mechanical elevator door restrictors

8/6/2019 Mechanical Elevator Door Restrictors

1/12

MECHANICAL ELEVATOR DOOR

RESTRICTORS: WHAT

FIREFIGHTERS NEED TO KNOW

BY BILL GUSTIN

Modern elevators have a remarkable safety record, transporting millions of

people each day without incident. Elevators are one of the safest means of

transportation because of their many safety features. Here, we will discuss one

of these safety features, door restrictors. These devices are typically found on

elevators built since 1980 but also may have been retrofitted on many older

installations. This article is not intended to be a stand-alone primer on the

basics of elevator nomenclature, operation, or rescue.1 It provides information

specific to a group of door restrictors and is intended only for fire personnel

who are thoroughly trained in elevators and understand the risks of removing

occupants of stalled elevators and the dangers of using elevators during a fire.

Members of the fire service have different points of view concerning elevators,

but there should be no debate on these two facts: (1) The vast majority of

occupants trapped in stalled elevators are safer (inside the elevator car)

awaiting the arrival of an elevator mechanic than risking removal by

undertrained firefighters, and (2) an elevator can be a deathtrap for civiliansand firefighters under fire conditions.

RESTRICTORS PREVENT ACCIDENTS

During the 1970s and 1980s, there were several accidents involving elevator

passengers who manually pried open the car doors and attempted to exit an

elevator stopped between floors. Youngsters living in public housing projects

and students in college dormitories have been known to pry open the car doors

of a moving elevator, which immediately stops the hoisting machine and sets

the brake. This can stall the elevator between floors, enabling the passengers toclimb on top of the car. "Elevator surfing," as it is called, is undoubtedly a

thrilling experience, riding the top of an elevator traveling at high speeds.

Unfortunately, some of these "surfers" were decapitated or lost limbs when

they were crushed between the elevator car, hoistway (shaftway), or

counterweights.


2/12

Occupants of an elevator stalled between floors have been known to force open

the car doors with their hands and then open the hoistway doors by manually

releasing the interlock. Unfortunately, some of these do-it-yourself rescuers

then fall to their deaths down an open elevator shaft. When an elevator stalls or

is intentionally stopped between floors, an occupant who manages to muscle

the car doors open may see two sets of hoistway doors: the upper portion of the

doors on the landing below the elevator and the lower portion of the doors on

the landing above the elevator. The interlock mechanism of the upper hoistway

doors will probably be above the occupant's reach, but the interlock on the

lower hoistway doors will be easily accessible. Therefore, the occupant will

release the interlock on the lower set of doors and attempt to squeeze out of the

elevator in the space between the floor of the elevator car and the top of the

hoistway opening. This places the escapee in grave danger because he can

easily fall in the space between the floor landing and the bottom of the elevator

car and plunge to his death down an open elevator shaft.

(1) Depressing the restrictor release duplicates the actions of the hostway door

release rollers, allowing the car doors to fully open. (Photos by Steve English.)

Click here to enlarge image


3/12

As a result of these accidents, the American Society of Mechanical Engineers,

which writes model codes and standards for the elevator industry, has

incorporated door restrictors since 1980. Additionally, the fear of liability for

elevator accidents has resulted in the installation of door restrictors on manyolder elevators.

(2) Closeup of restrictor at the top of elevator car doors.


Door restrictors prevent the car doors of an elevator from opening more thanfour inches when the elevator is not within its "landing zone," which is usually

18 inches above or below the floor landing. Door restrictors prevent surfers and

do-it-yourself escapees from forcing open the doors of an elevator car when it

is between floors. Restrictors can be re-leased on the outside of elevator car

doors or at the top of the elevator car. Firefighters not familiar with door

restrictors may cause unnecessary damage when they remove occupants of a

stalled elevator if they use hydraulic tools to defeat restriction devices.

There are two basic types of mechanical door restrictors: The clutch-type

restrictor consists of a latch located at the top of the car doors. On someassemblies, the latch is re-leased, permitting the car doors to fully open when

the clutch or driving vane on the car doors lines up with the release rollers of

the shaftway door. When the elevator is within its landing zone, the hoistway

door release rollers depress a release mechanism located next to the driving

vane or clutch of the car door. The release mechanism is connected to the latch

at the top of the car doors by a reach rod, similar to the linkage between the


4/12

door release rollers and the interlock at the top of the hoistway doors. The key

to releasing this type of restrictor is to duplicate the pressure of the hoistway

door release rollers on the restrictor release located on the car door. When the

release mechanism is within reach, simply depress it and push open the car

doors. When an elevator is too far above or below a floor landing to reach the

release by hand, use a pike pole to depress the release or access the top of the

car from a landing above the elevator and directly release the latch at the top of

the car doors.

