Transcript EQUIPMENT UTILIZATION - Civil Engineering Society
Chapter 17
Cranes
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MOBILE CRANES
CRANES
The crane is the primary machine used for the vertical movement of construction materials.
MOBILE CRANES
Boom Mast Counter weight Boom stop
CRAWLER or WHEEL MOUNT
COMMON MOBILE CRANE TYPES Telescoping-boom truck-mounted Crawler All-terrain Lattice-boom truck-mounted Cranes for heavy lift Rough-terrain
CRAWLER CRANES
The full revolving super-structure of this type of unit is mounted on a pair of parallel crawler tracks. The crawlers provide the crane with good travel capability around the job site.
CRAWLER CRANES Large crawler crane with a rear mast
CRAWLER CRANES
Lattice-boom crawler crane rigged with a jib extension
CRAWLER CRANES
Rubber-track telescoping boom crawler crane on an urban project
CRAWLER CRANES
CRAWLER CRANES
CRAWLER CRANES Extendable counter-weight to increase lifting capacity
CRAWLER CRANES Mobile crawler crane with tower attachment
CRAWLER CRANES
Common dimensions Maximum boom length: 100 to 400 ft Maximum fly-jib length: 30 to 120 ft Maximum radius (boom only): 80 to 300 ft Minimum radius: 10 to 15 ft
CRAWLER CRANES
Common capacities: Maximum lifting capacity (at minimum radius): 30 to 600 tons Maximum travel speed: 50 to 100 ft/min (0.6 to 1.2 mph) Ground bearing pressure: 7 to 20 psi
TELESCOPING-BOOM TRUCK-MOUNTED CRANES These are truck cranes that have a self-contained telescoping boom Outriggers
TELESCOPING-BOOM TRUCK-MOUNTED CRANES Outrigger on large steel mat to prevent damage to pavement Outrigger on layered steel mats; note the dangerous ground deformation
TELESCOPING-BOOM TRUCK-MOUNTED CRANES With extension jib Raised on outriggers
TELESCOPING-BOOM TRUCK-MOUNTED CRANES Point-load exerted by outrigger Crane positioned on hollow-core precast concrete panels ceiling Temporary panel support
TELESCOPING-BOOM TRUCK-MOUNTED CRANES Common dimensions: Maximum boom length: 70 to 170 ft Maximum fly-jib length: 30 to 100 ft Maximum radius (boom only): 60 to 140 ft Minimum radius: 10 ft for most models
TELESCOPING-BOOM TRUCK-MOUNTED CRANES Common capacities: Maximum lifting capacity (at minimum radius): 20 to 120 tons Maximum travel speed: 40 to 70 mph Number of axles: 3 to 4
LATTICE-BOOM TRUCK MOUNTED CRANES The lattice-boom structure is lightweight. This reduction in boom weight means additional lift capacity, as the machine predominately handles hoist load and less weight of boom.
LATTICE-BOOM TRUCK MOUNTED CRANES
LATTICE-BOOM TRUCK MOUNTED CRANES Common dimensions: Maximum boom length: 170 to 470 ft Maximum fly-jib length: 4 0 to 300 ft Maximum radius (boom only): 130 to 380 ft Minimum radius: 10 to 25 ft
LATTICE-BOOM TRUCK MOUNTED CRANES Common capacities: Maximum lifting capacity (at minimum radius): 50 to 600 tons Maximum travel speed: 40 to 60 mph Number of axles: 4 to 8
ROUGH-TERRAIN CRANES These units are equipped with unusually large wheels and closely spaced axles to improve maneuverability at the job site.
They earn the right to their name by their high ground clearance, as well as the ability to move on steep slopes.
ROUGH-TERRAIN CRANES
ROUGH-TERRAIN CRANES Common dimensions: Maximum boom length: 80 to 140 ft Maximum fly-jib length: 20 to 90 ft Maximum radius (boom only): 70 to 120 ft Minimum radius: 10 ft for most models
ROUGH-TERRAIN CRANES Common capacities: Maximum lifting capacity (at minimum radius): 20 to 90 tons Maximum travel speed: 15 to 35 mph Number of axles: 2 for all models
ALL-TERRAIN CRANES These cranes have an undercarriage capable of long-distance highway travel. Yet the carrier has all-axle drive and all wheel steering, crab steering, large tires, and high ground clearance.
