Which of the following is a key part of a load block?

The key part of a load block is comprised of sheaves and pins, which play a critical role in the operation of hoisting equipment. Sheaves are wheels that guide the movement of the hoisting cable or rope, ensuring it runs smoothly and efficiently. This helps to reduce friction and wear on the cable while also providing a way to redirect the load's path.

Pins, on the other hand, serve to secure the sheaves within the load block, maintaining the integrity and functionality of the assembly. They ensure that the sheaves do not dislodge and that the entire mechanism operates as intended without risk of failure.

Other components may contribute to the functionality of hoisting equipment, but sheaves and pins are essential for the load block to perform its intended role in lifting and lowering loads safely. The inclusion of only a hook, just the frame, or a clamping device does not provide the comprehensive function required for a load block, as they lack the necessary components to manage the load effectively.