Lecture 3- Excavation equipment

Question 1

What is the main use of excavators?

Answer 1

To place materials from point A to point B

Question 2

What is struck capacity?

Answer 2

The actual volume enclosed by the bucket with no allowance for the bucket teeth

Question 3

What is heaped capacity/volume?

Answer 3

Loose condition. The max volume in the bucket without spillage is based on the material’s angle response.

Question 4

What is a hydraulic excavator (hoes) mainly used for?
Photo is available at slide #6

Answer 4

Trenching work and other trenching functions. Laying pipe bedding, trenching functions, pulling trench shields, and backfilling (mainly ground level)

Question 5

What is the excavator production formula?

Answer 5

Production (Loose material/h) = B x C x E x S x V (BCEE x Sushiville (S&V))
B = Bucket fill factor
C = Cycles/h
E = Job efficiency
S = Swing depth factor
V = Heaped bucket volume (comes from the manufacturer)

Question 6

Criteria for selecting the proper excavator:

Answer 6

1) Max digging depth
2) Working radius (digging reach)
3) Dumping height

Question 7

What not to do with the bucket?

Answer 7

Use it as a sledge in attempting to fracture rock

Question 8

What can sufficiently loose rocks?

Answer 8

Light blasting, ripping or power hammer.

Question 9

In shovels, digging action is a combination of what forces?

Answer 9

Crowding force (stick cylinder) and breakout force (bucket cylinder)

Question 10

True or false: Shovels are the most efficient when digging below track level.

Answer 10

False. Shovels have limited ability to dig below track level but are most efficient when digging above track level.

Question 11

True or False: Shovels form its own roadway as it advances

Answer 11

True

Question 12

Compare the advantages and disadvantages of bottom dump bucket and front dump bucket in shovels

Answer 12

Bottom - More Versatile, greater reach & dump clearance. Less spillage but it is heavier than front dump buckets, which results in lower bucket capacity

Front - Less maintance, slight production disadvantage and less costly (maybe)

Question 13

What are the two major factors to control shovel production? Job management

Answer 13

1) Swing angle - ideally it should be kept to a minimum
2) Lost time during the production cycle: Haul trucks must be positioned to minimize the time lost as entering and exiting the loading position

Question 14

Explain what dragline is used for:

Answer 14

• A versatile machine to dig from above the machine level to significant depth in soft to medium-hard material
• Due to a lack of lateral control, the bucket may bounce or move sideways and spillage may occur

Question 15

True or false: Skilled operators should use bigger haul units in dragline compared to a shovel with a similar size

Answer 15

Facts

Question 16

Dragline: True or false.
Max production is obtained with a maximum swing angle

Answer 16

False
Max production is obtained with a MINIMUM swing angle.

Question 17

Dragline: What is the most efficient digging area?

Answer 17

15 degrees forward and back of the vertical line thought the boom point

Question 18

Dragline: What are the advantages of
using light bucket?

Answer 18

It will increase the allowable bucket size and reduce cycle time

Question 19

Dragline: What is the most efficient digging area?

Answer 19

15 degrees forward and back of the vertical line through the boom point

Question 20

What is the dragline production formula

Answer 20

Ideal output (table) x Swing depth (2 tables) x Efficiency
(ESO-efficiency, swing, output)
* Don’t forget to convert to LCY using the load factor

Question 21

Add the purpose of each tool (hydraulic excavators from the book)

Answer 21

page 7 in the slides. or at 1:50 in the video

Question 22

True or false: Using the back bucket to loosen up material will cause harm to the bucket and shorten its lifespan

Answer 22

True

Question 23

Explain what approach is best suitable for (frontal & parallel)

Answer 23

Frontal - Best for hard materials (mining operation)
Parallel - Good for limited spaces (highways)

Question 24

Draglines: Explain why dragline could have more spillage than a shovel

Answer 24

Due to a lack of lateral control, the bucket may bounce or move sideways during hard digging, which will create more spillage

Question 25

What are the two types of crane families

Answer 25

1. Mobile cranes - machine of use in NA
2. Tower crane - Became more popular since the 2000’s even for mid rise construction

Question 26

When the tower cranes the machine of choice

Answer 26

1. Site conditions are restrictive
2. Lift height and reach are great
3. There is no need for mobility
4. Noise limits are imposed (Very quiet)

Question 27

Explain what a top-slewing (fixed tower) is
Fits what construction.? Piles length?

Answer 27

partly stabilized at its base (by ballasts) and assembled from modular lattice-type sections. Can reach great heights, and fits mid-rise construction.
Pillings cannot be over 70 ft.

Question 28

Explain what a Bottom-slewing (slewing tower) is

Answer 28

with foldable or telescopic tubular mast, both the tower and jib assembly rotate to the base chassis. Ideal for low buildings. Can often be towed between job sites.

Question 29

Cranes: Bottom vs top-slewing.
1) How long does the setup of each take
2) Which one requires assistance?
3) Which one is mobile, and which one if fixed?

Answer 29

1) Bottom slewing can be built single-handedly, taking up to a few hours while top-slewing takes 1-7 days.
2) Only top-slewing requires assistance
3) Bottom slewing is mobile, top-slewing is fixed (usually)

Question 30

What are the most important factors to be considered when selecting a tower crane?

Answer 30

1. Operating radius (reach)
2. Lifting capacity
3. Lifting speed

Question 31

What is the main disadvantage of setting a crane on rails?
Advantages?

Answer 31

Dis: Space. Takes 13-27 ft and always requires this area to be empty/clean.
Adv: More economical option than dismantling and reassembly.

Question 32

What are the properties of a travelling tower crane?

Answer 32

Max grade is not usually more than 1%
Max height for top-slewing: 230ft, bottom slewing 100ft.
Speed: 65 to 100ft./min

Question 33

What are the advantages and disadvantages of using the elevator shaft for a crane setup?

Answer 33

1) No pre-strengthening is required
2) No temporary sharing
3) No openings are left

Dis:
1) Bring delay in elevator assembly
2) May limit the choice of forming system for the shaft

Question 34

How is a crane disassembled at the end of the construction?

Answer 34

1. Mobile Cranes, if the height is reachable.
2. Derrick (a lifting Device temporarily installed on the finished rooftop)
3. The use of a Helicopter

Question 35

What applied to the computed weight?

Answer 35

5% working margin

Question 36

Generally, what type is applied for the radius of below 90 ft and over 90 ft?

Answer 36

Usually, below a radius of 90 ft we use a four-part line, above 90 ft we use the two-part line.

Question 37

What factors must be considered for safe rigging?

Answer 37

1) weight
2) Center of graivty
3) Stresses
4) Motion of the load

Question 38

What are the 4 safety categories for crane operation?

Answer 38

1) Human factor - The competence and experience of the operator, slinger (rigger), signaler, & lift director

2) Project factor - Presence of powerlines, site congestion, crane’s oversailing, inside cab conditions

3) Environmental factors - Winds, severe temperature, visibility difficulties

4) Safety mgmt. factor: Site level safety, maintenance mgmt. of the cranes & lifting accessories

Question 39

Based on what parameters the lifting capacity is provided for a hydraulic excavator?

Answer 39

1. Distance - from the center of gravity of the load to the axis of rotation
2. Height of the bucket lift point above the bottom of the tracks