The topic I am going to present in this seminars is Skid Steer Loader and Multiterrain Loader. I have included relevant information on different types of loaders like, Crawler and Wheel Loader, their operation and classification uses as well as their advantages and disadvantages. I hope my seminars on this topic throws light on necessary information regarding different type of loader.
Chapter â€œ I
Skid-steer loaders began catching on in the construction field in the 1980s because they offered contractors a way to automate functions that had previously been performed by manual labor.
Those were small, inexpensive machines that improved labor productivity and reduced work-related injuries. Their small size and maneuverability allows them to operate in tight spaces. Their light weight allows them to be towed behind a full-size pickup truck, and the wide array of work-tools makes them very flexible. They were utility machines, used for odd jobs ranging from work site clean up to small scale digging, lifting, and loading. In most cases, they logged far fewer hours of usage each year than backhoe loaders and wheel loaders, but they were cheap, and so easy to operate that anyone on a job site could deploy them with very little training.
Since then, the category has become wildly popular in all avenues of construction. They are the best-selling type of construction equipment in North America, with annual sales exceeding 50,000 units. They still tend to be low-hour machines, but, thanks to a virtually unlimited variety of attachments, skid-steer loaders can handle a huge array of small-scale jobs, from general earthmoving and material handling to post hole digging and landscaping to pavement milling and demolition.
As the machine has grown in popularity, it has become one of the hottest rental items in North America. Equipment rental houses consume roughly one-third of the new units sold each year, and most stock a wide array of attachments, too. The ready availability of rental attachments â€ especially high-ticket, specialty items like planers, vibratory rollers, tillers, and snow blowers and pushers â€ has turned the machines potential for versatility into a cost-effective reality.
As the skid-steer has become more popular in construction, the average size of the machine has grown, too. In the mid-1980s, the most popular operating load class was 900 to 1,350 pounds. By the mid-1990s, the 1,350 to 1,750 pound class was the most popular. Today, the over-1,750-pound classifications are the fastest growing.
Larger machines have dominated new product introductions, too, though our survey of recent new product announcements has turned up a spate of compact and sub-compact introductions, too. The smallest of these are ride-behind models aimed mainly at the consumer rental trade, but they are also used in landscaping and other types of light construction essentially to automate jobs that would otherwise be done by laborers with shovels.
Road contractors and government highway departments should find the new super-duty class of skid-steer loaders especially interesting. These units have retained the skid-steer's traditional simplicity of operation and compact packaging, while also boasting power and weight specifications that let them perform many of the tasks done by backhoe loaders and compact wheel loaders. Nearly all boast high-pressure, high-flow hydraulic systems to run the most sophisticated hydraulic attachments. They also feature substantial break-out force ratings for serious loading and substantial lifting capacities for material handling.
The skid-steer loader represents an interesting alternative for fleets that have low- hour backhoe loaders in inventory. Led by Bobcat, Gehl, Mustang, and other companies that make skid-steers but not backhoe loaders, skid-steer marketers have been pushing the proposition that it is more cost effective to replace a backhoe loader with a skid-steer and a mini-excavator. The rationale: for about the same amount of money, you can get more hours of utilization because you have two machines that can be working simultaneously at different jobs.
While that rationale doesn't hold up in all cases â€ backhoe loader prices have come down substantially in the past few years, changing the cost-per-hour math â€ municipal fleets and other low-hour users may find that owning a skid-steer loader and renting a mini-excavator for occasional excavating needs is a more cost-effective solution than owning a backhoe loader.
The skid steer concept was introduced by Bobcat in 1960, in response to demands for a loader that would be able to maneuver effectively in confined spaces. The method of steering and propulsion is conceptually similar to that of a tracked vehicle, the two wheels on the same side move in unison, with each pair on opposite sides capable of being driven independently. If both pairs are driven forward with the same speed, then the loader moves forward, but if they are driven in opposite directions, the loader will turn on itself. This flexibility allows incredibly compact maneuvers to be effected, and skid steer loaders are now found in a wide variety of applications including construction, agriculture and industry.
The clever aspect of the concept lies in the distribution of weight in the vehicle. When unlades, the centre of gravity lies towards the rear of the vehicle near the engine, which makes the centre of steering occur right in the middle of the rear axle, with the front wheels skidding around this. If the loader has significant weight in the bucket, the centre of gravity moves to the front of the vehicle making the rear wheels skid around the front axle. While useful in this regard, the offset distribution of weight can sometimes lead to instability, particularly when traveling up and down inclines and suddenly changing direction from reverse to forward. Counterweights are sometimes employed to help reduce this effect.
