Working With Lifting Blocks
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
Straight laced reeving is a basic method of placing the rope through a set of blocks. The end of the rope is fed through the outside sheave of the upper block to the outside sheave of the lower (traveling) block. This continues to the last sheave.
- Allows blocks to run closer together
- Is simple
- Has no reverse bends
Tilting because of imbalanced loading can cause block rotation and wear the sheaves and wire rope.
Reeve blocks symmetrically to distribute load evenly. All sheaves must be reeved to achieve the full working load limit of the block.
- Reduce wire rope length
- Use even part reeving
- Dead end to boom
- Evaluate wire rope construction