The following glossary is not an exhaustive list of rigorous technical terms and definitions. Rather, it is derived from commonly fielded questions.
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The controller is the brain, controlling the movement and operation of an elevator.
Counterweight counterbalances the weight of traction elevator cars. When the car goes up, it goes down.
The cylinder is the stationary lifting component in a hydraulic elevator. It is either buried in the ground or is holeless and runs parallel to the elevator in the hoistway (shaft). It is normally made of a steel tube with a steel cap welded on the bottom and a head at the top through which the piston slides. A synthetic rubber reinforced packing fits into the head of the cylinder and very tightly against the piston. When the piston lifts the elevator, almost the entire load is transferred to the cylinder and, in turn, to the elevator pit floor on which it rests.
A door operator is composed of arms, belts, pulleys, chains and a motor that opens and closes the elevator doors. It is attached to the top of the elevator car and usually has an arm that is attached to the car door. When the elevator car is at a floor, linkages temporarily connect it to the hall (or hoistway) doors allowing them to open along with the car door.
Elevators fall into two basic types: Passenger/Freight elevators and specialty elevators. When the A17.1 code is read, the first three chapters pertain to electric and hydraulic passenger and freight elevators, and all the other chapters pertain to specialty elevators. The specialty elevator chapters basically just list the differences and exceptions between that particular elevator type and normal passenger/freight elevators.
The A17.1 code deals with many more subjects, such as engineering requirements, Seismic Zone requirements, shipboard elevators, automatic dumbwaiters with transfer devices, construction elevators, screw column elevators, inclined elevators, rack and pinion elevators, hand elevators, escalators and moving walks.
There are some basic differences between freight and passenger elevators. A passenger elevator can be a freight elevator, but a freight elevator cannot be a passenger elevator. A freight elevator can only be operated by authorized personnel.
- Must be publicly accessible if located in a commercial setting.
- Must conform to the requirements of the Americans with Disabilities Act if accessible to the public.
- Must be fully automatic. This means that their control buttons are momentary, the doors are powered and must be solid construction, and the cabs are fully enclosed.
- Must have top exits (see next point), inspect stations, safe refuge space above and below, emergency phones, emergency lights, Braille, etc. They cannot have emergency off buttons.
- Contrary to popular belief thanks to the movies, newer passenger elevators—per code—cannot be escaped from. New elevators require car door interlocks so that car doors cannot be pried open between floors. It is no longer possible to open the top exit of a legal passenger (or freight) elevator from inside the cab. This means that passengers must wait to be rescued from above. This prevents people from falling to their deaths.
- Can have manual gates and doors. This includes scissor gates.
- Do not have to conform to ADA requirements, and are not accessible to the public. Only authorized personnel operate them.
- Have different classes of loading.
- Class A General freight (50 lb/sq ft)
- Class B Automobile (30 lb/sq ft)
- Class C1 (for loaded fork trucks)
- Class C2 (Capacity loaded on to elevator with fork truck, elevator must be able to level 150% of capacity, basically the load and a portion of the fork truck)
- Class C3 Concentrated Loads (must be designed for a specific load, such as blocks of Plutonium)
Elevator inspectors generally leave behind an extensive paper trail behind. An inspector normally inspects your elevators at least two and perhaps as often as four times a year.
The escutcheon is the hole in the hall door, usually near the top of the door.
Pronounced “jib,” the gib is an often misunderstood, much maligned component. It is a small piece of metal and plastic that holds the elevator door in the track. The gib slides back and forth in the slots you see on the floor when you get in and out of the elevator. There are normally two gibs for each individual door panel. The plastic part of the gib actually touches the track in each sill. There is also a metal part. If there is a fire and the heat melts the plastic, the metal part is still there sticking down in the groove and keeping the door in place and the flames out of the elevator hoistway.
Quite simply, this device prevents the elevator from over-speeding. When an elevator over-speeds, the governor trips causing it (what?) to grip a cable. The cable, which normally moves up and down with the elevator, now becomes stationary while the elevator continues to move. The governor cable pulls on the safety device and brings the car to a rapid stop.
