Blocks, including Snatch Blocks Blocks can be crane and hook blocks, wire rope blocks, snatch blocks down to the simples of tackle blocks. The essential parts of any block are the shell, the sheaves, the center pin, the straps and the connections. They can be equipped with a number of end fittings including hooks, wedge sockets, clevis, shackles of all types and swivels of all types as well as combinations of these items. Blocks may also be equipped with a beckett, which is a term for a rope end anchorage point on the block. All fittings on blocks should be forged alloy steel. Shackles and eyes are inherently stronger than hooks; blocks equipped with them are rated at higher working loads. The anchorage point for the blocks must be able to carry the total weight of the load plus the weight of the blocks, plus the pull exerted on the lead line. Tackle Regulations, Part IV, Cargo Gear, 21(8): All chains......and all rings, hooks, shackles, swivels and pulley blocks shall be inspected by a competent person immediately before each occasion on which they are used in hoisting or lowering, unless they have been inspected within the preceding three months. A Few Tips: - If you find small metal particles on any surface of the block / sheave, stop the operation and inspect for damage. it is possible for bearing races to disintegrate or seize up and cause catastrophic failure. - Do not hesitate to completely dismantle blocks. Click on photos to see larger images. - Clean all components completely before inspection. - Check the blocks for excessive wear on the becketts, end connections, sheave bearings and center pins. - Ensure the greaseways and grease nipples are clear and free. Replace the grease nipple if necessary. - Ensure the sheave grooves are smooth. If a wire rope sheave shows the imprint of the rope, excessive rope wear will occur. - Hang the sheave from a piece of twine and tap it with a hammer. It should ring - if not it may be cracked. - Look for signs of overloading; elongated links, eyes or shackles; bent shackle, link or center pins; enlarged throat hooks. If such conditions are found, the block should be replaced. - Check the sheaves for proper rotation. - Ensure all cable keepers are in place. - Check the clearance between sheaves and cheek and partition plates. It should be small enough that there is no danger of the rope slipping between them. - This is also an ideal opportunity to take photos of, or sketch, anything unusual. This may be of use in the future. Click on photo to see larger image. - Make notes of what you found, where you found it and what, if anything, you did about it. - Measure the sheave groove with a groove gauge. - Measure the cross-section of the pins in at least three places to record wear. - Grease it well and re-install. - Ensure the cotter pin or other securing mechanism is in good condition. Refer to the Construction Safety Association of Ontario "Rigging Manual", Chapter 4, Rigging Hardware - Blocks.