Данилова_Английский_язык_Пособие134_copy

conveying. Items that are too small, too large, too heavy, too light, or too awkwardlyshapedmaynotconvey,ormaycausemanyproblems including jams,excesswearonconveyingequipment,motoroverloads,beltbreakage, or other damage, and may also consume extra man-hours in picking up objectsthatslippedbetweenrollers,ordamagedproductthatwasnotmeant for materials handling.

Drive Train: Parts of the drive trainshould bekeptinproper shape. Lossof power to even one or a few rollers on a conveyor can mean the ineffective and timely delivery.

Bad Belt Tracking or Timing: Regular inspection should be made to check if all belts are travelling at the proper speeds at all times. While usually a computercontrols this, anybelt notcontrolledmustbe monitoredtoensure accuracy and reduce the likelihood of problems.

Exercise 6. Translate Text C with a dictionary and make grammar analysis:

Text C

PUTZMEISTER TELEBELTTB110

1.In the construction business most contractors have to save as much time and labor as possible. 2. So, when time is short and spaces are small, you might want to use the PutzmeisterTelebelt TB 110 conveyor by L. Guerini Group, Inc.

3. Outfitted with elephant trunk with a discharge end that places back-fill easilyintotightareas,thismobile,high-capacityconveyorsystemcaneasily changefromonematerialtoanotherwhileprocessinggravel,crushedstone, concrete, flowable fill, mulch, loam, and other materials. 4. Used with a radio remote control that positions the unit on-site, the feed is lowered to

the desired position and the main boom is located over the work area.

5.The machine is so efficient that job times can be cut in half.

6.Luigi Guerini founded this business in 1917 as a construction trucking companybutinthelate’40sLuigiintroducedthefirsthydraulicbackhoeto the Boston area, thus expanding the business to include excavating. 7. In 1965, the second generation, Andrew and Richard Guerini, were ready to expand the business by acquiring mobile hydraulic cranes, and in 1969 the brothers ventured into an industry by purchasing their first concrete pump.

8.Today,the thirdgenerationof the familycarries onkeepingpace withthe newesttrends inconstructionequipment technology,the latestintroduction of the Putzmeister Telebelt Line having proved their position as industry innovators.

9.Bob Magliozzi tells about two projects that have involved the Telebelt.

10.“One project completed last April involved our Telebelt for moving materialintoaconstructionsite,”Magliozzisaid.11.“WeworkedforJames Flett Co. and cut days off of their very tight schedule by quickly and efficiently placing the material to grade over a maze of electrical and plumbing fixtures. 12. The conveyor was able to get right in there and get the job done.” 13. Magliozzi said that the Telebelt had been moved to a projectat theCollicott School inMilton, Mass. 14.“The contractor andhis site work had the problem of getting gravel fill into the gymnasium area of the new elementary school,” Magliozzi said. 15. “The only access was a 3-foot passdoor,andthiswouldhavebeenatime-consumingprocessonaprojectthat hadtobecompletedbythestartoftheschoolyearattheendofAugust.16.The Telebeltwasabletoconveythematerial,whichinthis casewasgravel,through a window opening and into the desired area, and the contractor saved several days as all the required material was placed in one day.”

1.Superlative degree; modal verb.

2.Modal verb; Infinitive (function).

3.Noun groups; meaning of “-s”.

4.Passive Voice.

5.Modal verb; Infinitive (function).

6.Ing-forms; ed-forms.

7.“Were” (function); Gerund( function).

8.Degree of comparison of the adjectives; Absolute Participle Construction.

9.Predicates (tense).

10.Gerund (function); ed-forms.

11.Adverbs.

12.Modal verb.

13.Predicates (tense).

14.Noun groups ; Gerund (function).

15.Have (function); would (function).Subjects and predicates (tense).

16.“Was” (function); Participle II (function); Infinitive (function).

42

Unit 7

Grammar: Complex Sentences.

