Trade vocabulary is where misunderstandings start: the same component carries three names depending on the manufacturer and the country, and some words mean different things to a mechanic and to an inspector. These definitions are the working meanings used throughout this library.
Codes and authorities
| Term |
Meaning |
| AHJ |
Authority Having Jurisdiction – the body that adopts and enforces the elevator code locally, and whose interpretation governs. |
| ASME A17.1 / CSA B44 |
North American safety code for elevators and escalators, covering design, construction, installation, alteration and testing. |
| ASME A17.2 |
Guide for inspection of elevators, escalators and moving walks – what an inspector examines and how. |
| ASME A17.3 |
Safety code for existing elevators and escalators – retroactive requirements for units already in service. |
| EN 81-20 / EN 81-50 |
European standards for the construction/installation and for the design, calculations and tests of new lifts. |
| EN 81-80 |
European approach to improving the safety of existing lifts, implemented nationally. |
| EN 13015 |
European standard for maintenance of lifts and escalators, including instructions and records. |
| Acceptance test |
Testing performed on new or altered equipment before it enters service. See acceptance and periodic tests. |
| Alteration |
Any change to the equipment other than maintenance or repair – typically triggers current-code requirements for the altered portion. |
Mechanical components
| Term |
Meaning |
| Car (cab, cage) |
The load-carrying unit: platform, sling, enclosure and doors. |
| Sling |
The structural frame supporting the platform, connected to the rope/belt attachments and to the safeties. |
| Counterweight |
Weighted mass on the opposite side of the sheave, roughly balancing car plus 40-50% of rated load. |
| Traction machine |
Machine that drives the sheave; geared (worm, helical) or gearless (often permanent magnet). |
| Sheave / traction sheave |
Grooved wheel that transmits motion to the ropes or belts. |
| Diverter / deflection sheave |
Sheave that changes rope direction without driving. |
| Governor |
Speed-sensing device that grips the governor rope when the car exceeds its trip speed, initiating safety operation. |
| Safety gear / safeties |
Device on the car (and sometimes the counterweight) that grips the guide rails to arrest the car. |
| Guide rails |
Vertical T-section rails guiding the car and counterweight. |
| Guide shoe / roller guide |
Sliding or rolling element transferring lateral loads from the car to the rails. |
| Buffer |
Energy-absorbing device in the pit for the car and counterweight; spring or oil type. |
| Compensation (rope/chain) |
Means of offsetting the weight of suspension ropes as the car travels. |
| Worm gear |
Geared traction machine type with a worm and wheel reduction; needs correct oil level and type. |
| Jack (hydraulic) |
Cylinder converting oil pressure into lift; direct-acting or telescopic. |
| Pump unit / power unit |
Tank, pump, motor, valve block and oil cooling for a hydraulic elevator. |
Doors and entrances
| Term |
Meaning |
| Car door / hoistway door |
Inner door on the car and outer door at each landing; both must be closed and locked before motion. |
| Interlock |
Mechanical and electrical device proving a hoistway door is closed and locked. |
| Gate switch / closed circuit |
Electrical contact proving the car door or gate is closed. |
| Gib |
Guide that keeps a door panel aligned in its track; wear changes interlock engagement. |
| Sill |
Threshold at the landing; the car door and landing door must align across it. |
| Reopening device |
Device that reopens the doors when something is detected in the entrance: mechanical safety edge or electronic detector (light curtain). |
| Door operator |
Mechanism that opens and closes the car door; linear cam, belt/VVVF, or two-speed. |
| Nudging |
Slow closure with an audible/visual warning when the door is held open beyond the set time. |
Control and drive
| Term |
Meaning |
| Controller |
Cabinet containing the logic that sequences motion, levelling, doors and safety monitoring. |
| Drive (VFD/VVVF) |
Variable frequency drive controlling motor speed and torque. |
| Relay logic |
Older control using relays and contactors, fully observable and printed on ladder diagrams. |
| Encoder |
Device reporting position/speed to the drive; incremental (counted) or absolute (measured). |
| Selector |
System that determines car position and direction, classically using a tape or perforated strip. |
| Group control / dispatcher |
Logic assigning cars to calls across a group; destination dispatch assigns passengers before boarding. |
| Jerk |
Rate of change of acceleration – the parameter that most affects perceived ride comfort. |
| Levelling |
Aligning the car floor with the landing within the required tolerance. |
| Relevelling |
Automatic correction of levelling while the doors are open as load changes. |
| Machine-room-less (MRL) |
Design with the machine in the hoistway, removing the separate machine room. |
Safety chain and service
| Term |
Meaning |
| Safety chain / safety circuit |
Series circuit of safety devices; if any opens, the machine stops. See safety chain and governor. |
| Final limits |
Switches that stop the car if it travels past the normal terminal landing. |
| Slack rope / slack belt device |
Device that opens the safety chain if a suspension member loses tension. |
| Pit switch |
Switch in the pit that prevents movement while the pit is occupied. |
| Stop switch (top of car) |
Switch on the car top with the same function for top-of-car work. |
| Emergency stop |
Manual device in the car that opens the safety chain. |
| Lockout / tagout |
Isolating and proving zero energy before work – the non-negotiable first step. |
| Running clearance |
Required gap between moving parts and fixed structures, measured with the gauge specified by the code. |
| Preventive maintenance |
Scheduled examination and servicing intended to keep the unit compliant and reliable. See maintenance program. |
| Callback rate |
Unplanned service calls per unit per period – the practical measure of maintenance quality. |
Escalators and moving walks
| Term |
Meaning |
| Step band |
The continuous chain of steps. |
| Comb plate / comb segment |
Tooth assembly at each landing where steps enter and leave the track. |
| Skirt panel |
Fixed panel beside the step band; clearance to the steps is a critical safety dimension. |
| Balustrade |
Side structure carrying the handrail and protecting the step band. |
| Handrail entry device |
Sensor at the handrail entry that stops the unit if an object is drawn in. |
| Moving walk (travelator) |
Moving belt or pallet surface for level or slightly inclined travel. |
A note on manufacturer vocabulary: the same function is often named differently between makers – “selector” vs “positioning system”, “level” vs “floor”, “safety block” vs “safety gear”. When ordering parts or discussing a fault, use the terminology in that unit’s own documentation.
Related reading: system anatomy, code map, door systems. Forum threads are indexed under terminology.