Mechanization of the process

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L E CTU R E 4
MECHANIZATION OF THE PROCESS

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§2.4 MECHANIZATION OF THE PROCESS
Machines organized by what they do
Machines involved in the complex technological process fall into five functional groups, depending on which operations they carry out:
Excavating
Earthmoving-transport
Transporting
Soil-compacting
Drilling
Single-bucket & continuous-action
excavators
Bulldozers, scrapers, graders,
grader-elevators, rippers
Dump trucks, earth-hauling carts,
conveyors, soil throwers
Rollers, tampers, vibratory
machines, and others
Machines for boring holes into the
ground
THREE LEVELS OF MECHANIZATION
Partial mechanization
Complex mechanization
Automation
Machines carry out only some of the individual processes.
Machines carry out all processes — preparatory, auxiliary, and
main.
Under complex mechanization, automatic machines also take
over control and supervision of the running processes, not just
production itself.
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3.

§2.4 MECHANIZATION OF THE PROCESS
Matching a machine to the soil's difficulty group
• Soils are ranked into difficulty groups for mechanized earthwork under the Unified Norms
and Rates (ENiR) for construction. The main sorting criterion is average density — the same
soil can land in different groups depending on which machine is digging it.
• The norms cover soils at their natural moisture content — not soil currently under the direct
action of groundwater, running water, or rain.
SINGLE-BUCKET EXCAVATORS
Dig soil difficulty Groups I–IV, plus mottled moraine clays of Group
V with no pre-ripping needed.
Groups V–VI (other than mottled moraine clays) must be preripped first.
Broken-up lump size after ripping must not exceed 1/3 of the
bucket width.
Continuous-action excavators may take stones up to bucket
capacity, or up to the height of their cutting element — but only if
the hard inclusions are no larger than about 1/4 of the bucket
width, or 1/3 of the cutting-element height.
• Continuous-action excavators work soils only up to difficulty Group III.
• Bulldozers handle thawed soil, and rock-frozen soil once it has been pre-ripped; by difficulty
they are graded into Groups I, II and III.
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§2.4.1 SIN GLE -BUCKET EXCAVATORS
One base machine, many working attachments
• Single-bucket excavators are cyclic-action, soil-excavating machines whose main working element is a toothed bucket, built to dig soils under a wide range
of site conditions.
• There are more than 700 excavator model names on the market, spanning about 400 distinct types.
EXCAVATORS ARE CLASSIFIED BY
Suspension type
Undercarriage
rigid, articulated-lever, or cable
wheeled, crawler, or walking
Working attachment
Drive
straight shovel, backhoe, dragline, grab, crane, pile driver, and more
cable or hydraulic — hydraulic machines use articulated-lever or telescopic gear, with quickchange attachment couplers
Rotation
full-slew or partial-slew turntable
The base machine of a single-bucket excavator can run different working attachments; the digging attachment is the primary one, and any attachment for other operations is a secondary one.
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§2.4.1 SIN GLE-BUCKET EXCAVATORS
Reading an excavator's model index
EXAMPLE: EO-5123XL
EO — universal single-bucket excavator
5 — size group 5
1 — crawler undercarriage
2 — rigid-suspension attachment
3 — 3rd model in this line
XL — northern climate version
This machine carries a standard 1.0 m³ bucket — the capacity matching size
group 5 — with 1.25 m³ and 1.6 m³ buckets available as swaps.
Undercarriage codes 1–9: 1 crawler (Г), 2 wide-track crawler (ГУ), 3 pneumatic-tire (П), 4
special truck chassis (СШ), 5 truck chassis (А), 6 tractor chassis (Тр), 7 trailed (Пр), 8–9
reserved.
Fig. 24. The excavator indexing system: ЭО stands for “universal single-bucket excavator”; the four digits give size group,
undercarriage type, attachment mounting, and model number.
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§2.4.1 SIN GLE -BUCKET EXCAVATORS
Bucket capacity by size group
Current production spans size groups 3 through 6. An excavator's overall size is set by its mass and its engine's power.
Size group
Main-bucket capacity, m³
2nd
3rd
4th
5th
6th
7th
0.25–0.28
0.40–0.65
0.65–1.00
1.00–1.60
1.60–2.50
2.50–4.00
Serially produced excavators of size groups 3–6 cover the great majority of general construction earthwork; larger groups 7–8 are reserved for quarry and heavy civil work.
