Working process of the earthmoving machines of cyclic operation consists of operations:
a) separation of soil from the mass and its transportation to the place of dumping
b) soil transportation to the place of dumping and unloading
c) transportation of soil to the dumping site with subsequent unloading and return of the machine to its initial position
Earthmoving machines equipped with a working body include:
d) all of the above, except for scrapers
The earthmoving machines equipped with a bucket working body include:
d) all of the above, except for scrapers
In the formula for calculating the technical performance of the bulldozer in excavating excavations the value Vapr denotes:
The formula for calculating the resistance to movement of the drag prism in front of the scraper gate value f denotes:
When the wheel formula of the motor grader 1 x 2 x 3 in the formula for calculating the traction of the driving wheels on the ground is taken into account:
Choosing a shrub shear: for what operations and how to use it efficiently
Neatly trimmed “live” hedges, no dry branches, nicely shaped bushes. any gardener dreams that his favorite garden will be well groomed!
The wide range of Greenworks garden tools and equipment makes it easy to keep your garden tidy and attractive, the main thing is to choose the right tools for different types of work. The care of small trees and bushes, giving a beautiful appearance to “live” fences, the formation of designer crowns of your favorite plants. in all of these works an indispensable helper is a functional and practical shrub shears.
What types of hedge trimmers exist, for what work they are designed, what are the advantages of battery-powered hedge trimmers and what are the advantages of electric hedge trimmers. a detailed review of hedge trimmers is presented in this article.
Road construction machines
Building and road-building machines of continuous action are:
b) multi-bucket excavators, equipment for hydromechanical development of soils
According to the degree of mobility construction and road-building machines can be:
a) mobile self-propelled b) semi-stationary c) trailed
Trailed road construction machines include:
a) some kinds of rollers and scrapers b) graders and bulldozers c) excavators
Self-propelled road construction machines include:
a) some kinds of rollers and scrapers b) graders and bulldozers c) backhoes
According to the principle of operation, crushing machines can be:
According to the nature of the destruction of materials crushing machines are:
According to the type of the working body, crushing machines are:
Maximum size of a loaded material of crusher SMD-109 is equal, mm:
Engine power of the main drive of the crusher SMD-109 is equal, kW:
1) designed to separate bulk materials by size using working bodies in the form of boxes, drums, equipped with a sifting surface with calibrated apertures, performing a continuous or oscillating motion.
2) designed to separate loose materials by means of working bodies in the form of boxes, drums, equipped with a screening surface, making a continuous or oscillating motion.
The capacity of the Chieftain 400 is equal, t/h:
The weight of the Chieftain 400 tracked screen is, kg:
Heavy trailed cam rollers are made:
Amazing Biggest Excavator Mulchers Modern Technology. Fastest Land Clearing Equipment
The degree of compaction of the roadway depends on:
The main parameter of the characteristic of a vibratory roller is:
On the vibrator axis of the vibrating roller are placed:
The speed of the bucket chain and the operating stroke of a vibratory roller when working on frozen ground:
For the final compaction of the pavement most often used road roller with:
A roller is considered heavy if its weight is:
1) a soil compaction machine with a wheel instead of a cylinder
2) a machine for removing earth pavement
3) A machine for compaction of soils, roadbeds and pavements by rolling
The crane railroad stacker KZHU-571 is designed for laying and disassembling of railroad track with rail-to-track links of mass:
Track cleaning machine POM-1 is designed for:
1) For supplying and restoring of rail-tracks by means of qualitative welding of any rails
2) For cutting and cleaning of crushed stone ballast
3) For mechanized clearing of snow and spillage of in-plant railroad tracks
4) For laying and dismantling of railroad track by means of railroad ties
Production capacity of straightening and stiffening machine VPR-02M:
1) Loading, unloading, and transporting freight on its own platform;
2) Cargo transportation on trailed platforms;
3) Transportation of long goods, including rails with the length of 25 m on its own and trailed platform;
4) Transportation of work crews to the place of work;
5) Shunting operations on station tracks;
6) Carrying out welding operations in the field;
Mechanization of railroad construction:
1) Use of general construction and special construction machines
2) Equipment and means of minor mechanization for construction and reconstruction of railway facilities
For ballasting track on small sections of railroads are used:
1) Tractor-mounted equipment set
VPRS-03 straightening and chiselling machine is designed for straightening the railroad track:
VPO-3000 continuous action machine is used:
1) For major and medium track repairs
2) For major, medium and surface repairs
3) For middle and ascending track repairs
1) Cutting and cleaning of crushed stone ballast
2) Mechanized clearing of snow and spillage of in-plant railroad tracks
3) To provide and restore the rails by quality welding of any rails
VPO-3000 continuous action machine provides capacity:
The capacity of mechanical piling hammers is:
The impact weight of the tubular diesel hammer can be:
Which of the following is a vibroloader:
For immersing reinforced concrete piles with continuous cross-section the following is used
The normal operation of a vibroplow during pile driving is defined by
The main parameters of the technical characteristics of pile driving hammers are:
Piles are used to make pile foundations:
Depending on the technology adopted by the work, the copter is equipped with:
4) any of the equipment listed above
2 To crush the soil and mix it with inorganic or organic binders.
Precompacting and flattening the asphalt-concrete mixture.
1 For transportation of liquid bituminous materials from the places of their production or from storage bases to the place of road works and their uniform distribution.
Which temperature is maintained in the truck paver?
By which the temperature is maintained in the tank of the pile-driving hammer?
1 Special equipment, in the form of stationary burners, which is installed in the tank.
4) tank is made on the thermos principle
What do the heating burners in the truck asphalt mixer work on??
Amazing Mega Clearing Machines Caught in Action !
1 Distribution of material and obtaining of necessary thickness and width layer
2) Mixing crushed stone with binding materials
4) Transportation of crushed stone to the road construction site
Tools & Equipment Used for Clearing Land
3) Hydraulic and pneumatic. 4) With a hopper or with a tank.
What does a wheeled paver compactor consist of??
What are self-propelled pavers typically equipped with for movement?
The main advantage of wheeled road milling machines?
2 ability to work in confined spaces
4) Relative cheapness of the work performed
Bushcutters are used to clear areas of:
d) shrubs, small and large trees
The working body of the hedge trimmer is:
a) a wedge-shaped blade b) a blade with teeth at the bottom c) a bulldozer blade
a) grubbing up stumps b) clearing areas of large rocks and fallen trees
c) loosening dense soils d) all works listed above
The working body of the puller is:
The efficiency of the main ripper depends on:
a) pulling and traction properties of the base tractor b) number of teeth of the implement c) mass of the ripping equipment
What are the main features when classifying road construction machines:
Volume of the working body, type of drive, mass of the machine.
Designation of machine, overall dimensions, tractive force.
Pulling power, range of application, type.
You can leave a comment or report a mistake in the selected paragraph here.
An extension cord is required if you are working with an electric chain saw. Choose products with an earthing terminal. To avoid damage to the cord by the cutting elements of the tool, mow bushes with the mains cord over your shoulder. A safety disconnect device must be activated.
Trimming plants with electric shears is recommended only in dry weather. Not to be used in rain, as there is a high risk of electrocution. If you plan to operate in wet weather, give preference to models with a gasoline engine. These units are more resistant to moisture.
In the Non-Black Soil Belt, there are many fallow field and meadow lands overgrown with bushes and small woods.
Thickets of grey alder with small admixture of birch, aspen, willow and spruce are widespread on fallow lands and some types of meadow lands with normal and temporarily excessive moisture conditions with loamy and clay soils.
On meadow lands with the same soils but with more prolonged excessive moisture willow bushes forming continuous bushes or located in separate clumps prevail.
Juniper, birch, partly willow, gray alder, pine, and some other species often develop shrubs in highly ashy loamy and light loamy soils of normal and variable moisture.
Depending on the nature of the overgrown lands various mechanized methods of tree vegetation removal are used.
Cutting of grays alder, birch, aspen, willow and other tree species from 4 to 20 cm in diameter at the root neck is made by shrub shears D-174B and K-3,2.
The wood cut by the brush-cutter and uprooted individual trees are raked into windrows and piles by tractor rakes (brush-pickers) TGB-3 and GKN-3.
