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Winches sheaves and purchases for flexible steel wire rope
Fleet angles
Use this page as a guide for how to measure fleet angles.
How to measure fleet angles
The maximum fleet angle is measured:
- step 1: from the centre of the drum
- step 2: to the centre of the first diverting sheave
- step 3: then back to the inside flange across to the middle of the drum.
The maximum fleet angle is 5° for a grooved drum is and 3° for an ungrooved drum. To achieve these angles the distance from the drum to the first diverting sheave must be a minimum of:
- 19 times half the width of the drum for an ungrooved drum
- 12 times half the width of the drum for a grooved drum.
Measuring the fleet angle
Examples of how to measure fleet angles
These examples show how fleet angles are measured.
Example 1:
Width of the grooved drum = 1 metre
12 X 1 X 0.5 = 6
Therefore, the sheave must be 6 metres from the drum.
Example 2:
Width of the ungrooved drum = 1 metre
19 X 1X 0.5 = 9.5
Therefore, the sheave must be 9.5 metres from the drum.
Include the rope block pulley.
Rope jumping sheave
When the fleet angle is large or the distance between the drum and the first lead or diverting sheave is short, the rope won't always lay neatly on the drum. This may causes significant wear on the rope and the sheave flange.
Rope jumping sheave