Tractel ET Notice D'utilisation page 17

Calculation of loading of a snatch blocks
The maximum Working Load Limit (WLL) written on the side of the block is the maximum load that should be exerted
on the block and its connecting fitting.
This total load value F varies with the angle (α) between the incoming and departing lines to the block. The following
Error! Reference source not found. indicates the factor to be multiplied by the line pull to obtain the total load F on
the block.
IMPORTANT REMARK
: In case on a 3 legs block assembly, add to the above calculated effort the load applied on
the becket. The total value of the calculated effort must be strictly lower to the working load limit (WLL) of the
block and the resistance of the anchorage point where the block is fitted.
Wire rope strength reduction
��������ℎ ∅ ( = ������ ∅ + 1 ��/�� ∅)
The ratio =
�������� �������� ∅
between the pitch diameter of the sheave and the wire rope diameter, called the
winding ratio, alters the tensile strength in the wire rope as hereafter.
* Values for information only, depending on the construction of the wire rope.
For more information, please ask your wire rope supplier.
M 6062 M
rev 13 – 06/2021
GB
Angle α Effort applied on suspension « F »
0°
15°
30°
45°
60°
90°
120°
150°
180°
Always ensure :
F < pulley WLLF < anchoring point resistance.
Example for EH/EGZ
if α = 0°
F = 2 x winch WLL + becket loading
WLL winch x 2
WLL winch x 1,98
WLL winch x 1,95
WLL winch x 1,85
WLL winch x 1,73
WLL winch x 1,41
WLL winch x 1
WLL winch x 0,52
WLL winch x 0
Winding
ratio
6
8
10
15
20
www.tractel.com
Reduction
21%
17%
14%
11%
9%
Page 17/66