In any commercial building, vertical transportation represents an important financial investment, as much as hundreds of thousands of dollars for just a medium-size building. With an asset this valuable, it is good business to have a well-defined program to ensure correct elevator maintenance. While this article focuses on maintenance of elevators, much of the general information applies to escalators as well.
An elevator is an extremely complex system with hundreds of parts that must be maintained. One function of maintenance is ensuring continued operation by preventing excessive wear and breakdown. In systems as complex as modern elevator systems, a more important aspect of maintenance is to ensure that the equipment continues to perform as it was originally designed. This can be accomplished only by qualified, trained technicians using the correct equipment and tools.
The components of an elevator system that require regular maintenance can be categorized by their location: in the machine room, the hoistway, or the car. (Note: Maintenance requirements specific to hydraulic or traction elevators are not addressed in this article.)
Elevator Machine Room
The elevator machine room is the heart of the elevator system. It contains the elevator hoisting machines, motor generator sets or solid-state power supply, and control equipment. The control equipment is an essential part of the total operating mechanism that accelerates, decelerates, and levels the car at each floor. Most of the routine maintenance takes place in the machine room. This includes routine servicing of motors, generators, switches, contacts, brakes, and controls.
The hoist way contains the guide rails on which the elevator car and counterweight run; the corridor doors, hangers, door locks, and operating mechanisms; switches and other operating and safety devices; and space for cables and other equipment. Equipment within hoistways that requires maintenance includes buffers, corridor door hangers and locks, switches, and safety devices. Most maintenance of these components must be performed from inside the hoistway and outside the elevator car. The hoistway pit houses the car and counterweights buffers, cable pulley and tensioning devices, and limit switches. The overhead of the hoistway may contain the overspeed governor mechanism and limit switches with space for the safety of personnel on the top of the elevator car.
The hoistway is a dangerous place to work. For safety, only qualified personnel should perform elevator maintenance and repair work.
With few exceptions, elevator cars are fire-resistant, well-ventilated structures. Maintenance requirements for elevator cars include servicing door operating equipment and ventilation equipment at the top of the car and safety equipment at the bottom. This work must also be performed from within the hoistway.
Flooring in elevator cars requires daily cleaning and service, and must be replaced more often than other flooring because of the amount of traffic. When replacing the floor, use nonslip material and nonflammable solutions in refinishing or cleaning the cab. Flooring, along with care of car interior finishes, is usually the responsibility of the property owner.
Routine Elevator Maintenance Checklist
To maintain proper elevator operation, check and correct:
Travel time between floors
Starting and stopping
Hall and call lights and floor indicators
To maintain elevator support systems, check and repair:
Emergency lighting and alarms
Communications devices (for example, intercoms or telephones)
To maintain the physical condition of an elevator:
Check for and repair interior damage
Check signage and repair when necessary
Elevator System Reviews
Periodic review of an elevator system is important to check that the system is being properly maintained and also to spot components that are candidates for modernization. Proper maintenance alone is not enough. Elevator system reviews can be conducted by in-house personnel or by an elevator professional and should be performed more often than maintenance or inspections. The following checklist outlines areas that should be checked during a property manager’s elevator system review:
Operation: Does elevator service appear to be adequate for daily passenger traffic loads?
Passenger satisfaction: Are people criticizing elevator service? Do they complain about waiting, crowding, or malfunctioning equipment?
Average elevator wait time:
25 seconds or less = excellent rating
26 to 30 seconds = good rating
31 to 35 seconds = fair rating
over 35 seconds = poor rating
Elevator maintenance callbacks: Are they within the industry standard of two per elevator per year?
Performance: Does current elevator operation compare with the performance specifications when the equipment was new? Have the insurance inspectors, maintenance contractor, or government recommended any repairs or adjustments?
Safety features: Are the emergency alarm bell and intercom or telephone operating? If there is an emergency lighting system, does it operate during a simulated shutdown?
Fixtures: Are hall and elevator call lights and floor indicators working correctly? Are overhead lights and ventilation systems operating?
Doors: At stops, do the doors operate noisily? Are passengers bumped by the doors?
Starting and stopping: Do elevators hesitate at floors too long after buttons are pressed? Do they start and stop abruptly or uncomfortably?
Leveling: Does the car level with the floor at each stop so passengers will not trip?
Ride: Do you hear squeaks and scrapes or feel vibrations when the elevators are running? Do they feel unbalanced?
Run times: Do elevators grouped in the same bank appear to operate at different speeds during comparable runs?
Elevator Performance Review
Elevator performance and maintenance go hand in hand. Poor maintenance or performance is indicated by increased floor-to-floor elevator operating and/or waiting times. Periodically, the property manager should time elevator functions and compare them with the manufacturer’s specifications in order to evaluate the overall system performance.
Check elevator performance by riding the elevators. Concentrate on sounds by alternately closing your eyes and covering your ears to intensify what you see, hear, and feel. Listen to the comments of people using the elevators.
Operations that are commonly timed and checked include the following:
Floor-to-floor time: Time required to make a one-floor run. Measured from the time the hoistway doors start to close at one floor until they are fully open at the next floor.
Performance time: Measured from the time the doors start to close at one floor until they are sufficiently open to allow passenger exchange at the next floor.
Car start time: Measured from the time the doors start to close until the elevator actually moves.
Brake-to-brake time: Measured from the time the car starts until it stops on a one-floor run.
Door open time: Measured from the time doors start to open until fully open.
Door dwell time: Length of time doors remain fully open by car or hall call without being affected by cancellation features.
The above tests should be performed near a mid-floor stop. Measurements should be taken in both directions and averaged.
Vertical Transportation Consultants
The elevator maintenance company or the original manufacturer of the equipment can resolve uncertainty about existing elevator equipment and the need for modernization. These companies should be able to analyze the building’s traffic and elevator service to ascertain the capabilities of the present elevator equipment.
A vertical transportation consultant should perform a traffic study to collect key data on elevator usage and performance during a preselected period. A traffic study provides a detailed traffic and performance analysis of the elevator, indicating whether the system is operating up to its original specificationsa sign of proper maintenanceor if performance levels have slipped.
In addition, vertical transportation consultants should recommend which elevator components need to be modernized and which can be retained. Some companies can collect data from the traffic study and create a computer simulation of the building. Using this model, they can demonstrate the effects of different modernization schemes. By showing the types of service improvements in advance, they can help determine the best decision for a particular building. Vertical transportation consultants can also help prepare bidding documents once the modernization approach is decided.