Hoist Cables are amazingly strong steel cables made up of over a hundred individual, high-strength, flexible steel wires. People are often surprised to hear that the core of each cable is not steel, but a twisted fiber, similar to a manila rope.
The hoistway, also called the shaft, is the structure that surrounds the elevator. Sometimes it is partially open at the rear as in some hotels and office buildings. Hoistways are meant to be fire resistant enclosures. Normally the walls and elevators are all 1 ½ hour fire rated. Elevator doors normally have a 1 ½ “B” label rating. The elevator door entrance frames also have this same fire rating. Hoistway walls must support anchor forces. ANSI code requires that hoistways of elevators shall be provided with means to prevent the accumulation of smoke and hot gases in case of fire as required by the building code.
A hydraulic elevator is an elevator moved by a fluid under pressure, acting upon a piston. Elevators have a single or dual piston/cylinder design. The hydraulic fluid, normally a paraffin based anti-wear hydraulic oil, is designed for operation under high temperatures and pressures. It is stored in a tank in the elevator machine room. When you push a button to go up, a motor begins turning. A screw type pump forces oil from the tank into the cylinder. The pressurized oil forces the piston, which is connected to the elevator car in the up direction. When you want to come down, the oil in the cylinder is released through a valve back into the tank. You will notice when standing in the machine room, that the elevator sounds different depending upon whether it is going up or down. It’s always louder in the up direction, because the motor and pump are turning. To go down, the valve opens allowing oil back into the tank. The noise you hear is the oil rushing through the piping and gushing up into the reservoir tank. Some earlier hydraulic elevators actually used water as the fluid that lifted the elevator.
The interlock is an elevator device designed to keep the elevator hoistway door (or hall door) closed when the car is at another floor.
Limited Use / Limited Application Elevators (LULA)
Referred to as LULA, Limited Use / Limited Application Elevators provide handicap accessibility for small office buildings and apartment dwellings where the authorities do not require an ADA legal passenger elevator. They are smaller, and do not have to be fully automatic. The current interpretation of the code is that either the car gate or the hoistway door must be power operated, and most manufacturers have both powered gates and powered swing doors, or powered two speed side opening doors. They still require pit refuge space, overhead refuge space, etc., but are allowed to substitute manually operated safety mechanisms to provide equivalent safety space. They have been allowed only for a few years.
Elevator maintenance contracts used to be shorter, simpler and easier to understand. They are now rather ponderous documents made for lawyers and engineers. At times, contracts become more concerned with ancillary issues, such as insurance, rather than making sure the equipment is being maintained and safety issues are being addressed.
Material Lifts or VRCs
- Do not allow riders. An elevator can carry people and/or goods. A freight elevator can carry goods and only authorized people.
- Do not need a pit or safe refuge space.
- Have no limits on size or capacity. They may be very small, or extremely large.
- Have no limits on travel distance, or car speed.
- Must have railing (with 4” kick plates) or panels to a minimum height of 42” per OSHA requirements. Must have a safety chain or locking bar at a minimum across the openings. They may have a full cab if desired.
- Cannot have a car operating station. The majority of these lifts are equipped with “constant-pressure” up and down buttons that must be held in for the lift to operate. If equipped with automatic up and down buttons, an Emergency Stop button must be added.
- Do not need top exits; inspect stations, leveling speeds, gate switches, etc.
- Must have what is known as a “backstop device”. This is either a broken chain/rope safety, or for directly coupled hydraulics, a pipe rupture or velocity fuse of some kind.
- Must have their landings protected by an OSHA legal gate, door, and enclosure at all landings. This door or gate must not be operable from outside if the lift is not at the landing. This means that the doors must have interlocks. Self-standing lifts need to be protected at the lower landing.
- Must follow all local and national electrical codes.
- Must be designed per ASME/ANSI B20.1 Safety Standard for Conveyors and Related Equipment. VRC’s are vertically reciprocating conveyors. Elevators of all kinds must be designed per ASME/ANSI A17.1 Safety Code for Elevators and Escalators, with a few exceptions for construction elevators, etc., which have their own code.
