RULES FOR EFFICIENT BLOCK OPERATION
Periodic inspection of tackle block installations is essential for satisfactory operation.
The following rules should be observed.

1. Check block for excessive wear on connections, sheave bearings, rope scores and center pins.

2. Be sure that rope scores are smooth. If a wire rope sheave shows the imprint of rope, excessive rope wear will occur. Such sheaves should be replaced.

3. Look for signs of overloading: Elongated links, eyes or shackles; bent shackle, link or center pins; hook throat opening larger than original size, etc. If such conditions are found, the block should be replaced.

4. Lubricate plain bore, roller bushed, and plain bronze bushed blocks periodically and frequently. Do not oil plug type self- lubricating bronze bushed blocks.

5. Wire ropes should not be used in manila rope blocks. They are not designed for the high load conditions associated with wire rope installations. The shallow score of manila rope sheaves does not give sufficient support to wire rope, and the small sheave diameter leads to early rope fatigue and short rope life.

6. Do not attach a block by the tip of the hook. This practice will result in the hook yielding or straightening out at much below rated strength. To develop full hook and block strength, the load should be centered on the hook.

7. Do not use an oversize rope. Wire rope too large for the sheave score will be pinched and prematurely worn. Such a condition will also cause excessive sheave rim wear and breakage. Manila rope too large for the block will not be supported properly by the sheave score, nor will it pass freely through the block mortise, resulting in chafing and premature rope failure.

8. A block should always be free to line up with the pull of the rope. Excessive fleet angles impose lateral strain on the block, resulting in short rope and sheave life and possible damage to the block.

9. Do not subject the block to loads in excess of its maximum work load rating. The observation of this sensible and selfevident rule will avoid accidents.

REEVING OF TACKLE BLOCKS
In reeving a pair of tackle blocks one of which has more than two sheaves, the hoisting rope should lead from one of the center sheaves of the upper block.

When so reeved, the hoisting strain comes on the center of the blocks and they are prevented from toppling, with consequent injury to the rope by cutting across the edges of the block shell.

To reeve by this method, the two blocks should be placed so that the sheaves in the upper block are at right angles to those in the lower one, as shown in the following illustrations. Start reeving with the becket, or standing end, of the rope.

It is good practice to use a shackle block as the upper one of a pair and a hook block as the lower one. A shackle is much stronger than a hook of the same size and the strain on the upper block is much greater than on the lower one. The lower block supports only the load whereas the upper block carries the load as well as the hoisting strain. A hook is more convenient on the lower block because it can more readily be attached to or detached from the load.