Compact Hydraulic Excavators
The compact hydraulic excavator is a tracked or wheeled excavating machine with an approximate operating weight of 13,300 pounds. Normally, it includes a standard backfill blade and features an independent boom swing. The compact hydraulic excavator is also known as a mini excavator.
A compact hydraulic excavator is different from other types of heavy machinery in the sense that all movement and functions of the machine are accomplished through the transfer of hydraulic fluid. The work group and blade are activated by hydraulic fluid acting upon hydraulic cylinders. The rotation and travel functions are also activated by hydraulic fluid powering hydraulic motors.
Most types of compact hydraulic excavators have three assemblies - house, undercarriage, and the work group.
House
The house structure contains the compartment for the operator, engine compartment, hydraulic pump and also the distribution components. The house structure is attached to the top of the undercarriage via swing bearing. Along with the work group, the house is able to rotate upon the undercarriage without limit due to a hydraulic distribution valve that supplies oil to the undercarriage components.
undercarriage
The undercarriage of compact excavators consists of rubber or steel tracks, drive sprockets, rollers, idlers, and associated components and structures. The undercarriage is also home to the house structure and the work group.
Work group
The work group consists of the boom, dipper or arm, and attachment. It is connected to the front of the house structure via a swinging frame that allows the work group to be hydraulically pivoted left or right in order to achieve offset digging for trenching parallel with the tracks.
Independent boom swing
The purpose of the boom swing is for offset digging around obstacles or along foundations, walls, and forms. Another use is for cycling in areas that are too narrow for cab rotation. Another major advantage of the compact excavator is the independent boom swing.
Backfill blade
The backfill blade on compact excavators are used for grading, leveling, backfilling, trenching, and general dozer work. The blade can also be used to increase the dumping height and digging depth depending on it’s position in relation to the workgroup.
The most common place you’ll find compact excavators is in residential dwellings. When digging phone lines or other things, these pieces of equipment are very common for getting between houses. Due to their small size, they can fit almost anywhere.
Over the years, the capabilities for compact excavators have expanded far beyond the tasks of excavation. With hydraulic powered attachments such as breakers, clamps, compactors and augers, the compact excavator is used with many other applications and serves as an effective attachment tool as well. Serving many purposes, the compact excavator is a great addition to any job that requires the use of machinery.
About Drag Line Excavators
What is a Drag Line Excavator?
Picture above is a drag line excavator commonly used in strip mining and large excavation projects.
Drag line excavator systems are heavy machinery that is used in civil engineering, surface mining, and excavation. With civil engineering, the smaller types are used for road and port construction. The larger types of drag line excavators are used in strip mining operations to extract coal. These are among the largest types of mobile equipment and weigh upwards of 10,000 tons!
The drag line excavator bucket system consists of a large bucket that is suspended from a boom. The bucket is moved by a number of chains and ropes. The hoisting rope, which is powered by either a large diesel or electric motor, will support the bucket and hoist coupler assembly from the boom. The drag rope on the assembly is used to draw the bucket assembly horizontally. Through skillful maneuvering of the hoist and drag rope, the bucket can be controlled for many different types of operations.
Operating A DragLine Excavator
With a typical excavation cycle, the bucket is positioned high above the material that is being excavated. The bucket is then lowered down and the drag rope is drawn so that the bucket is dragged along the materials surface. Using the hoist rope, the bucket is then lifted. A swing operation is then performed in order to move the bucket to the place where the material is going to be dropped. The drag rope is then released which will cause the bucket to tilt, making the material in the bucket fall down, which is commonly known as a dump operation.
With smaller drag line excavators, the bucket is thrown by winding up the jib then releasing a clutch on the drag cable, which swings the bucket like a pendulum. Skillful operators can make the bucket land about 1/2 the length of the jib further away than if it had just been spun or dropped.
DragLine Excavator Limitations
The limitations of drag line excavators are the height and length of their boom, as this limits where the drag line can dump waste material. Being inherent with their construction, the drag line is most effective when excavating material below the level of their tracks. Drag lines aren’t suitable for loading piled up material.
Despite their limitations and high capital cost, drag line excavators remain very popular with several mines, due to their very low waste removal cost, performance, and reliability.
They also have different cutting sequences. The first is the side casting method which uses offest benches. This method involves throwing the overburden sideways onto blasted material to make a bench.
The second method is a key pass. This pass will cut a key at the toe of the new highwall and will also shift the bench further towards the low wall. This can also require a chopping pass if the wall is blocky. A chopping pass will involve the bucket being dropped down onto an angled highwall to scale the surface.
