Monthly Archives: May 2017

Evaluate criteria to decide between conventional & reduced-tail-swing crawler excavators

Most contractors would agree that crawler excavators are a staple product in any construction company’s fleet. These machines regularly handle the heavy digging, lifting and loading in a variety of […]

Most contractors would agree that crawler excavators are a staple product in any construction company’s fleet. These machines regularly handle the heavy digging, lifting and loading in a variety of construction applications. There are two tail-swing types: conventional tail swing and reduced tail swing. So which one is best for you? There are several key factors that may influence your choice between conventional-tail-swing crawler excavators and reduced-tail-swing models. You may be able to improve your jobsite productivity by closely evaluating your typical jobsite conditions and implementing a reduced-tail-swing machine into your construction equipment fleet.

The most common excavator type is a crawler excavator with a conventional-tail-swing configuration. Conventional-tail-swing excavators have a rear counterweight profile that extends beyond the machine’s steel tracks when the house rotates, optimizing performance in digging, loading and lifting applications. However, some manufacturers offer excavators with a shorter/reduced tail swing to work on confined jobsites without sacrificing performance. A reduced-tail-swing excavator configuration is ideal for working in limited or restricted spaces, since the machine’s counterweight profile typically extends inches, rather than feet, beyond the machine’s tracks. Before selecting a conventional or reduced-tail-swing excavator, you should consider the following: typical jobsites, key machine specifications, attachments, machine efficiencies and maintenance considerations.

Jobsite Location

Excavators are routinely operated on a variety of small- and large-scale construction projects. It is important to properly match your machine to its work to maximize productivity. Conventional-tail-swing excavators are most often operated in excavating, grading and site development, where space constraints are not a concern. They are also commonly used on infrastructure commercial building site projects to load material into trucks. However, it is not always possible to put a conventional-tail-swing excavator on every jobsite. In many cases, space is limited and your crews and equipment are maneuvering around several other pieces of equipment or permanent structures. For these reasons, excavators designed with a reduced-tail-swing configuration are gaining popularity. Reduced-tail-swing excavators are used primarily in congested urban areas, such as road and bridge construction projects, where traditional excavators cannot fit as easily. For example, the reduced-tail-swing radius may allow excavator operators to work in one lane of a street or highway without blocking traffic in the adjacent lane. Reduced-tail-swing excavators are ideal when digging and backfilling trenches in a confined area.

The trend with reduced-tail-swing excavators is on the smaller side of the crawler excavator spectrum, typically between the 14- and 30-metric-ton size class. The smaller stature, coupled with reduced tail overhang, creates a popular combination for both transporting the excavator and operating it. Available as an option for some reduced-tail-swing models, the crawler excavators may be equipped with rubber track pads. This option may be popular if you are working on established surfaces to minimize ground disturbance, especially when compared with traditional steel tracks on crawler models. It may also save you and your crew time because you may not need to lay down plywood or other types of mats to minimize surface damage.
Dozer blades are another option available for some smaller crawler excavators. Simplify backfilling and use your excavator to fill, smooth and level trenches more efficiently. A smooth cutting edge on the excavator’s bucket allows you to clean right up to the edge of the dozer blade, reducing further cleanup.

In addition, the design of the dozer blade is suitable for moderate site grading, reducing the need for other equipment to complete the task.

Key Specifications

You should also review the machine’s specifications and determine what configuration will meet your expectations. It can be difficult to narrow down the specifications of conventional and reduced-tail-swing excavators, but reviewing the machine’s specifications is as fundamental to a purchase as a hands-on demonstration. Core excavator specifications that should be taken into consideration include:

  • Arm breakout force
  • Engine horsepower
  • Hydraulic flow
  • Lifting capacity
  • Maximum digging depth
  • Maximum loading height
  • Maximum reach, ground level
  • Operating weight

Attachment Versatility

You may think conventional-tail-swing excavators are more versatile than reduced-tail-swing models. However, reduced-tail-swing excavators can be just as versatile when paired with the right attachments. In addition to standard buckets, three of the most popular attachments are quick couplers, hydraulic clamps and hydraulic breakers, which offer a low initial investment with a high rate of return. For example, clamps enable precise movement and positioning and help secure material for superior loading and material-handling applications. When not in use, clamps can be retracted, making the attachment excellent for demolition, site preparation and land-clearing applications, as well as when the excavator operator is using a lifting mode to lift and place materials.

