Determination of the performance of bulldozers and bulldozers-rippers. Bulldozer performance and how to improve it Basic information about bulldozers
When cutting and embanking, it is advisable to use a bulldozer set of equipment if the average range of longitudinal or transverse hauling does not exceed 100 meters. To choose the most optimal model of special equipment, it is necessary to compare the performance of bulldozers with different traction classes and different types of working equipment.
The most promising are machines on pneumatic wheels. Equipment on pneumatic wheels is less in demand. When calculating productivity, it is necessary to take into account the conditions of the area, the nature of the work and other factors.
Bulldozer Basics
Bulldozer is an earth-moving machine for layer-by-layer excavation and transportation of soil, developed on the basis of a caterpillar or pneumatic wheeled tractor with replaceable attachments - a blade (a flat shield with side flaps), a frame and a control mechanism.
Used equipment with fixed and rotary blade. In the first case, the working equipment is located perpendicular to the longitudinal axis, which allows you to move soil masses only in front of the machine. The productivity of bulldozers with a rotary blade is much higher, since such specimens are able to move the soil to the side at an angle of 60 degrees, which allows for rough grading work.
The blade control mechanism can be cable-block and hydraulic. The second type of control is more productive, as it allows forcibly deepening the blade into the ground.
Traction class of machines
With the help of bulldozers, up to 40% of all earthworks on a construction site are carried out. They are most effective at an average range of longitudinal and transverse carriage from 100 to 150 meters. When equipping the machines with special scoop-type dumps, the effective range of hauling sandy soils increases to 200 meters.
The main parameter that affects productivity is the traction class - the force with which the bulldozer can push the soil forward. The technical characteristics of the machines affect the volume of the moved earthen mass, the speed of work. According to this parameter, all bulldozers are divided into three groups:
- Lightweight, the traction force of which does not exceed 60 kN. They are used during preparatory, agricultural and auxiliary work.
- Medium, with a pulling force of 100-150 kN. Used for development 1-3 with preliminary loosening.
- Heavy, the pulling force of which exceeds 250 kN. They are used in the development of dense and hard rocks.
Bulldozers are used in combination with other earthmoving machines. They can be used as pushers for self-propelled and trailed scrapers. Typically, a bulldozer set of equipment includes a rammer and a ripper.
Factors Affecting Performance
When calculating the performance of bulldozers, it is necessary to take into account the physical and mechanical characteristics of the developed earthen massif, as well as local conditions. The main physical and mechanical characteristics of the soil include:
- granulometric composition - the ratio of the sizes of soil particles by weight;
- density - the mass of soil per unit of its volume;
- porosity - the number of voids between the grains, expressed as a percentage by weight;
- plasticity number - the range of moisture in which the soil has plastic properties and does not go into a fluid state;
- swelling - the ability of an earthen mass to increase in volume when waterlogged;
- angle of internal friction - resistance of soil particles to shear.
The local conditions that affect the performance of bulldozers include the nature of the relief and the technological features of the construction site. In a flat and straight area with a minimum range of cross-carriage, the speed of work is much higher than in hilly terrain.
Bulldozer Performance Calculation
The productivity of a bulldozer depends on the type of work performed. It can be excavation and transport or planning work. In the first case, the productivity is expressed in m 3 / h, in the second - m 2 / h. Let us dwell on earthmoving and transport works in more detail.
Operational productivity is determined by the volume of the earthen massif that special equipment is able to develop and move per unit of time, that is, in one hour. The calculation of the performance of the bulldozer is carried out according to the formula
To calculate the performance as close as possible to the real one, correction factors are introduced:
- k y - the influence of the slope of the earthen area. While working on slopes from 5-15%, the value increases from 1.35 to 2.25; when developing the soil on the rise, the coefficient decreases from 0.67 to 0.4;
- k in - value taking into account the time of using the machine (k in = 0.8-0.9);
- k n is the filling factor of the geometric volume of the drawing prism (k n = 0.85-1.05).
To calculate productivity, it is also necessary to know the volume of the drawing prism (V gr) and the duration of the machine's working cycle (T c).
Calculation of the volume of the drawing prism
A characteristic feature of the operation of the machine is the fact that the bulldozer bucket moves the soil in the so-called drag form. In this case, the volume of the prism is calculated by the formula
Here B and H are the length and height of the dump, respectively, k n is the coefficient for taking into account the losses of the earth during its movement, is taken equal to 0.85-1.05, k p is the degree of loosening of the soil.
Cycle duration
To calculate the duration of the working cycle, that is, the time that the tractor-bulldozer will spend on developing one layer of soil, it is necessary to understand that the entire length of the longitudinal or transverse carriage is divided into several segments. The duration itself is calculated by the formula
Here l p , l n and l o = l p + l n are the lengths of the cutting sections, the movement of the soil mass and the reverse motion of special equipment, and v p , v n and v o are the maximum possible speeds in these sections. The coefficient t n takes into account the time that the driver spends shifting gears during work. Usually it is 15-20 seconds.
Bulldozer performance with wedge operation
The use of the wedge digging scheme is possible only with those machines that are equipped with a hydraulic blade control mechanism. Such, for example, is the Shantui SD32 bulldozer. A distinctive feature of this excavation principle is the fact that the cutting force gradually decreases as the drag wedge increases.
At the beginning of work, all the forces of the machine are aimed at immersing the blade into the ground to a maximum depth h max and cutting the earthen mass. As you move, the soil accumulates in front of the bulldozer, which increases the resistance to movement. For further work, the operator must increase the applied traction force or reduce the depth of cut.
Earth chip thickness
Most often, they resort to the second option, but in this case, part of the land is “lost” in the side rollers (which is also bad for the Shantui bulldozer). To compensate for these losses, the machine must cut off the “chips” along the entire path of movement, which is calculated by the formula
Here k p is an amendment that takes into account the loss of soil during transportation, k pr is the drawing prism coefficient, which is taken from the operational characteristics of the machine, L p is the length of the section where the soil is cut. It is defined as the ratio of the volume of the drawing prism to the area of the developed area.
Effect of Blade Type on Productivity
Depending on the characteristics of the soil, as well as on the tasks assigned to the bulldozer, it is advisable to use certain types of dumps. This will shorten the time of work, as well as increase the efficiency of special equipment.
Any machines, including those made in Japan, are equipped with a replaceable blade. Among the main types of working equipment it is worth highlighting:
- reclamation subspecies, which is used to remove the upper fertile layer of the earth, chernozem;
- a variety for moving coal and wood chips - used in the development of minerals, has a hemispherical shape and a hydroperiscope;
- The "peat" variety has a reduced height, but an increased length and is used to enrich agricultural fields;
- dumps for site preparation - brush cutters and uprooters, which are equipped with teeth, are produced in a V-shape and are designed to clear the area from trees and shrubs.
The most progressive (in terms of the possibility of installing various working equipment) is the Japanese Komatsu bulldozer. All models of special equipment can be equipped with any of the blades presented, which gives them high functionality and makes them universal machines for a construction site.
The calculation of the productivity of the bulldozer must be carried out to reduce the cost of earthworks. Based on the data obtained, you can choose the most optimal special equipment for work, reduce the time of work and save a lot of money.
Technical characteristics of some brands of bulldozers are given in table. 2, and performance calculations in formula (1).
Bulldozer performance in excavation and earthmoving
M 3 / h, (1)
where q- the volume of soil moved before the dump, m 3;
t C– full cycle time, h;
K GR- coefficient taking into account the soil group according to the difficulty of development (Table 3); table 2
Specifications of bulldozers
| Model | Blade length b, m | blade height h, m | Operating speeds, km/h | ||
| V Z | V P | V OB.X | |||
| TD 15E | 1,00 | 0,8 | 3,2 | 10,5 | 12,5 |
| TK-25.05 | 1,4 | 0,72 | 3,5 | 10,0 | 15,1 |
| D5C | 1,93 | 1,43 | 3,1 | 10,0 | 11,9 |
| DZ-42V | 2,52 | 0,8 | 2,5 | 5,0 | 8,0 |
| T-4AP2 | 2,84 | 1,05 | 3,0 | 6,0 | 7,5 |
| DZ-171.4 | 3,2 | 1,3 | 2,8 | 5,8 | 7,6 |
| DZ-186 | 2,52 | 1,52 | 3,0 | 6,0 | 7,5 |
| B10.02ER | 3,4 | 1,3 | 3,4 | 6,2 | 8,4 |
| T-50.01 | 3,94 | 1,4 | 3,5 | 12,0 | 14,2 |
| DET-350B1R2 | 4,2 | 1,8 | 4,7 | 9,5 | 13,2 |
| D355A-3 (KOMATSU) | 4,31 | 1,54 | 5,8 | 12,5 | 15,0 |
| D4C XL | 4,99 | 1,17 | 5,1 | 11,0 | 11,9 |
| D9R | 4,65 | 1,93 | 4,1 | 11,8 | 14,7 |
| DZ-141UHL | 4,8 | 2,0 | 4,0 | 8,0 | 11,5 |
| D10R | 5,26 | 2,12 | 5,2 | 12,5 | 15,6 |
| D11R | 6,35 | 2,37 | 4,8 | 11,6 | 14,1 |
Table 3
Values K GR
K B is the intra-shift time utilization factor ( K B =0,75);
K T- coefficient of transition from technical productivity to operational ( K T=0,70); 
, m 3 , (2)
where h– dump height, m (see Table 2);
b– blade length, m (see Table 2);
K P- coefficient taking into account the loss of soil during movement, K P=0,85;
K R– coefficient of soil loosening ( K R=1.1 for sandy soils, K R=1.2 for clay soils);
t W- time spent on cutting (setting) the soil, h;
– cutting length, m;
V Z– soil cutting speed, km/h (see Table 2);
h PAGE– cutting chip thickness, m ( h PAGE=0.10…0.25 m);
t P- time spent on moving and leveling the soil, h;
t OB.X– return stroke time, h;
t PER– time for shifting gears, raising and lowering the blade, h;
t PER=0.005 h.
, (6)
, (7)
where ℓ P– range of soil movement, m ( ℓ P=10…40 m);
V P- the speed of movement when leveling (moving) the soil (see Table 2);
V OB.X- reverse (idling) speed, km/h (see Table 2).
Rice. 1. Bulldozer
 |
The transverse and cross-sectional schemes of soil development by a bulldozer are shown in fig. 2.
Rice. 2. Typical schemes for excavation with a bulldozer:
a) transverse (shuttle); b) cross-sectional:
d - soil shaft; a- the width of the passage lane overlap; m - strip of a temporary road;
b- the length of the bulldozer blade; h PAGE– cutting chip thickness;
1,2,3 etc. – numbers of passages of the bulldozer
Bulldozer performance when leveling materials and soils
, m 3 /h, (8)
where q- the volume of material (soil) moved by the bulldozer blade, m 3;
t C– full cycle time, h;
K R.V- coefficient taking into account the part of the dumped material or soil moved during leveling (Table 4);
K GR- coefficient taking into account the group of material or soil according to the difficulty of development (see Table 3);
K B=0,75; K T=0,60; 
, m 3 , (9)
where h is the height of the bulldozer blade, m;
b- length of the bulldozer blade, m;
K P- coefficient taking into account the loss of material or soil during movement, K P = 0,85.
, h, (10)
, h (11)
, (12)
t PER=0.01 h,
where ℓ P– distance of movement of material or soil during leveling, m, depending on the thickness of the leveled layer h SL(see Table 4);
V P- the speed of movement when leveling (moving) the material or soil (see Table 2).
a) when developing the soil
M 3 / h (13)
where a– blade installation angle in plan, deg. ( a\u003d 50 ... 60 O);
h PAGE is the thickness of the removed soil layer, m;
K P.V- the coefficient of time loss for idling during turns and gear shifting ( K P.V=0,6);
K B=0,75; K T=0,70;
Table 4
Ground travel range valuesℓ Pand K R.V
The productivity of the bulldozer when working along the longitudinal and transverse
The technical performance of the bulldozer during grading work is determined by the length of the grading strip, the width of the blade and the installation angle in the plan (for rotary blades) with the number of passes P> I, m 2 / h
3600 S(B sinα y - bn)
P \u003d _________________
n(S/υ+to)
where S is the length of the planned section, m; α y - blade installation angle in plan, degrees (for non-rotating from the shaft a 90 °, for rotary 63 and 90 °); υ - average speed of the bulldozer, m/s; to- time to turn the bulldozer, s |( to = 16... ...45); B- dozer blade width, m; bn =(0,2,..0,3) AT.
When cutting and moving soils in embankments, development, excavations,
traps, trenches and other works of large volumes, technical productivity is determined per unit volume of soil in a state of natural density and moisture
P \u003d 3600 V6 Kk Ku Ks / Tts..b.
where V=0.5ВН²сtgφо/K Р, m e - the volume of the drawing prism cut off by the bulldozer blade; H- dump height along the chord, taking into account the canopy, m; φo - angle of repose of the material being moved, which is 15...50° depending on the type and condition of the soil (average value φo = 30° and сtg 30° = 1.73); K P is the coefficient of soil loosening, characterizing the transition from the volume of a prism in a loose body to the volume of soil in a dense body; Kk is the coefficient for taking into account the qualifications of the driver (taken as 1 when driving a caterpillar bulldozer by a driver of the highest qualification, 0.85-medium and 0.65-lower). Ku - coefficient for taking into account the influence of the slope of the terrain (Table 3.5); To with - coefficient of soil conservation during movement (accept K c = I - 0.005Sn, where Sn is the path of movement of the soil prism, m); Tts..b. - the duration of the working cycle of the bulldozer.
Soil loosening coefficient is taken:
Sand and sandy loam in unfrozen
standing .............................. 1,1… 1, 2
Loam and clay in unfrozen
state ....................................... 1.27...1.55
Rocky soil and coal. . . 1.34...1.67
Sand and sandy loam to frozen
research institutes. ......................................... 1,2...1, 75
Loam and clay in frozen soil
standing ............................... 1.75...2.0
3.5. Coefficient of taking into account the influence of the slope of the terrain
The duration of the working cycle of the bulldozer, s
Tts..b. = sp / υ p + Sx / υa+ toc + 3
where Sp and Sx are the length of the working and idling strokes, m; tos - stop time at the beginning and end
working stroke is: for a hydromechanical transmission in the presence of a high-speed reverse - 3 s; for a mechanical transmission with gears of constant mesh - 4-8 s, without constant mesh (greater than the value for 2 reverse levers) - 6 ... 10 s; 3 - time added for acceleration and deceleration, s.
The average speed of the working stroke of the tractor with the working equipment, operating weight, t. G , m/s
υр = NeηКzag (1 – δ)/Gqφк
where Ne- rated engine power, kW; η = 0.88..D95 - transmission efficiency; Kzag - load factor of the tractor engine (0.7 - with mechanical and 0.8 - with hydromechanical transmission); δ - the average value of the slip coefficient during the working stroke (0.18 - for a caterpillar tractor); φk- the average value of the coefficient of use of the adhesion weight for the working element of the cycle, which is 0.78 φкmax- 0.22 at maximum tangential friction coefficient φкmax ≥0,45; φкmax- free fall acceleration.
The value of the maximum friction coefficient during the operation of the bulldozer and the bulldozer-ripper φкmax =
The average idle speed depends on the type of suspension of the tractor running system and is υx= = 0.9= υx max, where x ma- maximum design reverse speed
in 1st or 2nd gear. It does not exceed, as a rule, 1.4 ... 1.7 m / s with a semi-rigid balancing suspension and 1.9 ... ... 2.2 m / s - elastic.
Technical performance of the ripper, m³/h
Pr \u003d 3600 V ... r. Ku Kk / Tts...r.
where Tc...r.- duration of the ripper operation cycle, s; V...r. ,= Вр heff Sp- volume of loosened soil, m 3; Вр - the average width of the loosening strip in one cycle with the number of teeth more than one or the pitch of adjacent furrows when loosening with one tooth, ensuring the destruction and cleaning of the loosened soil to the effective loosening depth he, m; he f = (0.6... ...0.8) H 0 . where H 0 is the average optimal depth of layer-by-layer loosening under given conditions.
The average optimal loosening depth (which determines the highest productivity) depends on the traction class of the base tractor, tip width, number of teeth, equipment of teeth with wideners. soil properties. When evaluating calculations. max can be accepted H 0 = And in where in- tip width, m; BUT - the coefficient of the component during the longitudinal loosening of hard-frozen soils with a single-tooth ripper 3 ... 5; transverse loosening - 4 ... 6.
3.6. Utilization rate by time for bulldozers and bulldozers-rippers
Digger
Coefficient Kv
Bulldozer on tractor DET-250
Bulldozers of other brands Bulldozers of all brands
Bulldozer-ripper on tractor DET-250 Bulldozers-rippers of other brands Bulldozers-rippers of all brands
Development and movement of non-rocky soil
Movement of loosened frozen soil
Movement of blasted rock
Leveling the soil when backfilling a trench
Cutting the vegetation layer Preliminary and final planning of areas, slope planning with slopes
Backfilling trenches and pits
Loosening frozen soil
Loosening of unfrozen soil
Soil loosening strip width
Br = Kn
3.8. Development and relocation soils bulldozers
where Kn- overlap ratio (for medium
conditions K n=0,75); γ - camber angle (15... 60°) depending on the type of loosened material, large values - for plastic-frozen soils, smaller ones for brittle ones; l - tooth pitch, m.
The duration of the working cycle is determined by the same formula as for bulldozer work.
When loosening the site in a longitudinally rotary way, the time of idling, stops and deceleration is excluded from the formula, adding the time to turn tr.
Operational productivity is determined taking into account organizational breaks in the operation of machines per shift.
Pe \u003d Fri-Sq.-N,
where N- the number of hours of operation of the machine per shift; Kv- coefficient of use of working time (tab. 3.6); Fri - hourly technical productivity, m 3 / h.
In table. 3.7 - Z.1O shows the approximate hourly outputs of bulldozers and bulldozers-rippers, determined on the basis of the time standards set by the ENiR (1988) and VNNR of the USSR Ministry of Transport (1987) for the main types of earthworks.
3.7. Layout of areas with bulldozers
Note. To the left of the line - with a working stroke in one direction; on the right - with a working stroke in two directions
| Traction class of the tractor | Soil group | Travel range, M | Norm of time per 100 m³, our -h | Hourly production. m³, |
| I | 0,94 | 106,4 | ||
| 1,81 | 55,2 | |||
| 2,68 | 37,3 | |||
| 3,55 | 28,1 | |||
| II | 1.1 | 90.9 | ||
| 2,04 | ||||
| 2.98 | 33,6 | |||
| 3,92 | 25,5 | |||
| III | 1.3 | 76,9 | ||
| 2.28 | 43,9 | |||
| 3,26 | 30,7 | |||
| 4,24 | 23,6 | |||
| I | 0.35 | 285,7 | ||
| 0.65 | 153,1 | |||
| 0.95 | 105,3 | |||
| 1.25 | ||||
| And | 0,41 | 243,9 | ||
| 0,74 | 135,1 | |||
| 1.07 | 93,5 | |||
| 1.40 | 71.4 | |||
| 0,47 | 212.8 | |||
| 0.82 | ||||
| 1.17 | 85,5 | |||
| 1,52 | 65,8 | |||
| 0.32 | 312,5 | |||
| 0.61 | 163,9 | |||
| 0.9 | 111,1 | |||
| 1.19 | ||||
| P | 0.38 | 263.2 | ||
| 0,68 | 147.1 | |||
| 0,98 | ||||
| 1,28 | 78,1 | |||
| III | YU | 0,4 | ||
| 0.72 | 138,9 | |||
| 1,04 | 96.2 | |||
| 1.36 | 73,5 | |||
| I | 0,22 | 454,5 | ||
| 0,42 | 238.1 | |||
| 0,62 | 161.3 | |||
| 0.82 | ||||
| II | 0.24 | 416.7 | ||
| 0.45 | 222,2 | |||
| 0,66 | 151.5 | |||
| 0,87 | 114,9 |
Continuation of the table. 3.8
3.10. Moving loosened soil with bulldozers-rippers
3.9. Loosening frozen soil with bulldozers-rippers
| Traction class | Soil group | Norm of time per 100 m³. | Hourly output m³ |
| Tractor | mash. -h | ||
| I m | 0,92 | 108,7 | |
| II m | 1,2 | 83,3 | |
| III m | 1,5 | 66,7 | |
| IVm | 1,9 | 52.6 | |
| I m | 0,73 | ||
| II m | |||
| III m | 1,3 | 76,9 | |
| IVm | 1,6 | 62,5 | |
| I m | 0,66 | 151,5 | |
| II m | 0.88 | 113,6 | |
| III m | 1,1 | 90,9 | |
| IVm | 1,3 | 70.9 | |
| I m | 0,27 | 370,4 | |
| II m | 0,34 | 294,1 | |
| III m | 0,44 | 227,3 | |
| IVm | 0,58 | 172,4 |
| Traction class of the tractor | Soil group | Travel range, m | Norm of time for 100 m³ bowls. -h | Hourly output, m³ |
| im | 0.54 | 185,2 | ||
| 0,94 | 106,4 | |||
| 1,34 | 74,6 | |||
| 1,74 | 57,5 | |||
| II m | 0,64 | 156.3 | ||
| 1,13 | 88,5 | |||
| 1,62 | 61,7 | |||
| 2,11 | 47,4 | |||
| III m | 0.71 | 140.8 | ||
| 1,25 | ||||
| 1,79 | 55,9 | |||
| 2,33 | 42,9 | |||
| I m | 0.28 | 357,1 | ||
| 0,5 | ||||
| 0.72 | 138,9 | |||
| 0,94 | 106,4 | |||
| II m | 0,31 | 322.6 | ||
| 0.55 | 181,8 | |||
| 0,79 | 126,6 | |||
| 1,03 | 97,1 | |||
| III m | 0,34 | 294,1 | ||
| 0.59 | 169,5 | |||
| 0.84 | ||||
| 1.09 | 91.7 | |||
| im | 0,21 | 476.2 | ||
| 0,39 | 256.4 | |||
| 0,57 | 175.4 | |||
| 0.75 | 133.3 | |||
| II m | 0,24 | 416,7 | ||
| 0,43 | 232,8 | |||
| 0,63 | 161,3 , | |||
| 0,81 | 123,5 | |||
| III m | 0.26 | 384.6 | ||
| 0,4 | 217,4 | |||
| 0.66 | 151.5 | |||
| 1,86 | 116.3 |
Chapter 4. Scrapers
4.1. Region applications
Scrapers are used in irrigation and drainage, automobile and railway construction, and in the mining industry.
In irrigation and drainage construction, scrapers develop soil in excavations (channels, pits, quarries, reserves); arrange bulk earthworks (dams, canal sections in semi-embankments or embankments, dams); carry out overburden works and preparation of the foundations of structures (removal of the vegetative layer of soil, removal of unsuitable soils from the area of the foundations of dams); carry out planning work on irrigated lands and construction sites.
Scrapers are especially widely used in the construction of large canals with an excavation depth of more than 5 ... 7 m, as well as earthen dams from bulk soil, where these machines perform almost a complete technological complex.
During the construction of the subgrade of roads and railways, scrapers remove the surface vegetation layer, pour embankments from reserves, develop excavations or quarries with the movement of soil into the embankment at a distance of 150 ... ... 500 m.
In the mining industry, scrapers are used for the extraction and transportation of loose rocks, overburden of quarries of building materials, excavation of waste rocks,
hiding minerals.
Scrapers are most effectively used in areas with a short winter period - in the southern and middle climatic zones of the country. In winter, at a depth of freezing of the soil of about 0.2 m, it is preliminarily loosened.
The configuration of an earthwork affects its ability to be erected by a scraper and the choice of a machine of a certain standard size. The cuts and pits most typical for excavation by scrapers have the shape of a rectangle without protrusions and pockets in plan, as well as various embankments, to which gentle access roads suit.
The range of soil movement largely determines the choice of the type of scraper and the capacity of its bucket (Table 4.1).
The solution to the question of choosing the standard size of a scraper for the construction of a particular earthwork depends on the amount of work and is determined by economic calculation.
When constructing structures with a concentrated volume of earthworks of 10 ... 250 thousand m³, it is advisable to use self-propelled scrapers with a bucket with a capacity of 8 m 3; large linear-extended structures with a volume of more than 200 thousand m per km (irrigation systems, canals, dams) - scrapers with buckets with a capacity of 10 ... 15 m³; embankments of earthen roadbed up to 1.5 m high -
trailed scrapers with a bucket with a capacity of 10 m³, and with a height of over 1.5 m - 15 m 3.
The development of cuts or quarries during the construction of the roadway with the movement of soil into the embankment at a distance of up to 500 m and the amount of work at the facility up to 80 thousand m! rationally trailed scrapers with a bucket with a capacity of 10 m 3, and when moving over a distance of more than 500 m and the same amount of work - self-propelled scrapers with a bucket with a capacity of 10 m 3.
When planning rice fields, trailed scrapers with a bucket with a capacity of 8 m 3 are mainly used. Due to the short range of soil movement (up to 100 m), scrapers with buckets with a capacity of 4.5 m³ are also used in these works. It is advisable to use trailed scrapers equipped with an automation system that can significantly improve the accuracy of planning.
4.2. Technological work flow charts
Features of the technological cycle. The full working cycle of the scraper includes the collection of soil, its transportation, unloading of the bucket, reverse (empty) run.
Soil set characterized by the thickness of the cut chips and the length of the set path. The thickness of the cut chips depends on the type of development
soil and traction force of the pusher (Table 4.2)
The most common method of filling the bucket with chips of variable cross section, starting from the thickest possible with a gradual decrease in it towards the end of the collection path. This causes a constant loading of the engines of the scraper and the pusher during the entire time of the set. This method is especially effective when working on cohesive soils.
During planning work, the ladle is filled with chips of constant thickness.
The best filling of the bucket is obtained when developing soils with a moisture content of up to 25%. Excessively dry soils should be pre-moistened. Heavy soils of categories III and IV before the start of development are loosened by scrapers in longitudinal strips with the help of bulldozers-rippers parallel to their passages with a shift equal to the specified grinding of the soil. Excessive grinding of the soil during loosening is undesirable, as it contributes to the formation of a drag prism and impairs the filling of the bucket. It is recommended to loosen the soil into clods of 10 ... 15 cm in size. The largest size of clods of loosened soil should not exceed 2/3 of the cutting depth of the scraper. The volume of loosened soil should be no more than a half-shift rate of working scrapers so that it does not dry out in the heat or
Depending on the type of work for which it is planned to perform a bulldozer (see for example), machine performance is expressed in different ways. When developing soil, productivity is considered in volume, and when planning an earthen surface, in area.
Performance is affected by the following factors:
- Physical indicators of the developed soil:
- granulometric filling
- density,
- porosity,
- plastic limit,
- swelling;
- Mechanical indicators: strength, compressibility, subsidence, modulus of elasticity, the nature of the structural bonds of the soil;
- Way of moving the earth;
- The relief of the construction site;
- Geometric components and blade type (see specifications).
It also depends on the characteristics of the soil how much it will fit in the back of a dump truck. Read about it
Formula for calculating when processing one volume of soil per unit of time (m3 / h)
Calculation during soil development
When working on the development of soil and its transportation over a distance, a bulldozer performs a repetitive cycle of actions. In this case, the productivity of the machine is expressed formula:
P \u003d (q * n * Kn * Ki * Kb) / Kp,
in which the components are:
- Р – productivity, m3/hour;
- q is the volume of soil that is moved by a shovel and is determined by the numerical dimensions of the dump and factors affecting the movement;
- n is the number of repeating circles per unit of time in relation to the transportation distance;
- Kn is the coefficient that takes into account the loss of volumes in the side rollers, depends on the distance of movement and the type of soil;
- Ki - coefficient characterizing the magnitude of the slope of the path of the machine;
- Kv - coefficient showing the degree of initial loosening of the soil;
- Kr is a coefficient that determines the rational use of labor time.
- Number of tractor operation cycles per time unit (hour):
- n= 3600/tc
Cycle duration:
- tc=tn+tg.h.+txx+2*tp+m*tp.p.+to=ln/kv*vn+lg.h./ kv*vg.h.+(ln+lg.h.) /(kv*vх.х.)+2*tp+m*tp.p.+t0
- where t is the duration:
- tn - soil collection, s;
- tg.x. - loaded passage, s;
- th.x. - idling, s;
- tp. – one rotary action (10-20 seconds);
- tp.p. – one transfer speed transfer (5-6 seconds);
- t0 - lowering the shovel to the initial position (2 seconds).
- m is the number of changes in bulldozer speeds during one stroke;
- lн – way of soil removal, m;
- lg.x. is the length of the movement distance to the place of accumulation, m;
- vн, vг.х, vx.x – tractor movement speeds during cutting, soil movement and return stroke, m/s;
- kv is a coefficient that takes into account the level of reduction in the speed of the tractor compared to the calculated one: 0.7-0.75 when moving the load, 0.85-0.90 when idling;
The coefficient of lost soil volumes in boulders depends only on the distance of soil movement and is expressed by the following dependence:
Kn=1-Ki*lg.x.
- K1 is a coefficient obtained by a laboratory method, the value of which varies within 0.008 ... 0.04, depending on the dry or cohesive state of the soil;
- Lg.x. - the length by which the soil moves, m.
If necessary moving soil over a distance of more than 30 m, the use of bulldozers is considered irrational due to large losses of soil during movement. In this case, you can transport goods by dump trucks, for example, on any of the model range
The volume of soil that the bulldozer can move a certain distance depends on the magnitude of the slope of the work site. So on the descents from the hill, the volume of the displaced soil will be much larger, which means that the productivity of the machine increases.
You can choose either an electric snow blower or a gasoline one. For clarity, check out the article on .
If you have a chainsaw, and you do not want to spend money on a snow blower, then you can make it yourself. Find out exactly how in .
Bulldozer Operating Performance and Power Calculation Example
Initial data:
- Bulldozer brand - DZ -28;
- Soil type - loam;
- Soil cutting distance - 10 m;
- Travel distance - 20 m.
Step 1. Determine the duration of one cycle:
For convenience, we will replace the literal values of the indicators with digital ones.
Т=t1+t2+t3+t4
- t1 – duration of soil collection, s;
- t1=l1/v1=3.6*10/3.2=11.25 s.
- l1 – soil cutting distance, l1=10 m (according to the condition);
- v1 is the speed of the tractor in low gear, v1=3.2 km/h.
- t2 is the duration of the loaded course of the bulldozer, s;
- t2=l2/v2=3.6*20/3.8=18.9 s.
- 3.6 is the conversion factor for speed units (km/h to m/s);
- l2 – soil movement distance, l2=20 m (according to the condition);
- v2 is the speed of the bulldozer, taking into account the reduction factor for a loaded tractor, v2=3.8 km/h.
- t3 – duration of idling of the bulldozer, s;
- t3=(l1+l2)/v3=3.6*(10+20)/5.2=20.8 s.
- v3 is the speed of the bulldozer during the reverse motion, taking into account the reduction factor of the empty tractor, v3=5.2 km/h.
- t4 - the duration of the additional time spent on raising and lowering the blade, switching speeds and turning the bulldozer in the opposite direction.
For this type of bulldozer and, based on the condition of setting t4=25 s.
Duration of one cycle is:
Т=t1+t2+t3+t4=11.25+18.9+20.8+25=76 s.
Step 2. Determine the machine performance of the bulldozer:
Tractor performance is calculated by the formula:
Fri \u003d q pr * n * kn: kr,
- qpr - volume of soil to be moved, m3;
- qpr \u003d L * H2: 2 * a \u003d 3.93 * 0.816 ^ 2 / 2 * 0.7 \u003d 1.92 m3
- L is the length of the bulldozer shovel, L = 3.93 m,
H is the length of the shovel blade, H=0.816 m,
a \u003d 0.7 - coefficient that determines the ratio of height and length,
n is the number of cycles per unit of operating time (1 hour): - n \u003d 3600 / T \u003d 3600: 76 \u003d 47.4
- kn=1.1 - coefficient depending on the volume of filling the dump prism with soil,
kp=1.3 - coefficient showing the degree of loosening of the soil,
Fri \u003d qpr * p * kn / kr \u003d 1.9 * 47.4 * 1.1: 1.3 \u003d 76.2 m3 / h
Operating performance tractor is defined as the ratio:
P= Fri*kv= 76.2* 0.8=60.96 m3/h Bulldozer Performance
Based on the presented formulas, it is obvious that the productivity of the bulldozer increases if at the initial moment of operation the blade is buried to the maximum possible depth, and as the soil accumulates, the depth decreases.
Before starting work dense soil is loosened by special teeth located on the back of the bulldozer. This allows you to increase productivity up to 30 percent.
Soil sawing is carried out in low gear downhill.
To reduce soil losses during transportation, it should be moved at a reduced speed.
To reduce the loss of volume of the moved soil, move it along the same track.
When moving soil over long distances, the whole volume is divided into portions.
The choice of an effective method of unloading the soil from the dump: in a pile, in layers or by pushing into a pit.
The return stroke of the bulldozer to the place of collection of soil is carried out at the maximum speed possible under the given operating conditions.
Performance is the most important technical characteristic and a defining indicator of the performance of a construction machine such as a bulldozer (see). The value of productivity for machines with a cyclical principle of operation depends primarily on the duration of the cycle.
Check out the biggest and most powerful bulldozers.
Bulldozer technical performance when cutting and moving soil, m 3 / h, is determined by the formula
P T \u003d 3600 V pr K U K S / T C, (2.21)
Where V PR is the geometric volume of the soil dragging prism (in a dense body), m 3;
V PR \u003d 0.5 L H 2 / ctg φ o K p, (2.22)
Where L, H are the length and height of the dump, respectively; φ o - angle of repose when moving material (average value φ o = 30°; ctg φ o = 1.73); K R - soil loosening coefficient (for soil of the 1st group it is 1.1; 2nd group - 1.2; 3rd group - 1.3); K U - coefficient taking into account the influence of the slope of the terrain (Table 2.22); К С is the coefficient of soil conservation during its transportation:
K C \u003d 1 - 0.005 S in, (2.23)
where S in is the range of movement (carriage) of soil, m; T C - cycle duration, s:
T C = S p / v p + S B / v B + S 0 / v o + Σ t, (2.24)
where S P , S B , S O - the length of the cutting path, hauling of soil and reverse motion, respectively, m; S O = S P + S B ; v P , v B , v O - tractor speed when cutting, moving soil and reverse, m / s, (Table 2.23); Σt is the time for gear shifting, blade lowering, stops at the beginning and end of the working stroke, and other auxiliary operations (on average Σ t = 15…20 s).
Soil cutting path length
S p \u003d V pr / L h c (2.25)
where V PR is the volume of the soil dragging prism, m 3; L is the length of the bulldozer blade, m; h С is the thickness of the cut soil layer, m, (Table 2.23).
Table 2.22
Effect of Terrain Slope on Bulldozer Performance
Table 2.23
The main technological parameters of the bulldozer
| Group soil | Traction bulldozer | Thickness soil, cm | Speed, m/s, at |
||
| cutting soil | loaded course | reverse course |
|||
| I | 1,4…4 | 18,5 | 0,7 | 1,1 | 2,0 |
| 6…15 | 25 | 0,75 | 1,2 | 2,5 |
|
| 25…35 | 35 | 0,76 | 1,0 | 2,1 |
|
| II | 1,4…4 | 17,5 | 0,65 | 1,0 | 2,0 |
| 6…15 | 22 | 0,7 | 1,1 | 2,5 |
|
| 25…35 | 31 | 0,74 | 0,9 | 2,1 |
|
| III | 1,4…4 | 12,5 | 0,5 | 0,7 | 2,0 |
| 6…15 | 18 | 0,65 | 1,0 | 2,5 |
|
| 25…35 | 27 | 0,72 | 0,8 | 2,1 |
|
Average hourly operating productivity bulldozer is equal to:
P E \u003d P T K V, (2.26)
where КВ is the coefficient of machine utilization by time during the shift: КВ = 0.8 - with bulldozer power up to 200 kW; K B \u003d 0.75 - with power over 200 kW.
2.5.2. Bulldozers-rippers
In order to combine an earth-moving and ripping machine in a bulldozer, which expands the scope of its application in various soil and weather-climatic conditions, ripping equipment is hung on the rear axle of the base caterpillar tractor (Fig. 2.10).
The ripping equipment consists of a hinged device in the form of a frame 1, a system of rods 2, a working beam 4, providing oriented mobility and fixed positions of the working bodies - a tooth with a tip 7 (or several teeth) in space using hydraulic cylinders 3. The hinged equipment is mounted on the base tractor by means of supporting elements: frames, beams, brackets rigidly fixed on the rear axle body.
Rice. 2.10. bulldozer ripper
1 - frame; 2 - thrust; 3 - hydraulic cylinders; 4 - beams; 5 - buffer;
6 - vane device; 7 - tooth with a tip
The design and classification differences of modern rippers are due to the traction class and chassis of the base tractor, the purpose of the ripper, the type of its attachment, the method of installation, the number of teeth and their fastening (Table 2.24).
Table 2.24
Ripper classification
The main classification parameter of the ripper, which determines the standard size, is the traction class of the base tractor. The technical characteristics of bulldozers-rippers are given in Table. 2.25.
Table 2.25
Technical characteristics of bulldozers-rippers
| Index | Basic Tractor | Weight, t |
||||
| brand | Class | power, | equipment | cars general |
||
| bulldozer | ripper |
|||||
| B10M.0100 | T-10M | 10 | 132 | 2,51 | 1,72 | 18,24 |
| CHETRA-11 | T-11.01 | 11 | 123 | 2,4 | 1,0 | 20,0 |
| T-15.01 | T-15.01 | 15 | 176 | 3,11 | 3,575 | 28,0 |
| T-20.01 | T-20.01 | 20 | 206 | 4,3 | 3,575 | 36 |
| TM-25.01 | TM-25.01 | 25 | 279 | 6,95 | 4,6 | 50,98 |
| DET-320 | DET-250M2 | 25 | 258 | 5,2 | 4,28 | 45,0 |
| DET-250M 2B1R1 | DET-250M2 | 25 | 237 | 6,2 | 3,95 | 41,34 |
| T-35.01 | T-35.01 | 35 | 353 | 8,95 | 6,12 | 61,55 |
| T-50.01 | T-50.01 | 50 | 550 | 12,0 | 12,5 | 95,5 |
| T-75.01 | T-800 | 75 | 603 | 16,295 | 11,2 | 106 |
Number of teeth Rippers accept one, three or five, depending on the purpose and size of the machine. On tractors with a power of up to 100 kW, three to five ripper teeth are used for auxiliary work in the destruction of dense unfrozen soils. When developing frozen and collapsible rocky soils, one to three teeth are installed on tractors with a power of over 100 kW.
Working cycle ripper consists of the following operations: lowering the ripper teeth and their penetration into the ground, loosening the soil, deepening the ripper teeth, returning the machine to its original position by idling. The volume of developed soil depends on the depth of loosening, the number of teeth and the distance between them.
Technical performance of bulldozer ripper, m 3 / h, when loosening the soil is determined by the formula
P T \u003d 3600 Q / T C, (2.27)
Where Q is the volume of soil loosened per cycle, m 3; T C - cycle duration, s:
Q = B h CP s, (2.28)
Where B is the average width of the loosening strip, depending on the number, pitch and thickness of the teeth, the camber angle (15 ... 60 °) and the overlap coefficient (0.75 ... 0.8) of cuts, m; h cf is the average loosening depth in these soil conditions, m; s is the length of the loosening path, m.
With the shuttle operation of the ripper
T C \u003d s / v p + s / v x + t c + t o , (2.29)
Where v p , v x - the speed of the machine, respectively, during loosening and idling, m / s; t c \u003d 5 s - average time for gear shifting; t o = 2…5 s is the average time to lower the ripper.
With a circular ripper operation, the duration of the machine turns at the end of the section (two turns) is added to the cycle time and the idle time is excluded.
2.5.3. Security questions for section 2.5
1. What are bulldozers for? What kind of work can they do? Give a classification of bulldozers.
2. What parts and assembly units does the bulldozer consist of?
3. Name the types and describe the principles of operation of the working equipment of the bulldozer.
4. How does a bulldozer with a fixed and rotary blade work and how does it work?
5. What interchangeable working bodies are bulldozers equipped with? What is their purpose?
6. What are the ways to develop the soil with a bulldozer? Under what conditions is the bulldozer's shuttle operation more productive than turning at the ends of the grip?
7. How is the technical performance of a bulldozer determined when developing soil in excavations and reserves?
8. What measures reduce the loss of soil when it is moved by a bulldozer? What other techniques are used to improve bulldozer performance?
9. What tasks are solved by using automatic control systems for the operation of a bulldozer? What typical automatic control systems are equipped with domestic bulldozers?
10. How does the ripper work? What are bulldozers used for?
11. List the composition of the working operations of the bulldozer-ripper and how to perform them.
12. How is the technical performance of a bulldozer-ripper determined for layer-by-layer loosening of the soil? What technological schemes are used in the operation of the ripper?
2.6. motor graders
2.6.1. General characteristics of motor graders
A motor grader is a self-propelled earth-moving machine with a knife working body for profiling and precise planning earthworks (Fig. 2.11). The working body of the motor grader is a grader blade with knives, mounted on a turning circle under the traction frame in the middle part of the machine between the front and rear wheels. When the motor grader moves, the knives cut the ground, and the blade, installed at an angle to the longitudinal axis of the machine, shifts it to the side.
Fig.2.11. Motor grader with scarifier
1 - a scarifier; 2 – hydraulic cylinder of the scarifier; 3 - dump; 4 - frame;
5 – blade hydraulic cylinder; 6 - wheels; 7 - cabin; 8 - cardan shaft;
The blade suspension in most cases allows its rotation around three orthogonal axes and translational movement along its own longitudinal axis. Thus, the blade can rotate in a horizontal plane 360 ° in any direction, become vertical to the right and left of the machine, extend to the right and left for more than a third of its length and rotate around its cutting edge. If necessary, the dump is equipped with special attachments, for example, for simultaneous leveling of the bottom and slope of the embankment, the top and slope of the excavation, etc.
The grader blade is the main, but not the only working body of the machine. As a rule, the motor grader is equipped with another permanent working body: a bulldozer blade installed in front of the machine; a scarifier placed in front of the front wheels (Fig. 2.11), immediately behind them or behind the grader blade; ripper located at the rear of the machine. The additional working body is designed to perform auxiliary working operations and ensures uninterrupted use of the main working body.
Motor graders have a common layout, with the engine and cab located at the rear of the machine, and the blade with the removal mechanism in the middle of the wheelbase. According to the design of the undercarriage, they are biaxial (Fig. 2.11) and triaxial (Fig. 2.12). Design features of the undercarriage are reflected wheel arrangement, which is written as AxBxB, where A, B and C are the number of axles, respectively controlled, leading and total. For example, a three-axle machine with two leading (rear) axles and a front axle with steerable wheels has the formula 1x2x3. Motor graders of this formula are most widely used in construction.
Motor graders are classified according to the following main features: by class, engine power, design of the working body, wheel arrangement, transmission type (Table 2.26).
Table 2.26
Motor grader classification scheme
To designate motor graders, as well as other earth-moving machines, a letter index is adopted - DZ. The digital part of the index corresponds to the number that is assigned when registering a new car (for example, DZ-98). When upgrading the machine, a letter is added in alphabetical order (for example, DZ-98V.1). The ordinal number (.1) indicates the modification of the machine). After 1991, some plants use other indexing systems (Table 2.27).
Almost all modern motor graders are equipped with automatic control systems, the main function of which is to maintain the given orientation of the grader blade in space. Depending on the modification of the machine, the "Profile - 10", "Profile - 20" and "Profile - 30" systems are used. ACS "Profile -10" is designed to automatically provide a given angular position of the motor grader blade with hydraulic control in the transverse plane, regardless of the transverse profile of the subgrade and is used in the final finishing (planning) of surfaces. ACS "Profile - 20" includes two control channels: stabilization of the angular position of the blade in the transverse direction and the height position of the blade relative to the rigid guide (copier).
Second generation equipment (basic set "Profile - 30") includes the ACS "Profile - 20", additionally equipped with a subsystem for stabilizing the set course of the motor grader. The main elements of the ACS "Profile - 30" are shown in fig. 2.12.
Rice. 2.12. The main elements of the self-propelled guns "Profile-30"
1 - onboard battery; 2 - control panel; 3 - hydraulic spools;
4 – angle sensor (DST); 5 – heading sensor;
6 – dump height position sensor (DShB); 7 - copy wire
The ACS under consideration also includes subsystems that protect the engine from overloads by controlling the crankshaft speed.
2.6.2. Motor grader performance
How a motor grader's performance is calculated depends on the type of work it does.
During the construction of a subgrade, the technical performance of a motor grader is determined as
P t \u003d 60 L sin ά H 2 / tg φ K p (S 1 / v 1 + S 2 / v 2 + t o + t p), (2.30)
Where L is the blade length, m; H is the dump height, m; ά - blade installation angle (grab angle) when cutting soil (Table 2.28); φ is the angle of internal friction of the soil; K p is the soil loosening coefficient: S 1 is the length of the cutting (cutting) path of the soil, m; S 2 - the length of the idling path, m; v 1 , v 2 - the corresponding speed of the motor grader, m / min .; t o - time for lowering and raising the blade (0.06 ... 0.07 min.); t p - time for gear shifting in one cycle (0.08 ... 0.09 min.).
The coefficient of motor grader utilization during the shift during excavation is assumed to be 0.7…0.75.
Table 2.27
Technical characteristics of motor graders
In the production of planning work, technical productivity
P t \u003d 1000 (L sin 
– b) v / n, (2.31)
Where L is the blade length, m; - blade installation angle in plan (Table 2.28); b - overlap width of adjacent planning lanes (0.3 ... 0.5 m); v is the speed of movement during planning, km / h, (usually the 1st speed is taken); n - the required number of passes: with manual control 4-10; with automatic control 2-4.
| Operation | Mounting angle dump, hail. |
|
| capture() | cutting (δ) |
|
| Cutting the soil without preliminary loosening | 40…45 | 30…35 |
| Soil cutting with preliminary loosening | 30…40 | 35…45 |
| Moving wet ground | 40…50 | 30…40 |
| Moving dry soil | 35…45 | 35…45 |
| The layout of the top of the subgrade | 45…60 | 35…45 |
| Slope layout | 60…65 | 40…45 |
The coefficient of use of the motor grader during the shift during planning work is assumed to be 0.8.