Brush cutters D-174B are attached to tractor C-80. These shrub shears are designed for clearing of land plots from bushes, small wood and hummocks. They are also used in the construction of firebreaks in forestry and forest clearings for high-voltage power lines and communication lines.
Shrub shear K-3,2 is designed for cutting of the bushes, small trees (with trunk diameter up to 20 cm) and bumps on the bogs and marshes. Is a detachable tool attached to tractor C-80 and consists of five basic units: working body, pushing frame, regulating device, lifting mechanism and safety guard.
Domestic industry also developed and manufactured shrub shears (two prototypes):
- First. a hinged shrub shearer active on tractor DT-55; working body of the shears at work to move apart and grasps part of a bush or a separate trunk, and at the moment of compression shears cut the tree stand and laid a small windrow on the ground;
- The second one is a hinged brush cutter mounted on DT-54 tractor; working body of the brush cutter is circular saws.
THGB-3 shrub picker is used in various agricultural works: shrub raking, clearing of twigs and deadwood from field and meadow grounds and collection of uprooted tree stumps into heaps.
Shrubbery clearing technology
Shrub clearing. Before starting the works to remove bushes we make a characteristic of the site. To do this, determine the following data: the species composition of the stand, the density of the stand, stand height and trunk diameter at the root, soil moisture, stumpiness and stoniness of the site.
Trunk diameters are measured at height.10-15 cm from the ground.
Stones and large stumps that may hinder the hedge trimmer’s work should be removed by the cutting machines or marked with milestones so that the tractor driver can bypass the obstacles in a timely manner.
By experience it was established that in summer time on sites overgrown with aspen, alder, spruce and birch trees with trunks from 4 to 15 cm in diameter, the shrub shear makes almost complete cutting of woody vegetation (up to 95%) with a single pass. The shrubs that remain uncut are crushed by the tractor’s crawler tracks and the shrub shear skis. The cuttings are placed on the ground in swaths on either side of the hedge trimmer.
Work in smaller shrubbery. the shrub shears only cut 60-65% of the bushes. one part is crushed by the tractor’s tracks and the other by the shrub shear. and then straighten out after the machine passes over the shrubbery.
In order to completely cut the shrubbery in such an area, you need a second pass of the shrub shear in the same place, but from the opposite side. Two passes over the same area will almost completely clear the hedge.
In the tractor’s second gear, the productivity of the unit is 0.9-1 ha/h at one pass, and at two passes over the same place. 0.6 ha/h.
Be careful when driving over ditches and swaths with the brushcutter; slow down the tractor when crossing the ditch.
The brushcutter blade must be free on the ground at all times while working The cable system must not be tensioned.
Before you start work on removing woody vegetation, you must determine the direction of the brushcutter’s passes. Plan as many passes as possible because excessive driving reduces the efficiency of the hedge trimmer and increases wear and tear on the tractor parts because of its frequent turns. It is therefore necessary to correctly set up the paddocks beforehand.
The shrubbery is cleared in a spiral fashion with gradual movement from the edge of the bush to the middle of the bush; after the last two passes it becomes more difficult to turn the machine and turns are made by shaped ploughing.
The main requirement for the quality of shrub shearing is to obtain a low and complete cut of trunks of woody vegetation.
The best quality of stand cutting is achieved in winter when the snow cover is up to 50 cm thick, when the trunks of shrubs and small woods are well fixed in the frozen soil. The hedge trimmer blades cut the trees well under these conditions.
Good shrub cutting in early spring, “when there is little snow on the field and the ground is still frozen.
In spring and summer (when the soil is very wet) the shrub shear blades deepen significantly, so they cut down trees with the soil, which makes it difficult for the shrub shearer to clean the cut vegetation afterwards. Besides, time is lost for tractor stops because of slipping and burying in the ground. Work becomes ineffective in such conditions.
It is established in practice that shrubbery should only be cut if it is possible to avoid subsequent uprooting and the remaining roots should be ploughed.
Cutting down trees followed by forced uprooting of stumps is not advisable. Shrubs should be cut if the diameter of trees in the bark does not exceed 15 cm. Trees over 15 cm in diameter should be mowed without preliminary cutting by D-210G grubber.
In order to obtain high productivity of the brush cutter tractor drivers. regularly perform knife pointing, timing it to coincide with the daily maintenance of the tractor in the morning and in the middle of the day.
MACHINES FOR PREPARATORY WORKS
Earthworks are preceded by preparatory works that include clearing of the future construction site of the forest, bushes and stones; removal of the vegetative layer, loosening of the ground; water drainage and dewatering. When performing preparatory work use brush cutters, rooters and rippers, as well as means of water drainage (pumps) and dewatering (needlefilters, airlifts and hydro-elevators).
Brush cutters are designed for cutting the above-ground part of bushes and shrubbery when clearing areas for construction and are the attachments to caterpillar tractors with drawbar category of 100 kN.
A distinction is made between hedge trimmers with a passive (rotary, fig. 5.3, а) and active (rotary, fig. 5.3, b, c) working bodies. The branch cutters could be mounted with mechanical (rope) and hydraulic control.
Figure. 5.3. Brush cutter tool diagrams
Bladed (passive) cutting unit hedge trimmer. double-sided wedge with flat, horizontal blades 1, set at an angle of 56. 60° to the direction of travel. Blades have smooth or saw-shaped cutting edges. As the clearing blades move, they cut the above-ground vegetation, wedge between the trees and allow the fallen vegetation to slide down sloping surfaces 3 and can be pulled out to either side. Front 2 The blade is additionally reinforced with a splitter for splitting tree stumps and reclaiming fallen trees. Shrubs and trees of small diameter (150. 200 mm) the hedgetrimmer cuts in one pass, but trees of 300. 400 mm cleaves and cuts from the opposite sides in 2-3 passes.
Rotary (circular) cutting head is a circular saw (cutter) 4 (see. Fig. 5.3, б) with cutting teeth attached to the end of the arm 5 or at the front of the tractor frame. Cutter is driven by tractor PTO or hydraulic motor. Cutter on arm can be positioned for cutting in desired plane and rotated by two hydraulic cylinders. A horizontal frontal cutter is covered with a horizontal sheet in front of the frame and a vertical steel plate is set at an angle to the axis of the machine to roll off the cut shrubs to the side.
Working body with rotating blades 6 (see “Rotary tool. cutter. disc cutter”). rice. 5.3, в) works the same way as a circular saw. Rotary cutting heads are capable of cutting tree trunks up to 300 mm in diameter.
Chain saws, circular saws, bulldozers are also used to remove trees from cleared areas.
The most common are hedge trimmers with a passive working body, which have a simple design and are more reliable in operation. Shrubbery productivity (area cleared of trees and bushes, m 2 /h)
where В. working width, m; vcp-average operating speed of the brush cutter including time loss for stops at turns and for speed reduction during slipping, m/s (vcp = (0,7. 0,8)v, here v is the nameplate value of the working speed of the brushcutter); п. number of passes on one track.
Stump pullers are designed to pull up large stumps, boulders, uproot parts of small forests, rake and shake them. They are attachments for crawler tractors or heavy duty wheeled tractors. Depending on the purpose of the working body distinguish pullers-gatherers and pullers-loaders, and from the place of installation on a base tractor. pullers of front and rear location.
Rake pickers Mouldboards are fitted with extensions that have nine tines, so they are better suited for shrub raking and pulling stumps and rocks into piles or swaths.
Currently, the most widespread are front-mounted puller-loaders based on tracked tractors class 30. 350 kN with power of 50. 390 kW.
The main components of the puller-picker (Fig. 5.4) are the moldboard 2 with teeth, pushing frame 1 and control system.
The blade is a lattice structure with slots for mounting teeth. Blades have both rigid mounts and articulated mounts. The moldboard in the picture is articulated, allowing for hydraulic cylinders to be used to lift and lower the tool 3 Turn the blade with the tines after digging under the stump; in doing so, the uprooting efficiency increases considerably. Hydraulic cylinders providing lifting and lowering of the pushing frame are operated by the tractor hydraulic system.
Backhoe loaders are equipped with a blade swing device and can load stumps and stones into vehicles.
