A General Idea Indicating The Safe Working Loads Of Our Blocks
Dia of Sheave Circf. of Rope
6”
1”-1¼”
7”
1¼”-1½”
8”
1½”-1¾”
10”
1¾”-2¼”
12”
2¼”-2½”
14”
2½”-3”
16”
3”-3½”
18”
3½”-4”
S.W. L. tons
Single
Sheave
0.75
1.5
2
3
5
6
7
10
Double
Sheave
1
2
3
5
8
10
15
20
Triple
Sheave
1.5
2.5
5
10
12
15
20
25
Safe Working Loads (S.W. L.) Of Rigs B. S.: 4018-1966
Dia of Sheave
Dia of Rope
S.W. L.
per Single
part of rope
Ton
Safe Working Loads of Rigs
inch
mm
inch
mm
1/1 Rig Ton
2/1 Rig Ton
2/2 Rig Ton
3/2 Rig Ton
3/3 Rig Ton
5
127
3/8
9
0.75
1.5
2.25
3.0
3.75
4.5
6
152
7/16
11
1.0
2.0
3.0
4.0
5.0
6
7
177
1/2
13
1.25
2.5
3.75
5.0
6.25
7.5
8
203
9/16
14
1.50
3.0
4.50
6.0
7.40
9.0
9
228
5/8
16
2.0
4.0
6.0
8.0
10.0
12.0
11
279
3/4
19
3.0
6.0
9.0
12.0
15.0
18.0
12
304
7/8
22
4.0
8.0
12.0
16.0
20.0
24.0
Selection Criteria: Sheave Dia/Rope Dia = At least 12
The safe working load per single part of rope is approximately one sixth of the nominal breaking load of ropes as
2 2 specified in B.S.302 621 in the 6 x 37 group of tensile strength 100/110 ton / inch (160/175 kgf/mm ). This is the
nominal breaking load on which the design of blocks to this standard is based.
The manner of test laid down in schedule II of DOCK Workers (Safety, Health, and Welfare)Regulations, 1990, is as follows:
Article of Gear
Proof Load
Single sheave pulley block
Four times the safe working load
Multiple sheave block with safe working load up to and including 20 tons
Twice the safe working load
Multiple sheave block with safe working load over 20 tons up to and including 40 tons
20 tons in excess of the safe working load
Multiple sheave block with safe working load over 40 tons
One and a half times the safe working load
Note
Higher capacity pulley blocks manufactured against order.
