Chapter 17Cranes

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Cranes

MOBILE

CRANES

CRANES

The crane is the primary machine used for the machine used for the vertical movement of construction materials.

Boom

Mast

MOBILE

CRANES

Counter weight

Mast

Boom stop

CRAWLER or WHEEL MOUNT

Telescoping-boom truck-mounted

COMMON MOBILE

CRANE TYPES

Crawler truck-mounted

Lattice-boom truck-mounted Rough-terrain

Cranes for heavy lift

All-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 crawlers provide the crane with good travel capabilityaround the job site.

CRAWLER CRANES

Large crawler crane with a rear mast

CRAWLER CRANES

Lattice-boom crawler crane rigged with a jib with a jib extension

Rubber-tracktelescoping-

CRAWLER

CRANES

telescoping-boom crawler crane on an urban project

CRAWLER CRANES

CRAWLER

CRANES

Extendable counter-weight to increase

CRAWLER CRANES

to increase lifting capacity

Mobile

CRAWLER

CRANES

Mobile crawler crane with tower attachment

CRAWLER CRANES

Common dimensionsMaximum boom length: 100 to 400 ftMaximum fly-jib length: 30 to 120 ftMaximum fly-jib length: 30 to 120 ftMaximum radius (boom only):

80 to 300 ftMinimum radius: 10 to 15 ft

CRAWLER CRANES

Common capacities:Maximum lifting capacity (at minimum

radius): 30 to 600 tonsradius): 30 to 600 tonsMaximum 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

OutriggersThese are truck cranes that have cranes that have a self-contained telescopingboom

TELESCOPING-BOOMTRUCK-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

Raised on

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

Common dimensions:Maximum boom length: 70 to 170 ft

TELESCOPING-BOOM

TRUCK-MOUNTED CRANES

Maximum fly-jib length: 30 to 100 ftMaximum radius (boom only):

60 to 140 ftMinimum radius: 10 ft for most models

Common capacities:Maximum lifting capacity

TELESCOPING-BOOM

TRUCK-MOUNTED CRANES

(at minimum radius): 20 to 120 tonsMaximum travel speed: 40 to 70 mphNumber 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

Common dimensions:Maximum boom length: 170 to 470 ft

LATTICE-BOOM TRUCK-

MOUNTED CRANES

Maximum boom length: 170 to 470 ftMaximum fly-jib length: 4 0 to 300 ftMaximum radius (boom only):

130 to 380 ftMinimum radius: 10 to 25 ft

Common capacities:Maximum lifting capacity

LATTICE-BOOM TRUCK-

MOUNTED CRANES

Maximum lifting capacity(at minimum radius): 50 to 600 tons

Maximum travel speed: 40 to 60 mphNumber of axles: 4 to 8

ROUGH-TERRAIN

CRANES

These units are equipped with unusually large wheels and closely spaced axles to improve 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

Common dimensions:Maximum boom length: 80 to 140 ftMaximum fly-jib length: 20 to 90 ft

ROUGH-TERRAIN CRANES

Maximum fly-jib length: 20 to 90 ftMaximum radius (boom only):

70 to 120 ftMinimum radius: 10 ft for most

models

Common capacities:Maximum lifting capacity (at

minimum radius): 20 to 90 tons

ROUGH-TERRAIN CRANES

minimum radius): 20 to 90 tonsMaximum travel speed: 15 to 35 mphNumber 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, wheel steering, crab steering, large tires, and high ground clearance.

Common dimensions:Maximum boom length: 100 to 270 ftMaximum fly-jib length: 30 to 240 ftMaximum radius (boom only):

ALL-TERRAIN CRANES

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

Common capacities:Maximum lifting capacity(at min. radius): 30 to 300 tons (and

ALL-TERRAIN CRANES

(at min. radius): 30 to 300 tons (and up to 800 tons)

Maximum travel speed: 40 to 55 mphNumber 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: Low rise structures short cycle times High rise structures long cycle times High rise structures long cycle times High speed/high volume operations (concrete placement)

Site conditions (position, locations) Vertical reach requirements

SUITABILITY

INDUSTRIAL PROJECTS: Very precise (one time hoists) Heavy loads (possibly dual hoists) Heavy loads (possibly dual hoists) Working around fixed objects Site conditions (position, locations) Vertical reach requirements

SUITABILITY

HEAVY PROJECTS: Very precise (one time hoists) Heavy loads (possibly dual hoists) Heavy loads (possibly dual hoists) High speed/high volumeoperations (concrete placement)

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 50%Overturning 19%Overturning 19%Load dropped 14%Boom collapsed 12%Two-block 5%

SAFETY

Crane Accidents:Overturning 61.0%Overturning 61.0%Overload 12.5%Rigging 12.5%Road accidents 10.0%

CRANE ACCIDENTS

Overturning 61.0%

CRANE ACCIDENTS

Plan the work Plan the work

Work the planSuccess is the result of procedural detail performed with demanding discipline

SELECTION FACTORS

Height of reach required Working envelope Working envelope Maximum load Time Duty cycle

HEIGHT OF REACH

REQUIRED

Height load is to be lifted Height of the load Height of the load Sling height Hook block height Size of the load

CONSIDER ALL

HEIGHTS

Hook Block

Sling Height

Load Height

Sling 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 ftHook Block Height 2 ftSling Height 6 ftLoad must be raised 25 ft

Hook 2 ftSling 6 ftLoad 12 ftRaised 25 ft

HEIGHT OF

REACH45 ft

CRANE MOTIONThe motions a mobile crane uses to move a load are:

1. Hoist2. Swing2. Swing3. Boom Up/Boom Down4. Travel

These are listed in descending order of fastest to slowest rate of motion.

