37201111
Description
Flashcards by Kara Biczykowski, updated more than 1 year ago
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Created by Kara Biczykowski
over 2 years ago
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| Question | Answer |
| 1) hydraulic elevators are lifted by a: 2) what is the downside of this type? 3) hydraulic elevators are only used for: | 1) plunger or "ram" in the ground directly under the car & operated w/ oil as the pressure fluid 2) the cylinder for the ram must be extended into the ground to a depth the same as the elevator's full height 3) passenger & freight loads in bldgs 2-6 stories high (~50ft) |
| 1) compared to electric elevators, a hydraulic's speed is: 2) single-ram elevator's weight capacity is: 3) multiple-ram units can lift: 4) a variation is the holeless hydraulic which uses a: 5) another type uses a roller chain mtd over: | 1) 25 ft/min to 150 ft/min & so are not appropriate for moving large #s of ppl quickly 2) 2000lbm to 20,000lbm 3) 20,000lbm to 100,000lbm 4) telescoping plunger in the shaft next to the cab 5) a wheel mtd on top of the hydraulic plunger, plunger in shaft abv ground |
| 1) electric elevators aka "traction elevators" (Fig 20.1) employs a cab that's: | 1) suspended by cables or "ropes" that are draped over a sheave & attached to a counterweight, a motor drives the sheave which transmits lifting power to the ropes by the friction of the ropes in grooves of the sheave |
| 1) electrical elevators are capable of what compared to hydraulic elevators 2) "gearless traction elevators" use a: 3) when are gearless used? | 1) much higher lifts & greater speeds at 250-1800 ft/min & can carry 2000-5000lbm or more for elec. freight elev. 2) direct current (dc) motor directly connected to the sheave, brake is mtd to same shaft 3) high-speed elevators |
| 1) "geared traction elevators" are used for: 2) geared types use a a high-speed DC or AC motor to drive a: 3) this type prvd's much flexibility for slow-speed, high capacity elev.'s b/c: | 1) low speeds of 25-450 ft/min 2) worm gear reduction assembly to prvd a slow sheave speed w/ high torque 3) there are many variations in gear reduction ratios, sheave diameters, motor speeds, & roping arrangements |
| 1) "roping" refers to: 1) the 'single wrap" is the most simple where the rope passes over the: 2) "double-wrap" is req.'d for: 3) what is the disadvg to double-wrapping | 1) the arrangement of cables supporting the elevator 2) sheave only once & is connected to the counterweight 3) high-speed elevators b/c add.'l traction is req.'d so rope is wound over sheave 2x 4) more bends in cable = shorter rope life |
| 1) what is 1:1 roping? 2) what is 2:1 roping? | 1) rope directly connected to the counterweight, the cable travels as far as car but in opp. direction 2) when rope is wrapped around a sheave on the counterweight & connected to the top of the shaft, rope moves 2x as far as cab; req.'s less weight be lifted, so a smaller high speed motor can be used, good for 700 ft/min |
| 1) "operation" is used to describe the way: 2) "control" describes the method of coord. all aspects of elev. service like: | 1) electrical systems for an elev. answer calls for service, to coord. response to signal calls on ea. flr to min. waiting time 2) travel speed, de / accelerating, door opening speed & delay, leveling, hall lantern signals |
| 1) the most simple type of system is the "single automatic" where attendants were no longer needed & now consist of: | 1) a single call button on ea. flr & in cab for ea. flr, it can only be called if no one is using it, passenger has exclusive rights until trip is complete, so only good for bldg's w/ little traffic |
| 1) the most common type of system for bldgs is the "selective collective operation" where the elevator: 2) when is a sim. type called "group automatic operation" used? | 1) remembers & answers all calls in one firection & reverses & does the same, after trip it can be programmed to return to a home landing, typ a lobby 2) for large bldgs w/ many elevators, even time of day or day of week can be included in programming |