The second basic type of door restrictor, the angle iron restrictor (commonly

found on Otis elevators), consists of projections fastened to the car door and

hoistway similar to an angle iron. When an elevator equipped with this

restrictor is outside its landing zone, the car door restricting angle will strike the

angle iron on the shaftway doors and the shaft, preventing the car door from

opening more than four inches. The car door can only open completely when

the elevator car is within its landing zone, where the car door angle and

shaftway angles do not line up to strike each other. On older installations, the

angle-type door restrictor could not be manually released. Some Otis elevators,

however, have restrictors that are hinged and spring-loaded. Depressing the

angle on the car door will allow it to clear the angle iron fastened to the

hoistway and hoistway doors.

There are other door restriction devices on the market, including the

electromechanical type of restrictor (see sidebar by Glenn P. Corbett above).

Fire departments should consult with elevator mechanics in their area to

become familiar with the types of door restrictors that they may encounter.


5/12


Figure 1: View of the outside of center-opening elevator car doors. When the

elevator is within its landing zone, the hoistway door release roller contacts the

restrictor vane, actuating the release of the car door restrictor. Depressing the

restrictor vane by hand or a pike pole will also release the device. Figure 2: The

car door restrictor strikes opposing restrictor angles mounted in the hoistway


6/12

and the bottom of each hoistway door, preventing the car doors from opening

more than four inches when the car is 18 inches or more away from the landing.

FORCIBLE EXIT FROM ELEVATORS

Although door restrictors save lives by preventing accidents, they can endanger

the lives of civilians and firefighters who become trapped in a stalled elevator

during a high-rise fire. This was reported to have occurred at the World Trade

Center, where several people lost their lives because door restriction devices

prevented them from prying open car doors to escape stalled elevators.

Using elevators during a high-rise fire is definitely risky business, but

examining the pros and cons of elevator use under fire conditions is beyond the

scope of this article. Firefighters who choose to use elevators during a fire will

substantially increase their chances of survival if they follow one of the basicrules of elevator use for fire operations: Always take tools with you in case you

have to break out of a stalled elevator.2

(3) Forcing the elevator car door. To achieve the

initial purchase, drive the tapered, beveled fork of thehalligan around the edge of the door recessed in the

jamb.


null


7/12

(4) 4-inch 2 4-inch cribbing fills the gap between the

door frame and the hydraulic forcible entry tool.Click here to enlarge image

What tools are necessary to escape a stalled elevator? Certainly, a prying tool

such as a halligan or claw tool is essential. The tool must, however, have a

long, tapered fork with a pronounced bevel to work the tool around the edge of

the car door where it is recessed into its jamb as much as 11/2 inches. The pry

tool is used to gain an initial purchase on the car door and overcome anyresistance exerted by the car drive motor and its mechanism.

It should be obvious that some type of striking tool is needed, both to drive the

pry tool around the edge of the door and break open the top escape hatch of the

elevator car. Escaping through the top hatch of an elevator is definitely an

option, but it can be very difficult because the hatch is locked at the top of the

elevator with wing nuts or sliding latch bolts.


8/12

(5) Use a pike pole to reach and release the interlock of the hoistway doors on the landing above the

elevator. Note the floor landing at chest height.


(6) The head of the pike pole actuates the

interlock.



9/12

Firefighters should also be equipped with a hydraulic forcible entry tool to

defeat elevator car door restrictors. The hydraulic tool alone may have

inadequate spread to force a restrictor that does not begin to restrain a door

until it opens four inches. For this reason, use a piece of 4-inch 2 4-inch

cribbing to fill the gap between the hydraulic tool and the door frame.

When an elevator is stalled between floors, a pike pole may be necessary to

reach and operate the interlock of the shaftway doors on the landing above the

elevator. It is much safer to exit an elevator by climbing up to a landing instead

of dropping to a lower landing because of the open hoistway below the elevator

car.

(7) This firefighter is in grave danger of falling down the elevatorshaft. It would be much safer to use a pike pole to release the shaftway

doors at the upper floor landing and climb up to the exit.



10/12

(8) A firefighter exits the elevator by climbing to the upper landing.


Breaking out of an elevator should definitely be considered a last resort. There

are no guarantees that it will be successful or that a stalled elevator will not

suddenly move and crush a firefighter. An elevator may stall in a blind shaft or

express hoistway, forcing firefighters to breach the hoistway wall. Often,

firefighters can wait safely in a stalled elevator for other firefighters or an

elevator mechanic to remove them, instead of attempting a risky forcible exit.