Text A

CONCRETE MIXER

Part I

A concrete mixer is a device that homogeneously combines cement, aggregate such as sand or gravel, and water to form concrete. A typical concrete mixer uses a revolving drum to mix the components. For smaller volume works portable concrete mixers are often used so that the concrete can be made at the construction site, giving the workers time to use the concrete before it hardens.An alternative to a machine is mixing concrete or cement by hand.

Industrial mixers Today’s market increasingly requires consistent homogeneityandshort mixingtimes forthe industrialproductionofreadymix concrete. This has resulted in refinement of mixing technologies for concrete production. Different styles of stationary mixers have been developed, each with its own inherent strengths targeting different parts of the concrete production market. The most common mixers used today fall into3categories:Twin-shaftmixers,VerticalaxismixersandDrummixers Twin-shaft mixers are known because their mixing intensity is high, and therefore mixing times are short. These mixers are typically used for high strength concrete, typically in batches of 2–6 m3 (2.6–7.8 cu yd).

Vertical axis mixers are most commonly used for precast and prestressed concrete.This style of mixer cleans well between batches, and is preferred for smaller batches (typically 0.75–3 m3 or 0.98–3.9 cu yd), and multiple dischargepoints.Withinthis category,thePanmixers arelosing popularity to the more efficient Planetary (or counter-current) ones as the additional mixing action helps in production of more critical* concrete mixes.

Drummixers (reversing drum mixer and tilting drum mixers) are usedwhere large volumes of concrete are being produced (batch sizes of 3–9 m3 or 3.9–12cuyd).Thistypeofmixerdominatestheready-mixedmarketas it is known to be capable of high production speeds, and where overall cost of production is important.

All three types of mixers which have their own inherent strengths and weaknesses are used in the construction industry.

*зд. нормируемый

43

Part II

Concrete mixing transport truck Special concrete transport trucks are made to transportandmixconcrete up to theconstruction site.Theycan be charged with dry materials and water, the mixing occurring during the transportation.Theconcretemixingtransporttruckmaintainsthematerial’s liquid state through agitation, or turning of the drum, until the delivery is accomplished.

The interior of the drum on a concrete mixing truck is fitted with a spiral blade. In one rotational direction, the concrete is pushed deeper into the drum. This is the direction the drum is rotated, while the concrete is being transported to the building site.When the drum rotates in the other direction, the screw-type arrangement discharges, or forces the concrete out of the drum. From there it maygoontochutes toguide the concrete directlytothe jobsite.If the truck cannot get close enough to the site to use the chutes,the concrete may be discharged into a concrete pump, connected to a flexible hose,orontoaconveyorbeltwhich can be extended some distance (typically ten or more metres).

Apump provides the means to move the material to precise locations. The drum is traditionally made of steel although fiberglass has been used on some newer trucks in order to reduce the weight.

Rear discharge trucks require both a driver and a worker who guides the truck and chute back and forth so that the concrete may be placed in the manner suitable to the contractor.Newerfrontdischargetruckshavecontrols inside the cab of the truck, which allows the driver to move the chute in all directions.

Concrete mixers are equipped with two or more axles. Mixers commonly will have multiple steering axles as well, which generally results in very large turning radii.

Tractor trailercombination mixers where the mixer is installed on a trailer instead of a truck chassis are sometimes used. Concrete mixers generally do not travel far from their plant, as the concrete begins to set as soon as it is in the truck. Many contractors require that the concrete should be in place within 90 minutes after loading. If the truck breaks down or for some other reason the concrete hardens in the truck, workers may need to enter the barrel with jackhammers; dynamite is still occasionally used to break up hardened concrete in the barrel under certain circumstances.

Trucks weigh 20,000 to 30,000 pounds (9,070 to 13,600 kg), and can carry roughly 40,000 pounds (18,100 kg) of concrete although many varying sizes of mixer trucks are currently in use.The mostcommontruckcapacity is 8 cubic yards (6.1 m3). Most concrete mixers in the UK are limited to a speed of 56 miles per hour (90 km/h).

