Working on scaffolding or platforms, constructors bolt or weld steel rails to the walls of the shaft to guide the elevator up and down. Elevator mechanics install electrical wires and controls by running tubing called conduit along the shaft's walls from floor to floor. Once the conduit is in place, mechanics pull plastic-covered electrical wires through it. They install electrical components and related devices required at each floor and at the main control panel in the machine room. Mechanics bolt or weld together the steel frame of the elevator car at the bottom of the shaft, install the car's platform, walls, and doors, and attach guide shoes and rollers which minimize the lateral motion of the car as it travels through the shaft.
Mechanics also install the outer doors and door frames at the elevator entrances on each floor.
For cabled elevators, workers install geared or gearless machines with a traction drive sheave which moves heavy steel cables connected to the elevator car and counterweight. The counterweight moves in the opposite direction from the car and aids in its swift and smooth movement. These workers also install elevators in which a car sits on a hydraulic plunger that is driven by a pump. The cylinder pushes the elevator car from underneath, like a lift in an auto service station. Elevator constructors also install escalators.