What is the difference between a traction elevator and a hydraulic elevator?

The two main types of elevators are electric traction and hydraulic:

Traction elevator:

• Operation: An electric motor drives a sheave that rotates steel cables. The cab is suspended from these cables, with a counterweight on the other side
• Advantages: Great height (up to 100 meters +), high speed (2-10 m/s), energy efficient (counterweight balances 40-50% of the load)
• Disadvantage: Requires a machine room at the top of the shaft (except MRL — machine room-less elevators)
• Use: Buildings 6 floors or more, office buildings, hospitals

Hydraulic elevator:

• Operation: A hydraulic cylinder (piston) pushes the cab from below. Oil is pumped into the cylinder by an electric pump
• Advantages: Simple, robust, no machine room at height (machinery is at ground level or in the basement), cheaper ($50,000 to $100,000 for 2-3 floors)
• Disadvantages: Limited height (6 floors max), slower speed (0.5-1 m/s), higher energy consumption
• Use: Buildings 2 to 6 floors, warehouses, freight elevators

Standards: Both types must comply with ASME A17.1/CSA B44.