The basic principle.

A traction lift moves a car and counterweight through suspension members passing over a driven sheave. The machine controls sheave rotation while the guide system maintains the intended path.

The motor supplies or absorbs mechanical power according to load, direction and acceleration. The counterweight reduces gravitational imbalance but does not remove inertia or losses.

Trace the suspension path

A simple one-to-one traction layoutA car rises while its counterweight descends. A continuous suspension path passes over the driven sheave. Separate guide rails constrain both to a vertical path; ropes do not wind onto a storage drum.Driven traction sheaveSuspensionCarCounterweightGuide rails
  1. Traction sheave: the machine turns the sheave. Contact between suspension and groove transfers force; the suspension passes over it rather than being stored on a drum.
  2. Car and counterweight: in this simple 1:1 example, one rises as the other descends by the same distance. Other roping arrangements introduce additional pulleys.
  3. Guide rails: guide the car and counterweight. They are separate from the suspension that carries the load.
  4. Machine: a motor supplies shaft torque directly or through gearing. The mechanical brake is a separate, coordinated part of the machine; it is omitted here to keep the suspension path visible.
Simplified 1:1 arrangement showing the car travelling upwards. One suspension line represents a set of ropes or belts. Motor, brake, doors, safety gear and position sensors are omitted; this is not a complete installation drawing.

A controlled journey.

A worked-through example

The controller establishes the required conditions and requests movement. The drive develops torque, the brake is released in the designed sequence, and the machine moves the suspension.

Follow the relationship.

  1. ControlPlans and permits the journey.
  2. Machine and suspensionTransmit force and movement.
  3. Position feedbackSupports approach and stopping.
Conceptual relationships; arrangements vary by installation.

Connect it to the lift.

At a landing, motion control and the brake coordinate stopping and holding before the intended door sequence. Door locks, safety gear and other protective provisions remain separate functions within the complete installation.

A closer look

Gearing, roping ratio and machine location vary. The basic energy path remains useful without treating one layout as universal.

Check your understanding

Does the traction machine usually store all the ropes by winding them onto a drum?

Reveal the explanation

No. A traction sheave transfers force through contact with passing suspension members.

Further reading.

Optional reading to explore this lesson in more detail.