Chapter â€œ II
A bucket is attached to the arms and capable of being raised, lowered and dumped through mechanical or hydraulic controls. The loaders having bucket in the front, known as Front-end loaders are very common. The loaders are versatile, self propelled equipment mounted either on crawler or wheel-type running gear. These loaders are fitted with front mounted general-purpose bucket operated through hydraulic rams, with which they dig, scoop, lift, transport, carry, dump or load into hauling units, bins, hoppers, conveyors and stockpiles. With the help of additional front and rear mounted attachments these can doze, scrap, grub, forklift, trench, grade, ditch rip, clamp, and winch. Applications of a loader vary from handling coal, sugar, sand, salt, stone etc. to earth moving and digging work in quarries.
TYPES OF LOADERS
Loaders are of the following types
(a) Crawler loaders.
(b) Wheel loaders.
CRAWLER LOADERS (Multiterrain Loader)
Crawler track types are generally preferred for digging and loading jobs where ground conditions are poor and low pressure characteristics are required, and are preferable for application involving rock and sharp stony ground as there is no possibility tire damage. These are best employed for short moves between loading and dumping points. These should be transported from one site to another after loading on the trailers.
WHEELED LOADERS( Skid steer loader)
As a result of the development of more capable power trains (axles and tires), there was a steady trend towards wheel loaders at the expense of crawlers. Protective chains for tires, that considerably increases tire operating life, even in quarry applications, additionally favored the wheel loader against the rather more difficult to maneuver crawler.
SKID STEER LOADER
Wheeled loaders are generally four wheel drive. However, for handling light jobs on good ground conditions two-wheel drive variants are also used. Four wheel drive loaders are generally used for construction jobs, whereas, two wheel drive loaders are used for bulk handling of coal, cement, fertilizer etc. into hoppers and trucks. From maneuverability point of view, wheel loaders are of following types:
(i) Articulated type (Pivot steer).
(ii) Rigid frame-two wheel steer or all wheel steer.
Articulated type of loaders
This type of loader is ringed in the middle of the front and rear axles, as shown in the Figure. Due to their operational characteristics and capability of working in limited space and short turning radius, resulting higher speed of work, these have become very popular. Because of the advantage of quick maneuvering and thereby easier spotting of loads, less rolling resistance on turns, better mobility on soft surface, these loaders give better performance and high productivity. The articulation permits the loader to pivot 30â€45 degree either side of the centre.
Articulated Type Loader
Rigid frame type-loaders.
These are comparatively cheaper than articulated frame type of loaders. With this type of loader sometimes operators misjudge hopper or truck body width and therefore he has to maneuver back and forth before dumping. Rigid frame loaders are of two types, namely two wheel steer and all wheel steer. By designing all wheel steer loader, maneuverability is gained along with the advantages of rigid frame construction. In all wheel steer loaders, operator can switch from 4 wheel to 2 wheel steer or vice-versa by using a lever. On stockpile operations, all wheel steering allows the operator to align the bucket in the pile quickly to ensure a heaped load in the minimum possible time. While moving on the roads operator can set his loader on front steer only and then handles it like a normal road vehicle.
Rigid Frame-Two Wheel steer
Construction of articulated type of wheel loader
As we have discussed earlier, articulated frame type of wheel loaders are very common in construction engineering, hence these are discussed here. The loader is consisting of two frames, the front frame and the rear frame, interlinked by means of a vertical centre pivot. The front frame of the equipment carries drivers seat buckets hydraulic rams etc., whereas the rear frame carries the engine assembly, transmission assembly and the hydraulic tank. The power is transmitted from the engine to the front and rear axle through a torque converter and power shift transmission assembly by means of propeller shafts. The load's have two stage hydraulic system, one for hoisting or lifting the bucket through raising the lift arms with hydraulically-operated rams, and another for the dumping through dump arms which are operated by another set of arms. The hydraulically actuated loader lift mechanism is located in-front of the operator for safety reasons. Lift control provides raise, hold, lower and float positions. Bucket control has roll-back, hold and dump positions. Additional hydraulic controls are also provided for optional attachment.