Fig. 5.4. Mower-gatherer
Modern thinning machines remove stumps by pulling on roots with the pushing power of the tractor, while simultaneously applying vertical power from the blade-advancing and rotating cylinders. When uprooting, raking and transporting uprooted (or cut by brush cutters) wood, these machines move swaths and piles, a significant amount of soil. Since a lot of soil is left on the stumps and large undergrowth holes are formed, subsequent planning of the area is necessary.
The capacity of the uprooters is determined in the same way as for the brush cutter. When pulling up stumps, their hourly output is up to 45. 55 pcs., When removing stones. up to 15. 20 м 3. when raking cut trees, uprooted stumps and shrubs. up to 2,500. 4000 м 2.
Rippers are tractor or backhoe attachments designed for loosening hard, stony, and frozen soils in layers. Static rippers enable the use of small excavators for strong soils, significantly increase productivity of more powerful machines, and significantly reduce the cost of work.
rippers are also used for ripping covers in road repair, construction of water and gas pipelines.
Static ripper (figs. 5.The first implement consists of a beam 8 1 (see Figure 5) that loosens the soil layer by layer and is a bolt-on tool that is mounted at the rear of the tractor 2. Bulldozer equipment is attached at the front of the tractor 1 (see Fig. § 5.3). The first working body consists of a beam 6, weather vane 8 (one to three) and the tines mounted on them, consisting of struts 9 with interchangeable tips 10. The ripper equipment is suspended from the frame 3 and traction 4. Frame, drawbar and beam form a parallelogram system ensuring a constant cutting angle at varying ripping depths. Working body is controlled by hydraulic cylinder 5 from the tractor hydraulics. To be able to work with a tractor-pusher, a removable buffer device 7 is mounted on the middle vane.
The teeth are driven into the ground to a given depth by forced pressure created by a hydraulic cylinder at the progressive movement of the machine. Further machine movement causes loosening of the soil.
Fig. 5.5. Static ripper with dozer blade
ripping can be performed according to two technological schemes: without turning at the edge of the site with return of the machine to initial position in reverse (shuttle circuit) and by turning the ripper at the end of each pass (longitudinal-turning scheme). Chain-and-turn scheme is the most rational at small amount of work in cramped conditions, longitudinal-turn. on the sites of a long distance. Maximum ripping depth is determined by the drawbar class of the base machine and ranges from 0.45. 1,2 м.
For tractors with hydro-mechanical transmissions the working and back travel speeds are vp = 1,7. 3,2 km/h, yh = 7,5. 14,5 km/h; for tractors with mechanical gears vp = 2,35. 3,2 km/h, v3x = 7,5. 8,5 km/h.
Operating capacity of static ripper (m 3 /h)
where b. average width of ripping strip at one passage with multitooth working body or between two adjacent passes with single-tooth working body, m h. average ripping depth in given soil conditions, m L. loosening path length, m; kv. factor of machine use in terms of time; Hz. cycle time, s.
At excavation by longitudinal-turning passes with turning at the ends of area
where /n, t. time required for turns and control of the machine within working cycle, s; v. v3x. speeds of working and return back passes, km/h.
Impact rippers. is an attachment mounted on a tractor or single-bucket excavator. The most common type of striking tool is a free-falling wedge-, cone- and pyramid-shaped hammer with a mass of 0.5. 4,0 т.
Hammer wedge is suspended to the hoisting rope of the hoisting friction hoist of the jib crane or the single-bucket mechanical excavator with a crane arm, pulling up to the jib head with a hoist winch and thrown from a height of 6 m. 8 м. The free falling hammer wedge strikes the ground non-directionally, reducing the quality of the work and making the process more energy intensive.
The most effective are percussion rippers, where the scraper moves in a rigid guide (Fig. 5.6). The working body, a wedge, is attached to the hammer 4, which is mounted in the guide 2 and suspended on a pulley 1. Air guide at top connected to excavator boom by pin, below connected to tracker rail 3 with shock absorber.
Chain block is actuated by a hydraulic cylinder whose dimensions allow the hammer to drop freely. Lift the hammer with the hydraulic selector lever in the “Lift” position. After extension of the hydraulic cylinder rod with blocks of the chain block and raising the hammer to a permissible height the lever of the hydraulic control valve is switched to the “Reset” position, when the hammer freely falls and strikes the ground with the working tip.