Active Vocabulary:

Exercise 1.Answer the following questions:

1.What does a mixer use to mix components?

2.What main types of industrial mixers are there?

3.Why are mixing times of twin-shaft mixers short?

4.When are vertical axis mixers preferred?

5.Why do drum mixers dominate the ready-mixed concrete market?

6.When does mixing occur in concrete transport trucks?

7.What does a pump provide?

8.What is the difference between rear and front discharge trucks?

9.Why can’t concrete mixers travel far from their plants?

Exercise2.AnalyzethesubordinateclausesunderlinedinTextA,define their types and the forms of their predicates.

Exercise 3. Translate the following sentences paying attention to attributive clauses:

a)without a conjunction:

1.The type of construction sites you are typicallyworking at will affect the amount of traction you require.

2.Aframe the barrel has is welded to the chassis rails, a single 11 5/8- inch frame being suitable.

3.The weight mixers have is very critical, because you have to save a lot to be able to haul an extra half-yard of concrete.

4.Another thing you should remember is air filtration.

b) with different meanings of “which”:

1.It is important to do the research in order to purchase the right piece of equipment which will meet your needs and do the job efficiently and cost-effectively.

2.Some states require compliance (согласие) with the Federal Bridge Formulaand othersdon’t,which willhaveabiginfluenceonhowthe axles of a mixer are set up and spaced.

3.Depending on the weight which is carried by the steer axle and the laws in your state, you may also need to use wide-based front tires.

4.Therearemixerconfigurationswithactivetire-pressurecontrolsystem whichallowsthedrivertoreducetirepressurewhentheyareoff-road to get the traction which is necessary in the sand.

5.Big horsepower is not a requirement for mixer applications, which means that generally 320 horsepower to 350 horsepower is enough for most applications

6.With the electronic controls on the newer automatics, the shifting is very smooth and responsive, which reduces stress on the drivetrain, and the truck can keep up in traffic much easier.

7.Such components as wheels, air tanks and clutch housings which are made in aluminum rather than steel reduce the weight of a mixer.

8.The shorter drill pipe also allows amuchsmaller mast, which gives a smallerandlighterrigwhichischeapertoshipoverseasandcanfitin a standard 20 foot (6.1 m) shipping container.

Exercise 4. Translate Text B without a dictionary and make questions to the text:

Text B

PETERBILT 382:AN EXCELLENT MIXER

Customers order lots of concrete at less than what producers consider full loads,soitmakessensetohavetrucks thatcandeliverthematalowercost. Forthis,truckbuildershave“Baby8”models:Class8chassiswithmidrange engines. One of the latest is this Peterbilt 382 that, like a growing number of competitors, uses Cummins’ ISL9 diesel.

The382 is an aerodynamicallystyled model that looks a lot like Peterbilt’s medium-duty conventional mixers. It debuted as a local and regional road tractor about the time that EPA-2010 diesels were adopted. Now it can be builtwithvocationalspecificationstohandlejobssuchasconcretedelivery. Amongotherthings, itsaluminumcabhasextrastructuralmemberstotake the twisting and shaking inherent in off-road running.

Ofcourse,acustomerneedingmoreweightcapacitywouldstilluseaModel 365, 367 or even a 388 or 389 with vocational components. But this 10wheel 382 with its 66,000-pound vehicle weight is ideal for lighter work. By now it should be available with one or two factory-installed pusher axles, not to increase GVW (gross vehicle weight), which is imposed by Cummins due tothe engine’smoderate size,but tobetterdistribute weight. The8.9-literISLdieselengineisbasedontheISC8.3andcanhandleheavy- duty stresses. It easily fits under the 382’s hood and is the only engine available in this model, except that the natural gas-burning ISL-G has just been added.

Although the 382 is compact, its chassis components caused the cab to sit high, so there are three well-placed steps and enough hand rails.

Inside, grey plastic panels cover most surfaces. Small gauges, nice-sized rocker switches, and rotary switches for headlamps and heater and air conditioning controls are all nicely laid out and easy to use.

