Contact Details:
Dymot Engineering Co. (Pty) Ltd.
11 Derrick Road
Spartan
Kempton Park
Gauteng
South Africa
Tel: +27 (0)11 970-1920
Fax: +27 (0)11 970-1979
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USEFULL INFORMATION FOR WINCHING APPLICATIONS
Product News Monday, March 6, 2017: Dymot Engineering Co. (Pty) Ltd.
There are several factors that need to be taken into account to achieve proper rope lay on a winch drum and rope life. Of these factors the most important is the magnitude of the D/d ratio (Drum/Sheave to Rope Diameter) and the fleet angle.
BENDING RATIO OF ROPE (D/d)
When the wire is bent, over a winch drum, a tensile load is subjected to the outer fibres of the rope.
The magnitude of these tensile stresses is inversely proportional to the radius of the bend.
Thus the larger the radius is the lesser the stresses will be.
TABLE 1 depicts the recommended minimum drum and sheave diameters in terms of the rope diameters for various rope constructions. These values are the minimum values when working on a single layer of rope and for speeds below 1 m/s. An addition of 5% should be added to the recommended diameter with every 0.5m/s increase in speed above 1m/s.
ROPE CONSTRUCTION
MINIMUM RECOMMENDED DRUM AND SHEAVE DIAMETERS
6 x 19 (9/9/1) F or IWRC
28 x Rope Diameter
6 x 25 (12/6 F+6/1) F or IWRC
23 x Rope Diameter
6 x 36 (14/7+7/7/1) F or IWRC
19 x Rope Diameter
6 x 41 (16/8+8/8/1) F or IWRC
18 x Rope Diameter
6 x 43 (14/14/7F+7/1) or IWRC
18 x Rope Diameter
6 x 49 (16/8+8/8/8/1) IWRC
18 x Rope Diameter
15 Strand N/S 9x6/6x19(9/9/1)IWRC
26 x Rope Diameter
18 Strand N/S 12x7(6/1)/6x7(6/1) F or IWRC
26 x Rope Diameter
18 Strand N/S 12x9(9/9/1)/6x19(9/9/1) F or IWRC
24 x Rope Diameter
8x25 (12/6F+6/1) IWRC Spin Reduced
19 x Rope Diameter
6x13(7/6Δ)F
42 x Rope Diameter
6x30(12/12/6Δ)F
42 x Rope Diameter
TABLE 1: The minimum recommended ratio of rope to drum and sheave diameters at < 1m/s.
In situations where the rope will only work intermittently the drum and sheave diameters can be reduced by as much as 25% from the recommended minimum values as listed in TABLE 1. Further reduction from this is not recommended under any circumstances as this will result in severe increase in bending stresses and will result in rapid rope fatigue. Please see FIGURE 1 for Illustration of D/d.
Dymot is involved with the majority of Mining Projects and have products in more than 40 countries.
For more information please contact us on 011 970 1920 or visit our website at www.dymot.co.za .
Jorick Snyman – Mechanical Engineer – Dymot Engineering Company