Machine Performance

Many excavator manufacturers continue to refine their designs and improve the optimization between the engine and hydraulic system for greater efficiencies and improved fuel economy. Some machines, both conventional and reduced tail swing, are designed with variable-speed-control technologies to reduce engine rpm during low workload requirements. This reduces the total energy required to perform a task and can measurably improve fuel efficiency. With pump torque control, your operators can effectively match a machine’s hydraulic pump torque and engine response to the task, preventing engine overload and excess fuel consumption.

Maintenance Considerations

Both conventional and reduced-tail-swing crawler excavators have similar maintenance considerations, especially when used in construction applications.

Excavator owners should closely follow the maintenance interval schedule provided by the manufacturer in its operation and maintenance manual. As a general guideline, it is a good idea to clean your excavator on a regular basis, especially when performing service or maintenance procedures. Perform daily lubrication duties in addition to other key maintenance intervals recommended by manufacturers. It is also important to routinely complete a full undercarriage inspection for excessive or uneven wear. The tracks should also be inspected to see if any components look out of place. If so, this could indicate a loose trackpad or a broken track pin. Rollers, idlers and drives should also be inspected for oil leakage. Oil leaks could indicate a failed seal, which could lead to a major failure in the rollers, idler or drive motor.

The best method for comparing conventional-tail-swing and reduced-tail-swing excavators is to demo them side by side in your specific application. You should operate the two types of excavators in real-life applications, so you can better assess which tail-swing configuration will have the most benefit on your jobsite.

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Excavators: More than just a digger

Excavators have continued to prove themselves to be highly adaptable machines that can be applied to unusual tasks and enhanced to perform heavy work in small spaces. They are even […]

Excavators have continued to prove themselves to be highly adaptable machines that can be applied to unusual tasks and enhanced to perform heavy work in small spaces. They are even leading the way in electric power. And all this has been achieved while continuing to improve in terms of operator comfort.

The latest crawler excavator from UK-based construction equipment manufacturer JCB is the JZ141. It combines the performance of the outgoing JZ140, which it is replacing, with the 55 kW JCB EcoMAX engine solution from the JS131 excavator.

With a reduced tail swing that was said to be 29% shorter than a conventional machine of this weight, the JZ141 was specifically designed to operate in confined urban site conditions with a significantly reduced risk of damage to the rear of the machine. The shorter tail swing also makes the excavator suitable for working within single-traffic carriageways.

Despite the reduced dimensions, operator comfort has not been compromised. The KAB seating can be adjusted easily and has air suspension, heating and ventilation. Electric lumbar support is also available as an option on the higher specification seat.

In terms of safety, the full-size JS series cab structure incorporates a tip-over protection structure (TOPS) as standard, and an additional roll-over protection structure (ROPS) and falling object protection structure (FOPS) are also available as options.

Furthermore, due to the heavy counterweight and innovative positioning of the engine and hydraulic components, the centre of gravity has been optimised to provide stability on rough terrain.

Safety is also improved by the all-round visibility provided by the rear-view cameras. They are connected to the seven inch multi-colour display, which offers clear operational information and a home screen that can be customised to display the operator’s preferred data.

This excavator has achieved a fuel saving of up to 20% compared to the JZ140, in part due to the use of larger 130 litre/min hydraulic pumps that maintain the overall maximum pump flow while allowing the engine speed to be reduced from 2,050 rpm to 1,800 rpm. This has the added benefit of reducing internal noise levels to 70 dB.