Loading arrangement with
(a) Articulated (b) Rigid frame loaders.
In a skid steer loader and Multiterrain Loader, the power consists of a diesel engine and a set of hydraulic pumps.
Diesel engines are more efficient than gasoline engines. A skid steer loader or multiterrain Loader may operate eight or more hours every day. Over the course of a year, a 5 or 10 percent difference in efficiency can make a real difference in fuel costs.
Although the engine, cooling system and other accessories are tightly packed into the skid steer loader, the engine compartment is designed to make maintenance easy. A door on the back opens wide, and the radiator and fan tilt up to allow clear access to the engine and all of the maintenance items (such as filters).
The engines in the Caterpillar Skid Steer Loaders and Multi Terrain Loaders range from 49-horsepower (37-kilowatt), naturally aspirated diesel engine to a 74-hp (55-kW), turbocharged diesel engine. This power is transmitted to a set of hydraulic pumps bolted directly to the output of the engine.
THE HYDRAULIC PUMPS
There are a total of four hydraulic pumps hooked up to the engine. Two variable-displacement pumps located in a single housing provide hydraulic power for the two hydraulic drive motors. A fixed-displacement pump provides hydraulic power for the loader arms and accessories.
A smaller fixed-displacement pump provides hydraulic power for circulating the hydraulic fluid through filters, and provides pressure to the pilot controls. This setup allows the skid steer loader to make good utilization of the engine's power without ever stalling it. An engine stalls when the load on it is greater than the power it can produce. On hydraulic machines like these, the power that the engine can produce has to be balanced with the power that the hydraulic system uses. The maximum amount of power that the engine can make depends on the speed it's running at. On a skid steer loader or multi terrain loader, an engine at full speed can produce its top rated horsepower.
Between the pumps that power the wheels and the pump that powers the work tools, the hydraulic system can demand more power from the engine than the engine can generate. The system is designed this way so the operator can apply the full power of the engine to either the wheels or the implements at any given time. On most skid steer loaders, it is up to the operator to carefully modulate the controls to keep the engine from stalling (which requires skill and practice). On Caterpillar Skid Steer Loaders, the operator doesn't have to worry about stalling the engine â€ the machine makes sure this doesn't happen.
The power used by a hydraulic pump is equal to its pressure multiplied by the flow rate of its fluid. On the Caterpillar machines, the implement pump is a fixed-displacement pump. In this type of pump, the flow rate is determined by the pump's speed (which is equal to the speed of the engine) and its displacement (the volume of the cylinders in the pump). The faster a given pump spins, the higher the flow rate. The pressure is determined by the tasks the operator is performing. For instance, the pressure is high when the operator is digging a bucket of dirt out of a pile, and it is low when he tilts the bucket to dump the load.
This pump is designed so that at its maximum pressure and flow rate, it does not stall the engine. But, if the hydraulic pumps that drive the wheels were to draw any power while the implement pump is at maximum pressure and flow, the engine could stall. This is why the pumps for the wheels are variable-displacement pumps.
When the operator is not using an implement, the pumps can operate at their maximum displacement, using the full power of the engine to drive the wheels or tracks. The speed of the machine is determined by the flow rate of fluid from the pumps, while the torque is determined by the pressure.
During an operation like loading a pile of dirt into a truck, the operator uses a lot of the engine power to push the machine into the pile. When the operator lifts a bucket load of dirt out, it takes a lot of force to break the load out of the pile. If the implement pump were to supply the pressure and flow for this operation while the drive pumps were still drawing power, the engine would stall.
Hydraulic line diagram
The drive system on the skid steer loader and multi terrain loader has no transmission. Instead, it uses pumps and hydraulic motors to provide power to the wheels or tracks.
The skid steer drive system, shown
mounted in the lower frame of the machine
For the skid steer loader, each side of the machine is powered by a hydraulic motor. Each of the two motors (one for each side) connects to a sprocket, and each sprocket is connected by two chains to each wheel. The sprockets and chains serve two purposes. They distribute the power from a single hydraulic motor to both wheels, and they provide a gear reduction to increase the torque at the wheels. The chains and sprockets are located inside the frame, in a sealed compartment. They are immersed in an oil bath that keeps them lubricated. Each drive sprocket is connected to a hub via a short shaft. The shaft passes through several seals before connecting to the hub, which holds the wheel.