CRAWLER CRANE

SWINGA key aspect of crane capacity is quadrant of operation. A track-mounted crane has three 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.

Over the Side

Over the drive end (back)

RADIUS DEFINITION

Over the SideOver the idler end

(front)

Over the Side

Over the drive end (back)

RADIUS DEFINITION

Over the SideOver the idler end

(front)

FRONT or BACK?

Drive end (back)

Load capacity depends on the quadrant position of the boom with respect to the machines undercarriage. In the case of

RATED LOADS FOR

CRAWLER CRANES

undercarriage. In the case of crawler cranes, the quadrants that should be considered are:Over the sideOver the drive end of tracksOver the idler end of tracks

WHEEL-MOUNTED

CRANE SWING

A wheel-mounted crane has three quadrants that are established by a radius running established by a radius running from the superstructure center of rotation through the outrigger support on each side of the crane.

COver the side Over the front

LOver the rear Over the side

L

RATED LOADS FOR WHEEL-

MOUNTED CRANES

Quadrants of consideration will vary with the configuration of the outrigger locations. 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 structure center of rotation through the position of theoutrigger support:Over the sideOver the rear of the carrierOver the front of the carrier

LOAD CHART

Crane size Operating radius Boom length Boom length Boom height (angle) Maximum capacity rear Maximum capacity side

Some load charts give load capacity based on quadrant

LOAD CHART

capacity based on quadrant of operation; others give a 360 degree rating.

STABILITY

Counterweight and Loadsuperstructure

Load distance

Short distance

STABILITY

Load distance

Short distance

LEVERAGE

MAXIMUM LOAD

Cranes may fail by two different mechanisms: Stability

Table 17.2

Structural capacity

Table 17.2 loads appearing below the solid line.

LOAD CHART

Load charts usually specify the boom and boom top for the load ratings, examples:ratings, examples: Boom No. 22A or No. 22C with

open throat top. 77 SA Hammerhead Boom

BOOMS

AngularTubular

RATED LOAD

For a crawler crane rated crane rated load is 75% of tipping 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.

RATED LOAD

Stability (tipping) Proper use of outriggers

MAXIMUM LOAD

Proper use of outriggers Ground conditions Level

Proper use of outriggersMAXIMUM LOAD

Proper use of outriggers

OUTRIGGERS ON CITY

STREETS

KEEP IT

LEVEL

Mats may be requiredrequired

MAXIMUM LOAD

Structural capacity: At short radii capacity may depend on boom or outrigger strength. Whether the load 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 CAPACITYGROSS CAPACITYDEDUCTIONS

Deductions differ between crane manufacturers and with crane types.

COMMON

DEDUCTIONS

Weight of hook &Weight of hook &headache ball

Weight of slings & rigging

SLING WEIGHT

HOOK BLOCK WEIGHT

ADD ALL

WEIGHTS

GROSS CAPACITY

NET CAPACITY

SLING WEIGHT

COMMON

DEDUCTIONS

Weight of wire rope Weight of wire rope from tip sheave to auxiliary hook

Weight of auxiliary hook

Is the jib being used?

COMMON

DEDUCTIONS

Is the jib being used?Then look up a different load chart.

Weight of stowed jib

COMMON DEDUCTIONS

stowed jib

SAFE LOADYou are to place beams on a bridge project using a crane w/180 ft of boom.LOAD WEIGHT 35,200 lbHOOK BLOCK WT 2,250 lbSLING WEIGHT 975 lbSLING WEIGHT 975 lbHEIGHT OF LIFT 126 ftLOAD 16 ftHOOK 4 ftSLING 10 ftOPERATING 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 ftLOAD 16 ftLOAD 16 ftHOOK 4 ftSLING 10 ftTOTAL 156 ft

SAFE HOIST

At a radius of 40 ft, gross capacity must be greater 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 chart47,700 lb @ 40 ftElev. Boom point 182.9 ftTherefore lift is OK.

HOIST ANALYSIS

LOAD HEIGHT 16 ft LOAD WT 35,200 lbSLING HEIGHT 10 ft SLING WT 975 lbHOOK BK HT _4 ft HOOK BK WT 2,250 lbLIFT HEIGHT 126 ft ADDITIONAL WT 0 LIFT HEIGHT 126 ft ADDITIONAL WT 0 TOTAL HT 156 ft TOTAL WT 38,425lbCRANE SIZE 200 tnOPERATING RAD. 40 ftBOOM HEIGHT 183 ftBOOM LENGTH 180 ftBOOM ANGLE 78.3