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Version A is similar to Version B except for the following differences:
- Version A's shell is not anodized.
- The lower hole on Version A is larger (15 mm. vs. 13 mm)
Luc Bourguignon sent me this ascender in late 2005, but it is probably the earliest Petzl in my collection.
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I obtained this ascender from Speleoshoppe in about 1982.
The ascender is right-handed, as are all Jammers that I have seen. The ascender is is 100 mm. high, 76 mm. wide, 24 mm. thick, and weighs 122 grams. The ascender shell is subtriangular light blue anodized shape bent from 4.2 mm. aluminum sheet. The rope channel is formed by bending the left side of the ascender into a U. The rope channel is 15 mm. in diameter. The main sling attachment point is an beveled 13 mm. hole located below the cam near the rope channel. A second attachment point consists of two beveled 13 mm. holes through the rope channel U and just above the cam. The right end 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 sits into a stamped depression on the back of the cam, while the roll is exposed on the open side. The pivot is centered 49 mm. from the inside of the rope groove.
The cam is a plated skeletonized aluminum casting. The cam radius, measured from the pivot, increases from 40 to 51 mm. over an angle of 42 degrees. The cam has 12 "z" teeth cast into the cam, plus a single sprue between the fifth and sixth "z" teeth. A spring-loaded manual safety bar is mounted on the bottom of the cam with a solid pin. The normal action of the spring holds the safety against the cam. When the cam is opened, the shell interferes with the safety bar, thus preventing opening the cam. If the safety bar is moved away from the cam (opposing the spring), it will clear the shell and the cam will open. At full open the safety can be released and the spring will hold the safety against the back of the shell. A small tab fits into a small drilled in the back of the shell cam U and holds the cam open. A bent tab on the bottom of the safety bar assists in operating the safety mechanism.
The back of the shell is stamped "F. PETZL" and "FRANCE". The cam has "ZEDEL" in raised cast letters.
This ascender dates from the 1960s. The shell is adequate but the cam is not. The soft cam wears quickly, the teeth are inadequate in mud, and in general the cam is poorly executed. Versions B and C are much better ascenders.
Bob Thrun (Prusiking, 1971) reports that these were available in left and right handed Versions, with and without safety catch, for a total of four Versions. I'd like to acquire the Versions I don't have. Bob also tested one of these ascenders to failure. He wrote, "At 800 lbs the body was bending. At 900 lbs, the body sprang apart enough for the cam to swing through. The ascender was totally inoperable. Even the cam had been bent. These units are weaker than other mechanical ascenders, but are comparable in strength to quarter-inch poly slings, which some cavers use."
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I have a second ascender which has the cam assembly of Version B, but a shell that is identical to Version D's (including markings) except Version C has a drilled detent for the cam safety.
When I bought this ascender, it was paired with the Version B ascender.
[ Top | Version A | Version B | Version C | Version E | Version F | Return to E.C. Ascenders ]
I acquired a pair of these ascenders from Speleoshoppe in 1979.
The ascenders are right-handed,100 mm. high, 76 mm. wide, 26 mm. thick, and weighs 138 grams. The shell is essentially identical to Version B except the anodizing is a darker blue, and the upper end of the rope groove is flared to 17.5 mm. The lower attachment hole is not beveled. The back of the shell is stamped "PETZL", "MAXI 400 KG","BREVETE", and "FRANCE". The cam assembly is the same as that on the Petzl Croll Version B. The shell detent is omitted since the new cam safety design does not require it.
With the advent of the steel cam, the Petzl Jammer became a viable ascender. The ascender is well made, and the cam teeth are among the finest in my collection. The only oversight is that the lower attachment hole is not beveled. Single handed operation of the Jammer is rather difficult. Left-handed operation particularly difficult as expected for a right-handed ascender.
The flat area on the cam caused some confusion. Some cavers thought it was a design defect, but actually it was provided as a feature. The flat area allows one to cant the ascender then slide it down the rope without opening the cam. This feature was later abandoned.
The Jammer is a very popular ascender, particularly in Europe. Its light weight and small size certainly enhance its popularity.
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I obtained this ascender from Bob & Bob at the 1988 NSS convention.
The ascender is right-handed,100 mm. high, 76 mm. wide, 26 mm. thick, and weighs 145 grams. The shell has a few minor improvements over Version D. The upper attachment hole has been enlarged to a near vertical 19x13.5 mm. oval. A second 15 mm. upper attachment hole is provided. It goes through the back of the ascender only, missing the rope groove. A raised area is stamped into the back of the ascender, presumably to increase the rigidity of the device. A cylindrical cam closing stop is provided.
The cam is identical to the one on the Petzl Croll Versions B, C, and D, but the cam safety is shaped differently. The large semicircle is eliminated, and a simple elbow shape is used. A cylindrical knob on the safety bar assists in operating the safety mechanism.
The back of the shell is stamped "PETZL", "MAXI 400 KG", and "BREVETE FRANCE". The front of the shell is stamped "CORDE", "ROPE", "Ø MINI." and "10 m/m". A Sieg Heil icon is also stamped onto the front. The word "PETZL" is cast into each side of the cam, and "OIL" and an arrow are stamped on each side of the cam safety.
This Version has a slightly more convenient shell design than the previous one. The extra hole may occasionally be useful, and this time all holes are beveled. The comments on the Petzl Croll Version B cam slots apply here as well. The cam safety design is more reasonable than that on the Croll. In general this is a well made ascender suitable for a wide range of uses.
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I obtained this ascender from Bob & Bob at the 1997 NSS convention.
The ascender is right-handed,102 mm. high, 76 mm. wide, 35 mm. thick, and weighs 139 grams. The shell has a few minor changes from Version E. First, the back is not flat; instead, the lower part of the shell bends backward. The upper attachment hole is shorter and wider, measuring 18.6x16.6 mm. oval. There is no second upper attachment hole; instead, a triangular cam stop is punched from rear to front. Its location is too high to reach the cam. A raised area is stamped into the back of the ascender, presumably to increase the rigidity of the device. The bend in the shell distorts the lower attachment hole so that it is 14.8 mm. high and 16.3 mm. wide. A 6 mm. accessory cord hole lies outside and slightly above the main lower attachment hole.
The cam is identical to the Petzl Croll Versions E and F, but the injection-molded plastic cam safety has a different shape, with five thin grooves on top and a sharp point on the outside. Like other Versions of the Basic, the cam safety can hook over the cam channel to hold the cam open. The cam rivet is not placed front-to-back which improves the look of the ascender without having any effect on function.
The back of the shell is stamped with "97332F," the Petzl logo, "CE0197 EN567", the UIAA logo, and the Reading is Dangerous icon. The front is stamped with a Sieg Heil icon and "ROPE*8<Ø<13" where the asterisk indicates two concentric circles. The Petzl logo is cast into the cam.
Version F uses a new cam design with some nicely-made teeth and a thin, redesigned mud groove that has more clearance, but still seems to be ineffective except in ideal situations. The cam safety remains difficult to use one-handed, but this is more because the ascender is small than a criticism of the safety. The sharp point on the cam safety is mildly uncomfortable, but one can easily file it off.
I do not like the bend in the shell because it increases the ascender thickness with no apparent need to do so. Although the upper attachment hole on earlier versions was not essential, replacing it with an ineffective cam stop does nothing. Remember, these cam stops only increase the ascender strength in unrealistic laboratory tests, they serve no function in proper field use.
All in all, this is a nice ascender.
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©2007, Gary D. Storrick