Today’s rope driven elevators contain six to eight lengths of wire or steel cable. These cables are attached to the top of the elevator cab and wound around a drive sheave in special grooves. The other ends of the cables are attached to a collection of metal weights equal to the weight of the car and a little less than half of its rated load.

Chains or cables loop through the bottom of the counterweight to the underside of the car to help maintain balance by offsetting the weight of the suspension ropes. Guide rails that run the length of the shaft keep the car and counterweight from swaying or twisting during travel. Rollers are attached to the car and the counterweight to provide a smooth ride along the guide rails. An electric motor then turns the sheave. These motors are able to control speed, and allow for the parking lift‘s smooth acceleration and deceleration. Signal switches also stop the cab at each floor level.

In a hydraulic elevator, the car is lifted by a hydraulic-fluid driven piston mounted inside a cylinder. The cylinder is connected to a pumping system. The pump forces fluid into the tank leading to the cylinder. When enough fluid is collected, the piston is pushed upward, lifting the elevator car on its journey. When the car is signaled that it is approaching the correct floor, the control system will trigger the electric motor to gradually shut off the pump. To get the scissor car elevator to descend, the control system will send a signal to the valve operated electronically by a switch. When the valve is opened, the fluid flows out into a central reservoir, and the weight of the car and its cargo pushes down on the piston, driving more fluid out and causing the cab to move down.

Many of the most recent improvements in elevator design are safety-based, particularly in the newer computerized, solid-state systems. And in general, in newer solid-state elevators, the car won’t move unless all the circuits are operating and all the doors are closed. Of course, computerization can give rise to its own errors, this reporter was once in an elevator heading to the ground floor when, sensing a signal from an upper floor, the car hoist hovered for a second or so, then changed directions and headed up.