Despite their diminutive size, compact excavators are often subjected to harsh applications. Yet, when properly selected and fitted, these machines can thrive in the most demanding environments.
Bobcat Co. designs it excavators with the assumption they will be used in tough applications. "We assume that almost any excavator we build is going to end up with a breaker on it just because it is such a commonly owned or rented attachment," says Tom Connor, excavator product specialist. "From the basic plumbing, work group structure, pin sizing, etc., we basically assume there is a high probability the excavator will spend 10% to 50% of its life in demolition applications. Your main focus may be excavation. But if you run into a situation where you have to bust rock, we don't want you to have to rent another machine or beef up your machine to allow that."
The design of key components will give you an idea of the unit's overall durability in such applications. "For example, IHI compact excavators come standard with a one-piece boom, which is more durable in a demolition application," notes Kendall Aldridge, IHI/Compact Excavator Sales.
Wacker Neuson incorporates structural steel and high-quality components in its compact excavator line. "Our torsion-resistant X-shaped chassis frame, the solid welded structures and the steel castings used in high-stress areas ensure that our machines are robust," says Jay Baudhuin, compact equipment manager. "Also, our pins and bushings are purposely designed to be oversized."
High-stressed bearings are supported by replaceable hardened steel bushings with special machined grease grooves. "These bearings, pins and bushings mean the machines can withstand severe-duty applications, there will be lower maintenance cost and higher resale value," says Baudhuin.
Select tracks for conditions
One of the most important considerations with compact excavators is track selection. Three types are available: rubber, steel and hybrid, which is steel with rubber pads.
"Rubber tracks are the most popular choice because they do less damage to grass, asphalt or concrete pavement, or other sensitive surfaces on the way into or on the jobsite," says Bill Gearhart, marketing and product manager, Yanmar Construction Equipment. "If the jobsite or jobsite entrance is covered with broken concrete or jagged rocks, steel tracks would be preferable, as these conditions can prematurely wear or damage rubber tracks."
Steel tracks are suggested for demolition applications, where sharp metal parts could slice rubber track and expose the embedded steel cables. "The advantage of steel tracks in these harsh conditions is that they will wear better than a rubber track," says Baudhuin. "The disadvantage is if used on sensitive, soft ground, such as landscaping or asphalt, the tracks can damage the ground. Also, steel tracks will have more of a tendency to slip on some surfaces (like a wet trailer ramp) than a rubber track."
You really need to evaluate how you intend to use the machine. "Extreme demolition applications where debris becomes a factor in tearing up tracks is an excellent time to look at steel tracks," says Aldridge. "The advantage to steel track is the longevity factor. The disadvantage is that the contractor is limited where the unit can be used."
Weight can become an issue if you are close to the 10,000-lb. commercial license requirement with the truck, trailer and equipment. "Typically, a steel track will up the operating weight of the machine 1% to 5%," says Connor. Noise can be another concern. "Some people object because they are noisy compared to a rubber track."
And while they last longer, a steel track is typically more expensive to get into than rubber track. "That kind of flip-flops when you get into the 16,000- to 20,000-lb. machines," notes Connor. "Rubber tracks are kind of a new thing for that size."
Hybrid tracks, which have been popular on paving machines, are now finding their way onto compact excavators."We offer a steel track with rubber pads as an option to the contractor," says Aldridge. "This allows the contractor to customize his unit to the ground conditions."
Wacker Neuson offers a hybrid version that combines the benefits of a rubber track with those of steel. "The hybrid track is a series of rubber pads, which are reinforced with high-strength tempered steel inserts," Baudhuin explains. "This helps achieve a much higher service life, while still giving you all the benefits of the rubber track. If damage should occur to an individual pad, the pad can easily be replaced."
Bobcat is also integrating a steel track with rubber pads into several of its models. "It will attack the rough and tough applications, but you can still drive across somebody's asphalt driveway without concern of chipping or damaging a surface," says Connor. "They are a lot more resilient than rubber tracks. You don't have to worry about poking a hole in the track with a piece of rebar."
The downside of hybrid tracks is the initial purchase price. "It about doubles the cost of going to a steel track," Connor notes. But the added versatility can pay for the difference. For example, you could tackle a demolition job, then go back to working in sensitive areas.
Hybrids may also get around problems associated with access to work areas. "There are many areas where you cannot run a steel track machine on a city street. That means you can't unload it in front of the project and drive it 50 ft. off the street," says Connor. "Unless you have the luxury of unloading it right on the surface where you are working, a lot of times you have to drive half a block to [the work site]. I think rubber pads will get you by."
Is plumbing protected?
Protecting hydraulic plumbing is critical to uptime with any excavator used in a severe-service application."You want to make sure your plumbing throughout the work group is protected," says Connor, "so when stuff is falling and you are banging into things, you are not squashing hoses or tube lines."
Torn hoses are a fairly common downtime item. "If you lose any of those hoses, you are done," Connor states.