The JZ141 was said to be the only 15-tonne class crawler excavator to meet Tier 4 Final emissions standards without the need for a diesel particulate filter (DPF) or the exhaust fluid additive AdBlue.

Minimised footprint

US-based construction equipment manufacturer Case Equipment has also introduced a new crawler excavator with short tail swing.

The CX245D SR is the latest addition to the company’s D series and has been designed to provide increased digging and lifting power in confined work areas, such as road and bridge work, residential projects and urban construction.

At an operating weight of 24 tonnes, the new excavator features a compact counterweight, along with modified boom placement to minimise the machine’s footprint.

Along with other D series models, the CX245D SR has been designed to provide significant operational gains, such as the reduction of cycle times. Bucket digging forces and lift capacity have been increased due to the use of an electronically-controlled hydraulic pump, larger control and solenoid valves, and multiple sensors.

These features combine with the Case Intelligent Hydraulic System, as well as the advanced energy management with its five integrated control systems, to make the best use of the machine’s hydraulic power and momentum. This has resulted in greater strength while simultaneously improving fuel efficiency.

The Case Intelligent Hydraulic System includes an automatic idle function that lowers engine rpm after five seconds of lever inactivity, while the idle shutdown function shuts the engine down after a pre-set time. Also, the Boom Economy Control reduces rpm by using gravity during boom lowering and swinging.

The excavator’s 119 kW engine was said to provide a low-maintenance solution that meets US Tier 4 Final/EU Stage IV emissions standards through a combination of selective catalytic reduction (SCR) and diesel oxidation catalyst (DOC) technologies. These are intended to help maximise uptime and performance, while keeping maintenance requirements to a minimum.

The engine does not require a DPF and was said to be economical in its use of AdBlue, equating to between 2.5 and 3% of fuel consumption. With no DPF regeneration needed and an AdBlue tank that only has to be replenished every five fuel refills, downtime has been reduced and the associated lifetime service costs kept low.

Improved performance

The latest model in German light equipment manufacturer Wacker Neuson’s 5 to 9 tonne excavator series has also been built to work in confined spaces.

The EZ80 has zero tail swing and was said to offer precision and efficiency.

The load-sensing hydraulic system ensures that the work speed of all movements remains constant and independent of load – due to the load-independent flow control – even if multiple movements are performed at the same time. This makes operating the excavator simple and precise.

Performance has been further improved by the increase in bucket torque and extension of the bucket’s angle of rotation to 200˚.

An articulated boom is available as an option, for greater flexibility, extended reach, and increased digging depth and dumping height.

Up to five auxiliary control circuits are available with this new model – as with other models in the series. The fast and continuous setting of the individual circuits takes place via the jog dial, which is an operating concept that has been borrowed from the automotive industry. Individual storage of the attachments can therefore be performed without any problems, even during operation.

The revised machine and cabin design includes the offsetting of the boom and a strongly forward rounded hood, providing improved 360˚ visibility of the working area, as well as of the track and the attachment on both sides.

Built to last

Compact construction equipment manufacturer Doosan Bobcat EMEA (Europe, Middle East and Asia) has introduced two new high-track crawler excavators for jobs that require higher ground clearance, a reinforced track frame and a strong traction system with reinforced upper rollers for work in harsh environments and on projects where greater travelling distances are required.

This means they are able to move with ease over rough terrain, negotiate obstacles and pull trailers.

The 16-tonne DX160LC-5 HT and 18-tonne DX180LC-5 HT complement the company’s standard configuration 14-tonne DX140LC-5 and 18-tonne DX180LC-5 mid-range excavators.

The DX160LC-5 HT combines the upper structure of the DX140LC-5 model with an 18-tonne class high track undercarriage system, thereby increasing the ground clearance from 410 mm to 615 mm.

The DX180LC-5 HT, on the other hand, is an enhanced version of the DX180LC-5 excavator. It incorporates a reinforced structure and a re-engineered, high-performance braking system, offering a ground clearance of 615 mm – compared to 460 mm on the DX180LC-5.

