1.A4.5 USE OF ROPE BLOCKS WITH SUPPORTING STRUCTURES

It should be noted that when rope blocks are used, the load imposed on the supporting structure is increased by the value of the hoisting effort. This additional load is also imposed on any equipment used to connect the top hook or eye of the pulley blocks to the structure. Care should therefore be taken to ensure that the structure, together with all other above hook equipment (e.g. trolleys, beam clamps, shackles, eyebolts) is of adequate capacity. The increase in load is as shown below:

Number of Sheaves

Top Block

1

1

2

2

3

3

Figure 1.A4.5-1 

Bottom Block

0

1

1

2

2

3

Load on Top Shackle

= load lifted x Factor

2.08

1.56

1.39

1.3

1.25

1.22

Assuming 8% per sheave for friction