The next method is the slowest, known as the blocks pass. This method will however, move the most material. The blocks pass involves using the key to access the bottom of the material to lift it up to spoil or to an elevated bench level. If required, the final cut is a pull back, which pulls the material back further to the low wall side.
For construction, mining, or excavation, drag line excavators are great to have. They can move even the biggest of material, which is great for deep holes in the ground. If you’ve been looking for a great way to maximize mining or excavation productivity, the drag line excavator is just what you need.
Comparing Compact Excavators and Compact Trenchers
Both of these machines are affordable, popular, highly productive, and they both have helped lay a lot of cable and pipe in the ground. While they both can do the work, there are differences as to how they perform when stacked up against each other in residential utility installations.
Compare Size and Price
The average dig depth for utility installations in residential applications is between 40 and 48 inches. The basic trencher that digs to the above depth will boast a 20 - 30 horsepower engine and cost around 40,000 dollars.
The most popular type of compact excavator is the 2.5 metric ton size class, and it uses a 30 HP engine and costs around the same price. The biggest difference in the two surfaces when you need the trencher to dig deeper. The 2.5 metric ton excavator has no trouble at all digging to 8 feet or more, although a trencher that can dig that deep will require an engine with around 100 horsepower and cost upwards of 90,000 dollars!
Compare Life Costs
Not counting the bucket teeth and the replacement of the rubber tracks at 2,000 hours, fuel and routine maintenance are your only daily costs with a compact excavator. The digging chain, teeth, and sprockets on the trenchers are considered wear items and need to be replaced often. Even with the high consumable costs of trenchers, the differences will tend to even out when productivity is taken into effect.
Compare Productivity
For straight line trenching at an average depth, trenchers will flat out lead compact excavators. Under reasonable conditions, a trencher can work three to four times faster than that of a compact excavator. Another area where trenchers really excel is wooded areas, where tree roots and logs can make for slow and sloppy digging when using a bucket.
Compare Versatility
When it comes down to it, compact excavators can do a lot of things that trenchers can’t, especially when they have attachments on hand. If you are digging with a compact excavator, you can’t go anywhere near as fast as you can with a good quality trencher.
Keep in mind that a trencher isn’t a single minded machine either. Most styles of trenchers can be outfitted with a backhoe attachment that attaches to the front end. Whenever concrete, rocks, or asphalt stands in the way, the boom and chain can be replaced with rock teeth and a wheel. In soft soils, you can set up a trencher with a plow attachment and plow in cables faster than using any other available method.
When it comes down to choosing, keep in mind that it all depends on your needs. There are some cases where the compact excavator is best to choose, while there will also be jobs in which the trencher is going to do the best work.
What is Excavation?
The definition of excavation. Excavation is commonly and best known for a technique within the science of archaeology. The individual types of excavation are known simply as digs to those who participate, with this being an over literal description of the process. An excavation concerns itself with a specific archaeological site or connected series of sites, and may be carried on over a number of years, since the work is normally seasonal.
Within the industry of excavation, many more techniques may be utilized, with each dig having its own particular features that may necessitate differences of approach. Resources and other practical issues don’t allow archaeologists to carry out excavations whenever and wherever they choose, as many known sites have been deliberately left alone and non excavated.
Initially, excavation involves the removal of any topsoil that is uncovered by machine. What is dug up may be examined by a metal detector for stray finds but unless the excavation site has remained untouched for a long period of time, there is a small layer of modern material on the surface that is of limited archaeological interest.
In rural areas, any type of archaeological features should be visible beneath the surface. With urban areas, they may be thick layers of human deposits and only the uppermost will be visible to the naked eye. With either case, the first task is drawing a scaled site plan that will show the edges of the excavation.
This plan can be composed using tape measures, or as it is more common these days, an electronic total station. A grid is normally set up, to divide the site.
Excavation is also useful for digging out houses and trenches. When clearing dirt out for roads or sub divisions, excavation is what takes care of things. Even though there are a few means, the term excavation is used anytime that the earth or dirt is disturbed.
Heavy machinery is also very common with excavation, such as excavators or backhoes. Excavating crews run the equipment and dig up soil and rocks for whatever the purpose may be. Excavators are the most used machinery, as they can move a lot of dirt in a little bit of time.
