Tackle Block Information
How to Determine Overhauling Weights
To determine the weight of the block or overhaul ball that is required to free fall the block, the following information is needed: size of wire rope, number of
line parts, type of sheave bearing, length of crane boom, and drum friction (use 50 pounds, unless other information is available).
line parts, type of sheave bearing, length of crane boom, and drum friction (use 50 pounds, unless other information is available).
| Wire Rope Size | Factor A – Wire Rope Weight |
| Lbs. Per Ft., 6 x 19 IWRC | |
| 3/8 | .26 |
| 7/16 | .35 |
| 1/2 | .46 |
| 9/16 | .59 |
| 5/8 | .72 |
| 3/4 | 1.04 |
| 7/8 | 1.42 |
| 1 | 1.85 |
| 1 1/8 | 2.34 |
| 1 1/4 | 2.89 |
| Number of Line Parts | Factor B – Overhaul Factors | |
| Roller Bearing Sheaves | Bronze Bushed Sheaves | |
| 1 | 1.03 | 1.05 |
| 2 | 2.07 | 2.14 |
| 3 | 3.15 | 3.28 |
| 4 | 4.25 | 4.48 |
| 5 | 5.38 | 5.72 |
| 6 | 6.54 | 7.03 |
| 7 | 7.73 | 8.39 |
| 8 | 8.94 | 9.80 |
| 9 | 10.20 | 11.30 |
| 10 | 11.50 | 12.80 |
The Formula is:
Required Block Weight = [(Boom Length × Factor A) + Drum Friction] × Factor B
Required Block Weight = [(Boom Length × Factor A) + Drum Friction] × Factor B
Example:
To determine the required block or overhaul weight using 5 parts of 7/8” diameter wire rope, a 50 ft. boom and roller bearing sheaves:
