Glossary of Terms : P - T


Packing Gland

(1) The substance, usually of elastic or flexible material formed in rings used in the stuffing box of the worm shaft of a geared machine or of a hydraulic lift to prevent excessive leakage.

(2) Strips or blocks of material used for shimming.

Parking

A feature for a single lift or a lift group. With this feature, the lift receives a signal to always return to a pre-selected landing after all the car or landing calls have been completed.

Passenger lift

A lift primarily used to carry passengers.

Peak

In a waveform or other changing parameter, a peak is an instantaneous or local maximum or minimum.

Pickup Rollers

Devices on the hoistway door which mate with the clutch on the car door to allow the hoistway doors to be pulled open and closed.

Pit

A portion of the lift shaft extending from the sill level of the lowest landing to the lift shaft floor.

Pit Channels

Steel channels on the pit floor to anchor the guide rails and other pit-mounted devices.

Platform

The entire floor assembly of a lift, on which passengers stand or the load is carried.

Plumbing

A method for: a) checking the lift shaft to ensure that it is constructed according to the requirements and b) determining the correct position of the components.

Position Indicator

A device that indicates the position of the lift car in the hoistway, it is called a hall position indicator when placed at a landing, or car position indicator when placed in the lift car.

Power factor

Power factor defines the ratio between true power and apparent power. The power factor of a circuit is calculated based on a formula: pf = P / S, (kW / kVA).

Power Unit

The device on a hydraulic lift which supplies the motive force to run the lift car.

Preventative Maintenance

Inspections, tests, adjustments, cleaning and similar activities carried out on lift and escalator equipment with the intention of preventing malfunctions from occurring during operation. It is designed to keep equipment in proper operating order and is done on a scheduled basis. It is also referred to as scheduled maintenance.

Pump

The device which draws oil from the tank and pushes it through the oil line to the jack to move the lift up.

Push Button Station

A decorative device containing one or more hand-operated devices (buttons or switches) by which the passenger tells the controller what action is desired.

Rated load

The load for which the equipment has been built. See also car load.

Rail Clips

Devices bolted to guide rail brackets to clamp rails firmly in place.

Relay

An electric device that is designed to interpret input conditions in a prescribed manner and after specified conditions are met, to respond and cause contact operation or create change in associated electric control circuits.

Remote alarm

An emergency alarm system working over a distance.

Retardation

The operation of reducing the lift drive motor speed from normal operating speed to stop. Also referred to as Deceleration.

Revolutions Per Minute (RPM)

The number of completed turns per minute that an object revolves around its axis.

Ride comfort

Ride comfort of a lift is defined in terms of noise level, vertical vibration, lateral quaking, acceleration / deceleration rate, and jerk.

Riser

A series of hall stations for a lift or group of lifts

Roller Guides

Guide shoes which use rollers that rotate on guide rails rather than sliding on the rails.

Rotor

The rotating element of an AC induction motor.

Safety Edge

A mechanical door protective and automatic door reopening device, used with automatic power door operators. It is arranged so that in the event the door either approaches or meets an obstruction when closing, the safe edge will actuate an edge safety switch that will automatically cause the doors to stop and reopen. It is vertically mounted to extend from the bottom to the top of a horizontally sliding panel and projects forward of the leading edge of the panel.

Safe lightray

A photoelectric door protective and automatic door reopening device for automatic power door operators. It consists of a photoelectric receiving unit and light source device arranged to project a light ray across the lift door entrance. The interruption of the light ray will cause the doors to remain open as long as the ray is interrupted, or cause the reversal and reopening of doors that are closing.

Safety gear

A mechanical safety device attached to the car frame, and in some circumstances to the counterweight frame also. The device acts to stop and hold an overspeeding car or counterweight through the use of clamping jaws closing around the guide rails. The device is activated by the speed governor.

Seal

A device mounted on the guide to minimize oil escaping around the plunger.

Secondary Sheave

A pulley on a gearless machine which serves two purposes: (1) To allow each cable to second pass over the drive sheave and (2) To deflect the cable for a straight drop to the counterweight.

Selector

An electrical device, driven by the lift, which simulates lift movements.

Shaft fascia panel

A steel plate fixed on the shaft wall below the landing door sill and above the landing door to reduce the distance between the car door sill and shaft wall.

Shim

A piece of metal or other material used to fill out a space.

Sill

The bottom horizontal member of an entrance which provides the foundation and footing for the entrance frame. The sill extends the full width of the door travel.

Single Speed Door

A type of door consisting of one horizontal sliding panel.

Sling

The basic structural frame, which consists of two sides, a crosshead and a bottom support, which supports the platform and cab of a lift.

Skirting

Decorative and protective element at the bottom of the car wall.

Specifications

A detailed itemized description of the plans, materials, dimensions and all other requirements proposed for the installation of the equipment.

Spring Buffer

One type of buffer, for lifts with speeds less then 1 meter per second, which cushions the lift. It is located in the lift pit.

Stator

The non-rotating part of the magnetic structure in an induction motor.

Suspended load

The load that includes the weights of raw car, car interior, car door(s), rated load and car sling with all accessories. The weight does not include suspension ropes, compensation ropes or chains, rope compensation device, travelling cable or counterweight.

Suspension rope

The ropes suspending the lift car and counterweight.

Synchronisation drive

A lift drive mode in which the lift drives downwards until it reaches a deceleration or synchronisation switch.

Tachometer

A device which measures the feedback of a revolving shaft.

Tank (Reservoir)

A container to store the oil used to move the lift.

Terminal floor

The top or bottom landing served by an lift car.

Through-type car

A lift with entrances on two opposite sides of the lift shaft.

Thrust Bearing

A bearing designed to withstand an axial load placed on a shaft such as that imposed by a worm and worm gear.

Top-of-car Inspection

Controls on the top of the car used by a lift engineer to operate the car at inspection speed. It provides a means of operating a lift from on top of the car at slow speed during adjustment, inspection, maintenance and repair.

Torque

A force that produces or tends to produce rotation or torsion.

The pressure, measured in foot pounds, exerted by a rotating shaft.

The turning power of a motor.

The turning effort a brake is designed to stop.

Traction

One of two methods by which the lift is moved, whereby the lift is "pulled" up by cables.

Traction Machine

An electric machine in which the friction between the hoist ropes and the machine sheave is used to move the lift car.

Traction test

A safety test to ensure that there is correct amount of friction between the suspension ropes and the traction sheave.

Traveling Cable

A cable made up of electric conductors, which provides electrical connection between a lift or dumbwaiter car, or material lift, and a fixed outlet in the hoistway or machine room.

Triplex

Three elevators in a group.

Two Speed AC

A type of traction machine powered by an AC-driven motor (actually 2 motors built into one), which has 2 distinct speeds.

Two Speed Door

A type of door consisting of two horizontal sliding panels, which move, in the same direction.