Which of the following is not a rigging device?

The hydraulic jack is not classified as a rigging device because its primary function is to lift heavy loads through the application of hydraulic pressure. While it can be used in conjunction with rigging systems for lifting tasks, it does not serve the primary purpose of rigging devices, which are specifically designed to facilitate the movement and support of loads through various mechanical means.

On the other hand, shackles, pulleys, and hoisting straps are integral components of rigging systems. Shackles are used to connect various rigging components, allowing for secure load attachment. Pulleys assist in changing the direction of the force applied to lift a load, making lifting easier. Hoisting straps are utilized to wrap around and secure loads, providing a means of lifting them safely. Each of these devices directly contributes to the mechanics of rigging, making them essential for proper load handling and safety during lifting operations.