2.6.3. Security questions for section 2.6
1. What are motor graders for? What kind of work can they do? Indicate the area of effective use of motor graders in railway construction.
2. Give a general classification of motor graders. What is the structure of the motor grader wheel arrangement? Which motor graders (with which wheel scheme) are most common in construction?
3. How is the motor grader arranged and how does it work? How is the leveling capability of a motor grader ensured?
4. Name the technological schemes of the motor grader. Under what conditions are they implemented?
5. What tasks are solved due to the use of automatic control systems (ACS) by a motor grader? What types of ACS are used on motor graders?
6. List the main elements of the ACS and explain how they work.
7. How is the technical and operational performance of a motor grader determined when it performs various types of work?
2.7. Machinery and equipment for soil compaction
2.7.1. General characteristics of soil compaction machines
Soil compaction machines and equipment are designed to restore the density and strength of soils laid in earthworks, to give them the necessary stability, bearing capacity and water tightness.
Soils are compacted in layers of the same thickness, for which the dumped soil is leveled with bulldozers or graders. The thickness of the leveled layers depends on the conditions of work, the type of soil and the technical characteristics of compacting machines and equipment.
Layer-by-layer soil compaction is carried out by rolling, tamping, vibrating and combined action. Ground compactors allow you to use all methods of soil compaction.
At rolling soil compaction occurs as a result of the pressure created by the drum or wheel on the surface of the compacted layer.
At ramming the soil is compacted by the falling mass, which has a certain speed at the moment of contact with the soil surface.
At vibrating oscillatory movements are imparted to the compacted soil layer, which lead to a relative displacement of particles and their denser packing.
Combined methods of soil compaction - vibroroller and vibrotamping.
A generalized characteristic of soil-compacting machines and equipment is given in Table. 2.29.
Table 2.29
Classification scheme for soil-compacting machines and equipment
| Machinery and equipment for soil compaction | Ground impact | static dynamic Combined |
| Sealing method | Rolling tamping Vibration Rolling + vibrating Vibration + tamping |
|
| Method of moving the working body | trailed self propelled semitrailer hinged With the help of impulse reactive forces |
|
| Type of equipment | Rollers of static action Vibratory rollers Rammer machines Vibratory rammers Vibrating plates |
|
| Roller type | Smooth-roller cam Lattice segmental pneumatic wheel |
Ground compactors are assigned index, consisting of the letters DU and two digits, which are sometimes followed by an ordinal letter (A, B, C, etc.) or an ordinal number (, 2, 3, etc.). The letters DU indicate that the machine belongs to the group of road machines for soil compaction. Two digits in the index - the serial number of the factory model. Letters A, B, C, D, etc. indicate the next modernization of the machine. For example, the index DU-16G stands for: DU - road machine for soil compaction; 16 - factory model number; G - the fourth modernization of the 16th factory model. Recently, instead of letters, numbers are also used to denote modernization, for example, DU-70-1; DU-85-1.
In railway construction, the most common are trailed and semi-trailed pneumatic wheeled rollers, trailed cam, lattice and vibration rollers, as well as soil-compacting machines with shock and vibro-impact action.
Pneumatic roller consists of four or five pneumatic wheels and one or more (according to the number of wheels) ballast boxes. In the latter case, the axle of each wheel is attached to the bottom of the corresponding ballast box in such a way that, depending on the unevenness of the rolled surface, all the wheels of the roller come into contact with the ground. Iron castings or reinforced concrete blocks are used as ballast, with the help of which it is possible to significantly increase the mass of the rink. Trailed pneumatic rollers work in conjunction with caterpillar tractors. Semi-trailer and self-propelled pneumatic rollers are self-propelled units consisting of single-axle wheeled tractors and single-axle rollers connected to them by trunks with wheels on pneumatic tires.
trailed cam rollers work in conjunction with a caterpillar tractor. These are very efficient machines. However, they are used only on cohesive soils, since on non-cohesive soil, the soil is ejected with the cams up, as a result of which the compacted layer is loosened.
Lattice and segment rollers can be used for compaction of cloddy and waterlogged cohesive soils, as well as loosened frozen and rocky coarse-grained soils.
Vibratory rollers produced with a smooth, cam or lattice roller, inside of which a vibrator of directional vibrations is mounted. The vibrator is driven by an independent engine mounted on the roller frame. The maximum effect when using vibratory rollers is achieved when compacting wet sandy, sandy, gravel-sandy and other non-cohesive soils.
In cramped conditions, the soil can be compacted with self-propelled vibrating plates. The area of the working surface of such a plate is 0.5 ... 2 m 2, the thickness of the compacted layer of non-cohesive soil is up to 0.6 m.
To tamping machines include mounted tamping plates on excavators, rammers with falling plates and diesel rammers based on caterpillar tractors. Among the main advantages of these machines is the ability to compact cohesive and non-cohesive soils in layers up to 1 m or more. However, they have not found wide application in transport construction, since free-falling slabs are slow-moving, and diesel-rammer machines are effective only on pre-compacted soils.
Vibro-rammers are attachments on a self-propelled machine based on a caterpillar tractor. The working equipment consists of two vibrohammers driven by a hydraulic motor-reducer through a two-stage V-belt transmission. The impacts of vibrohammers are transmitted to the tamping plate, creating the effect of tamping and vibrating. The suspension of the tamping plate allows it to be moved in the transverse direction by 0.5 ... 0.7 m from the track of the base tractor in order to compact the edge of the embankment in compliance with safety requirements.
In table. 2.30 shows the technical characteristics of some models of domestic soil-compacting machines.
Table 2.30
Technical characteristics of soil compaction machines
| Index | Weight, t | Speed, km/h | Width seals, m |
|
| without ballast | with ballast |
|||
| Trailed cam and lattice rollers |
||||
| DU-2 ZUR-25 | 9,2 | 17,6 | 0-3 | 4 |
| Trailed pneumatic rollers |
||||
| DU-4 DU-39B | 5,65 | 25 | 0- 5 | 2,5 |
| Semi-trailed pneumatic rollers |
||||
| DU-16V DU-74 | 25,4 | 35,9 | 0-40 | 2,6 |
| Self-propelled pneumatic rollers |
||||
| DU-29 DU-100 | 23 | 30 | 0-23 | 2,22 |
| Self-propelled vibratory (combined) rollers |
||||
| DU-52 DU-99 | 16 | – | 0-10,8 | 2,0 |
| Trailed vibratory roller |
||||
| A-4 | 3,8 | – | on | 1,5 |
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