Pit depth and overhead clearance are in accordance with ANSI code requirements. Local codes may vary these requirements. Elevators designed for shallow pit (as little as 8”) or limited overhead situations (as little as 8’ 6”) are possible but will require a variance. A pit ladder is required. Pit floor must be adequately reinforced to transmit jack, buffer, and safety setting forces.
A modern elevator platform has steel stringer supports and steel sheet fireproofing.
Also called a pump unit, a power unit is a major component of hydraulic elevators, which consists of a reservoir tank for the oil, a motor, pump and valve. Sometimes a controller is attached to the front or side of the power unit. This is considered, at least from an operational standpoint, an entirely separate major component.
These small elevators are restricted in size (12 sq ft, 750 lbs, 40 fpm, 50 ft), capacity speed, and travel, but do not need to conform to many of the more stringent elevator rules, such as speed governors, pit and overhead spaces, and automatic operation.
Similar to sidewalk elevators, rooftop elevators open up a horizontal roof door by penetrating through the door itself. They are relatively new, and it is still uncertain whether or not they can be operated through the roof from the cab. It makes more sense if they can be, and normally special effort is made to make sure the roof door is safe before proceeding, by receiving an OK from a control tower, or viewing closed circuit TV cameras. They certainly are not expected to be accessible to the public, and are usually attendant operated.
We can thank Elisha Graves Otis for this device. It quickly brings an elevator to a rapid stop if it over-speeds while moving in the down direction, by forcefully gripping the rails. The jaw type devices are usually attached to the bottom of the elevator car frame. Buildings having occupied space under the elevator pit normally have safety devices on the counterweight. The original Otis safety device was designed to work when the cables or wire ropes broke, which then being made of fiber were prone to do. Otis publicly demonstrated his invention in New York in 1854.
Also called a full load safety test, this test is performed every five years on traction elevators and roped hydraulic elevators. A traction elevator is an elevator in which the elevator cab or car is moved by cables. If your elevator has a capacity plate reading 2,500 pounds, then that amount in steel, concrete or lead weights is placed on the elevator. Both the governor and safety device are tested and the test puts a strain on the elevator equipment.
Sidewalk elevators can carry authorized people, and can only be “driven” through the sidewalk door when the unit has safety screens. Two stop sidewalk elevators, therefore, do not have up/down controls in the cab unless they have safety screens. A recent change in the code allows for the addition of Hinged Safety Screens under the sidewalk door for full use as a freight elevator. Operation with the safety screens is as follows: Car is called to grade; a bar is used to secure the door in the open position; the authorized person can then enter the car and operate it as a full freight elevator. When finished, the authorized operator exits at grade, removes the bar from the door and lowers the car below grade.
Sidewalk elevators and lift do not need a canopy, or a top exit. If they have a canopy, they must comply with refuge space below the “bow”. There are no limits on the size or capacity, but are limited to a speed of 25 feet per minute through the sidewalk door.
Special Purpose Personnel Elevators
These small elevators are limited in size, capacity and speed, (1000 lbs, 13 sq ft, 150 fpm) but not in travel. Drum machines are, of course, still limited to 40 ft. They have reduced overhead (30”), but the code is unclear about the pit requirements, so it is a safe bet to provide a deep enough pit for bottom car clearance. We have an interpretation that says bottom car clearance is not required. They can have manual gates and doors.
Many elevators were installed years ago and still don’t have a phone. The latest telephones are push to talk, auto dial or “handsfree” phones. You push a single button and the designated phone number is automatically dialed. They normally require a dedicated phone line.
A traction elevator is one that uses cables and counterweights to move the car. The cables get “traction” by the way they ride in the grooves of the machine sheave. Also sometimes called an electric elevator, geared elevator or gearless elevator.
A valve is a component of the elevator power unit (or pump unit) which controls the speed at which oil flows into and out of the cylinder, and thereby the speed or velocity of the elevator. A hard start or stop is usually related to the valve operation.
These small elevators are restricted in travel, size, and capacity (12 ft, 18 sq ft, 750 lbs). They are usually thought of as the self-standing platform lift with half-height sides that can be seen in office buildings, town halls, etc. They now have their own code, A18.1.