Shared Flashcard Set

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Crane Theory
Crane and hoist
66
Engineering
Not Applicable
12/03/2015

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Cards

Term
Outriggers are only to be used in special circumstances
True/False?
Definition
False
Term
A crane is designed to pick up the same load in all 4 quadrants
True/False?
Definition
False
Term
Blocks under outrigger floats should be.....
Times the area of outriggers
Definition
3 times
Term
Load charts are charts that give the cranes gross capacity under various conditions and situations
True/False?
Definition
True
Term
A cranes leverage is equal to the crane weight times the horizontal distance from its tipping axis to its centre of gravity
True/False?
Definition
True
Term
The loads leverage is equal to the load weight times the horizontal distance from its tipping axis to to the loads centre of gravity
True/False?
Definition
True
Term
A mobile crane is stable when the loads leverage exceeds the cranes leverage
True/False?
Definition
False
Term
A cranes centre of gravity changes as the upper works rotates
True/False?
Definition
True
Term
A cranes capacity changes when it upper works move from quadrant to quadrant
True/False?
Definition
True
Term
A cranes capacity increases as the boom telescopes out
True/False?
Definition
False
Term
Overloading a crane can cause:
Definition
Tipping and structural failure
Term
Important considerations before making a lift include:
Definition
Radius
Quadrants load will be rotated through
Loads weight
Wind speed and direction,
Load placement
Term
A loads chart is not crane specific
True/False?
Definition
False
Term
When using the load chart you must know?
Definition
Config of crane
Quadrants of operation
Boom length
Boom angle
Load radius
Weight of line,block,ball,etc
Term
A crane config includes:
Definition
Use of outriggers
Job or boom extensions
Term
The four quadrants are:
Definition
Over the front
Over the rear
Over the sides
Term
AT's capacity can vary from:?
Definition
30t to 1200t
Term
AT's boom length can vary from:?
Definition
30-100M
Term
AT's ability to resist tipping forward
On outriggers:
On tires:?
Definition
Outriggers 85%
Tires 75%
Term
RT's ability to resist tipping forward
On outriggers:
On tires:?
Definition
Outriggers 85%
Tires 75%
Term
Boom trucks ability to resist tipping forward
On outriggers:?
Definition
On outriggers 85%
Term
Crawler cranes ability to resist tipping forward
Definition
75%
Term
What is static load?
Definition
Stationary load under hook
Term
Dynamic load?
Definition
Loads change in motion
Ex. Sudden stoping,
Snatching the load
Term
Most blocks on cranes are?
Definition
Laced
Term
If a block is reeved 6 parts, it's a mechanical advantage of
Definition
6:1
Term
Sheave diameter rule of thumb
D/d
Definition
20:1
Term
Crane blocks have what on the sides to help down haul the block when unloaded
Definition
Weights
Term
If a block has a mechanical advantage of 6:1
The lead line will travel
Definition
6ft for every 1ft the load is lifted and will travel 6 times as fast
Term
The relationship between a rope sheave and friction is called?
Definition
Efficiency and usually expressed in %
Term
How to calculate lead line pull?
Definition
Weight of load divided by chart ratio= lead line pull
Term
Friction loss for
Roller bearings:
Bronze bushings:
Bronze bushed fibre rope
Definition
3%
5%
10%
Term
Calculate maximum load
Definition
WLL multiplied by Ratio=
Maximum load
Term
Determine parts of line required using ratio chart
Definition
D2 times 45 divided by 5= WLL
For IWRC
Total weight of load divided by chart ratio=
Parts of line
Term
When both blocks have the same # of sheaves the becket is attached to?
Definition
The stationary block
Term
When the # of sheaves varies the becket is attached to?
Definition
The traveling block
Term
The most popular methods of reeving are:
Definition
Lacing
Skip reeving
Square reeving
Term
Lacing advantages:
Definition
It's easy to reeve
Blocks pull close together
No reverse bends
Term
Lacing disadvantages
Definition
Rope and sheave speed is faster on one side
Blocks tilt together on one end
Blocks rotate and lines twist together
Term
Skip reeving
Advantages
Definition
Line speed is balanced
Blocks remain more level
Term
Skip reeving
Disadvantages
Definition
2 reverse bends
Term
Square reeving
Advantages
Definition
Blocks are balanced
Blocks run smooth and level
Term
Square reeving
Disadvantages
Definition
The blocks can not be brought close together, this will cause the wire rope to come off the sheaves
Wire rope continually goes through reverse
Bending, this can cause premature fatigue
Term
When is the most weight transferred to the lead crane on a tailing lift
Definition
80-90degres
Term
Load block positions
Definition
A= NC2 divided by NC1 multiplied by B

B= NC1 divided by NC2 multiplied by A
Term
Load on crane one

Load on crane 2
Definition
Nc1
B divided by A+B multiplied by load weight

Nc2
A divided by A+B multiplied by load weight
Term
Weight shift
Definition
Crane one
Crane 2 touch down first

C+D divided by B+C+D multiplied by load weight
Term
What is the number 1 cause of crane accidents?
Definition
Improper setup
Term
Equalizer beams do what?
Definition
Distribute weight of load to 2 cranes
Term
By adjusting the crane and or attachment points on the beam it is possible to share the load in any proportion desired
T/F
Definition
True
Term
Disadvantages of a EQ beam
Definition
Limited rotation
Communication and signalling requires a higher degree of planning and ability
Term
The greatest transfer of load share from the tailing crane to the lead crane occurs when the load is?
Definition
80-90* from the horizontal
Term
When 2 or more cranes are used to lift one load one -------- person shall be responsible for the operation
Definition
Competent person
Term
Who is allowed to deviate from the lift plan?
Definition
Nobody
Term
Is a lift plan necessary for a multi crane lift?
Definition
Yes
Term
What could happen if the cranes are not synchronized when making the lift?
Definition
The weight can transfer
Term
When operating the crane you should operate it ---------- & ---------
Definition
Slowly and smoothly
Term
Why is there a rule for 75% on multi crane lift?
Definition
Allow for a safety margin
Term
Boom torque is due to what
Definition
Block not centred on the boom
Term
What % of injuries happen when getting on and off the machine?
Definition
20%
Term
The outriggers are the fulcrum point for the crane
T/F
Definition
True
Term
At high boom angles much of the load is on
Definition
The boom cylinders
Term
The highest loss of capacity when out of level occurs when
Definition
Long boom minimum radius
Term
For high speed duty cycle operations most crane manufacturers reduce the load chart by
Definition
20%
Term
What must you be aware of when using a crane on retracted outriggers
Definition
Backwards stability
Term
The sweep area is defined as
Definition
The total area the crane can swing over
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