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Tackle Block Information

How to Figure Line Parts

To help figure the number of parts of line to be used for a given load, or the line pull required for a given load, the following ratio table is provided with
examples of how to use it.

Ratio A Bronze Brushed Sheaves Ratio B Anti-Friction Bearing Sheaves Number of Line Parts
.96 .98 1
1.87 1.94 2
2.75 2.88 3
3.59 3.81 4
4.39 4.71 5
5.16 5.60 6
5.90 6.47 7
6.60 7.32 8
7.27 8.16 9
7.91 8.98 10
8.52 9.79 11
9.11 10.60 12
9.68 11.40 13
10.20 12.10 14
10.70 12.90 15
11.20 13.60 16
11.70 14.30 17
12.20 15.00 18
12.60 15.70 19
13.00 16.40 20

How to Figure Line Parts

After calculating Ratio A or B, consult table to determine number of parts of line.

Examples:
To find the number of parts of line needed when weight of load and single line pull are known, and using Bronze Bushed Sheaves.

How to Figure Line Parts
Refer to ratio 9.02 in table or number nearest to it, then check column under heading “Number of Line Parts”= 12 parts of line to be used for this load.
To find the single line pull needed when weight of load and number of parts of line are known, and using antifriction bearing sheaves.
How to Figure Line Parts
9,290 lbs. single line pull required to lift this load on 8 parts of line.
To find the lift capacity when the parts of line and single line pull are known, and using anti-friction bearing sheaves.
How to Figure Line Parts
10,000 lbs. single line pull with 5 parts of line will accommodate 47,100 lbs. lift capacity.