Although hauling systems and the equipment that is used to construct them can vary significantly, the actual principles and purposes of these systems technically remain same.
As in any situation, all the components should undergo a pre-use inspection to eliminate the risk of defective items being included in the hauling system.
Any equipment used in any hauling system should be appropriate in design and adequate in strength for the intended purpose and the potential loadings that will be applied to them; this will also include all anchorages. Equipment should also conform to the relevant national or international standards which differ from region to region.
Also, all equipment that is to be used in the system will need to be compatible with one another; can that belay device be used with that type of rope? Don’t forget to check the manufactures instructions and also carry out research for any product information updates and more importantly any care or recall advisories.
Here are some typical examples of the basic types of equipment that are commonly used to create hauling systems. You will be able to view these items in more detail when the equipment section of this site is developed, until then this is a brief summary;
These days there is a vast array of rope types and models available on the market, each one designed with a specific function in mind. Selecting the correct type of rope for your system and the situation it is to be used in will be a key point of planning. For the purposes of this page and in keeping with the theme of the ropebook site, we are mainly going to focus on the kernmantle type of rope typically used in climbing, caving, rope access and rope rescue.
We are not going to go into depth regarding the different types of rope on this page as further detailed information will soon be available in equipment section. All we need to understand is that the main types of rope we will normally come across will consist of either dynamic rope (such as EN 892) or low-stretch rope (EN 1891).
The design properties and construction of dynamic rope provides it with very good elasticity attributes enabling it to absorb and dissipate the energy applied to it. The inherent stretching of dynamic rope is what allows it to deal with the forces involved when arresting a falling climber.
If we were to opt to utilise a dynamic type rope within a hauling system, its characteristics would result in some loss of energy and therefore the overall mechanical advantage will be affected. When compared to low-stretch or semi-static rope, employing a rope with a reduced stretching ability should result in less energy being lost.
Normally a pulley is employed to change the path or direction of a rope, they can also be used to attach loads to rope or cable systems such as in a tensioned line or Tyrolean traverse (aerial tramway).
All pulley devices will have an inherent coefficient of friction that will resist a certain percentage of the effort that is applied into a pulley or hauling system. The frictional resistance between the pulley sheave, the bearing and the axle will vary from device to device. Modern pulley design and improved bearing components have increased efficiency although this will still be affected by lack of regular care and maintenance.
Progress Capture Pulleys
In certain hauling systems a progress capture pulley can be incorporated, these devices consist of a standard pulley combined with a locking device. When the locking device is engaged it restricts the movement of the rope around the pulley sheave, forming a one-way pulley.
The locking mechanism on the majority of progress capture pulleys will consist of a toothed cam which bites onto and grips the rope. Similar to a toothed ascender, shock-loading of these types of devices should be prevented as excessive forces can significantly damage the rope.
Descenders & Belay Devices
Using self-breaking descenders or belay devices instead of progress capture pulleys allows the rope to be quickly released, lowering the load in a controlled way without the need for the system to be significantly altered in-situ.
There are many self-breaking type devices available, when under load the device should automatically lock out, preventing rope travel through the device. This action is usually achieved by a pivoting cam inside the device, the position of the cam can also be manipulated, typically by operating a handle or leaver which allows the rope to be gradually released.
Unlike a standard pulley where the sheave fully rotates about its axle, self-breaking cams pivot from a fixed point and trap the rope between the cam and a friction plate. The downside is that this results in increased frictional resistance against the effort that is applied into the hauling system to lift the load.
These devices are used in hauling systems to either clamp or bite on to a load bearing section of the hauling rope. Additional pulleys can then be attached to the rope-clamps to increase the overall mechanical advantage of the hauling system.
Using rope-clamps allows for a more effective hauling system to be created as the hauling rope does not have to run from the main anchor point to the load multiple times to form the mechanical advantage. The mechanical advantage can also be altered quickly to either increase or decrease input effort as required by adding or removing rope-clamps and pulleys within the hauling system.
Some typical rope-clamps commonly used in hauling systems include devices such as the Petzl Shunt and the Petzl Ascension. Rope-clamps that conform to the European test standard will be marked with EN 567. Some devices grip onto the rope by engaging a toothed cam, shock-loading of rope-clamp devices should be avoided as the clamping mechanism can significantly damage the rope if excessive forces are applied.
Where mechanical rope-clamps are not available, it is possible to use a smaller diameter of cordage (typically 5-6mm) to achieve the same effect by tying a Prusik or Klemheist knot. Caution should be made to the type of cordage being used as materials such as Dyneema / Spectra have low melting points.
Connectors & Rigging components
It is the connectors that will attach the rope(s) to the load, join hauling devices together and also fix the hauling system to the anchorage devices. As the connectors are significant components of the hauling system it is highly important that the right type, shape and size of connectors are used. See the equipment section for more information on connectors.
In addition to connectors, some more complex hauling systems may require additional rigging components to ensure that the connectors used in the system are both correctly loaded and not over-crowded. Components such as flat and three-dimensional rigging plates, rigging hubs, anchor multipliers and swivels may be incorporated into a hauling system to allow for a variety of haul options and more flexibility of the system.
To be continued…