Leading manufacturers. Domestic: KZTM “Krastyazhmash”, OMZ / UralMashIzhora, VEKS, Kovrov, SarExsOAO, TVEKS, ATLAS-TEREX, EXSKO. International: Komatsu, Caterpillar, Volvo,
Mitachi, Daewoo, and others.
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§2.4.1 WORKING ATTACHMENTS
Straight shovel: digging above the excavator's own level
The straight shovel (прямая лопата) is the primary attachment for digging soil above the level
where the excavator itself stands.
The bucket is hinged to the arm (рукоять), which is in turn hinged to the boom (стрела), and the
boom is hinged to the turntable.
On hydraulic machines the bucket is free to pivot on the arm — a hydraulic cylinder tips it to
discharge. On cable machines the bucket's position relative to the arm stays fixed; it discharges by
opening its own bottom, and always digs away from the excavator.
It delivers the highest digging force and the highest output of any attachment, thanks to the fewest
operations per digging cycle — ideal for mineral extraction, loading work, and deep-pit excavation.
Fig. 25. A quarry excavator with a straight shovel and cable drive.
Highest
digging force & output of any working attachment
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§2.4.1 WORKING ATTACHMENTS
The straight-shovel digging cycle
1
2
3
4
Load the bucket
Slew the turntable
Raise the boom
Discharge the bucket
The arm swings relative to the boom, cutting
and filling the bucket; bucket-to-arm and
boom-to-machine geometry stay fixed.
Once loaded, the turntable slews the whole
attachment; the bucket carries to the
discharge point without changing position
on the arm.
The boom lifts just before discharge, to gain
dumping height over the truck bed or spoil
pile.
Hydraulic machines tip the bucket on the
arm; cable machines open the bucket's
bottom door.
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§2.4.1 WORKING ATTACHMENTS
Backhoe: digging below the excavator's own level
• The backhoe (обратная лопата) is the primary attachment for digging soil below the
level where the excavator stands.
• It is used to dig pits and trenches, grade slopes, and place fill — and can also do loading
work.
• When digging with a backhoe, soil is cut toward the excavator, not away from it.
• Hydraulic backhoe excavators can also dig above their own standing level, though less
efficiently than a straight shovel.
• It is the most versatile working attachment: it positions the bucket precisely relative to
both the ground and the hauling vehicle being loaded.
Fig. 26. An excavator fitted with a backhoe attachment.
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§2.4.1 WORKING ATTACHMENTS
The backhoe cycle depends on how it is driven
HYDRAULIC — independent boom, arm & bucket drives
MECHANICAL — two-cable drive, fixed arm position, fixed bucket
position
Plunge the boom into the pit while positioning the arm
Plunge boom and arm into the pit by paying out the hoist cable
Load the bucket by pivoting it relative to the arm
Load the bucket by pivoting the arm toward the excavator, tensioning the drag
cable while the hoist cable is locked
Lift the boom while rotating both arm and bucket, to keep soil from spilling
Slew the turntable with the loaded attachment
Lift boom and arm out of the pit by tensioning the hoist cable while the drag cable
is locked
Discharge the bucket by pivoting it relative to the arm
Slew the turntable with the loaded attachment
Discharge by pivoting the arm away from the excavator, tensioning the hoist cable
while paying out the drag cable
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§2.4.1 WORKING ATTACHMENTS
Dragline and grab: cable-hung buckets
Fig. 27. Dragline: a bucket hung freely on cables.
Digs soil below the excavator's standing level, cutting toward the machine, with the largest
digging radius, depth, and dumping height of any attachment.
The base excavator needs no re-equipping to run a dragline.
Used for deep pits, spoil-pile placement, mineral extraction, and dredging work under
water.
TECHNOLOGY OF CONSTRUCTION PRODUCTION · CH. 2 EARTHWORK PROCESS DESIGN
Fig. 28. Two-jaw grab (clamshell).
Used for narrow, deep pits and shafts, and for loading and unloading loose bulk materials.
On hydraulic excavators it can mount on a telescopic boom for pit depths of 6 m or more;
on cable machines it hangs on ropes, and its digging force comes from its own weight or a
hydraulic clamp drive.
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12.

§2.4.1 WORKING ATTACHMENTS
Over 40 attachments turn one base machine into many
A crane hook lets the excavator handle lifting and rigging work.
A pile-driving mast turns it into a pile driver.
