Vertical Transport Flashcards
hydraulic elevator
• Used for low-rise, or less than 5 story buildings, or about 50’-0”
• Speed varies between 25 - 150 feet per minute
• Can carry about 10 tons
• Commonly used for freight in industrial and low-rise commercial buildings,
passengers in small buildings, or single family residential
• Sit over a plunger or ram which operates a cylinder that extends as far into the
ground as it is tall.
• Oil serves as the pressure fluid and is controlled by high speed pumps
• The main advantage of hydraulic elevator systems is that they don’t require a
penthouse machine room or heavily braced roof over the shaft
• Cost less than electric elevators because they are more simple
• Holeless Hydraulic: uses a telescoping plunger set into the shaft next to the
cab. Lift is provided by applying force to the upper member of the car frame
• Electric (Traction) Elevator:
• Used in commercial and industrial buildings greater than 5 stories/50’-0”
• Speeds up to 1,800 feet per minute
• Capacities up to 10,000 pounds
• Traction is used to transmit lifting power to the hoisting cables by means of
friction that develops when cables run over grooves in the sheave
• On one end is the elevator cab and the other are counterweights that weigh
about the weight of an empty car plus 40% of the live load capacity
• Traction machine: Motor and drum assembly that is geared or gearless
• Gearless: motor, sheave, and break all mounded on a common shaft, so 1
revolution of the motor means one turn of the main sheave (typically used for
passenger service)
• Geared: motor and break on one shaft which drives a second main shaft, used
for high speed installation
• Roping: the arrangement of cables supporting the elevator
• Single wrap: simplest, cables pass only once over elevator machine sheave and
then connected to the counterweight
• Double wrap:
cables pass over the sheave twice, get worn out faster, used for high speed elevators where more traction is required
• 1:1 Roping:
when the rope is directly connected to the counterweight, the cable travels in the opposite direction as far as the car
• 1:2 Roping:
when the rope is wrapped around a sheave on the counterweight and connected to the top of the shaft the rope moves twice as fast as the car, but requires less weigh to be lifted. (Car travels twice as far as the piston)
• Freight Elevators:
• Designed only to transport equipment and materials (and the passengers needed to handle them)
• Commonly available in 2500 lbm - 8000 lbm
• Freight elevators are available as standard designs for capacities of up to
20,000 lbs beyond this point, they must be specially engineered.
• Speeds range from 50 ftm - 200 ftm
• Capacity takes prescience over speed
• Classifications for freight elevators:
• Class A: general freight, no item can exceed 1/4 the rated capacity of the elevator (no less than 50 lbm/sq. ft of platform area)
• Class B: used for motor vehicle loading and no less than 30/lbm/sq. ft.
• Class C1: includes industrial truck loading based on 50/lbm/sq.ft.
• Class C2: includes no industrial truck loading based on 50/lbm/sq.ft
• Class C3: concentrated load for the truck not carried and with increments
greater than 25% rated capacity
• Safety features:
• Numerous due to all the potential hazards
• Main Break: is mounded on shaft and operated by the control mechanism
• Break is self applying so the car will stop in the event of a power failure • Governor: measures and limits the elevator speed by means of the control
panel.
• It will actuate the safety rail clamp if the elevator tries to exceed its proper
rate of travel
• Safety Rail Clamps: grip the side of the rails if there is an emergency
• Car Buffers/Bumpers: located on the bottom to stop the car if it over travels at
low speed….won’t do much to stop a car traveling at a higher speed
• Interlocks: prevent the elevator from operating unless the hoistway door is
closed and locked
• Safety Edges: Doors have spring loaded lip that retract open if it encounters a
person/object when attempting to close
• Proximity Dictators: similar to safety edges, but senses the presence of a
person near the door and can stop the closing motion • Cabs will self level to reduce tripping hazard
• Main Break:
is mounded on shaft and operated by the control mechanism
• Break is self applying so the car will stop in the event of a power failure
• Governor:
measures and limits the elevator speed by means of the control
panel.
• It will actuate the safety rail clamp if the elevator tries to exceed its proper
rate of travel
• Safety Rail Clamps:
grip the side of the rails if there is an emergency
• Car Buffers/Bumpers:
located on the bottom to stop the car if it over travels at
low speed….won’t do much to stop a car traveling at a higher speed
• Interlocks:
prevent the elevator from operating unless the hoistway door is
closed and locked
• Safety Edges:
Doors have spring loaded lip that retract open if it encounters a
person/object when attempting to close
• Proximity Dictators:
similar to safety edges, but senses the presence of a
person near the door and can stop the closing motion • Cabs will self level to reduce tripping hazard
single automatic
elevator can only be called if no one is using it, and onece inside, the passenger has exclusive use of elevator until trip is complete
-only good for s,all buildings with light traffic
