topic 14: building conveying systems Flashcards
_____ is a platform or compartment housed in a shaft for raising and lowering people or things to different floors or levels.
elevator
______ is a small elevator for carrying things, especially food and dishes, between the floors of a building.
dumbwaiter
What are the 2 types of elevators?
- electric elevators
- oil hydraulic elevators
_____ are a type of elevator that operates using electric power for various components of its system.
electric elevators
Unlike traditional hydraulic elevators that use a system of pistons and fluid for movement, electric elevators rely on a system of _____, powered by an electric motor.
ropes and sheaves
What are the 9 parts of an electric elevator?
- shaft
- car
- cables
- counter weights
- guide rails
- machine room
- elevator machine
- controls
- safety devices
______ is the vertical passageway for car and counterweights.
shaft
______ is a cage of light metal supported on a structural frame, the top member of which the cables, that carry the car, are fastened.
car
_____ are the means for lifting or lowering the car, usually 3 to 8 cables placed in parallel fastened to top of car by cable sockets passing over a motor driven cylindrical sheave to the counterweights.
cables
Cables for electric elevators are usually ______ cables placed in parallel.
3-8
____ are rectangular blocks of cast iron stacked in one frame which is fastened to the opposite ends of the cables to which the car is fastened.
counterweights
_____ are vertical tracks that guide the car and the counterweights.
guide rails
_____ is a room usually placed directly above the shaft in which the elevator machine is housed.
machine room
The _____ contains the motor-generator (MG) set which supplies energy to the elevator machine, the control board and the control equipment.
machine rooms
The _____ turns the sheave that lifts and lowers the car.
elevator machine
The _____ is a combination of push buttons, contacts, relays, and devices, operated manually or automatically to initiate door opening, starting acceleration, retardation, leveling and stopping of the car.
controls
What are the 4 safety devices?
- main brake
- safety switch
- electrical final limit switches
- oil or spring buffers
The ____ is mounted directly on the shaft of the elevator machine.
main brake
The _____ is designed to stop an elevator car automatically before car speed becomes excessive.
safety switch
On overspeed, the _____ will cut off power to the motor and set the brake.
speed governor
The ______ usually stops the car, but should speed still increase, the governor will actuate rail clamps mounted at the bottom of the car one on each side.
speed governor
_____ are located a few feet below and above safe travel limits of elevator car.
electric final limit switches
If car over-travels, either down or up, these switches de-energizes the motor and sets the main brake.
electric final limit switches
_____ are placed at the bottom of the elevator pit, not to stop a falling car, but to bring it to a partially cushion stop if the car should overshoot the lower terminal.
oil or spring buffers
What are the 4 methods of arranging elevator machines, sheaves and ropes?
- single wrap traction machine
- one-to-one double wrap traction machine
- two-to-one double wrap traction machine (for freight elevators)
- underslung system
_____ is when supporting cables pass over the sheave in grooves and connect to the counterweights.
single wrap traction machine
The lifting power is exerted by the sheave through the traction of the cables in the grooves.
single wrap traction method
____ is when the cables first wrap over the traction sheave T, then around the secondary or idler sheave S, and once more going around T and S to the counterweights.
one-to-one double wrap traction machine
____ provides greater traction and is used in many automatic high-speed installations.
one-to-one double wrap traction machine
This 2:1 roping, has a mechanical advantage of 2, which results in a high- speed, low-power and therefore, low-cost traction machine.
two-to-one double wrap traction machine
____ is used where the elevator machine is located at the basement.
underslung system
What are the 2 types of elevator machines?
- gearless traction machine
- geared traction machine
_____ consists of a DC motor, the shaft of which is directly connected to the brake wheel and to the driving sheave.
gearless traction machine