Loaders are used to carry out following main operations
Loading operation is the main operation performed by the loaders. Loading consists of scooping, lifting, turning and dumping materials such as sand, gravel and crushed materials from stockpiles, bank or construction site into the hauling units. For better output the bucket should be filled full and the number of hauling units deployed for the work should be such that there is no waiting time for the loader and there should not be more than one hauling unit in the Que.
Wheel loaders are excellent for moving loose materials over short distances to dump into hauling unite, hoppers, conveyors, bins or any other place of work in the construction sites.
Two different linkages and the arcs they follow
A cycle time for a loader consists of the following:
a) Time for scooping, lifting and dumping the bucket along with time required for changing the directions and taking the turns.
b) Hauling time, i.e. the travel time for load carrying and empty returning. Generally the high reverse speeds reduce the returning time enabling the reduction in cycle time and thus more work in one hour.
Crawler loaders and heavy duty wheel loaders are excellent for many excavation jobs, like basement digging etc. With excavator attachment it can also handle several other types of excavation works. These loaders can excavate as well as lift the excavated material and dump it into trucks or on the stockpiles. In case surface is hard for excavating and scooping the earth ripper or scarifier attachment is mounted on the rear of the loader to loosen such surface. The operator can then easily dig and load the material into bucket for removal.
Loaders can scoop up and load the debris of demolished buildings into hauling units. They also knock down small and temporary buildings ; Loaders are also used for clean up the areas after snow-storms, tornadoes, floods etc. A grubber blade attachment is used in place of bucket for large-scale clearing work. Thus the loaders are the first equipment to prepare the site for building and construction operations and also the last equipment in order to backfill, spread, level and top with selected good soil for grass and landscaping.
Following are the main attachments which can be fitted to a wheel loader:
a) Back filling attachments.
Backfilling can be done with the bucket of this attachment when used with the loader.
b) Fork lift attachment.
An industrial fork lift when attached with a loader gives more stability, more tractive power and greater clearance than with a normal fork lift truck.
c) Side bucket attachment.
Side dump bucket is used to load snow for removal when work is required to be carried out in tight area. By reducing the maneuvering time production is boosted by using this attachment.
d) Sweeping attachment.
A sweeping attachment can be fitted to a wheel loader for general cleaning of roads and parking area in the industries.
e) Multipurpose bucket.
A multipurpose or four-in-one bucket can be used as a dozer, scraper, clamshell and general purpose loading. The multipurpose bucket is much heavier than the general purpose bucket, and therefore a loader equipped with it will generally need more counter-weight for the same operating load rating.
f) Ripper-scarifier attachment.
These are mounted on rear of the loader to loosen hard surfaces such as compacted earth; hardpan, shale, slate, decomposed rock ; to tear up old brick, asphalt or broken concrete pavement, that do not readily yield to direct bucket loading.
g) Miscellaneous other attachments.
A large number of attachments for specialized jobs are also available for fitting to the loaders. Some of these are pipe laying attachments, wooden log or concrete pipe attachments, pole handling attachments, boom for loader crane set-up.
h) Stacking Rake.
Stacking rakes are designed for follow-up clearing, racking and piling after trees and brushes have been cut by other attachments. The teeth are curved and of extra long length to carry a full load up into the fine line pile or wind row.
i) Snow Removal Attachment.
Snow-removal V-plow normally used for high speed plowing of snow on long stretches highway, airport runways and places where there is ample room to throw the snow.
j) Protective chains.
These chains offer the protection for wheel loaders where tires are exposed to sever wear, cuttings, and sudden failures due to punctures, epical applications for the use of these chains would be in quarries, mines, or heavy rock.
LOADER BUCKETS AND THEIR APPLICATION
i) Standard bucket
This is most universally used loader attachment and can be used in practically every type of material encountered during earthmoving operations. Applications of this bucket includes loading, excavation, scraping and level grading.
j) Rock Bucket
It is designed primarily for quarry operations and is very rugged, 1b achieve good penetration it has a V-shaped cutting edge. This V-shaped cutting edge also enables the operator to concentrate breakout forces on one point.
k) Side dump bucket
This is designed for loading operations in extremely confined quarters, such as sub way tunnel, etc. It is available with the opening on either or both sides, material is dumped to the side.
l) Log grapples
This is designed for log loading operations. It consists of a loading fork and a hydraulically powered clamp, keeping the logs from shifting or rolling out.
m) Stockpile bucket
This performs best when loading relatively light and non-cohesive materials. It weighs less than a standard bucket and offers greater volumetric capacity. Since it is used in stockpile environment, it is not equipped with teeth.