The windshield is made of two pieces, a perfect design that limits damage when stones get intoone side orthe other.The viewthrough it andoverthe

sloped hood is good. Nice-size glass is also in the doors and the cab’s rear wall. Rear corners had curved glass windows that complete a 360-degree view, except of course to the rear where the barrel is. As with any mixer truck, there’s a big gap between cab and barrel that aids visibility to the right-rear.

Thesteeringispreciseandhasanicefeel,andthetruckisabletomakevery tight turns, even with thebig 425-series front tires.This allows the truck to easily maneuver on city streets and job sites.

Exercise 6. Translate Text C with a dictionary and make grammar analysis:

Text C

TEREX MIXER SHOWS COCEPT’SADVANTAGES

1.Front-dischargeconcretemixershavebeenaroundformorethan40years, but they are not used in many markets so they might seem foreign to many peopleintheconstructionbusiness,thoughtheygivespeedandproductivity that contractors and workers appreciate.

2.Terex’s basic modelis called FD3000 and is said tobe verypopular with customers and an easy truck to drive. 3. On the three-section instrument panel, gauges are to the driver’s front and left, and most controls are to the right, all being well laid out and easy to use. 4. Power windows are among the standard features of the cab, and this one had air conditioning as well. 5.Thecabiswideenoughforasecondfold-uptypeseat,tothedriver’s left, which allows a driver-trainer to ride along and give instructions to a new driver, and closely watch what he is doing. 6. With the previous narrow cab, one or the other had to get to the jobsite in a separate vehicle.

7. Good visibility, decent maneuverability and theAllison automatic make the truck easy to drive, but are also important to its delivery role. 8. If you have seen one of these working, you know that a front-discharge mixer drives right up to a pour site and quickly begins off-loading. 9. The driver gets out to attach extensions to the chute, then returns to the cab to control the hydraulically powered chute and drum. 10. With a control lever, he raises and lowers the chute and swings it left or right, while moving the truck to keep the end of the chute properly positioned. 11. He speeds and slows thedrum with a foot pedalnext to thesteeringcolumn. 12.Amanual transmission with its clutch pedal and shift lever would add considerable clumsinesstotheoperation,sotheAllisonisakeycomponent.13.External controls, either mechanical or electronic, with a hand-held remote, allow someone of the crew to run the chute if he wants to, and the driver uses them to wash out the chute and funnel.

14. Driver operation of the chute means the contractor can eliminate one manfromhiscrew.15.That andthespeedof thepoursavehimmoney,and he and other contractors begin demanding their concrete to be delivered this way. 16.This is whyfront-discharge mixers became popular in certain markets,mostlyintheMidwest,NortheastandFlorida(and,ofcourse,Salt Lake City), but not in most others, where producers have so far avoided them. 17.Partlybecause of theAllison, a front-discharge mixer costs more than a conventional mixer truck does. 18. Because a front-discharge mixer unloads fast, it can usually haul one extra load in a work shift, helping to pay off its cost.

1.Subjects and predicates (tense); types of subordinate clauses.

2.Possessive case; Complex Subject.

3.Absolute Participle Construction; “be” (function).

4.One (function).

5.Complex Object; “is” (function); meaning of “s”.

6.Modal verb.

8.Conditional sentence.

9.Infinitive (function).

10.It (function); ing-form.

11.Conversion.

12.“Would” (function).

13.Complex object.

to a smooth material transportation through the paver with less segregation andexcellentpavingresults.Dynapacintroducesalargenumberoffeatures to the new F-series and SD-series to make service and maintenance quick andeasy,ensuringmaximumavailabilityof thepaverswithlessdowntime. Service is made simple by many effective designs, such as concentrating pumpstooneside.Thetotalnumberofhydrauliccouplingshasbeenreduced significantly. This also reduces the risk of leaks.