| 1) in a "destination floor guidance system" it uses computer ctrl w/ AI to put riders in: 2) 1st type of drive ctrl is "unit multivoltage" (UMV) ctrl system, it uses: | 1) the same car who are going to the same floors or nearby, destination is selected in lobby rather than cab, which reduces travel time & fewer stops 2) an AC motor to operate a DC generator, the DC current from the generator is then varied to run a DC traction motor (from before elec elev.'s) |
| 1) the 2nd type of drive ctrl is "silicon-ctrl'd rectifier" (SCR) ctrl system, it provides: 2) the SCR provides good: 3) the 3rd type is "variable-voltage, variable frequency" (VVVF) AC ctrl system uses: | 1) variable DC voltage to a DC traction motor 2) drive & leveling ctrl, but like the UMV has a low power factor & high thermal loss 3) a rectifier & inverter to convert AC power to DC power & then to variable-voltage, variable-frequency, 3-phase AC current |
| 1) in the VVVF, the current ctrls a standard: 2) VVVF systems have accurate & efficient speed ctrl systems, is energy efficient, & is 3) how is the brake on a the sheave or motor shaft operated? | 1) AC motor, which operates at the speed corresponding to the frequency of input 2) useful for elev.'s of all speeds & travel distances w/ min. maintenance b/c of solid-state design 3) by the ctrl mechanism, it's automatically applied if power fails |
| 1) what senses the cab's speed? 2) what do safety clamp rails do? 3) what safety feature is in the elev. pit? | 1) a governor, & if speed limit is exceeded brake is automatically applied 2) they grip the side rails if there's an emergency 3) car buffers to stop a cab's motion if it over-travels the lowest stop, but can't stop a free falling cab |
| 1) what do hoistway door interlocks do? 2) what prevents the doors from closing on someone? 3) ^what is another device that serves this purpose? 4) what is a proximity detector? | 1) prevent the elev. from operating unless the hoistway door is closed & locked 2) "safety edges," moveable strips on leading edge of dr that activate a switch to reopen if something contacts it 3) photoelectric devices 4) can sense presence of a person near door & stop the closing motion |
| 1) how is overloading in a cab prevented? 2) other safety device features in an elev. include: | 1) underfloor sensors detect when the max weight is reached by deflection, makes warning noise, & prevents more ppl pickup 2) multiple ropes, escape hatches in top of cab, alarm buttons on ctrl panel, tele's for direct communication |
| 1) where do the cars stop if power fails? 2) typ what does code req. if power fails? 3) code req.'s if a fire alarm is activated, all elev. cars: | 1) at their current location 2) that emergency power be available to operate at least one car at a time, which allows unloading of occupied cabs 3) return to the lobby w/out stopping & switch ctrl to manual mode that can only be operated by fire fighters using a key |
| 1) elev.'s must be accessible to the disabled, which req.'s that in lobbies: 2) what is the min time btwn notification a car answered a call & dr starts to close? 3) elev. cars need to be sized for a wheelchair to maneuver w/in reach of ctrls & entering/ exiting, what are these clearances? | 1) visual signals can be easily seen & audible signals indicate car landing, & call buttons & raised braille floor designations be placed w/in height limit 2) 5 seconds 3) min dr opening = 36in, car ctrls max 54in for side approach & 48in for front approach, car ctrls, entry flr, alarm, emergency stop buttons to be in braille & raised alphabet characters |
| *Practice Question What type of elevator should be specified for a 40-story office bldg? 1) hydraulic 2) gearless traction 3) geared traction 4) electric | 2) gearless traction (type of electric elev.) - can travel at highest speeds of those listed, can accommodate rush of ppl at diff. times of day - geared traction travels at slower speeds, but can adjust to suit bldg needs -hydraulic typ only used 6-stories or less, slower than elec., better for freight or low-occ. passenger elev. where speed isn't an issue |
| 1) for most bldgs, the "handling capacity" or # of ppl to be served is based on: 2) the # of ppl an elevator can carry is a function of its: 3) the max # of passengers in an elev. car is directly related to: | 1) a 5 minute peak period, ex for an office in the morning for ppl arriving 2) capacity which is measured in weight, see table 20.1 3) the capacity in weight, see table 20.2 *table 20.3 has recommended elev. speeds |