There are other designs of rippers with percussive action, for example with the use of hydraulic and pneumatic hammers, hanged instead of a bucket on the backhoe handle of an excavator. Use of hinged pneumatic hammers as replaceable work equipment
Fig. 5.6. Impact ripper
in single-bucket hydraulic excavators does not require modification of the base machine design. Workers in two for 10. 15 min can install a pneumatic hammer instead of a bucket.
Air hammers have a simple design and consist of three main assemblies (Fig. 5.7): the tool fastening assembly, the striker mechanism with the air distributing device, the assembly of automatic starting of the air hammer in operation. The design of all air hammers is essentially the same, the only difference being their overall dimensions and weight (350. 500 kg).
Fig. 5.7. Air hammer
The striking part of the air hammer consists of the barrel 3, in which under the action of compressed air (operating pressure of 0,6 MPa) the hammer 4 performs a reciprocating motion. Air supply to the barrel is controlled with a three-stage spool
In the pneumatic hammers a wedge or a spade is installed in the box as a working tool 2 a wedge or a spade is installed in the box.
To start the pneumatic hammer it is necessary to push it against the material to be broken, as a result the starting valve opens and the pneumatic hammer is put into operation. Air hammers are supplied with compressed air by mobile compressor stations with a capacity of 10 m/min or stationary air networks. Technical capacity of pneumatic hammers per 1 hour of operation is 16. 22 m 3 of the crushed rock. Compared to foreign machines, Russian hinged pneumatic hammers have 1.5-2 times higher impact energy (1300 Joules) at a metal intensity which is 2-2.5 times lower. 2400 J).
Hydraulic hammers are currently in great use due to the widespread use of hydraulic excavators for ripping frozen ground and destroying hard pavement.
The hydraulic breaker is powered directly from the excavator hydraulic system, which provides better use of installed power and lower operating costs. Compared with pneumatic hammers, hydraulic hammers provide higher impact energy (up to 9000 J). Besides, an excavator with a hydraulic hammer is more mobile.
All Russian breakers are designed according to a single principal scheme and are unified with each other by a switchgear (fig. 5.8). The breaker with the working tool is attached to the excavator arm and its hydraulic cylinders.
The breaker is lifted by a boom cylinder, while the arm cylinders are used to rotate the breaker and set the desired inclination. A single operator can replace the breaker with a stick and a bucket in 1.5 hours. 2 ч.
There are also different vibratory ripper designs in the form of a vibrating wedge, a shovel-type vibratory bucket, etc. Most ripper machines are very energy intensive in frozen ground and have to be used only when they are applied to relatively weak soils.
When operating percussion machines it should be borne in mind that their operation generates significant dynamic loads that are detrimental to both the base machine and nearby structures and utility lines.
Dewatering and dewatering is performed by pumping water out of excavations or artificially lowering the water table with the help of needle-filter systems, airlift or hydro-elevator.
Drainage pumps are subdivided into diaphragm pumps, centrifugal pumps and piston pumps.
Diaphragm pump (Fig. 5.9, а) consists of the body 1 with suction branch pipe 8, cap 4 с diverting nozzle 3, rubber diaphragm 6, attached to the cap 5, suction 7 and discharge 2 valves. The shroud moves up and down in a reciprocating motion from the drive. As it rises, the diaphragm flexes upwards, the discharge valve closes, vacuum is created in the housing, the suction valve opens and the liquid is sucked into the pump housing. When the bell moves back, valve 7 closes and valve 2 closes 2 opens and water flows into the outlet pipe. The pump drive can be manual, with a combustion engine or an electric motor. The suction height of diaphragm pumps is up to 6 m and the suction capacity is 30. 45 m 3 /h.
Figure. 5.9. Diagrams of dewatering pumps
The centrifugal pump (Fig. 5.9, б) is an impeller 4, installed in the casing 3, having a suction 2 and pressure line 5 of the mowing line. The rotation of the wheel creates a vacuum in the pump suction line which sucks the water into the suction pipe and pumps it first into the discharge connection and then into the discharge hose 6. In order to prevent larger mechanical particles from entering the pump there is a strainer at the suction hose end 7.
