The function of the elevator is to allow residents easy access to and from their floors without having to walk up any steps. Because of the importance and convenience of the elevator to everyone who enters the building, it is critical that the elevator is kept neat, clean, and functional at all times. We want to ensure that the elevator is safe and that all of its components comply with applicable codes.
Since the development of the traction elevator in 1853, a number of other types of elevators have been developed. The two most prevalent elevators in service today are the traction and hydraulic. The traction system lifts the cab by cables, using counterweights to minimize energy expenditure. Hydraulic systems push the cab up on a shaft filled with compressed oil.
Hydraulic elevators operate at slower than traction elevators and are suitable only in low-rise/low-demand situations such as small apartment buildings. Additionally, hydraulic systems cost ten to fifteen percent less and require less space to install than traction type systems.
Hydraulic elevators consist of four parts:
The hydraulic elevator contains a cylinder that is connected by a fluid pumping system. The fluid pumping system usually uses oil, but other non-compressible fluids are sometimes used.
The pump creates a vacuum on the hydraulic tank and forces the fluid into discharge piping. Depending upon the position of the directional valve, the fluid is either directed to the cylinder or is returned back to the tank.
To lift the elevator cab, the pump is turned on and the control valve directs the pressurized fluid to the bottom end of the cylinder. The cab rises until another signal is sent to turn off the pump, trapping the fluid and maintaining the cab on the proper floor. To lower the cab, the directional valve opens, allowing the flow of oil back to the hydraulic reservoir. The weight of the cab pushes the piston down, directing the fluid into the tank. When the cab reaches the appropriate floor, a signal is sent to close the directional control valve. As you can see, this system is incredibly simple and yet highly effective.
The traction drive depends on the friction, or traction, between the hoisting cables and the traction sheave. The hoisting cables roll over the traction sheave and down to the counter weight. This arrangement compensates for the weight of the empty elevator cab and significantly reduces the power needed by the hoisting motor. While any length of cable may be used, above 100 stories the weights of the cables become a critical factor.
The invention of the "traction" type drive removed almost all limits on the height of buildings, enabling the construction of "skyscrapers." At present, nearly all elevators above six stories are traction drive.
Each floor elevator hall station consists of two buttons with the exception of the top and bottom floors. The lighted buttons operate individually to indicate that a call has been registered at the floor for the indicated direction. Lights are extinguished as the calls are answered. At the lobby, a fire department key switch must be incorporated into the pushbutton station.
By opening the elevator door, you will find that the cab is fitted with an infrared door protective device (the green light strip along the front edge of the door) that provides a protective screen across the full width of the door opening. This infrared device consists of 47 light beams accurately positioned in conformance to all applicable codes. An interruption of the screen by a person or object will cause the door to reverse to the full open position and remain open for one-half second.
The door operator at the top of the elevator cab is used to operate the cab and hoistway door at the same time. The doors should operate smoothly, and without slamming in either direction. Each hatchway and cab door is cushioned in its final movement in each direction of travel by electric power. Electric power is used when opening and electric power or a spring is used when closing.
Opening and closing times are adjustable to ensure smooth operation and that both final limits of travel are cushioned. The door operator is designed so that if power is interrupted, the cab doors cannot easily be opened by hand from within the elevator cab, and the elevator cannot move away from the landing until the door panel is fully closed.
Directly beneath the door operator is a cab door hanger and track. The door tracks are constructed of high strength bar steel with working surfaces contoured to match the door sheaves. One of the most common sources of elevator breakdown is when these tracks are not kept clean. Hangers are designed for power operation and have provisions for vertical and lateral adjustments.
Open the elevator door and enter the cab. Locate the elevator cab pushbutton station inside the elevator, which is tamper-proof and in our model is finished in brushed stainless steel. All signage is engraved and filled. The cab station contains the following items required to be displayed in the elevator:
The Emergency Fire Operation is designed to meet current codes for Phase I and Phase II operation, assisting Fire Department personnel in controlling an elevator during a fire. The following instructions for the activation of the Fireman’s Recall System have been provided for informational purposes only.
Phase I Emergency Operation takes place in the lobby. A two-position, key-operated switch, installed at the required height position, next to each elevator with switches labeled at the designated level marked “Normal” and “Firemen Service” abbreviated “Fire Serv.”
Only Phase I switches or the smoke detector in an elevator lobby, motor room, or hoistway will initiate Phase I operation.
Normal elevator service will be provided when all Phase I switches are in the “Normal” position.
When the switch is in the “Firemen Service” position, all cabs controlled by this switch will return non-stop to the designated level and power-operated doors will open and remain open.
Phase II Emergency in-Cab Operation is a three-position system labeled “Normal,” “Hold,” and “Fireman Service.” The key-operated switch is mounted in the operating panel in the cab. Take a moment to locate the Phase II switch in the elevator training unit display.
Phase II will become effective only when the designated level Phase I switch is in the “Fireman’s Service” position or a smoke detector has been activated.
Elevators can only be removed from Phase II operation when the Phase II switch is in the “Normal” position and the cab is at the designated level with the doors in the open position.
The elevator should have resetting smoke detectors at the top of each elevator shaftway that must connect to the elevator Fire Recall system. All features must meet the governing Firemen Recall codes.
Owners of elevators located in New York City are required to maintain a contract with a licensed elevator service provider. As elevators are serviced, the contractor should be at your building for a minimum of 1 hour per elevator. During monthly service, the mechanic should adjust, lubricate, repair, and replace any worn components. Preventive maintenance will be performed once each month.
Ultimately, the owner is responsible for ensuring that the contractor is performing services as contracted. It is important to note that some elevator technology is considered proprietary to the elevator company who installed your elevator. Before any decisions are made on changing elevator service contracts, ensure that you investigate the costs of repairing proprietary items.
The physically disabled are often dependent on elevators and care should be taken to ensure that their needs are met. Elevator companies have responded to the need by developing special features for the disabled.
There are many components and requirements to safely operate an elevator for all residents. Remember that the appearance and condition of the elevator is an immediate reflection of the overall quality and condition of the maintenance of the entire building.