Elevator Technologies
Conceptually, an elevator mechanism is quite simple - it involves the pushing and pulling of a compartment attached to a lifting system. A rope tied to a box gives you a basic elevator. An elevator is essentially a platform that is either pulled or pushed up by a mechanical means.

Following elevator mechanisms are used commonly today:
1) hydraulic elevators
2) traction elevators
3) roped or cable elevators
4) climbing elevators

Hydraulic Elevators:

Hydraulic elevator systems lift a car using a hydraulic ram, a fluid-driven piston mounted inside a cylinder. The cylinder is connected to a fluid-pumping system (typically, hydraulic systems like this use oil, but other incompressible fluids would also work). There have been recent innovations in hydraulic elevators such as microprocessor controls, permanent earth magnet motors, machine room-less rail and mounted gearless machines.

Hydraulic lifts are cheaper, but installing cylinders greater is not practical for very high lift hoistways. Over buildings over six to seven stories, traction lift must be employed instead. These kind of elevators are explained below.

Traction Elevators:

A modern-day elevator consists of a car (also known as cage or a cab) mounted on a platform within an enclosed space called a shaft ("hoistway"). In the past, lift drive mechanisms were powered by steam and water hydraulic pistons. In a "traction" elevator, cars are usually pulled up by means of rolling steel ropes over a deeply grooved pulley, also called a sheave. The weight of the car is balanced with a counterweight. Sometimes two lifts moving synchronously in opposite directions act as each other's counterweight.

There are two types of traction elevators: Geared Traction and Gearless Traction Elevators. Worm gears are used to drive the mechanical movement in the geared traction elevators unlike gearless traction elevators. There is a gearbox attached to the drive sheave and this gearbox is driven by a high speed motor. This is unlike the geared traction elevators where the drive sheave is directly attached to the motor. Relatively, gearless traction elevators have lower speeds than geared traction elevators.

Roped or Cable Elevators:
Roped or Cable elevators are the most popular form of elevator designs used widely across the world. They consist of traction steel ropes that are attached to the elevator car and looped around a sheave. The sheave acts as a pulley and has grooves around its circumference. Thus when the sheave is rotated, the ropes also move. This is because the sheave grips the hoist ropes. An electic motor powers the sheave and as per the turning of the motor, the sheave raises or lowers the rope and thus the elevator.

Typically, the sheave, the motor and the control system are housed in a machine room above the elevator shaft. Counterweight used in this mechanism weigh about the same as the car filled to approximately 40% capacity. Almost perfect balance is achieved by the car with the counterweight when it's 40% full. This balance conserves energy.

Roped elevators are more efficient and versatile than hydraulic elevators.

Climbing Elevators:
A climbing elevator has its own propulsion. It produces the propulsion via an electric or a (traditionally) combustion engine. Climbing elevators are often used at construction sitesas temporary lifts. It is often used to carry equipment and not more than one person for maintenance purposes.