Standard Bucket Rock Bucket
Side dump bucket Log grapples
Bucket factor vary from 1.0 to 0.4 depending upon the height of bench, nature of fragmentation, efficiency of the bucket mechanism, operator's skill. Loading conditions affect the bucket factor as mentioned below:
As explained earlier cycle time means the sum of times required for excavation, swing, dump and back swing.
Cycle Time= Excavating time + 2 * swing time + dumping time.
Â¢ Excavating time is the time required for excavation and depends on digging depth and other digging conditions.
Â¢ Swing time is the time required for moving the bucket from one position to another keeping the height same. This time depends on the degree and speed of swing and the skill of the operators.
Wheel Loader Production.
Figure gives a range of production likely to be achieved with a particular size of bucket, depending upon the cycle time. The chart is drawn considering the density of material as 1.8 tons/m3.
Wheel loader Production in t/hr.
For general purpose, loaders with bucket sizes varying between 1.4 to 2.8 cubic meters are commonly used. However loaders up to 18 cu meters are also available for light materials handling. Engines with power ranging between 65 to 250 B.H.P. is generally available. Capacities of the buckets are indicated by the struck capacity as well as heaped capacity. The crawler loaders use rock bucket for use in rocky, consolidated soils and are generally used for movements up to 50 meters (as compared to that of 300 meters in wheel loaders). Articulation permitting 90Ã‚Â° rotation of the bucket (45Ã‚Â° to each side of the centre line) is available in most wheel loaders.
Output of loader. Hourly production in m /hr (Q)
= q * (3600/c) * Efficiency
where, q = production per cycle (m3 )
= Heaped Capacity *Swell factor
* Bucket factor.
and C = Cycle time (in secs)
Cycle time is the time required for loading into the bucket, swing, moving, dumping and back swing.
INCREASING LOADER PRODUCTION
Loader production can be increased by adopting following methods:
Loosening of rock by blasting results in good fragmentation which permits faster digging, greater payloads due to fewer voids, and also helps in increased crusher production with lesser strains. Loosening of rock by blasting also reduces the danger of rock slides while the loader is in operation.
(b) Helping the Loader by a Dozer.
Loader production can be increased if it is spared from digging and collecting the material. These operations if performed by a dozer, the loader is then allowed to concentrate only on loading functions resulting in increased production. This is possible if either the quantum of work is very heavy or a dozer working in the area is not fully occupied.
© Planning the work.
Locating the dumpers, and the place in the stockpile from where it takes the material for loading greatly effect the loading cycle time. This should be carried out in such a way that cycle time is kept minimum. During idle time i.e. when it is not loading, the loader should be used to work a stockpile, clean the area in order to save the tires of hauling units. If idle time is long, it can be used to maintain haul roads and other jobs which can be performed by the loader including those with special attachments.
Building the Skid Steer Loader and Multi Terrain Loader
Caterpillar takes every bit as much care in the building of loaders as it does in the building of the much larger, more expensive machines it manufactures. Great measures are taken to ensure that the loaders leaving the assembly line meet the high expectations of Caterpillar's customers:
Â¢ Several layers of corrosion-resistant coatings are applied to most metal components.
Â¢ Quality validation takes place throughout the process, not just afterward.
Â¢ Electronically controlled torque tools for tightening bolts are utilized.
One of the most impressive things about the Caterpillar Skid Steer Loader and Multi Terrain Loader assembly plant is the coating and painting operation. Caterpillar has contracted with a company called Metokote to build an electro coating and painting facility that is in the same building as the assembly line.
All of the metal parts, including the frame, roll cage, loader arms, buckets and most brackets on the machine, are sent though this process, which starts with a thorough cleaning. The parts are then coated with zinc phosphate and sealed with a chrome sealant. This gives them a base layer of protection in case the paint and electro coat are scratched.
After the zinc phosphate and sealant are applied, the parts are electro coated. They pass through a tank of water filled with paint particles. The tank and particles are electrically charged to 200 volts, and the hangers that hold the parts are grounded. This attracts the charged paint particles to the grounded parts, coating the parts uniformly. After the parts come out of the tank, they are cured in an oven until the coating hardens.