A hydraulic hammer replaces the backhoe bucket for ripping hard or frozen
ground.
A ripper attachment cuts slots for blasting or trims final grades.
A slope-trimming (planning) attachment finishes cut and fill faces.
Any working equipment built from straight-shovel or backhoe parts is called
“universal” equipment.
Fig. 29. Interchangeable excavator attachments: a straight shovel; b backhoe; v dragline; g grab; d crane; e pile
driver; zh ripper (scarifier); z slope trimmer; i ground ripper.
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§2.4.2 EXCAV ATING WITH SINGLE -BUCKET MACHINES
Nine ways to work a pit
TECHNOLOGY OF CONSTRUCTION PRODUCTION · CH. 2 EARTHWORK PROCESS DESIGN
The excavator's working area is called the face (забой); its size depends on the
excavator model, the transport used, and the chosen digging scheme.
In a frontal cut the excavator digs straight ahead of itself, loading trucks fed in
from behind on either side of the travel line.
In a side cut it digs to one side of its travel line only, with trucks fed from the
other side.
A backhoe or dragline working an end-on face travels along the axis of the
trench or pit it is opening, and the resulting pit is dug “toward” the machine.
Deep cuts are worked in several benches (ярус), each bench height equal to
that excavator's face height; a dragline’s shuttle scheme keeps its slewing angle
to a minimum.
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14.

§2.4.3 EART HMOVING -TRANSPORT MACHINES
Scrapers: cut, haul, spread — in one pass
• Earthmoving-transport machines dig soil, move it, dump it into a fill or spoil pile, and
return empty, all in a single cycle. The main machines in this class are scrapers, bulldozers,
and graders.
• Scrapers are the highest-output machines in this class — used for excavating pits, grading
surfaces, building dams and dikes, and stripping overburden.
• The scraper's working element is a bucket with a cutting edge at the front, built to cut soil
in layers, haul it, spread it in layers, and partly compact soils of difficulty Groups I–IV as it
discharges.
• Scrapers work best on medium, only lightly moist soils — sandy loam, loam, chernozem
— free of large stones.
Fig. 31. Scrapers: a — trailed (1 tractor, 2 frame, 3 tailgate, 4 bucket, 5–6 blades, 7 apron); v — selfpropelled two-axle (1 tractor unit, 2 fifth-wheel hitch, 3 draw frame, 4 bucket with apron).
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§2.4.3 EART HMOVING -TRANSPORT MACHINES
Scraper capacity and how it discharges
< 5 m³
Small-capacity bucket
5–15 m³
Medium-capacity bucket
> 15 m³
Large-capacity bucket
• The scraper's main parameter is its bucket's geometric capacity, sorting machines into small (under 5 m³), medium (5–15 m³), and large (over 15 m³) classes.
• Trailed scrapers (towed by a separate tractor) carry buckets of 2.25–10 m³; self-propelled scrapers are more capable machines, with buckets of 8 m³ and up, better
maneuverability, and higher travel speed.
• The bucket discharges while the scraper keeps moving, spreading soil in a layer 220–550 mm thick and leveling it in the same pass.
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§2.4.3 EAR T H MOV IN G-TRANSPORT MACHINES
How a scraper cuts and lays out its pass
Fig. 32. Chip shapes cut by a scraper: a constant-thickness; b wedge; v comb; g pinch.
Constant-thickness — a thin, uniform chip, used on any cohesive soil, including stripping topsoil and grading work.
Wedge — chip thickness tapers down steadily as the bucket fills, deepest at the start of the cut.
Comb — alternating plunge-and-lift cuts; thickness varies from 20–30 cm down to 8–12 cm over the pass.
Pinch — repeated, aggressive plunges to the greatest depth possible, then a full withdrawal; used on dry sand and
sandy loam on level or sloped ground.
TECHNOLOGY OF CONSTRUCTION PRODUCTION · CH. 2 EARTHWORK PROCESS DESIGN
Fig. 33. Cutting strips for bucket filling: a strip-to-strip; b through-strip — leapfrogging one strip to lower
cutting resistance in the strips left standing between earlier passes.
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§2.4.3 EART HMOVING -TRANSPORT MACHINES
Six travel patterns for a scraper's work cycle
Fig. 34. a zig-zag; b ellipse; v figure-eight; g
spiral; d shuttle-transverse; e shuttlelongitudinal.
Choosing a route: keep the path as short as possible with
the fewest sharp turns; alternate left and right turns to
wear the machine evenly; size the cut/fill face to allow a
full load-and-dump cycle; and minimize climbs made
both loaded and empty.
Pattern
Max. height/depth,
m
Typical use
Zig-zag
2.5–6
Fills from one- or two-sided borrow ≥200 m long; cuts ≥20 m long, spoil to a stockpile
Ellipse
4–7 / 1–1.5
Fills from one- or two-sided borrow; cross-cut grading work
Figure-eight
4–6 / 1–1.5
One-sided borrow fills or cuts to ≤200 m; grading over a 50–100 m face
Spiral
2–2.5
Wide fills from two-sided borrow, or wide cuts to stockpile
Shuttle-transverse
4–6 / 1–1.5
Two-sided-borrow fills; cuts with spoil split to both sides
Shuttle-longitudinal
4–6
Two-sided borrow with 1:2 slopes, or cuts split to both sides
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§2.4.3 EART HMOVING -TRANSPORT MACHINES
How far a scraper can economically haul
≤ 1000 m
Haul distance, trailed scrapers
≤ 3000 m
Haul distance, self-propelled scrapers
120–320 mm
Cut thickness per scraper pass
• Dense, compact soils must be pre-ripped before a scraper starts work on them.
• The thickness of soil taken off in a single scraper pass depends on the machine's power, and typically runs 120–320 mm.
• These distance limits are why scraper choice — trailed vs. self-propelled — tracks directly with how far the cut is from the fill on a given site.
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§2.4.3 EAR T H MOV IN G-TRANSPORT MACHINES
Bulldozers: the all-purpose earthmover
• Bulldozers are cyclic-action machines built to cut, move, discharge, and place soil.
• They excavate pits under building foundations, work soils of difficulty Groups I–IV in layers and move them, and build road and rail embankments while
cutting through high ground and filling in low ground.
• Bulldozers grade construction sites in forward or reverse travel, spread materials, push scrapers through difficult ground, level soil dumped by other
machines, backfill trenches on pipeline projects, and build dams, dikes, and canals for land-reclamation and hydraulic-engineering work.
• They can also fell trees, grub out stumps, clear brush and scrub, and clear sites of snow, stone, and construction debris.
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§2.4.3 EART HMOVING -TRANSPORT MACHINES
Thirteen jobs, one blade
FIG. 35 — MAIN TYPES OF BULLDOZER WORK
TECHNOLOGY OF CONSTRUCTION PRODUCTION · CH. 2 EARTHWORK PROCESS DESIGN
a — digging pits, trenches & canals, casting spoil to a stockpile or fill
b — cutting a hillside, filling the low ground alongside it
v — stripping topsoil
g / d / e — grading forward, spreading, grading in reverse
zh — backfilling a trench
z — pushing a scraper while it fills its bucket
i / k / l — felling trees, grubbing stumps, clearing brush
m — snow-clearing
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§2.4.3 EART HMOVING -TRANSPORT MACHINES
The bulldozer work cycle
1
2
3
4
Cut the soil
Haul while still cutting
Discharge
Return empty
The blade bites into the ground, building a
wedge of loose material (a soil prism) ahead
of it.
The bulldozer pushes the growing prism
toward the fill, trimming more soil into it
along the way.
The prism is dumped and struck off at the fill
or stockpile.
The blade lifts clear and the machine travels
back to the cut to start again.
SHUTTLE SCHEME (< 50 m)
LOOP SCHEME (≥ 50 m)
The bulldozer returns to the cut in reverse gear — no turnaround needed over such a
short round trip.
The bulldozer turns around and drives forward back to the cut — worthwhile once the
extra travel distance outweighs the time lost turning around.
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§2.4.3 EART HMOVING -TRANSPORT MACHINES
How a bulldozer blade cuts its chip
The blade cuts in layers up to 30 cm thick, using whichever pattern suits the soil's resistance to cutting:
Constant thickness
Wedge (hydraulic or cable blade control)
Comb (hydraulic or cable blade control)
A uniform cut depth throughout the pass — used for
most soil types, and where cutting resistance is
significant.
Depth tapers off through the pass — suited to soils that
resist cutting only lightly.
The blade alternately plunges and lifts along the pass,
for uneven or patchy ground.
45–50°
Optimal cutting angle — moist soils
TECHNOLOGY OF CONSTRUCTION PRODUCTION · CH. 2 EARTHWORK PROCESS DESIGN
60–65°
Optimal cutting angle — dry soils
≤ 30 cm
Maximum layer thickness per pass
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§2.4.3 EAR T H MOV IN G-TRANSPORT MACHINES
Getting more soil per pass
Same-track travel
Trench-cutting method
Paired bulldozers
Downhill cutting
After 2–3 passes on one track, side ridges build
up and cut down how much soil escapes
sideways.
Working inside a shallow trench, its own walls
hold soil in front of the blade, growing the prism.
Two or three machines run side by side, sharing
one soil prism between them — needs careful
coordination.
Working down a slope speeds travel and grows
the prism — useful on sloped ground and in pit
excavation.
Double / triple prism
Optimal cutting angle
Blade extensions / wideners
Time-loss control
A first prism is left mid-route; later passes add a
second, then a third, moving the combined mass
further each time.
45–50° on moist ground, 60–65° on dry ground
— matched to how the soil piles up ahead of the
blade.
Boost output by 20–30% on light soils; openframe attachments add another 10–15% by preripping dense ground.
Keep the machine's utilization rate up: minimize
idle time from poor site organization,
breakdowns, and maintenance stops.
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§2.4.3 EART HMOVING -TRANSPORT MACHINES
Working a deep cut: trench method vs. layer method
TRENCH METHOD
LAYER METHOD
The bulldozer cuts a series of parallel trenches, each 400–500 mm deep, spread
across the excavation's width. Strips of undisturbed soil, 400–600 mm wide, are
left standing between the trenches to guide the blade and are cut away last.
The bulldozer strips the cut in successive full-width layers, working across the
whole excavation — or a section of it — one layer at a time, at the thickness set
by the blade's cutting-chip depth.
Beyond about 40 m of haul, use an intermediate ridge, or pair two bulldozers working together, to cut down on the soil lost off the sides of the blade.
Fill is placed in layers, working outward from the point farthest from the cut.
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§2.4.4 MECHANIZATION FOR COMPACTING SOIL
Compaction: the last step that makes soil trustworthy
• Soil is compacted to give a fill the design density it needs, and to hold down how much — and
how unevenly — foundations and earth structures will settle afterward.
MATCH THE METHOD TO THE SOIL
• Compaction raises a soil's strength and cuts its compressibility and permeability to water.
Cohesive soils (clays, loams, sandy loams) — compacted by
rolling.
Non-cohesive soils (sands, gravels) — compaction by tamping or
vibration is recommended.
• How compacted a soil is gets scored by its compaction coefficient — the ratio of the achieved
(or required) density to that soil's standard maximum density, measured on purpose-built test
equipment.
• Depending on how critical the earth structure is, the target compaction coefficient is set
anywhere from 0.9 to 1.0.
• Soil is always compacted in layers, as it is placed.
TECHNOLOGY OF CONSTRUCTION PRODUCTION · CH. 2 EARTHWORK PROCESS DESIGN
Compaction machines fall into these groups:
Static rollers — smooth-drum, sheepsfoot, or pneumatic-tired
Tamping machines — with rollers, drop-weight rammers
Vibrating machines — vibratory rollers and vibrating plates
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§2.4.4 MECHANIZATION FOR COMPACTING SOIL
Compaction equipment, by the numbers
10–100 t
Pneumatic-tire rollers, mass incl. ballast
≤8t
Self-propelled vibratory rollers
0.4 m
Layer thickness, smooth pneumatic rollers
• A compaction machine's key parameter is its own mass, including ballast — heavier machines compact thicker layers in fewer passes.
• Key technological parameters are the width of the strip a machine compacts per pass, the thickness of the layer it can reach, and how many passes that layer
needs.
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SUMMARY
The earthwork process, start to finish
DESIGN THE EARTHWORK
EXCAVATE IT
MOVE, SHAPE & COMPACT IT
Cuts and fills, permanent and temporary
structures, with their own profiles and
requirements
Single-bucket excavators — shovel, backhoe,
dragline, grab — chosen by digging direction and
depth
Scrapers cut-haul-spread in one pass; bulldozers
cut, push, grade, and clear across 13+ job types
A complex process built from preparatory, main,
and auxiliary operations, sized to the actual site
Matched to the soil's ENiR difficulty group, with
pre-ripping where the ground demands it
Rolling, tamping, or vibration bring the fill to its
required compaction coefficient of 0.9–1.0
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