Practicing forcible exit from an elevator can cause damage; therefore,

firefighters practicing such techniques should do so only under the direct

supervision of an elevator mechanic. Firefighters practicing forcible exittechniques must kill the power to the elevator at the main switches in the

machine room and use ladders or other barriers to block the shaftway opening

between the elevator and floor landing.

Working with elevators, like all fire department operations, must be performed

in accordance with an ongoing risk vs. benefit analysis. Firefighters must

realize their limitation in terms of the knowledge and skills necessary to safely

rescue themselves or others from an elevator and know when it is better to wait

for an elevator mechanic. They must also realize how vulnerable an elevator

can be under fire conditions and recognize that taking an elevator to fight a firejust isn't worth the risk.

Endnotes

1. For complete instructions on elevator rescue, see chapter 4 of Truck

Company Operations by John W. Mittendorf (Fire Engineering, 1998).


11/12

2. "Elevators were disaster within disaster," Dennis Cauchon and Martha T.

Moore, www.USAtoday.com, Sept. 4, 2002.

BILL GUSTIN, a 30-year veteran of the fire service, is a captain with Miami-

Dade (FL) Fire Rescue and lead instructor in his department's officer training

program. He began his fire service career in the Chicago area and teaches firetraining programs in Florida and other states. He is a marine firefighting

instructor and has taught fire tactics to ship crews and firefighters in Caribbean

countries. He also teaches forcible entry tactics to fire departments and SWAT

teams of local and federal law enforcement agencies. Gustin is an editorial

advisory board member of Fire Engineering.

ELEVATORS AND THE CODES

BY GLENN P. CORBETT

Although elevators have been in existence for 150 years, the codes that regulate

their construction and maintenance still continue to be updated. Generally

speaking, it is your local building code that provides for overall regulation of

elevators. This includes mandating periodic inspections by building department

inspectorsone of the very few "maintenance" inspections that a building

inspections department performs.

Your local building code very likely also references and mandates the use of

ASME (American Society of Mechanical Engineers) Standard A17.1, Safety

Code for Elevators and Escalators. It is this standard that provides the detailed

requirements for elevator design and use, including the "phase one" recall of

elevators during a fire emergency as well as their use by firefighters under

"phase two" operation. This standard also incorporates the requirements

pertaining to the use of elevator door restrictors.

Door restrictors are installed for one primary reasonto keep people from

opening the door of a stalled elevator car and falling down the shaft below.

When a car is 18 inches above or below the floor landing, the door restrictor isengaged, preventing the car door from being opened

ASME A17.1 first included provisions for door restrictors in 1980. The door

restrictors can be placed into two broad categories: mechanical and

electromechanical. Mechanical restrictors include both special devices mounted

on elevator cab doors and a set of "angle iron" door restrictors. These angle

irons mount on the hoistway (shaft) door and the elevator cab door. In some


12/12

cases, the angle iron on the car door is made to be collapsible, allowing for it to

be moved out of the way.

Electromechanical devices typically use a microprocessor to control electrical

power to the restrictor device, keeping the doors closed. Depend-ing on the

type of solenoid used, the door restrictor may or may not be released on loss ofpower. Those using a "gravity"-type solenoid will not usually allow the

restrictor to open with loss of power; spring-loaded types will typically fail-safe

and release the door when there is a loss of power. Some manufacturers also

provide emergency release buttons (often located on the top or bottom of the

car), which allow firefighters to disable the restrictor outside the car. Some

restrictor devices also provide a "fire service override," which disables the

device when the elevator is in phase two operation.

As a firefighter, you must preplan the types of door restrictors used in your

jurisdiction. Many manufacturers make these pieces of equipment, and youmust familiarize yourself with all of them. Ask elevator mechanics to show you

how the devices work and to help you develop your operational guidelines.

GLENN P. CORBETT is a professor of fire science at John Jay College in

New York City, a technical editor of Fire Engineering, and a captain with the

Waldwick (NJ) Fire Department. He previously held the position of

administrator of engineering services with the San Antonio (TX) Fire

Department. Corbett has a master of engineering degree from Worcester

Polytechnic Institute in Massachusetts. He authored two chapters on fire

prevention/protection in The Fire Chief's Handbook, Fifth Edition (Fire

Engineering Books, 1995). Corbett has been in the fire service since 1978.

mechanical elevator door restrictors

Documents