| 1) # of elevators is based on the probability of: 2) then the actual # of elevators req.'d if found by taking the total: 3) recommended "interval" or avg waiting time for diversified offices is: 4) for apartments & hotels is: | 1) # of stops, highest floor, car capacity & speed, door opening & closing time, delays at stops, avg round trip time, & handling capacity of 1 car in 5 min period 2) # of ppl to be accommodated in a 5 min peak period & dividing by the handling capacity of 1 car 3) 30 - 35 seconds 4) 40 - 70 seconds or more |
| 1) all hall lanterns on elevators should be located so: 2) ppl should be able to wait for elev. w/out 3) max # of cars in a "group" & "line" 4) what is the 1st method to keep acceptable wait & travel times for towers | 1) they can be seen from 1 point 2) interfering w/ oth circulation 3) 8 cars in a group, 4 cars in a line, see Fig20.2 for lobby elev diagram (min dims) 4) divide the total # of elevators into banks that serve separate zones, ex bank 1 serves floors 1-14, bank 2 serves flr 15-28 |
| 1) the 2nd method for towers is using the 2) the 3rd method is: | 1) sky lobby method, elev. takes ppl up to oth. lobbies where they transfer to new elev.'s to their destination, reduces space occ.'d by elev. since shafts don't extend full height 2) the double-stacked elev. cabs, where traffic to even flrs is directed to one flr & traffic to odd flrs to an adj flr, shaft capacity is doubled, elev. area reduced, local stops is decreased |
| 1) the "hoistway" or elev. shaft prvd.'s a dedicated space that is: 2) if an elev. connects no more than 3 flrs the shaft & openings req. a (__) rating 3) & if elev. connects 4 or + stories: 4) how should the hoistway be illuminated | 1) fire-rated + doors & oth openings 2) 1 hour fire rating 3) shaft a 2 hr rating, openings & doors a 1-1/2 hr rating 4) min 1fc for the entire length & must activate during an emergency operation |
| 1) max # of cars in a hoistway is 4 elev. cars & if 4 or more cars serve a flr they must: 2) what must be prvd.'d in the elev. pit? | 1) be in 2 separate hoistway enclosures, ex 6 cars serve a flr, must be divided either by 3-3 or 2-4 2) a "car buffer," a device to bring elev. car to cushioned stop if car travels past lowest stop, access ladder or separate access dr, permanent lighting, drain or sump to remove accumulated water |
| 1) what are the 3 types of elevator doors? 2) what is the min clear opening width? | 1) single-speed + center-opening (most common for passenger loading), two-speed + side-opening doors (w/ 2 telescoping leaves), or two-speed + center-opening (4 leaves) 2) 3'-6", but 4'-0" better b/c it allows 2 ppl to pass simultaneously |
| 1) where are machine rooms best located? 2) list all the components in a machine room that req. servicing & access clearance 3) typ what is necessary size of machine rm 4) min ceiling height of machine rm is: | 1) above the hoistway 2) motor, sheave, brake, ctrl board, speed governor, flr selector mechanism, motor generator 3) as wide as hoistway, 12-16 ft deeper than hoistway 4) range 7'-6" to over 10'-0" |
| 1) what type of elevators not always req. a machine room anymore? 2) describe how a "machine-roomless elevator" (MRL) works | 1) some hydraulic or gearless elevators in low & mid-rise bldgs 2) motor & ctrl can be placed in hoistway, they use coated steel belts w/ smaller bending radius that wire rope to use smaller more efficient drive sheaves that can be in the hoistway |
| 1) how do MRL rooms reduce energy consumption? 2) how do regenerative drives generate electricity w/ a MRL room? | 1) thru use of more efficient motors, LED lighting, sleep mode (car lights & fans off when not in use), & regenerative drives 2) when a heavily loaded car travels down outweighing the counterweight or when a lightly loaded car travels up when counterweight outweighs the car |
| OTHER MRL ADVANTAGES: 1) reduced noise & vibration due to the coated steel belts 2) elimination of the lubrication needed for traditional wire ropes 3) faster installation | 4) ability to place call buttons in the elevator door jambs, simplifying coord. w/ other trades 5) shorter ordering lead times |
