Part B Steps And Ladders
Steep and moderate slopes covered with ice or snow make climbing difficult. Since there is less oxygen at high altitudes, men tire rapidly. Handlines can assist but do not solve the problem. The following procedures should be observed when building steps:
• Steps cut in the slope (Figure 2-4) can assist climbers. The rise of the step should not exceed 20 to 25 cm (8 to 10 inches). On gradual slopes a single 20-cm (8-inch) step can be cut every few meters, and the surface between steps can be leveled. On steeper slopes the steps are cut closer together but should not be less than 25 to 30 cm (10 to 12 inches) apart. Each step should extend the full width of the path.
• For snow and earth, a shovel or pick-mattock should be used to cut the steps. Steps in ice are harder to cut and an ice axe, pick, or pick-mattock should be used. The steps can be cut before or after handlines are erected, but it is easier to cut them after the handlines are up, since the handlines can assist the crew when cutting the steps.
During the operation, the use of ladders may be necessary. Hanging ladders are made of wire or fiber rope anchored at the top and suspended vertically. They are difficult to ascend or descend, especially for a man carrying a pack or load, and should be used only when necessary. These ladders act as a traffic bottleneck and three or four of them should be provided at each location. Standoff ladders have two wooden or metal uprights, which are placed at an angle for easier climbing. Both types can be constructed to the required size and carried to their final location.
During the construction of standoff ladders; hanging ladders; wire rope ladders with pipe rungs; wire rope ladders with wire rope rungs; fiber rope ladders with fiber rope rungs; and rope ladders with wood rungs, the following procedures should be observed:
• Standoff Ladders. Standoff ladders are built in dimensions to suit the circumstances. The two uprights are 5- by 10-cm (2- by 4-inch) lumber placed on end, or poles 8 cm (3 inches) in diameter roughly cut and dressed at the site. The uprights should extend 5 or 6 meters (16 or 20 feet). The uprights are placed 45 cm (18 inches) apart and the rungs are nailed at 25-cm (10-inch) intervals. At least two nails are used at each end of each rung.
For standoff ladders made of finished material (Figure 2-5A), the rungs are made of 2.5- to 5-cm (1- to 2-inch) lumber. For ladders made of native material (Figure 2-5B), the rungs are made of timber 5 cm (2 inches) in diameter. Timber should be carefully trimmed clean to avoid snagging clothing and equipment. Each ladder is anchored firmly in place with a wire or fiber rope anchor and fastened around the upper rung to a solid anchor. The ladder should also be braced at the base to lesson excessive motion during use.
• Hanging Ladders. Uprights of hanging ladders may be made of wire or fiber rope. Both uprights should be anchored at the top and bottom. Wire rope uprights with pipe rungs make the best hanging ladders since they are stiff and have minimal sag. Wire rope uprights with wire rungs can be used but are not as rigid. Fiber rope uprights can be used with wood or fiber rope rungs. They should be used sparingly since they are highly flexible, which causes them to twist under a climber. A secure anchor should be used to anchor each upright of a hanging ladder at the top (Figure 2-6). A log is placed at the break of the ladder at the top to hold the uprights and rungs away from the rock face, which provides better handholds and footholds. A single anchor is usually sufficient at the bottom of the ladder (Figure 2-7).
• Wire Rope Ladder With Pipe Rungs. A wire rope ladder can be made using 2.5-cm (1-inch) or 1.9-cm (3/4-inch) pipe rungs; the 2.5-cm (1-inch) pipe rungs are best.
Standard pipe stanchions (Figure 2-3) are used for wire rope ladders. They are spaced 30 cm (12 inches) apart in the ladder (Figure 2-8), and then 1.9-cm (3/4-inch) wire rope clips are inserted over 1.9-cm (3/4-inch) wire rope uprights. If .9-cm (3/8-inch) wire rope uprights are used, the wire rope clips are removed from the pipe stanchions and .9-cm (3/8-inch) wire rope clips are inserted in the pipe over the wire rope uprights.
Continue reading here: Bottom of Ladder
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