Both excavators are part of Doosan’s new generation LC-5 range of machines that are EU Stage IV compliant.

The two excavators are powered by a Perkins 1204F engine, which provides an output of 81.6 kW in the DX160LC-5 HT and 94.9 kW in the DX180LC-5 HT at 2000 rpm. It uses an electronically controlled high-pressure common-rail fuel system that reduces particulate matter emissions from the cylinder, and a waste-gate turbocharger.

The engine also provides trouble-free operation by meeting EU Stage IV emissions standards without the need for a DPF. This is achieved by the use of cooled exhaust gas recirculation (EGR) and SCR aftertreatment technologies.

Doosan has further refined the operator’s cab by introducing a system that enables attachments to be operated from either the joystick or a two-way pedal. This is intended to lessen any potential discomfort caused by the extended or repetitive use of the joystick alone for attachments such as a shear or a breaker. It is also helpful when precision is required, since the operator can keep full control of the excavator with the joystick while using the two-way pedal for attachments.

Operator benefits

Operator comfort was also a central concern in the development of US-based construction equipment manufacturer Cat’s latest wheeled excavators.

On both the M315D2 and the M317D2, the operator station is spacious and has seat options that include heated cushions and automatic weight adjustment. Automatic air conditioning comes as standard, and the ergonomic control layout makes for easy operation.

In terms of safety, visibility is optimised by the use of large glass areas, and the handrails up to the cabin allow the operator to maintain three points of contact when climbing into and out of the machine. Also, anti-skid plates on all walking surfaces reduce slipping hazards.

The new D2 series versions build on the reputation of the M315 and M317 by offering a more robust fuel-injection system, versatile front-linkage configurations and an expanded work tool capability.

The new Cat C4.4 ACERT engine that powers these two excavators meets China Non-road Stage III emissions standards, which are equivalent to US EPA Tier 3/EU Stage IIIA standards. It delivers the same power and fuel economy as the predecessor engines in both working and travelling modes, while also managing worldwide fuel quality.

The primary fuel filter and water separator features a water-in-fuel switch that indicates when draining is required, reducing the risk of fuel-system contamination.

The two excavators have a variable adjustable boom that was designed to improve balance and right-side visibility, as well as to facilitate working in tight quarters and the lifting of heavy loads, since the new models can serve as utility machines for moving material on site.

They are also able to travel independently between job sites at a speed of up to 37 kph, thereby reducing transport costs.

Excavators have also been playing a pioneering role in the shift from petroleum to electric.

Hybrid advances

Japanese excavator manufacturer Kobelco recently launched what it said is the world’s first lithium-ion battery powered hybrid excavator in the 20-tonne operating class with US Tier 4 compliance.

At the heart of the SK210HLC-10 are two major power-drive units. The large lithium-ion battery allows for greater retention of stored electricity and provides the necessary electrical output to the new Kobelco-developed 25 kW power-assist generator motor. This was said to be comparable to the engine output of a much larger 5-tonne excavator.

When the engine is in low-to-normal loading mode, the generator motor reverts to charging the new battery – the charging levels of which can be seen on the operator’s in-cabin monitoring system.

The stored electricity content also powers the new all-electric swing motor and was said to give greater control functionality in terms of response and smooth operation. In addition, when the electric swing motor decelerates, it generates charge to the lithium-ion battery.

Digging the future

Likewise, Belgium-based manufacturer Volvo Construction Equipment (CE) recently unveiled its latest concept machine – an electric compact excavator prototype.

Boasting zero emissions, the EX2 was said to offer lower total ownership costs, ten times greater efficiency and ten times less noise, compared to its conventional counterparts.

This prototype stems from the company’s earlier ELEXC research project, during which Volvo CE worked with a team of six partner companies who all contributed to the $7.9 million project.

Ahcène Nedjimi, electrics and electronics systems lead engineer and EX2 project leader, said, “The electrification of construction equipment will produce cleaner, quieter and more efficient machines – this represents the future of our industry.”

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