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Key
Concepts:
- Considerations for proper crane selection and the various types of
mobile cranes used in construction.
- Factors that affect stability, capacity and the proper set-up of mobile
cranes.
Considerations:
- The weights, dimensions and lift radii expected.
- The type of lifting to be done.
- Serviceability of the equipment.
- The site conditions.
Recommendations:
- Be capable of making all its lifts in its standard configuration.
- 5% working margin.
- Crawler Cranes
- Locomotive Cranes
- Wheel-Mounted Cranes (Multiple Control Stations)
- Wheel-Mounted Cranes (Single Control Stations)
- Commercial Truck-Mounted Cranes
- When selecting a mobile crane, what are some things that its size
and characteristics must be considered against.
- Name four (4) different types of cranes used in the industry.
Jobsite Conditions:
- Supporting Surfaces
- Access & Stability (transporting a crane)
- Working area
Assembly Hazards:
- Lattice Boom Assembly & Disassembly
- Reeving the load line
- Leveling the crane
- Soil Conditions must be sufficient.
- Blocking & Cribbing should be used.
VIOLATION
1. Spreads out the load so the supporting surface can support it.
2.Transmits the load without bending or breaking.
Method 1
Area of float (in square feet) x 3 = Blocking area (in square feet)
Method 2
Capacity of crane (in tons) / 5 = Blocking area (in square feet)
VIOLATION
Transmitting the Load - Properly placed with no gaps or spaces between pieces.
Transmitting the Load; must always be level.
Transmitting the Load; must always be stable and never block under outrigger
beams inside the floats.
WRONG
VIOLATION
- Usually made of hardwood.
- Through bolted together
- 8 - 12 inches thick.
If soil conditions are poor enough to require mats, the input of a soil
engineer may be needed. Do not make any assumptions.
Recommended Safe Work Practice: Affected Zone
Be
aware of existing underground
utilities and backfill. |
Affected
Zone (Depth x 1.5) *Average Soil Only |
Check for these problems and conditions:
- Compact and traction of surfaces
- Overhead clearance
- Tight turns
- Bridge capacities
- Weight laws
- Special permits needed
- Follow all manufacturer's recommendations and ensure crew is qualified
and competent to make decisions.
ANSI requires that hook balls and blocks be lashed or secured during transit.
- Site allows for full extension of outriggers or crawlers.
- Minimum clearance of 2 feet from all objects for counterweight.
- Must be level within manufacturer's specifications.
- Notification to the Federal Aviation Administration may be required.
- Advisory Circular 70/7460-2K, Proposed Construction or Alteration
of Objects that May Affect the Navigable Airspace.
- Form 7460-1 must be filed as early as possible but not less than
30 days before construction begins.
Manual of Uniform Traffic Control Devices
- Signs
- Barricades
- Trained Signal Persons
MUTCD is published by the Federal Highway Administration (FHWA) under 23
Code of Federal Regulations (CFR), Part 655, Subpart F.
The following precautions
shall be taken when necessary to dissipate induced voltages:
- Electrical ground
directly to the upper rotating supporting the boom.
- Ground jumper
cables.
- Combustible and
flammable material shall be removed from the immediate area..
- Area must be
level, firm and large enough to allow room to lay out boom.
- Read and understand
manufacturer's instructions (before assembly).
- Sufficient blocking
must be available.
- Proper tools
available, including ladders.
WRONG - never work under
the boom
Follow manufacturers' specifications on boom assembly and disassembly.
Boom must be secured
against collapse when working inside.
Operator is familiar
with following terms:
- Available line
pull
- Allowable line
pull or Safe Working Load (SWL)
- Total Load
- Friction Loss
Side loading the hoist
block.
- Matching the
load line with sheaves.
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Properly
matched rope and sheave
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Rope
is too large, will pinch
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Rope
is too small, will flatten
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Should not rely on manufacturer's
supplied level.
Determine if the ball
is hanging parallel to the boom.
Use a 4 foot carpenter's
level on a sturdy part of the crane.
Poor ground conditions.
Not level.
- Before attempting
to set up the crane, the employer should review the work to be done,
plan the entire operation and check the following three (3) site conditions.
- The use of blocking
or cribbing performs what two (2) important functions?
- What are four
(4) considerations when placing blocking or cribbing?
- What are three
(3) considerations when determining the access and usability of cranes
to the job site?
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