With past designs, he notes, "You would have a loop of hose that was typically hanging outside of the arm, extending down to the quick couplers on the arm. But those were proven to be very vulnerable to catching on material, plus they are flexing every time, whether there is an attachment or not."
Consequently, Bobcat made the decision years ago to terminate and locate quick couplers on the boom. Now there is no hose flexing unless there is an attachment. "Plus, the couplers are up higher and they are more out of harm's way," says Connor.
Manufacturers employ a variety of methods to protect the plumbing. According to Baudhuin, "Wacker Neuson makes a point to protect our hoses that run to the boom and bucket cylinders. This is done by routing the hoses through the cast steel pivot, then internally in the boom arm."
"Yanmar protects exposed hoses with cordura fabric covering, wound spring-like metal coverings or both to protect from abrasion, physical damage and UV radiation from the sun that prematurely ages rubber," states Gearhart. "Hydraulic fitting design and placement are also considered in the design of the machine to minimize physical damage during operation."
As an extra measure of protection, Yanmar incorporates a spring steel bucket cylinder guard and arm cylinder guard as standard equipment, in addition to the boom cylinder guard. "That is invaluable in severe construction/demolition environments," Gearhart asserts. "It makes a lot of sense to protect these areas, since they are out where all the work is done and susceptible to damage from falling concrete/rocks."
Reduce slewing risks
When it comes to the upper structure/housing, even zero tailswing compact excavators need protection. "You will see zero tailswing machines that, in theory, should have never been able to slew and hit anything, but they do," Connor comments.
"The counterweight is usually built to absorb the energy as you slew and back into something," he continues. "But then you move into other portions of the machine - more forward items.
"If you look at most of the machines out there, the lower portion of the upper-structures are comprised of metal, providing protection for internal components," he points out. "Generally, most [manufacturers] are running composites of some type from there on up. Usually, the composite panel will be at the rear door or the side hood. It is typically inset an inch or so. It makes a huge difference on protection."
Wacker Neuson incorporates steel castings welded into collision-prone areas on the chassis, along with steel bumpers. "Our counterweights are designed to extend beyond the engine cover to offer extra protection," says Baudhuin. "Zero and short tail designs also help reduce collisions of the back end with obstacles."
Ground clearance can make a difference, as well. "In general, higher ground clearance would be a plus because you are traversing concrete chunks and stumps," says Connor.
Lights are a must for many operations, yet they can be easily damaged during severe-service tasks. So Yanmar protects the boom light by mounting it integrally with the boom, notes Gearhart.
All IHI units come standard with protected lighting systems, Aldridge points out. "For more extreme conditions, we will customize the units to the contractor's request," he adds.
The boom-mounted light on Bobcat's mid-size and larger excavators is fully encased in metal for added protection, plus is mounted on the left side of the boom to ensure visibility by the operator. "We did learn that if you put it on the right side of the boom, you can't see it," says Connor. "If you were digging up against a house in the offset position, you could catch the siding on the house."
Isolate the operator
If you work in severe environments, make sure the operator is properly protected. In particular, check for ROPS/FOPS certification. "Some brands are sold without 'certified' ROPS/FOPS cabins or canopies," Gearhart cautions.
For added protection, some companies offer additional guarding for the cab. Bobcat, for example, offers a special applications kit. "It is basically a mesh screen for the front of the cabin area. It protects the operator from debris entering the cab," says Connor.
In addition, Bobcat offers a top guard kit, shaped like an eyebrow, that goes across the front of the machine. The top of the cab is rounded and the glass is extended for the vast majority of people who want optimum visibility to see overhead restrictions or for loading trucks. "But in some applications, you want protection from debris falling from above," says Connor. "So we do have a top guard - FOGS (Falling Object Guard Structure)."
Many compact excavators now feature cabs with heat and air conditioning, which is important for comfort and helps to isolate the operator from dust and debris. Cab filtration further promotes operator cleanliness and comfort. "Our [cabin-equipped] machines filter the incoming air and, with the fan on, provide a positive pressure... that helps prevent dust from entering the cabin," says Gearhart.
Cabs also increase safety in certain applications. "The cabin would offer more protection of the operator from horizontally moving objects than a canopy," Gearhart states. Cabs are equipped with safety glass, but there are also third-party suppliers that make window guards for cabs.
Focus on attachments
Many companies offer auxiliary hydraulics as part of the standard package. However, you should take a close look at other features that can boost attachment productivity.
For example, a standard item on Yanmar excavators is a double-acting/single-acting valve for the hydraulic PTO. "Being able to switch the PTO circuit to a single-acting setting helps reduce hydraulic oil temperature in a continuously run attachment like a hammer/breaker or a compactor," Gearhart asserts.
But perhaps the most critical device to maximize productivity - and equipment longevity - is a hydraulic quick attach.
"There are guys that change attachments 10 times a day because they are using the right attachment for the job," Connor points out. "If you are using the right attachment for the right task, it helps the attachment live, it helps the productivity and it helps the structure of the excavator live."