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Single Rope Technique
Hand Ascenders

G.P., Version A G.P., Version B
G.P., Version A G.P., Version B
A3 Explorer, Version A A3 Explorer, Version B A3 EXP 6 Explorer
A3 Explorer, Version A A3 Explorer, Version B A3 EXP 6 Explorer

Overview


G.P. Version A
(#16)

Front Rear
Front Rear

Technical Details

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

My pair consisted of two left-handed ascenders, although a left and a right were supposed to be packaged together. Each ascender is is 96 mm. high, 76 mm. wide, 26 mm. thick, and weighs 176 grams. The shell is milled from a custom aluminum extrusion which appears to be a direct copy of CMI's extrusion. The shell body is 6.5 mm. thick and painted yellow. The rope groove is 14.2 mm. in diameter and U shaped. The cam mounting groove is rectangular. Two cam pivot holes are provided; one for the left and one for the right-handed configuration. The attachment points are 15.5 mm. beveled circular holes, one located below the cam and one above.

The cam is a plated skeletonized, reinforced stainless steel casting with a (4.5)3(4.3)3 conical tooth count. The teeth axes are perpendicular to the cam face. The cam radius, measured from the pivot, increases from 41 to 58 mm. over an angle of 42 degrees. The cam, cam spring, and a cam housing are mounted on a 6.4 mm. semi-tubular rivet (the pin with retaining ring seen on the right ascender is a modification described in the comments). The cam pivot is centered 55 mm. from the inside of the rope groove. A single spring serves as cam spring and safety spring. 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. There is no cam safety.

The inside of the shell is stamped "SRT," "AUSTRALIA," and "EQUIP." There is a kangaroo cast into each side of the cam.

Comments

The SRT is a compact, well made ascender. The carabiner attachment eliminates the need for a cam safety in the same manner as that on the Clog. The extrusion is so similar to CMI's that the CMI Optional Safety Kit can be installed on the SRT, although it will allow the cam to open too far to prevent rope escape. The attachment points are located too far from the main rope channel, so ascender canting occurs, losing efficiency. The cam is very well made, reminiscent of Jumar's. I'm not thrilled with semi-tubular rivets for cam pivots, but at least the SRT's are not cracked. The cam housing is lightweight and crude, and on one of my ascenders had been trimmed with pliers. The resulting sharp edges were not smoothed.

I was rather surprised when I received my pair in 1988 and discovered that SRT had packaged two left-handed ascenders together. The orientation of the stampings on the ascender shells showed that one of the pair was assembled upside down, making a perfectly functional left-handed ascender out of a right. If SRT had used a pivot pin like CMI's, the cam could have been easily reversed. Fortunately, I had a set of extra CMI Shorti pins, so took the reversed ascender and drilled out the semi-tubular rivet, then reassembled the ascender as a right-handed model using the CMI Shorti pin. This incident seemed quite atypical of of SRT's normally excellent quality control, and I'm sure that I could have simply gotten an exchange if I had chosen.


G.P. Version B
(#1969)

Front Rear
Front Rear

Technical Details

I acquired my Single Rope Technique G.P., Version B from Melody Dawson in 2013.

This version is 96 mm. tall, 76 mm. wide, 26 mm. thick, and weighs 182 g. The rope channel is 14 mm. wide. The cam radius increases from 40 to 58 mm. over an angle of 44°, giving a 26° cam angle. The tooth pattern is (4.5)^3(4.3^)3.

The inside of the shell is stamped "SRT," "AUSTRALIA," and "EQUIP." There is a kangaroo, "UP," and an up-pointing arrow cast into each side of the cam.

Comments

This version is anodized instead of painted.


A3 Explorer, Version A
(#2207)

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 my Single Rope Technique A3 Explorer, Version A in 2017 as part of Bob Thrun's collection.

The Single Rope Technique A3 Explorer is 111 mm. tall, 78 mm. wide, 26 mm. thick, and weighs 229 g. The rope channel is 15 mm. wide. The cam radius increases from 41 to 57 mm. over an angle of 37°, giving a 27° cam angle. The tooth pattern is (4.5)^3(4.3)^2(4.F).

The rear of the body is stamped with "AUSTRALIA," "SRT" inside a map of Australia, and "PATENTED." The cam has a cast kangaroo.

Comments

The A3 Explorer is made out of the same extrusion as the G.P., but is larger and heavier. The extra size allows adding a cam safety and extra holes, but I doubt that this is the best use of the space. The A3 Explorer is smaller than the SRT Climber, yet it weighs more. I would prefer that more of the frame had been milled away, perhaps eliminating one each of the top and bottom holes. Although this is a very solid ascender and it is quite well-made, it could have been made much lighter.

All of my A3 Explorers are right-hand models, but a left-hand model was also available.

If you can help me acquire a left-handed A3 Explorer, please email me.

 


A3 Explorer, Version B
(#18)

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 my Single Rope Technique A3 Explorer, Version B from Inner Mountain Outfitters at the 1994 Speleofest.

Version B is 114 mm. tall, 78 mm. wide, 27 mm. thick, and weighs 239 g. The rope channel is 15 mm. wide. The cam radius increases from 46 to 62 mm. over an angle of 37°, giving a 25° cam angle. The tooth pattern is (4.3)^5(F).

The rear of the body is stamped with "AUSTRALIA," "SRT" inside a map of Australia, and "PATENTED." The cam has a raised up-pointing arrow labeled "UP" in raised letters, and "S R T" in raised letters.

Comments

Version B has a different cam with a new tooth pattern.

All of my A3 Explorers are right-hand models, but a left-hand model was also available.

If you can help me acquire a left-handed A3 Explorer, please email me.

 


A3 EXP 6 Explorer
(#146)

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 my Single Rope Technique A3 EXP 6 from Single Rope Technique in 2000.

The Single Rope Technique A3 EXP 6 is 113 mm. tall, 82 mm. wide, 31 mm. thick, and weighs 280 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).

The rear of the body is stamped with "S.R.T.," "AUSTRALIA, "EQUIP." and "19908901." The cam has a raised up-pointing arrow labeled "UP" in raised letters, and "S R T" in raised letters.

Comments

The A3 EXP 6 is a larger ascender made to work on 8 to 16 mm ropes (the "bigger is better" crowd will like this). As with the normal A3, it could have been made much lighter if more of the frame had been milled away.