring, and a cam housing are mounted on a 6.4 mm. semi-tubular rivet. The cam housing is a piece of thin sheet metal bent to cover the top of the cam channel and serve as a spacer along the sides of the cam. The top of the housing is indented; this limits cam closing so that the teeth do not hit the inside of the rope channel. The cam safety is a piece of green anodized aluminum mounted on a 4 mm. stainless steel semi-tubular rivet located half way up the handle. A second stainless steel pin provides a thumb grip on the safety. The ends of this pin are well rounded. The safety is designed to sit almost completely inside the cam/safety channel, so it does not interfere with one's hand in the handle.

The inside of the frame (behind the cam) is stamped "S.R.T," "AUSTRALIA," and "EQUIP" A kangaroo logo is cast on each side of the cam.

Comments

The S.R.T. is a very well made ascender. I have not broken an S.R.T. ascender, but the frame is undoubtedly very strong. The sling attachment holes are nicely beveled. The sling attachment holes could theoretically have the same safety problem described for the Clog ascender, so I don't recommend using carabiners in them. There is one more upper sling attachment hole than C.M.I. provides. Unfortunately, the upper frame is still more difficult to grasp from above than either the Jumar or the small C.M.I. UltrAscender. This latter point is more important than the number of attachment holes available. Like the C.M.I.'s, the main rope could get caught in the cam/safety channel, but I've never seen this happen in practice.

The cam is very well made, reminiscent of Jumar's. I suspect that it is also quite strong. I'm not thrilled with semi-tubular rivets for cam pivots, but at least the S.R.T.'s are not cracked. S.R.T. should consider using a grooved pin and external retaining ring similar to the C.M.I. design. The cam housing is lightweight and crude, but it doesn't serve any critical function so I'm not too concerned with its design. It may even be possible to eliminate the cam housing completely and substitute two washers, or even widen the cam a bit and eliminate them too. The main drawback is that the cam housing helps keep mud out of the cam pivot, and eliminating the housing might cause the ascender to jam more easily in muddy conditions.

The cam safety is designed to be out of the way, so it is a little more difficult to operate than the Jumar's, but not by much. The ascender is still easily operated by either hand. I like having metal cam safeties like the S.R.T.'s. I've seen too many broken plastic ones on other ascenders to enjoy that technological "improvement." There is no partial cam hold open feature, nor is one needed. The safety design does allow holding the cam in the full open position if desired.

In general, this is a very well made, rugged ascender which is suitable for a wide variety of uses.


Caver 8-15 mm
(#52, 53, 2216)

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

Technical Details

I acquired a left-hand ascender from J. E. Weinel, Inc. in June, 1989, and a right-hand ascender from Single Rope Techniques in October, 1989. I acquired another pair in 2017 as part of Bob Thrun's collection.

The Single Rope Technique Caver, 8-15mm is 196 mm. tall, 80 mm. wide, 31 mm. thick, and weighs 340 g. The rope channel is 18 mm. wide. The cam radius increases from 38 to 56 mm. over an angle of 43°, giving a 28° cam angle. The tooth pattern is (4.5)^3(4.3)^2(4).

Comments

This is a larger version of the preceding model. It is designed for ropes up to 16 mm. in diameter. The frame is larger and the cam, cam housing, and cam safety are wider. The cam tooth count is reduced to (4.5)^3(4.3)^2(4), and the teeth are not nearly as well formed as in the smaller model.

My comments on the preceding model apply to this one too. This ascender is more appropriate if you anticipate needing to climb ropes larger than about 13 mm., but the price paid is an increase in weight and bulk. This should please the "bigger is better" crowd and few others.


Climber
(#50, 2215)

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

Technical Details

I acquired this pair of ascenders from Inner Mountain Outfitters at the 1988 Old Timers Reunion. I acquired another pair in 2017 as part of Bob Thrun's collection.

This ascender is a shortened Version of the Caver Version A. The only significant difference is in the frame, which has been shortened by about 50 mm. The cam safety on mine is red instead of green, and a punch was made to help hold the thumb pin in place.

Comments

Once again, most of the comments on the Caver Version A apply here. This ascender is very well made. The small size makes it a desirable alternative handled ascender to the full size ascenders in many situations. In those cases the S.R.T. Climber and the C.M.I. small UltrAscender are the two options available. The C.M.I. small UltrAscender is smaller and lighter, but the S.R.T. has a better safety design. The C.M.I. is easier to grasp from above The C.M.I. has a larger handle opening, but the sling must go through that opening. The C.M.I. cam is easier to replace, but the paint on the S.R.T. is more durable. In short, there are a number of things to consider. Although I prefer the C.M.I. (particularly after making some modifications to the safety), the decision boils down to personal preference; either one is acceptable. I choose the C.M.I., but one of my partners, after borrowing part of my collection to try, chose the S.R.T.