elevator rope

What are Elevator Ropes?

Elevator ropes (often called "hoist ropes" or "cables") are the critical components that connect the elevator car to the counterweight and are driven by the machine to move the car up and down the hoistway. They are engineered for extreme strength, durability, and safety.

The most common type in modern elevators is the steel wire rope.

1. Types of Elevator Roping Systems

How the ropes are arranged determines the elevator's speed, capacity, and mechanical advantage.

• Single Wrap (1:1) Roping:

  • How it works: The rope is fastened at one end to the top of the hoistway, wraps around the drive sheave on the machine, and is fastened to the counterweight. The car is connected directly to the rope. For every one meter the sheave turns, the car travels one meter.

  • Use Case: Best for mid to high-rise buildings. It allows for higher speeds and is more efficient.

• Double Wrap (2:1) Roping:

  • How it works: The rope is fixed to the top of the hoistway, goes down and under a deflector sheave on the car, up to the drive sheave on the machine, back down to a sheave on the counterweight, and is finally fixed back at the top of the hoistway. This creates a 2:1 mechanical advantage.

  • Advantage: The load on the drive sheave is halved. This allows the use of a smaller, less powerful machine.

  • Use Case: Common for heavy freight elevators and traction elevators in low to mid-rise buildings.

• Underslung Roping:

  • How it works: The drive sheave is located below the car, and the ropes are attached to the sides of the car and run underneath it. This is a less common configuration, often used to save space in the machine room.

2. Construction of Steel Wire Ropes

Elevator ropes are not a single thick wire but a complex assembly for flexibility and strength.

• Core: The center of the rope. It can be made of fiber (for flexibility) or a steel strand (for strength and resistance to crushing).

• Wires: Thin, high-strength steel wires are twisted together to form a strand.

• Strands: Multiple strands (typically 8 or 9 for elevators) are then laid helically around the core to form the complete rope.

• Preforming: The wires and strands are preformed during manufacturing into their helical shape. This makes the rope more flexible, resistant to kinking, and reduces internal stress when cut.