Mobile 3 Principles Of Operation Flashcards
On what principle are cranes able to lift heavy loads ?
Leverage
In simple terms how would a crane remain stable and safely lift/move a load ?
By having greater leverage than the load
Define centre of gravity
The point relative to a body around which it’s weight is evenly distributed
Give two examples necessary for a stable centre of gravity when picking
If the cranes hook is directly over the COG
if the COG is below the attachment points
Where will a loads COG always attempt to position itself when lifting
Directly under the hook
Name the three parts of a class one lever
Effort
Pivot
Load
Name the three parts of a class 3 lever
Fulcrum
Force
Load
Name the percentage tipping capacity’s are de rated on crawler
Mobile/rt on outrigger and tire and boom trucks
Crawler 75%
Mobile/RT
Outriggers 85%
Rubber 75%
Boom truck 85%
What is the tipping load utilization for us standard and din 15019
US standard 85%
Din 15019 75%
What is the formula for a class one lever
WxD = WxD
How would you convert a tipping load to a rated load or GC
Depending on the machine times by .85 or .75
What is the formula for a class 3 lever
F1xD1 = F2xD2
Does a cranes centre of gravity change during rotation ?
Yes
Does leverage change during rotation
Yes
What is backwards stability
The cranes resistance to tipping in the backwards direction
Define a static load
The weight of the gross load when the load is stationary
Dynamic loading is caused by the sudden change in speed of the lift and attachment
Give three examples
Sudden stopping
Snatching the load
Swingout
Give examples of duty cycle operations and what is a common manufactures reduction
High speed steel erection
Concrete placement
Dragline
Grapple
Clamshell
20%
When a jib is erected but not in use could the effective weight be lower than the actual weight ?
No but it may be higher
Is the effective weight of a stowed jib higher or lower than its actual weight
Lower
What are the three types of failure caused by overloading
Structural
Tipping
Mechanical
If structural damage occurs is it visible
Not always cranes can weaken and fail within capacity down the road
When does tipping failure occur and give 4 examples
Occurs when the loads leverage outweighs the cranes leverage
Exceeding load chart
Booming down to increase radius
Extending boom to increase radius
Crane not level or comes out of level
Give 4 examples of mechanical failure
Winch
Valves
Lmi
Pumps
At 3 degrees out of level what is the biggest loss of capacity and its boom configuration/radius
50 %
Long boom minimum radius
At 3 degree out of level what is the second highest loss of capacity and its boom configuration/radius
30%
Short boom min radius
If the crane is position on a slope what can happen to the radius when you face downhill
It increases
When is much of the load displaced into the boom cylinder
At high angles
When would the load cause bending strain on the boom
At low angles
With winds on the back of the boom would your load weight read higher or lower
Higher
With wind on the front of the boom would your load read higher or lower
Lower
What are the four quadrants of operation for a crawler
Over the drive end
Over the idler end
Side
Side