Anytime you are taking part in excavation, you should always use common sense and be safe. If you plan to get down into a hole or trench, you should always use a trench box. Even though the hole may not be that deep, excavation sites can always cave in and at that point - things are very dangerous and possibly even deadly.
For digging up rare artifacts or putting in houses or roads, excavation is something that has been around for years and years. There is a lot to learn with excavation, as you’ll need to know how to run machinery, shoot grade, and how to properly dig holes and trenches so they won’t cave in.
All About Forklifts
Forklifts are ometimes called a forklift truck. The forklift is a powerful industrial truck that is used to lift and transport any heavy materials using steel forks that are inserted under the load. Forklifts are commonly used to move loads and equipment that are stored on pallets. The forklift was developed in 1920, and has since become a valuable piece of equipment in many manufacturing and warehousing operations.
Types of Forklifts
The most common type of design for a forklift is the counter balance. Other types of designs include the reach truck and side loader, both of which are used in environments where the space is at a minimum.
Control and capability
Forklifts are available in many types and different load capacities. In the average warehouse setting, most forklifts have load capacities of around five tons.
Along with the control to raise and lower the forks, you can also tilt the mast to compensate for the tendency of the load to angle the blades towards the ground and risk slipping it off the forks. The tilt will also provide a limited ability to operate on ground that isn’t level.
There are some variations that allow forklift operators to move the forks and backrest laterally, which allows easier placement of a load. In addition to this, there are some machines that offer hydraulic control to move the forks together or further apart, which removes the need for you to get out of the cab to manually adjust for a different size
load.
Another variation of the forklift that is sometimes used in manufacturing facilities, will utilize forklifts with a clamp attachment that operators can open and close around a load, instead of having to use forks. Products such as boxes, cartons, etc., can be moved with the clamp attachment.
Forklift Safety
Forklifts are rated for loads at a specified maximum weight and a specified forward type center of gravity. All of this information is located
on a nameplate that is provided by the manufacturer and the loads cannot exceed these specifications.
One of the most important aspects of operating a forklift is the rear wheel steering. Even though this helps to increase maneuverability in tight cornering situations, it differs from the traditional experience of a driver with other wheeled vehicles as there is no caster action. Forklift drivers should be certified.
Another critical aspect of the forklift is the instability. Both the forklift and the load must be considered a unit, with a varying center of gravity with every movement of the load. You must never negotiate a turn with a forklift at full speed with a raised load, as this can easily tip the forklift over.
Normally, to drive a forklift, you’ll need to pass a basic test to be certified. They aren’t difficult to operate, although you’ll need to be safe when you operate them. Once you have operated one for a while, you’ll have no problems being safe.
About Front Loaders and Bucket Loaders
Front loaders are also commonly known as bucket loaders, scoop loaders, or shovels, the front end loader is a type of tractor that is normally wheeled and uses a wide square tilting bucket on the end of movable arms to lift and move material around.
The loader assembly can be a removable attachment or permanently mounted on the machine. Often times, the bucket can be replaced with other attachments or tools, such as forks or a bucket that is hydraulically operated.
Large style front loaders, like the Caterpillar 950G or the Volvo L120E, normally have only a front bucket and are known as front loaders, where the small front loaders are often times equipped with a small backhoe as well. They are referred to as backhoe loaders or loader backhoes.
Loaders are primarily used for loading materials into trucks, laying pipe, clearing rubble, and also digging. Loaders aren’t the most efficient machines for digging, as they can’t dig very deep below the level of their wheels, like the backhoe can.
The deep bucket on the front loader can normally store around 3 - 6 cubic meters of dirt, as the bucket capacity of the loader is much bigger than the bucket capacity of a backhoe loader. Loaders aren’t classified as excavating machinery, as their primary purpose is other than moving dirt.
In construction areas, mainly when fixing roads in the middle of the city, front loaders are used to transport building materials such as pipe, bricks, metal bars, and digging tools.
Front loaders are also very useful for snow removal as well, as you can use their bucket or as a snow plow. They can clear snow from the streets and highways, even parking lots. They will sometimes load the snow into dump trucks which will then haul it away.
Unlike the bulldozer, most loaders are wheeled and not tracked. The wheels will provide better mobility and speed and won’t damage paved roads near as much as tracks, although this will come at the cost of reduced traction.
Unlike backhoes or tractors fitted with a steel bucket, large loaders don’t use automotive steering mechanisms, as they instead steer by a hydraulically actuated pivot point set exactly between the front and rear axles. This is known as articulated steering and will allow the front axle to be solid, therefore allowing it to carry a heavier weight.
