Question

what construction machine use pulleys and balanced levers

Answer 1

Common construction machines that use pulleys and/or balanced-lever (counterbalanced) principles:

- Cranes (tower cranes, mobile/all-terrain cranes, luffing jib cranes)
- Use pulley blocks (sheaves) and wire ropes for lifting (block-and-tackle style arrangements give mechanical advantage).
- Use counterweights on the rear of the superstructure or jib to balance the boom moment (a lever/counterbalance principle).

- Derricks and gin poles
- Simple mast plus guyed pulley blocks for raising loads; often use block-and-tackle for mechanical advantage.

- Overhead/gantry cranes and hoists
- Electric or manual hoists use pulley drums and sheaves; multi‑sheave arrangements reduce required lifting force.

- Winches and cable cranes (skyways)
- Winch drums and pulleys route cable; pulleys reduce friction and change direction of force, block systems multiply force.

- Block-and-tackle (manual lifting rigs)
- Traditional pulley assemblies used on sites for heavy lifting where powered cranes aren’t used.

- Backhoe/excavator boom and loader arms (linkage systems)
- These use lever linkages (often hydraulic) that operate like levers; some linkages are designed to balance loads or optimize force transmission (not usually rope pulleys, but mechanical-lever principles).

Why these elements are used
- Pulleys change force direction, reduce required input force (mechanical advantage = number of supporting rope segments), and let a compact winch or motor lift larger loads.
- Balanced levers (counterweights, boom geometry) reduce required torque on the slewing/boom pivot and improve stability/safety.

If you want, I can:
- Give a simple calculation example (mechanical advantage of a given block-and-tackle).
- Show which parts of a specific crane are pulleys vs. counterweights.
- Suggest diagrams or photos to illustrate.