Designed for high productivity on demanding city roads and highways, two new medium class, tracked pavers – the SD115C and SD135C – offer maximizedoperator efficiency, highlaydownproduction ratesofupto750 t/h, increased fuel efficiency and reduced engine and fan noise. The new tracked pavers offer a basic width of 2.50 – 3 m depending on the model and mode which, when equipped with the hydraulic extendable screeds, provide a working width of up to 6 m. This can be increased further with extension boxes to 8 – 10 m, again, depending on the model.

To offer increased operator comfort and efficiency, the driver’s seat can be easilyturned45є, providingthedriver withanexcellentunobstructed view intothehopper,theaugercompartment,screed,laneindicatorandunloading lorry, withoutturninghis head. Onecaneasilyslide, pivot and lockseats in everyposition.Featuringanewlydevelopedcontrolpanel,allfunctionkeys are arranged according to the function group and frequency of operation, i.e.frequently-usedfunctions,often-usedandseldom-usedones.Allbuttons are raised and waterproofed, allowing safe operation even without the operator needing to look at the keyboard.

The new SD Series retains many well proven features of Dynapac pavers such as the auger with a smaller inner drive unit ensuring no material segregation. Other features include the patented screed system with four guiding tubes, excellent traction even on unbound surfaces and no reinforcement of the screed.

Exercise 1.Answer the following questions:

1.What is the main objective of the paver?

2.What basic parts does the paver need to do its work?

3.What are electronic and hydraulic systems used for?

4.How can sufficient compaction be provided?

5.What factors are necessary for producing a satisfactory asphalt mat?

6.WhatarethemostremarkablefeaturesofnewDinapactrackedasphalt pavers?

7.How is service and maintenance made quick and easy on new F and SD series?

8.How can operator comfort and efficiency be increased?

9.WhatwellprovenfeaturesofDynapacpaversdoesthenewSDSeries retain?

Exercise 2.Analyze the functions of the words underlined in TextA.

Exercise 3. Translate the following sentences paying attention to the functions of “one’ and “that”:

1.Two boom types in one concrete pump give contractors maneuverability and compact travel.

2.The company’s RZ boom design combines the Roll and Fold boom withaZ-fold one tooffera five-sectionunitwith918 degrees of total articulation.

3.Thosesmall andportable drillingrigs are usedin mineral exploration drilling.

4.Onecandoinfrastructurework,lightcommercialprojectsandbridges using this type of a paver.

5.The smoothness specifications in today’s contracts require that the paving process should be as continuous as possible to eliminate the stopsandstartsthatcansoeasilyjeopardize(подвергатьопасности) the level mat surface.

6.In fact, that requirement may influence the practical definition of a “highway class” paver.

7.Thatthesystemcombinesalasersensorwithanultrasonicsensorand tilt control improves the efficiency of asphalt pavers.

8.Among the newest types of control systems are non-contacting ones that can measure the distance to a grade reference with lasers and sonic sensors.

9.Some of the greatest advances in recent years have been not in the design of the paver but in that of its control systems that monitor grade and slope.

10.Thatrubber-tiredmachineshavebeenpreferredforresurfacingwork is due to the fact that they are less inclined to damage existing road surfaces.

11.The average consumption of fuel per hour is significantly less than that of comparable competitors’ machines.

12.The advantage of direct push technology is that in the right soil type itcanproducealargenumberofhighqualitysamplesquicklyandcheaply.

13.It is because of deviation (отклонение) that drill holes must be surveyed.

