Comeup Heavy Duty DC Hoist (Ver:01) User Manual download pdf (Page 9)

V. Hoisting Principles

Load Rated

Load and speed varies according to

how much wire rope is on the drum. The first

layer of rope on the drum delivers the slowest

speed and the maximum load. The top layer

of rope on the drum delivers the maximum

speed and the minimum load. For this reason,

all hoists are rated at their top layer capacities.

The flanged drum end plates shall protrude beyond the rope wound on the drum at the

top layer by at least 1.5 x the nominal rope diameter.

Calculating Head Loads

P: Rope tension

η: Sheave efficient

θ: Angle

W: Load

μ: Friction factor

First layer (Min.speed Max.load)

Half layer (Med.speed Med.load)

Top layer (Max.speed Min.load)

Flange of drum

sinθ +

cosθ

Calculating Fleet Angle

● The hoist should be mounted as close to centre

and as perpendicular as possible to the direction

of the line pull. This will keep the wire rope fleet

angle centred on the drum as small as possible.

● If the proper fleet angle is not maintained, the

wire rope could wind onto one side of the drum.

This could cause failure of the hoist or wire rope, resulting in damage, injury or death.

● Experience has shown that the best wire rope service is obtained when the maximum fleet

angle is not more than 1.5° for smooth drums.

● Therefore the correct distance between centre of drum and of should be derived as a fleet angle

of 1.5° is the equivalents of approximately 19 cm of lead for each centimetre of overall drum

length.

Correct Distance

Drum Length

Fleet Angle

No. of sheaves 1 2

Roller bearing 0.98 0.96

Sleeve bearing 0.96 0.92

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

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Comeup Heavy Duty DC Hoist (Ver:01) User Manual Page 9