ALL-TERRAIN CRANES Common dimensions: Maximum boom length: 100 to 270 ft Maximum fly-jib length: 30 to 240 ft Maximum radius (boom only): 70 to 250 ft Maximum radius (with fly jib): 100 to 300 ft (and up to 400 ft for the largest machines) Minimum radius: 8 to 10 ft
ALL-TERRAIN CRANES Common capacities: Maximum lifting capacity (at min. radius): 30 to 300 tons (and up to 800 tons) Maximum travel speed: 40 to 55 mph Number of axles: 2 to 6 (and up to 8 or 9)
CRAWLER CRANES FOR HEAVY-LIFTING Additional counterweight mounted on a wheeled platform to increase lifting capacity
CRAWLER CRANES FOR HEAVY-LIFTING Ring system (“ringer”): the heavy counterweight system is supported on a large circular turntable ring
SUITABILITY
BUILDING PROJECTS:
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Low rise structures – short cycle times
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High rise structures – long cycle times
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High speed/high volume operations (concrete placement)
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Site conditions (position, locations)
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Vertical reach requirements
SUITABILITY
INDUSTRIAL PROJECTS:
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Very precise (one time hoists)
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Heavy loads (possibly dual hoists)
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Working around fixed objects
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Site conditions (position, locations)
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Vertical reach requirements
SUITABILITY
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HEAVY PROJECTS: Very precise (one time hoists) Heavy loads (possibly dual hoists) High speed/high volume operations (concrete placement)
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Multiple work locations Site conditions (position, locations) Vertical reach requirements
SUITABILITY
HEAVY PROJECTS: Heavy loads (possibly dual hoists)
SAFETY
OSHA Crane
fatality
data: Energized power lines Overturning Load dropped Boom collapsed Two-block 50% 19% 14% 12% 5%
SAFETY
Crane Accidents: Overturning Overload Rigging Road accidents 61.0% 12.5% 12.5% 10.0%
CRANE ACCIDENTS Overturning 61.0%
CRANE ACCIDENTS
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Plan the work
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Work the plan Success is the result of procedural detail performed with demanding discipline
SELECTION FACTORS
Height of reach required Working envelope Maximum load Time Duty cycle
HEIGHT OF REACH REQUIRED
Height load is to be lifted Height of the load Sling height Hook block height Size of the load
CONSIDER ALL HEIGHTS Hook Block Sling Height Load Height Height Load is to be Lifted
HEIGHT OF LOAD
SLING HEIGHT
HOOK BLOCK HEIGHT
SAFE LOAD LIFTING
You are tasked to place concrete into column forms using a bucket. The following information describes the lift.
Load Height (Bucket) 12 ft Hook Block Height 2 ft Sling Height 6 ft Load must be raised 25 ft
Hook Sling 2 ft 6 ft Load 12 ft Raised 25 ft HEIGHT OF REACH 45 ft
CRANE MOTION
The motions a mobile crane uses to move a load are: 1. Hoist 2. Swing 3. Boom Up/Boom Down 4. Travel These are listed in descending order of fastest to slowest rate of motion.
CRAWLER CRANE SWING
A key aspect of crane capacity is quadrant of operation. A track-mounted crane has three quadrants that are established by a radius running from the center of rotation through both the idler and final drive on each side of the crane
or
by lines parallel to the tracks.
RADIUS DEFINITION
Over the Side Over the drive end (back) Over the idler end (front) Over the Side
RADIUS DEFINITION
Over the Over the Side drive end (back) Over the idler end (front) Over the Side
FRONT or BACK?
Drive end (back)
RATED LOADS FOR CRAWLER CRANES Load capacity depends on the quadrant position of the boom with respect to the machine ’ s undercarriage. In the case of crawler cranes, the quadrants that should be considered are: Over the side Over the drive end of tracks Over the idler end of tracks
WHEEL-MOUNTED CRANE SWING
A wheel-mounted crane three quadrants that are has established by a radius running from the superstructure center of rotation through the outrigger support on each side of the crane.