After the electro coat is cured, any of the parts that are going to be exposed to sunlight are painted in a spray booth. This multi-layer protection makes the parts rust resistant so resistant that if a scratch were to penetrate all of the coatings down to the bare metal, the zinc phosphate would keep any rust from spreading.
Electronic Torque Control
A lot of construction machinery is assembled using air-powered impact wrenches (like the ones you see your mechanic using). These wrenches are notoriously inaccurate (plus or minus 10 percent, at best) at controlling the torque on a bolt or nut.
Getting the correct torque on the nuts and bolts is important. The torque is used as an indicator for how much the bolt stretches. For a good joint, the bolt has to stretch a little (this is what gives it its clamping force). A bolt with too little stretch won't hold the parts on tightly, and could even work loose over time. A bolt with too much stretch could break during installation, or be weakened during installation and break later.
The Caterpillar assembly line uses all electronically controlled wrenches. These wrenches can control the torque on the bolts to within 2 percent, ensuring a more accurate amount of bolt-stretch.
Some joints are so critical to the machine that an even more advanced technique is used. For instance, on the skid steer loader, the lug nuts that hold the wheels on are tightened by a special, electronically controlled tool that uses the torque-turn method. This tool tightens the nuts until a threshold torque is reached, and then it turns them a fixed amount maybe one more revolution. This enables even more accurate control of the bolt stretch.
MODERN TRENDS IN WHEEL LOADERS
Wheel loader is the most widely used piece of construction equipment. From mundane road patching jobs to billion-dollar dams, in tiny quarries, and vast open cast mines, it is the indispensable tool. While users keep finding new jobs for wheel loaders, most still spend much of their lives adducing and reversing from stock pile or bank to truck o~ hopper making nearly 1000 or so directional changes per shift. Both semi-automatic and fully automatic power shifts are now in the market. On the semi-automatic models, the transmission will shuttle between two gearsâ€first and second or third and fourthâ€depending on the speed selected. The fully automatic version just requires the operator to set the travel direction, and the transmission handles all the gear changing. Few models have come into the market, on which, the hydraulic transmission works through a three-speed power shift gear box, providing infinitely variable speed up to more than 35km/hr in top gear. The electro-hydraulically selected gear ratios and travel direction can be selected under full power. A unique feature is the multi-function lever that controls all buckets, gear selection, and travel direction functions. The system allows the operator to keep one hand on the steering wheel at all limes, greatly enhancing safety.
The Skid Steer Loader and Multi terrain Loader is the most widely used piece of construction equipment. Skid-steer loaders catching on in the construction field because they offered contractors a way to automate functions. Their small size and maneuverability allows them to operate in tight spaces. Their light weight allows them to be towed behind a full-size pickup truck, and the wide array of work-tools makes them very flexible. In most cases, they logged far fewer hours of usage each year than backhoe loaders and wheel loaders, but they were cheap, and so easy to operate that anyone on a job site could deploy them with very little training.
Led by Bobcat, Gehl, Mustang, Caterpillar and other companies that make skid-steers, skid-steer marketers have been pushing the proposition that it is more cost effective to replace a backhoe loader with a skid-steer and Multi terrain loader.
2. CONSTRUCTION EQUIPMENT AND MANAGEMENT
First of all I thank the almighty for providing me with the strength and courage to present the seminars.
I avail this opportunity to express my sincere gratitude towards
Dr. T.N. Sathyanesan, head of mechanical engineering department, for permitting me to conduct the seminars. I also at the outset thank and express my profound gratitude to my seminars guide Mr. Ajithkumar and staff incharge Asst. Prof. Mrs. Jumailath Beevi. D., for their inspiring assistance, encouragement and useful guidance.
I am also indebted to all the teaching and non- teaching staff of the department of mechanical engineering for their cooperation and suggestions, which is the spirit behind this report. Last but not the least, I wish to express my sincere thanks to all my friends for their goodwill and constructive ideas.
1. INTRODUCTION 1
2. CONCEPT 4
3. LOADERS 5
4. THE POWER 11
5. DRIVE SYSTEM 15
6. OPERATIONS 16
7. ATTACHMENTS 18
8. INCREASING LOADER PRODUCTION 25
9. MODERN TRENDS IN WHEEL LOADERS 29
10. CONCLUSION 30
11. REFERENCES 31