| FREIGHT ELEVATORS 1) Class A is for: 2) Class B 3) Class C1 4) Class C2 5) Class C3 | 1) general freight, no item can exceed 1/4 of rated capacity which can't be less than 50 lbm/sf platform area 2) motor vehicle loading, min 30lbm/sf 3) industrial truck loading w/ truck, min 50 lbm/sf 4) ^doesn't include truck 5) ^concentrated loading w/ truck not carried & increments >25% capacity |
| 1) common available capacities of freight elevators is: 2) speed ranges of freight elevators: | 1) 2500lbm to 8000lbm, some multiple-ram hydraulics capable of 100,000lbm 2) 50 - 200 ft/min, some up to 800 ft/min for very tall bldgs (interval time not as important as capacity) |
| ESCALATORS 1) what is the industry std. speed? 2) 3 sizes available & "T" tread size is: 3) the observed capacity of a 32" & 48" escalator (most common types) is: 4) escalators are set in a truss assembly at (__) degrees | 1) 100 ft/min (but typ 120ft/min in sports facilities) 2) 32" (24"T), 40" (32"T), 48" (40"T) 3) 2300 ppl/hr (32"), 4500 ppl/hr (48") 4) 30 degrees (motors, drives, oth mechanisms extend blw floor at top & btm, so keep flr to flr head ht in acct) Fig20.3 |
| 1) what is the most common escalator arrangement? 2) what is the arrangement of the "crisscross walkaround?" 3) what is the arrangement of the "parallel spiral?" 4) of the "stacked parallel arrangement?" | 1) "crisscross spiral arrangement," user makes a U-turn to enter next escalator 2) all the up escalators are abv ea. oth. & all the down escalators are abv ea. oth. 3) rider can reach escalator that cont.'s to next flr w/ simple U-turn, entrances to up & dn are near ea. oth, but req.'d width is 4 escalators 4) rider must walk to oth side of escalator to cont. to next flr |
| STAIRS & RAMPS 1) what is the min width of any stair 2) ^ & when the occ. load exceeds 50? 3) ^stair prvd's evacuation assistance? 4) how much can handrails project in on both sides of a stair? 5) the bldg code only allows winding, circular, & spiral stairs in: | 1) 36 in 2) 44 in 3) 48 in 4) 4-1/2" max 5) in private residences like houses, apts, condos |
| 1) winding stairs are classified as such b/c they have: 2) circular stairways sides are shaped as an arc, & the inside arc cannot be: 3) spiral stairs use wedge-shaped treads that: 4) what can the allowable riser height of a spiral stair be? | 1) tapered treads that are wider at one end than the other Fig20.6a 2) less than 2x width of the stair Fig20.6b or it's classified as a winding stair 3) radiate from a center support column Fig20.6c 4) max 9-1/2" but w/ a min head height of 6'-6" |
| 1) req.'d top handrail extension length 2) req.'d btm handrail extension length 3) what is the req.'d landing width? 4) what is the req.'d landing depth? 5) if space for evacuation assistance is req.'d, where is it typ located? | 1) 12 in 2) tread + tread *but in cali we do tread + 12 in 3) at least as wide as the stair it serves 4) min stair width but doesn't need to be greater than 48 in 5) in the bldg exit stairways |
| 1) in an exit stair, code req.'s doors adj to landings not project into exit path more than (__) distance when door is opening or fully opened 2) extensive research proves which combo of stair tread & height is best? 3) the stair tread is the horiz. projection of the distance from: | 1) 7in from wall & 7in from tangent of clear radius, see Fig20.7 2) max rise 7in & min tread 11in 3) edge of one nosing to the next, doesn't include any part of tread under nosing |
| 1) which formula can be used to determine the total # of stairs when the total rise is known & risers must be whole # w/out exceeding 7" or 8" in private stairs: 2) total run of a stair is calc.'d by: | 1) 2R + T = 25 ^Eq20.1 17th century, can be used in most designs; uses a wider tread which is safer 2) taking total rise in inches & dividing by an estimated riser height, usually 7in, if result isn't a whole #, take next largest whole #, this is then divided into total rise to get req.'d riser height |
| 1) the # of treads for a straight-run stair is: 2) what is the max distance btwn landings? 3) top & btm treads should have: 4) accessible design req.'s nosings not be abrupt & have: | 1) one less than # of risers, this # is multiplied by tread dimension to get total req.'d run 2) 12 ft (but debate shows 9ft may be better for disable ppl) 3) contrasting strips at nosings for visually impaired, & non-slip material 4) max rounded edge of 1/2" |
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