Over the side C
L
Over the rear Over the front Over the side
RATED LOADS FOR WHEEL MOUNTED CRANES Quadrants of consideration will vary with the configuration of the outrigger locations.
RATED LOADS FOR WHEEL MOUNTED CRANES For 4 outriggers, the three quadrants to consider are usually defined by imaginary lines running from the super structure center of rotation through the position of the outrigger support: Over the side Over the rear of the carrier Over the front of the carrier
LOAD CHART
• • • • • •
Crane size Operating radius Boom length Boom height (angle) Maximum capacity rear Maximum capacity side
LOAD CHART
Some load charts give load capacity based on quadrant of operation; others give a 360 degree rating.
STABILITY
Counterweight and superstructure Load Short distance Load distance
STABILITY
Short distance Load distance
LEVERAGE
MAXIMUM LOAD
Cranes may fail by two different
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mechanisms: Stability Table 17.2 loads appearing below the
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solid line.
Structural capacity
LOAD CHART
Load charts usually specify the boom and boom top for the load ratings, examples:
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Boom No. 22A or No. 22C with open throat top.
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77 SA Hammerhead Boom
BOOMS
Angular Tubular
RATED LOAD
For a crawler crane rated load is 75% of tipping load.
RATED LOAD
For a carrier-mounted crane on outriggers rated load is 85% of tipping load.
RATED LOAD
For a carrier-mounted crane on rubber rated load is 85% of tipping load.
MAXIMUM LOAD
Stability (tipping)
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Proper use of outriggers
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Ground conditions
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Level
MAXIMUM LOAD
Proper use of outriggers
Proper use of outriggers
OUTRIGGERS ON CITY STREETS
KEEP IT LEVEL Mats may be required
MAXIMUM LOAD
Structural capacity
: At short radii capacity may depend on boom or outrigger strength. Whether the load is limited by tipping or other factors will be noted on the load chart. Table 17.2, above the line is controlled by other factors.
MAXIMUM LOAD
Table 17.2, above the line is controlled by other factors.
MAXIMUM LOAD
NET HOISTING CAPACITY (LOAD WEIGHT) = GROSS CAPACITY
DEDUCTIONS Deductions differ between crane manufacturers and with crane types.
COMMON DEDUCTIONS Weight of hook & headache ball Weight of slings & rigging
ADD ALL WEIGHTS HOOK BLOCK WEIGHT GROSS CAPACITY SLING WEIGHT NET CAPACITY
COMMON DEDUCTIONS Weight of wire rope from tip sheave to auxiliary hook Weight of auxiliary hook
COMMON DEDUCTIONS Is the jib being used?
Then look up a different load chart.
COMMON DEDUCTIONS Weight of stowed jib
SAFE LOAD
You are to place beams on a bridge project using a crane w/180 ft of boom.
LOAD WEIGHT 35,200 lb HOOK BLOCK WT 2,250 lb SLING WEIGHT 975 lb HEIGHT OF LIFT 126 ft LOAD 16 ft HOOK 4 ft SLING 10 ft OPERATING RADIUS 40 ft
MAXIMUM LOAD
DEDUCTIONS: 3,225 lb (2,250 lb + 975 lb) Gross Capacity must be greater than: 38,425 lb (35,200 lb + 3,225 lb)
LIFTING HEIGHT
LIFT 126 ft LOAD 16 ft HOOK 4 ft SLING 10 ft TOTAL 156 ft
SAFE HOIST
At a radius of 40 ft, gross capacity must be greater than 38,425 lb.
CHECK following chart
SAFE HOIST
At a radius of 40 ft, gross capacity must be greater than 38,425 lb.
from the chart 47,700 lb @ 40 ft Elev. Boom point 182.9 ft Therefore lift is OK.
HOIST ANALYSIS
LOAD HEIGHT 16 ft LOAD WT 35,200 lb SLING HEIGHT 10 ft SLING WT 975 lb HOOK BK HT _4 ft HOOK BK WT 2,250 lb LIFT HEIGHT 126 ft TOTAL HT 156 ft ADDITIONAL WT 0 TOTAL WT 38,425lb CRANE SIZE 200 tn OPERATING RAD. 40 ft BOOM HEIGHT 183 ft BOOM LENGTH 180 ft BOOM ANGLE 78.3º