Articulated steering will also give a reduced turn in radius for a given wheelbase. With the front wheels and attachment rotating on the same axis, the operator is able to steer his load in an arc after positioning the machine, which can come in quite handy. The problem is that when the machine is twisted to one side and a heavy load is lifted high in the air, it has a bigger risk of turning over.
Definitions of Common Excavator Parts
The basic parts and descriptions of a common excavator.
Arm
This part functions the same as the lower arm from the elbow to the wrist.
Boom
This part functions like the upper arm from the shoulder to the elbow.
Main Cab/Compartment
The importand devices to make the machine move are stored here. They include fuel,oil,an engine, a motor, and a cab for controls for the operator.
Bucket
This part can be replaced with a drill type, scissors, or other attachments depending on the job.
Crawler
The crawler makes it posiible for the machine to literally “crawl”. It has no problem moving on tough terrain and roads.
How to Operate A Backhoe Safely
Are you operating your backhoe safely?
If you have a skid steer loader with backhoe attachment or any backhoe loader it can be very productive if it is operated in a safe, efficient manner. The best way to get the job done safely and efficiently is to know yourself, the job site, and your equipment.
No matter what type or model of backhoe, there will be safety features that include steps and grab handles for getting on and off of the machine. Backhoes also feature frame lock levers and attaching levers to keep the backhoe securely fastened to the loader frame during operation as well as transporting.
In addition to these standard safety features, there are some backhoes that provide a safety chain. The safety chain will prevent the backhoe mounting frame from rotating backwards and unexpectedly trapping the operator, which can result in serious injury or death. Therefore, it is always important to know and check all of the mounting and attachment points and the safety chain before you operate the backhoe.
After you have attached the backhoe to the loader, you should take a moment to inspect it and perform any necessary maintenance. Check for broken or damaged parts, also making sure to check for leaks, cracks, excessive wear, and check the control levers.
Please pay close attention to all warning, safety signs, and instructional decals are very important and will help you to avoid injury. You should always take them seriously and replace any damaged or missing decals.
Quick tips to always follow are: Every 8 hours or so, you should grease all of the zerk fittings, and check the hydraulic fluid and oil and a daily basis. If the fluid is low, the backhoe will not operate. Therefore, you should always take the time to check your machine.
Each time you have to leave the operator seat of the backhoe, you should lower the bucket or attachment to the ground, always turn the engine off, remember to remove the ignition key, then exit the machine.
When it’s time to drive to the next job site, you should always make sure that you have fully raised both the front and rear stabilizers and make sure you’ve put the backhoe seat into the “down” position for better visibility. Before you drive off, make sure that you’ve installed the transport locking pin.
Here are some other safety tips to keep in mind:
- Always select the right size bucket for the job.
- Stake out the work area that is going to be excavated and use flags to mark the area.
- Never work in areas that have inadequate overhead clearances.
Remember its your job to always make sure that you keep bystanders or other workers out of the swing area. If anyone gets in the way of the boom swinging, they can very easily get injured. The machine has no feelings, therefore you should always be aware of who is around you and where they are standing.
About Skid Loaders
What is a skid loader? A skid loader is an engine powered machine that has a rigid frame. Skid loaders have lift arms that are used to attach a wide variety of labor saving tools or attachments. Skid loaders are normally four wheel drive with left side drive wheels that are independent of right side drive wheels. With each side being independent to the other, the wheel speed and direction of rotation of the wheels will determine which direction the loader turns.
Skid loaders are capable of turning in their own tracks, which makes them very maneuverable and valuable for jobs that require the use of compact, agile loader.
Unlike conventional front loaders, the lift arms lay beside the driver with the major pivot points located behind the shoulders of the operator. Due to the operator being in close proximity to moving booms and buckets, earlier models of skid loaders weren’t as safe as conventional front loaders, particularly during entering and exiting.
Skid loaders today have fully enclosed cabs and other safety features that will protect the operator from injury. Just like other front loaders, the skid steer can scrape material from one location to another, carry material in a bucket, or load material on a truck or a trailer.
Operating a Skid Loader
A skid loader can sometimes take the place of a large excavator by digging a hole out from the inside. The skid loader will first dig a ramp that leads to the edge of the hole. Then, the loader will use the ramp to carry material out of the hole.
The skid loader will then reshape the ramp by making it steeper and longer as the excavation gets deeper. This method is very useful for digging under an overhead structure where the overhead clearance doesn’t allow for the boom of a large excavator, such as those situations where you are digging a basement under a house.