Exercise4.TranslateTextBwithoutadictionaryandmakequestionto the text:

Text B

VOGELE SUPER 700ASPHALT PAVER

The 11,700-pound Super 700 asphalt paver from Vogele is a compact machine with a track of 3 feet 7 inches and clearance width of 4 feet. The electrically heated screed paves widths from 20 inches to 10 feet 6 inches. The screed allows paving up to within 2 inches of obstacles such as walls, trees,andcurbs.Eachpartofthe5.5-tonhoppercanberaisedindependently, and there are three individual, reversible drives for the conveyor and each auger.TheSuper700ispoweredbyaliquid-cooledDeutzdieselratedat57 horsepower. Schwing’s new S 43 SX pump is the first one to utilize two boomtypesinonemachine.Thetwoboomdesignstogetheroffermaximum boom maneuverabilitywith a compacttravel position. Operators have a lot of options for placement concrete up to 138 feet 8 inches vertically, and 125 feet horizontally. The reach and the relatively low profile mean the pumpcanworkabout 140feetawayfromthepourarea andbelowfloorsor obstacles above. A slewing range of 740 degrees adapts to many job site requirements. Its pipeline is 5 inches. Schwing’s Super X outriggers are designedtobecompact,withafastset-uptime.Thesecurvedfrontoutriggers telescope out and around obstacles, allowing placement of the pump as close to the pour area as possible. The S 43 SX requires a 27-foot 1-inch outrigger spread (the spread is the same, front and rear) for maximum stability. The standard Schwing Vector Control features twin joysticks for proportional boomcontrolandaccuracy. Inaddition,Vectorisalso the only

systemprovidingtwo-waycommunicationbetweenthepumpandoperator. Here’s how it works: a display on the remote box informs the operator of operational conditions, including: hydraulic pressure; PTO rpm; strokes per minute; hydraulic oil temperature; and hopper grate status. The “Generation 3” concrete pump is a low-maintenance, 213-cubic-yard-per- hour unit that provides long action. An open circuit design provides continuoushydraulicoilflowforfuelefficiency,filtrationandcooling.The S 43 SX candoinfrastructure work,lightcommercial projects andbridges. Inconjunctionwiththe5-inchpipeline,contractorscanperformhigh-volume pours orprovide a slowdelivery withinfinite volume control.A160-gallon water tank on the unit helps with clean-up at the yard or on the job site.

Exercise 6. Translate Text C with a dictionary and make grammar analysis:

Text C

ASPHALT MILLING MACHINES

1.Asphalt millingmachines have been aroundfor over30years. 2.Asphalt milling is the process of grinding up asphalt that can then be recycled. 3. Theprocesscameaboutbecausemanystreetsweregettinghigherandhigher on curbs, and therefore drainage of the roadway was becoming an increasingly bad problem. 4. The first production milling machines were called Galions after their manufacturer, Galion IronWorks, and resembled graders in shape and size. 5. They differed as there was a 30-inch-wide (760 mm) milling head where the scraper blade would normally be. 6.The cutter drum was set into action by a rather large hydraulic pump.

7.Today’sasphaltmachinesaremuchlargerandtheyalsohaveanelaborate conveyor system which reduces the labour of picking up the material from theroadway.8.Withmanynewtypesofasphaltaggregatesinusetodaythe asphalt cold milling machines are often used. 9. These new production machines are designed to tackle any mix design. 10. Some of the larger

machines,dependingon the depthof the cut,can cut close to15,000square yards (13,000 m2) a day, at 75 feet per minute.

11.A cold planer (also known as a pavement planer, pavement recycler, asphalt milling machine or roto-mill) is a construction machine used to removebituminouspavementorasphaltconcretefromroadways,resulting inasomewhatrough,evensurfacethatcanbeimmediatelyopenedtotraffic.

12.This is accomplished by bringing a rotating mandrel or “head” into contact with the pavement at an exact depth or slope. 13. The mandrel has hundreds of hardened spikes on its surface to bite and tear away at the roadway’ssurface.14.Thesurfacematerialthatisremovedisnormallyfed by conveyor into a dump truck or semi-trailer, but can be left in place or windrowed to be removed at a later date or recycled. 15. A water spray system provides cooling for the mandrel, as well as dust management.

16.An asphalt milling machine being a complex unit, operating it requires specialized training. 17. Typically newer machines require two or more people to operate them safely and efficiently, the operator standing on the deckofthemachineandcontrollingmostof themachine’s functions,while another persononthegroundcontrolsthedepthofthe cutandkeepsaneye out for obstructions in the roadway such as manholes and/or water valves.

