Block and tackle

What's in the lesson

1. One sheave. One wire rope over one sheave in a block hung from a beam clamp.
2. Parts of line. The same rig.
3. Reeving to advantage. Two single-sheave blocks lifting 900 lb.
4. Distance and work. A four-part tackle lifting 4,000 lb, no friction.
5. Sheave friction. The four-part tackle and 4,000 lb again.
6. The anchor. A four-part tackle on a 2 t (4,000 lb) beam clamp.
7. Chain falls. A 2 t Harrington CB hand chain hoist on a beam clamp, lifting 4,000 lb.
8. Putting it together. A 6,000 lb test weight, a 3 t (6,000 lb) beam clamp and blocks with up to four sheaves each.

How it works

• One idea per page, each built around a simulator you work yourself. The last page puts it all together on one job.
• A narrator reads each step aloud. Mute it or slow it down at the top right, or read it yourself.
• Each step tells you what to do and what to watch. Stuck? Hint, then Show me: the simulator does it, then hands back.
• Practice questions along the way. Pick a wrong answer and you see why it's wrong, then get a new, similar question.
• After the steps, free play: every control unlocked, Reset, and "Give me a challenge".
• Nothing locks. Back and Next always work, and your place is kept in this browser.
• Print the short summary sheet: the rules and key numbers, light on toner.