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Wire Rope Selection for Gate Operating Devices


Quiz Questions

1.Wire rope consists of multi-wire strands laid helically around a core (Figure 2-1). The way the wires are laid to form the strands, the way the strands are laid about the core, the core construction, and the materials and coatings used for the components contribute to the overall properties of the rope.
True
False
2. Wire rope classification is designated by the construction of the rope as seen in cross section. The number of strands and the number of wires in each strand are respectively given in its label, for example: 6×19, 6×37, 7×19, 8×61, etc. (Figures 2-2 and 2-3).
True
False
3.The lay of a wire rope is designated by direction and type (Figure 2-7). Direction is right or left according to how the strands have been laid around the core. The lay type is either regular or lang, depending on whether the wires in the strands are laid in the opposite direction of the strands or the same direction as the strands.
True
False
4.The wires in regular lay wire rope appear to line up with the axis of the rope. In contrast, the wires in lang lay wire rope appear to form an angle with the axis of the rope.
True
False
5.wire rope consists of multi-wire strands laid helically around a central core. The core contributes very significantly to the overall properties of the rope. There are two types of cores, Fiber Core (FC) and Independent Wire Rope Core (IWRC).
True
False
6.The core in FC wire rope provides no real strength for either crushing or tension. The fiber tends to dampen out vibration, an advantage for some applications, such as elevators.
True
False
7.FC is more flexible than IWRC, but flattens under load, inhibiting the free internal adjustment of the wires, which increases stresses. In the past it was thought that its core had a significant lubricant holding ability. That is not presently considered a real advantage. FC wire rope is not well suited for gate- lifting devices.
True
False
8.The advantages of IWRC are its strength in tension and its resistance to crushing. Its only disadvantage is decreased flexibility. Since bending around drums and sheaves at high loads is required for most gate- operating devices, IWRC wire rope is generally preferred for these applications.
True
False
9.Swaged sockets are mechanically pressed onto wire rope (Figure 3-1).
They are occasionally used for gate-operating devices. If properly designed and attached, they can develop 100 percent of the strength of the rope. Note that swaged sockets are not suitable for lang lay rope, nor are they suitable for ropes with a fiber core.
True
False
10.The following six properties must be considered when selecting a wire rope:
a. Resistance to breaking.
b. Resistance to fatigue.
c. Resistance to abrasive wear.
d. Resistance to crushing.
e. Resistance to corrosion.
f. Reserve strength.
True
False
11. The static load (no movement conditions) for various single- and multiple-sheave block tackles is calculated by dividing the total load by the part-number (number of supporting ropes) of the sheave (Figure 4-2). However, note that rope selection is not based on static load.
True
False
12. The factor of safety (FOS) for a dynamic loaded rope on a new Corps gate-operating device should be at least 5, based on nominal strength, the part-number, and the dynamic load.
True
False
13.Standard wire rope specification nomenclature gives the following rope requirements: length, direction and type of lay, diameter, finish, classification, material, preformed or non-preformed, and core type.
True
False
14.Figure 7-2 shows various types of wire end welding.
True
False