1.Predicate (tense).

2.Gerund (function); “be” (function).

3.Participle I (function); Comparative degree.

4.Ed-forms.

5.“Would” (function).

6.Noun group; Participle II (function).

7.“S” (function); ing-form.

8.Noun group; ing-form.

9.Noun groups.

10.Comparative degree; modal verb.

11.Participle I, II (function).

12.Ing-forms.

13.Infinitive (function); “-‘s” (meaning).

14.Passive Voice.

15.Noun groups; Gerund (function).

16.Absolute Participle Construction; gerund (function).

17.Infinitive (function); Absolute Participle Construction; adverbs;

Possessive case.

Unit 9

Grammar: Polysemantic Words.

Text A

CRUSHER

Part I

A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust. Crushing devices hold material between two parallel or tangent solid surfaces, and apply sufficient force to bring the surfaces together to generate enough energy within the material being crushed.

Crushers are commonly classified by the degree to which they crush the starting material. Primary and secondary crushers handle coarse materials, tertiaryandquaternarycrushersreducingparticlestofinergradations.Each crusher is designed to work with a certain maximum size of raw material, andoftendeliversitsoutput toa screeningmachinewhichsorts anddirects the product for further processing. Typically, crushing stages are followed by milling stages if the materials need to be further reduced.

In operation, the raw material of various sizes is usually delivered to the primarycrusher’shopperbydumptrucks, excavators or wheeledfront-end loaders.Afeederdevicesuchasanapronfeeder,conveyororvibratinggrid controlstherateatwhichthismaterialentersthecrusher,andoftencontains a preliminaryscreeningdevicewhichallowssmallermaterialtobypassthe crusher itself, thus improving efficiency.

Some crushers are mobile and can crush rocks as large as 60 inches. These units are able to move with the large feeding machines (mainly shovels) to increase the tonnage produced. In a mobile road operation, these crushed rocks are directly combined with concrete and asphalt which are then deposited on to a road surface. This removes the need for hauling oversized material to a stationary crusher and then back to the road surface.

Part II

There are several types of crushers Jaw crusher

A jaw or toggle crusher consists of a set of vertical jaws, one jaw being fixed and the other being moved back and forth relative to it by a cam or pitmanmechanism.The jaws are fartherapartatthe topthanat the bottom,

forming a tapered chute so that the material is crushed smaller and smaller as it travels downward until it is small enough to escape from the bottom opening. The movement of the jaw can be quite small, since complete crushing is not performed in one stroke.

Single and double toggle jaw crushers are constructed of heavy duty plate frames with reinforcing ribs throughout.

Gyratory crusher

Agyratorycrusherissimilarinbasicconcepttoajawcrusher,consistingof a concave surface and a conical head. The inner cone has a slight circular movement, but does not rotate; the movement is generated by an eccentric arrangement.

Gyratory crushers can be used for primary or secondary crushing. The crushing action is caused by the closing of the gap between the mantle mounted on the central vertical spindle and the concave liners mounted on the main frame of the crusher.

Cone crusher

A cone crusher is similar in operation to a gyratory crusher, with less steepnessinthecrushingchamberandmoreparallelzonebetweencrushing zones. A cone crusher breaks rock by squeezing the rock between an eccentricallygyratingspindle,whichiscovered bya wearresistantmantle, andthe concave hopper.Acone crusheris suitable forcrushinga variety of mid-hardandabovemid-hardoresandrocks.Ithastheadvantageofreliable construction,highproductivity,easyadjustmentandloweroperationalcosts. The spring release system of a cone crusher acts as an overload protection. Impact crusher

Impact crushers use impact rather than pressure to crush material. The material is contained within a cage, with openings on the bottom, end, or side of the desired size to allow pulverized material to escape. There are two types of impact crushers: horizontal shaft impactor and vertical shaft impactor.

Active Vocabulary: