A car consists basically of a platform for transporting passengers and goods. The platform is raised or lowered by wire ropes or a hydraulic piston or plunger. The car is required to be completely enclosed. Car enclosures of sheet metal or plywood are common; some decorative elevators are enclosed in laminated glass. To provide access to the car, openings protected by doors are provided in one or two of the car walls. In addition, the platform and the car enclosures are supported on a structural steel frame (Fig. 16.12).
For electric elevators, the wire ropes that move the car are attached to the frame or threaded around sheaves connected to it. For hydraulic elevators, the frame is seated on the piston. The frame also supports the upper and lower wheels that roll along the vertical guide rails in the hoistway (Fig. 16.13). In addition, car frames of electric elevators carry safety devices that stop an overspeeding elevator mechanically.
Design, construction, and installation of elevator cars should meet the requirements of the National Standard Safety Code for Elevators, Dumbwaiters, Escalators and Moving Walks, ANSI A17.1.
Car doors may be horizontally or vertically sliding. They usually are power operated.
For safety, they should be equipped with devices that prevent them from opening while the car is moving or is outside the landing zones, the space 18 in above and below a landing. Also, ANSI A17.1 requires safety devices that will keep the car from moving while the doors are open. The Americans with Disabilities Act requires specific door-open dwell times in response to car and landing calls.
Additional devices are needed for power-operated doors to reopen the car and hoistway doors when they start to close on a passenger or other object. The National Elevator Industry standard, Suggested Minimum Passenger Elevator Requirements for the Handicapped, recommends that the devices be capable of sensing a person or object in the path of a closing door, without requiring contact for activation, at a nominal 5 and 29 in above the floor. Also, the doors should be kept open for at least 20 s after reopening. Still other devices should be installed for other safety reasons, for example, to prevent car and hoistway doors from closing and the car from moving when it is overloaded.
The interior of the car should be ventilated and illuminated with at least two electric lamps. Lighting provided at the landing edge of the car platform should be at least 5 fc for passenger elevators and 2.5 fc for freight elevators. In addition, an emergency electric-lighting power source should be installed, to operate immediately after failure of the normal power source. For a period of at least 4 h, this system should maintain at least 0.2 fc at a level 4 ft above the car floor and about 1 ft in front of a car station.
The car must also house an approved communication device consistent with rules outlined in the Americans with Disabilities Act. The communication device provides a means for two-way communication with persons outside the hoistway.
To be available for use by persons in wheelchairs, an alarm button should be installed in the car. When pressed, this button should sound an alarm outside the hoistway, and an emergency stop switch should be installed about 35 in above the platform. The height of the highest push button or of a telephone should not exceed 48 in. A handrail should be provided about 32 in above the floor along the rear car wall.
It is also required that the car contain a car position indicator, located above the push buttons or the door. It should indicate the number of the floor that the car is passing or at which it has stopped. An audible signal should be given to advise passengers that the car is stopping or passing a floor that is served by the elevator.
Similarly, a visual and audible signal should be given at each hoistway door to??indicate in the hall, or lobby, that the car is stopping at that floor in response to a call. The audible signal should sound once for the up direction and twice for the down direction of car travel. Call buttons for summoning cars should be located in the elevator lobbies about 42 in above the floor. A lamp should light when a call is registered and go out when the call has been answered by a car.
An emergency exit should be provided in the roof of each car. Also, means should be available for operating the car from its top during inspection, maintenance, and repair. In addition, an electric light and convenience outlet should be installed on the roof, with a switch near the fixture.
See also Art. 16.9.
Car Capacities and Sizes
Cars are rated in accordance with their load-carrying capacity. For passenger elevators, capacities generally range from 1500 lb for use in apartment buildings to 5000 lb for use in department stores and hospitals. (Approximate capacity in passengers
can be estimated by dividing the rated capacity, in pounds, by 150.) Capacities of freight elevators usually range from 1500 lb for light duty up to 10,000 lb for general-purpose work or 20,000 lb for heavy duty.
The National Elevator Industry standard, Elevator Engineering Standard Layouts,
lists standard car platform sizes for various rated capacities for electric and hydraulic passenger, hospital, and freight elevators. The sizes give clear inside width and depth of the cars. To obtain the outside dimensions of a car, add 4 in to the clear width (parallel to car door) and the following to the clear depth:
10 in for passenger elevators with center-opening doors or a single sliding door 111â„2 in for passenger and hospital elevators with two-speed or two-speed, centeropening doors at one end only
19 in for hospital elevators with two-speed front and rear doors
7 in for freight elevators with front doors only
10 in for freight elevators with front and rear doors
Cars supplied by various manufacturers, however, may differ somewhat in sizes from those recommended in the standard. Consequently, it is advisable to obtain recommended car sizes from the car manufacturer or elevator installer for a specific installation.