Ascender is a device that is used to climb the rope. In climbing it is often convenient substitute for prusik hitch. Ascenders are equipped with blocking system that under the load grips the rope and hold on it together with suspended load. After lowering the load is the blocking system released and the ascender can be moved up the rope. Other expressions for ascenders are “jugs”, “Jümar”, etc. Jümar (read “yee-mar”) is a slang term for any type of ascender. It comes from very first ascender, which was called “Jümar”. Climbing up the rope with ascender was therefore often called jümaring. There is a bit of confusion concerning the origin of this name and we can find several theories related to the origin of the name, but probably the most likely version agreed upon by most historical sources is the explanation claiming that the very first Jümar was constructed in 1958 by mountain guide Adolf Jüsy and technician Walter Marti, and the name was the composition of the first syllables of their surnames.

There are many types of ascenders, but they can be generally divided into two types:

  • Jümar type ascenders
  • Gibbs type ascenders

Principle of the ascender is based on rope going through suitably shaped metal object (body) where the rope is at the precise moment of ascender’s loading by a climber’s body pinched by a metal cam. Metal cam is attached to ascender’s body by axis.

Jümar type ascenders are designed so that the gripping of the ascender on the rope will happen only if the ascender’s cam is pressed to the rope by the spring inserted between the cam and body of ascender. With these ascenders is possible to grasp the ascender’s body during its load by hand (whether by grabbing designated handle or in any other way; but be careful, do not open the control trigger of ascender’s cam!).

Jümar ascenders are sometimes called: mechanical, catching, etc.

Gibbs type ascenders are ascenders that can be loaded only one functional way, and they loose its grip on the rope when grabbed and loaded any other way (mostly from the top by the body of ascender). They are designed so that the pressing of ascender’s cam to the rope was somehow activated only by the weight of the climber.

Gibbs ascenders are sometimes called: levering, clamping, etc.

During the ascent is ascender moving along the rope only in one direction (upward), but when the ascender is loaded and there is an attempt to move him downward the cam grips the rope and prevents the movement of ascender down. Some ascenders have body extended by handle, which facilitates handling of ascender (better pull with the hand). Most ascenders are designed for ropes of a diameter in the range of 8 mm to 12 mm. Lot of them work on ropes and cords of smaller diameter, but it can not be recommended. With the thin rope there can be a situation where ascender’s cam does not grip the rope and ascender will slide down the rope. Also, the thinner rope or cord may not hold (lower load capacity). It is also necessary to know the load capacity of the ascender and subject it only to the force it is able to bear! In any case, the rule while using ascenders is to observe the manufacturer’s recommendations.

Ascenders with handle are sometimes called upper or hand ascenders; ascenders without handle are called lower or chest ascenders.

Ascenders (mostly hand ascenders of Jümar type) are divided to the right and left, used for right and left hand of a climber. This is to allow the climber to look into the ascender area where the rope is inserted. During the climbing is visible only one side of the ascender, and should the climber switch the hand ascender from one hand (correct hand) to the other hand, he/she would see only smooth side of the ascender’s body and wouldn’t have visual control over the fact, whether the rope is properly threaded through the ascender. In addition, with some ascenders there is anatomically shaped handle for left or right hand of climber, and holding such ascenders in the wrong hand would be less comfortable.

Left-hand and right-hand Jümar.

Left-hand and right-hand Jümar.

Any jümaring is generally hard on the rope, and frequent and intense jümaring is not good for the rope.

The ascenders usually state two load capacity values. First actual strength of the ascender (that more or less means what amount of load can withstand ascender parts and their mutual connection). This value is usually higher, mostly approx. 20 kN.

Another value is the load capacity on the rope, which is in regard of ascender use more important value and we are more interested in this. Of course this value is lower and ranges from 4 kN–7 kN, depending on the type of ascender. UIAA standard requires that the ascender on the rope can withstand load min. 4 kN.

Ascenders and standard EN 567

EN standard requires ascenders (in the standard they are called rope clamps) to have certain properties, without which they were not allowed to be sold in the Czech Republic and in the EU countries.

