Mobile 3 Principles Of Operation

Question 1

On what principle are cranes able to lift heavy loads ?

Answer 1

Leverage

Question 2

In simple terms how would a crane remain stable and safely lift/move a load ?

Answer 2

By having greater leverage than the load

Question 3

Define centre of gravity

Answer 3

The point relative to a body around which it’s weight is evenly distributed

Question 4

Give two examples necessary for a stable centre of gravity when picking

Answer 4

If the cranes hook is directly over the COG

if the COG is below the attachment points

Question 5

Where will a loads COG always attempt to position itself when lifting

Answer 5

Directly under the hook

Question 6

Name the three parts of a class one lever

Answer 6

Effort

Pivot

Load

Question 7

Name the three parts of a class 3 lever

Answer 7

Fulcrum

Force

Load

Question 8

Name the percentage tipping capacity’s are de rated on crawler
Mobile/rt on outrigger and tire and boom trucks

Answer 8

Crawler 75%

Mobile/RT

Outriggers 85%

Rubber 75%

Boom truck 85%

Question 9

What is the tipping load utilization for us standard and din 15019

Answer 9

US standard 85%

Din 15019 75%

Question 10

What is the formula for a class one lever

Answer 10

WxD = WxD

Question 11

How would you convert a tipping load to a rated load or GC

Answer 11

Depending on the machine times by .85 or .75

Question 12

What is the formula for a class 3 lever

Answer 12

F1xD1 = F2xD2

Question 13

Does a cranes centre of gravity change during rotation ?

Answer 13

Yes

Question 14

Does leverage change during rotation

Answer 14

Yes

Question 15

What is backwards stability

Answer 15

The cranes resistance to tipping in the backwards direction

Question 16

Define a static load

Answer 16

The weight of the gross load when the load is stationary

Question 17

Dynamic loading is caused by the sudden change in speed of the lift and attachment

Give three examples

Answer 17

Sudden stopping

Snatching the load

Swingout

Question 18

Give examples of duty cycle operations and what is a common manufactures reduction

Answer 18

High speed steel erection

Concrete placement

Dragline

Grapple

Clamshell

20%

Question 19

When a jib is erected but not in use could the effective weight be lower than the actual weight ?

Answer 19

No but it may be higher

Question 20

Is the effective weight of a stowed jib higher or lower than its actual weight

Answer 20

Lower

Question 21

What are the three types of failure caused by overloading

Answer 21

Structural

Tipping

Mechanical

Question 22

If structural damage occurs is it visible

Answer 22

Not always cranes can weaken and fail within capacity down the road

Question 23

When does tipping failure occur and give 4 examples

Answer 23

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

Question 24

Give 4 examples of mechanical failure

Answer 24

Winch

Valves

Lmi

Pumps

Question 25

At 3 degrees out of level what is the biggest loss of capacity and its boom configuration/radius

Answer 25

50 %

Long boom minimum radius

Question 26

At 3 degree out of level what is the second highest loss of capacity and its boom configuration/radius

Answer 26

30%

Short boom min radius

Question 27

If the crane is position on a slope what can happen to the radius when you face downhill

Answer 27

It increases

Question 28

When is much of the load displaced into the boom cylinder

Answer 28

At high angles

Question 29

When would the load cause bending strain on the boom

Answer 29

At low angles

Question 30

With winds on the back of the boom would your load weight read higher or lower

Answer 30

Higher

Question 31

With wind on the front of the boom would your load read higher or lower

Answer 31

Lower

Question 32

What are the four quadrants of operation for a crawler

Answer 32

Over the drive end

Over the idler end

Side

Side