Centrifugal pumps are divided into one-stage and multistage by the number of impellers, and by the head created. into low-pressure (up to 0.2 MPa), medium-pressure (0.2 MPa), medium-pressure (up to 2 MPa). 0,6 MPa) and high-pressure (over 0,6 MPa). Main features of centrifugal pumps: Suction height up to 7 m, delivery rate 24. 250 m 3 /h.
Piston pumps, which are used for pumping heavily polluted water, provide a large suction height and do not require priming before operation.
Needle filter unit (Fig. 5.10) consists of several needle filters 7 submerged into the ground to a depth of 6-8 m and a water collector. 8 m, a drainage collector 2, vortex self-priming pump 3 and electric motor 4. To immerse the needle filters into the ground the method of underflooding with a stream of water supplied at pressure through the filter is used. Needle filters are placed at a distance of 0,75. 2 m one from another and with the help of rubber reinforced hoses connect to the water collector. When the pump is running, water is sucked out of the ground and flows into the water collector, from where it flows by gravity
Fig. 5.10. Needle filter unit
goes into the receivers or is discharged into the sewage system. Suction height of the air needle filter unit is not more than 6 m, and productivity up to 100 m3 /h.
When developing flooded pits with a water level of more than 3 m airlifts and hydro-elevators are used.
Earlifts. Air-water lifting devices (Fig. 5.11, а); despite its comparatively low efficiency (up to 36%), it has several advantages: simple construction, reliability and continuous operation. Compressed air or gas at up to 0.3 MPa is forced through a gas pipe 1 into the liquid pipe 2, where emulsion is formed. mixture of air or gas with water. Water is carried upward by air or gas bubbles. Working pressure of air or gasр (MPa) is numerically equal to р = 0,01 (H- I), where Н- minimum immersion depth of the mixing chamber, m; h. height of pulp lifting, m.
Fig. 5.11. Schematics of erlift (a) and hydro-elevator (b)
Hydro-elevator (Fig. 5.11, б) draws in pulp under vacuum produced by high-speed running of water stream through the holes of mixing chamber. Hydro-elevator held by a rope 6, is lowered by the crane onto the loosened ground to be excavated and the suction shoe is cut into it by the toothed crown 3. Through the pipeline 7 under pressure not less than 0,4 MPa water is supplied. Water passing through the slurry pipe 5 creates vacuum inside the ejector 4, providing suction and lifting of the slurry through the slurry pipeline. At a water pressure of 0.4. 0,8 MPa suction height reaches 1. 1.5 m discharge, 6. 7 м. The feed of hydro-elevators and airlifts at the development of sandy loam soil is 5. 20 m3 /h at a pulp saturation of 5. 20%.
How shrub shears differ from mowers?
The cutting tool of mowers is optimized for cutting grass and small shrubs, so the main types of these tools are:
The cutting tool of shrub shears is optimized for cutting branches, so the main types are:
Sabel-shaped cutter is a variation of the rotary cutter, only instead of small blades fixed on a large disc, it has long blades that cut branches effectively, but not too well grass.
Circular saw, as the name implies, is a circular saw with differently shaped teeth, thanks to which it can extremely badly cope with grass, but easily cuts not only branches, but also trees.
The helicoidal rotor is similar to the cutting tool of a hand-held mechanical mower, but thanks to the large mass of the knife with a sharp edge and the enormous torque, it cuts even thick branches. For mowing grass such devices are rarely used in Russia because of their high cost.
Often manufacturers or sellers call mowers shrub cutters, hoping that this will increase the demand for them, so when choosing such a device, be careful. the shrub cutter can not mulch and qualitatively cut the grass, and the mower does not cut thick branches of bushes or trees.
Features and types of brush cutters
Work in the cottage and in the countryside is in many cases complicated by a large number of small bushes. Knife and secateurs are already labor-intensive to use against them, and saws (conventional, gasoline, electric) are extremely inconvenient. Specialised equipment is helpful, but you need to know how to use it correctly.
Features of handheld shrub shears
Handheld shrub shears are ideal for cutting low shrubs and young fruit trees. The tool is indispensable for forming hedges and carrying out decorative pruning of some conifers. If you do not have many trees, there is no need for electric or cordless pruning shears.
Surely many will like the idea of working with their hands in the fresh air and bring beauty and order to their area.