Ascenders must meet these safety requirements, and to succeed in these tests:

  • Ascender must be fitted with a safety that prevents spontaneous slipping of the rope out of the ascender.
  • Opening for insertion of carabiner or sling must be at least 13 mm wide; the edges of the opening must be rounded.
  • All edges (e.g. handles) which may come into contact with the hands of the climber must be rounded.
  • Ascender tests are carried at the temperature approx. 23°C.
  • Ascender is fitted upon a rope and loaded by force of 4 kN 5 times in a row (+/- 0.1 kN) at the speed of approx. 10 cm/1 min.; ascender is always placed between each attempt to the different part of the rope, that wasn’t loaded yet; this test is carried out both with the rope of the greatest diameter that is possible to use with the specified type of ascender, and also with a rope or cord of the smallest diameter, that is possible to use for the specified type of the ascender.
  • During and after the tests the ascenders may not show any signs of damage; the ropes, on which were the ascenders tested, can’t be damaged either.

The leaflets, the instructions for use, tie-on tags, etc. that come with the sold ascenders, must contain the following:

  • Name of the Company
  • Number of standard it complies with
  • Use of the ascender
  • Meaning of all markings on the ascender
  • Method if insertion a taking out of the rope
  • Method of rope securing in the ascender
  • Where and how to connect the ascender
  • Selection of other ascender’s components
  • Method of maintenance
  • Lifespan of ascender
  • Effect of chemicals and temperature on the ascender

The body of ascender must contain these informations:

  • Name of the Company
  • Range of applicable rope diameters for specified ascender, the numerical value of diameter must be preceded by symbol “diagonally crossed circle” (i.e. diameter), the values are given in mm.
  • Symbol showing the right direction for operational use (usually small figure of a man with a raised hand, which have to point upwards, but there may be different symbols).
Jümar type ascender

Jümar type ascender

Jümar type ascenders

They are designed so that the climber directly loads the body of ascender. If ascender is not loaded by the climber it holds on the rope as well. It is thanks to the spring inserted between the cam and body of ascender; this spring maintains permanent pressing of the cam to the rope. The ascender’s cam, which is set against the rope in an advantageous angle, will under the load of the ascender by the climber pinch the rope. In order to achieve even greater prevention of the ascender’s slipping down the rope is ascender’s cam in the contact place with the rope provided with small teeth or needles, which are catching on the sheath of the rope. However, if these needles or teeth get obstructed, for example by ice or mud, the ascenders can begin to jerkily slip down. Jümar type ascenders sometimes “bite” into a rope after heavy load and to move them up again can be uncomfortable or even impossible. When they are in “bitten” state it is harder to take them off the rope. Further in the text you will find out how to release them. On the other hand, the advantage of Jümar type ascenders is that during the climb they can be grabbed in many different ways and used for pulling up (however, be careful not to open the control trigger of ascender’s cam or ascender’s cam itself, that would result in fall).

The picture shows inserting of the rope into a Jümar type ascender. From left: 1 – opening of the ascender’s cam by control trigger, 2 – control trigger is hooked to the ascender’s body so that ascender’s cam was held in opened position, the rope is inserted into Jümar, 3 – control trigger is released from the body of ascender, ascender’s cam presses on the rope by the force of spring.

The picture shows inserting of the rope into a Jümar type ascender. From left: 1 – opening of the ascender’s cam by control trigger, 2 – control trigger is hooked to the ascender’s body so that ascender’s cam was held in opened position, the rope is inserted into Jümar, 3 – control trigger is released from the body of ascender, ascender’s cam presses on the rope by the force of spring.

Another advantage of this type of ascender is that they can be relatively easily operated with one hand (of course it takes a little practice and skill). Types with handles find its use especially in the climbing of long pitches, and during the winter, when climbers wear gloves and are less skilled. In winter you have to watch out for the obstructing of the teeth on the cam’s contact place with ice!

From left: Petzl Ascension – Petzl Croll – Black Diamond nForce.

From left: Petzl Ascension – Petzl Croll – Black Diamond nForce.

More in e-book.

Title Part 2Mountaineering Methodology – Part 2 – Gear and Accessories

ISBN 978-80-87715-08-6

MMPublishing, 2013

Available for download from Apple iTunes (in the Books section).

For example U.S. store – link

Another countries – look on the page Download

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Another possibility is Google Play. This version is a simplified (as PDF).

Title Part 2 GPMountaineering Methodology – Part 2 – Gear and Accessories

ISBN 978-80-87715-13-0

MMPublishing, 2014

Available for download from Google Play.