The bucket of most types of skid loaders can be replaced with several specialized buckets or attachments, many of which are powered by the hydraulic system of the loader.
History of Skid Loaders
The first 3 wheeled front end loader was invented by two brothers, Cyril and Louis Keller in their machinist shop in Minnesota back in 1957. The Kellers built the loader to help a nearby farmer clean turkey manure from his two story barn. The light and compact loader, with the rear caster wheel, was able to turn around within the length of itself, while performing the very same tasks as conventional front end loaders.
Down the road, the Melroe manufacturing company in Gwinner ND, purchased the rights to the Keller loader in 1958 and hired the brothers to continue their loader invention. Resulting from the partnership, the M-200 self propelled loader was introduced at the end of 1958.
The loader featured two independent front drive wheels and a rear caster wheel, a 12.9 engine and a 750 lb lift capacity. Two years later, they ended up replacing the caster wheel with a rear axle and introduced the M-400 loader, which was the first four wheel skid steer loader in the world.
In 1962, the Bobcat name was added to describe the key features of the machine - touch, agile, and quick. The M-440 was powered by a 15.5 HP engine and offered a 1100 lb rated operating capacity. In the mid 1960s, the skid steer loader progressed with the introduction of the M600 loader.
Years later, the Bobcat skid steer loader experienced quite a few changes, including the development of a hydrostatic drive system, enforced cab structures, radius and vertical lift arm configurations, deluxe instrumentation, and even heating and air conditioning.
In addition to the rubber tire skid loaders of today, there are now all-wheel steer loaders and even compact track loaders. Compact track loads offer less ground disturbance and feature better traction and control in soft, muddy, wet, and even sandy ground conditions.
Skid Loader Stories
Trench Digging
Digging a trenche is one of the oldest types of excavatin work in construction of all types. Prior to World War 2, trenches were almost always dug by hand. As workers began digging the trenches deeper, the sides needed to be shored or supported, this kept the walls of the trench from caving in.
After the World War, several innovations were made in backhoes, and trench digging by hand seemed to fade away as a profession. By 1950, hydraulically actuated backhoes were developed, which make it possible to rapidly dig very deep trenches. Resulting from the innovations with backhoes, and because there were no workers inside digging the trenches, the walls no longer needed to be shored.
All types of trenches have what’s known as a stand up time. This time is the amount of time that elapses from the time the ditch is dug until the time the trench walls start to collapse. The stand up time is dependant on many factors, which include the type of soil, water content, trench depth, weather conditions, and whether or not the soil has been disturbed.
The stand up time can be as short as zero seconds or as long as several months, as they are very difficult to predict. Before the trench can be dug, someone must take soil samples as way of estimating the stand up time. Keep in mind that the soil conditions can be dramatically different only a few feet from where the sample of the soil was taken.
After the trench has been dug, workers will go down into the trench, and perform whatever work is needed, such as laying pipe or installing telephone lines, welding pipe, or installing valves. If the trench walls aren’t supported, there is the possibility of the walls collapsing and trapping the workers in the trench. Throughout history, there have been 100 - 300 people killed in the U.S. each year due to trenches collapsing.
The public has become very aware that industrial progress will often have negative side effects as well. The place of engineers protecting the public from these types of side effects is a very controversial issue. The use of trench boxes on the site, will help to ease this debate.
The trench box, also called a trench shield, may be placed in the trench to prevent failures from injuring workers. The trench box consists of two large plates, normally made from steel, which are parallel to the walls of the trench, and horizontal cross members which will hold the two plates apart.
The lower edge of the trench box rests at the bottom of the trench, with the top edge of the box extending above the top of the trench. The workers will stay between the plates of the trench box, so that if the trench does collapse, the dirt will be stopped by the outside of the trench box. As the work progresses, the trench box is pulled
along in the trench with a backhoe or other machine.
When a project calls for a large excavation such as digging the foundation for a tall building, the supporting structure for the excavated walls will be specified in the plans. The big problem with not using trench boxes occurs in cities, when water or sewer lines are being installed or repaired. The engineer doesn’t specify for the trench box in the plans, but instead leaves it up to the contractor.
Anytime you are going to be digging trenches or working in them, you should always use common sense and take your time. Trenches can be very deadly, especially if trench boxes aren’t used. To be on the safe side, you should always use a trench box if you need to be in the trench. If you don’t need to be in the trench - do the smart thing and let the machines do all of the work.
