Chapter 17 Cranes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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 Outriggers These are truck cranes that have a self-contained telescoping boom

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: Low rise structures – short 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) Working around fixed objects Site conditions (position, locations) Vertical reach requirements

SUITABILITY HEAVY PROJECTS: Very precise (one time hoists) Heavy loads (possibly dual hoists) High speed/high volume operations (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% Load dropped 14% Boom collapsed 12% Two-block 5%

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

CRANE ACCIDENTS Overturning 61.0%

CRANE ACCIDENTS Plan the work 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 Hook Block Height 2 ft Sling Height 6 ft 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 2 ft Sling 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 drive end (back) Over the Side Over the idler end (front)

RADIUS DEFINITION Over the drive end (back) Over the Side Over the idler end (front)

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

Over the side Over the front L C Over the rear 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 Load superstructure Short distance Load distance

STABILITY Short distance Load distance

LEVERAGE

MAXIMUM LOAD Cranes may fail by two different mechanisms: Stability Table 17.2 loads appearing below the solid line. Structural capacity

LOAD CHART Load charts usually specify the boom and boom top for the load ratings, examples: Boom No. 22A or No. 22C with open throat top. 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) Proper use of outriggers Ground conditions 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 (35,200 lb + 3,225 lb) DEDUCTIONS: 3,225 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 ADDITIONAL WT 0 TOTAL HT 156 ft TOTAL WT 38,425lb CRANE SIZE 200 tn OPERATING RAD. 40 ft BOOM HEIGHT 183 ft BOOM LENGTH 180 ft BOOM ANGLE 78.3º