August 2008

The hydraulic advantage By Tara Vantimmeren

It is difficult to imagine walking into an equipment dealership or onto a construction site and not finding an industry staple: the portable air compressor. The history of pneumatic power dates back to the 19th century. And the popularity of compressors and air-powered tools such as handheld breakers suggests pneumatics will not be leaving us anytime soon.

But that is not to say contractors do not have alternatives.

An electric tool is generally a safer option for interior projects, and gas-powered equipment allows for more freedom of movement to increase efficiency in remote work locations. But both electric and gas-powered equipment are better suited to their own specialties, with neither being able to match the overall performance of pneumatics in most applications. Therefore it is hard to consider either a true alternative.

To discover a real contender, contractors need look no further than other equipment commonly found on their jobsitesÑspecifically those units operated by hydraulic power. While it is basically a given that a majority of workers are using pneumatic breakers for handheld applications, some jobs require more breaking force. In such cases, a common and effective solution is a rig-mounted breaker. A breaker attachment of this sort is usually powered (or at least assisted) by the hydraulics of the skid-steer loader, backhoe or excavator to which it is mounted.

The use of hydraulic power for attachments like breakers is universally accepted, so it should not seem like a drastic leap for hydraulics to become a popular power source for handheld equipment. However, even though hydraulic handheld equipment has been around for more than three decades, pneumatics are preferred and used far moreÑby approximately a 6-1 margin over hydraulics. And some believe even that ratio is overestimating the penetration of hydraulics into the handheld equipment market.

Such a discrepancy would be easier to comprehend if it were the case that a pneumatic tool powered by an air compressor provided substantial advantages over a hydraulic tool and a hydraulic power pack. But in fact, a closer comparison between the two options actually indicates that hydraulic handheld equipment may be the superior choice.

Worth the cost

While reliability and performance certainly factor into equipment selection for contractors, a great enough differential in initial cost can play a heavy role as well. When comparing the initial purchase price of an air compressor to that of a hydraulic power pack, there really is no comparison.

Power packs are much less expensiveÑin many cases less than half the price of a comparably performing air compressor. This purchase price differential alone allows the initial investment to be paid off more quickly. It also immediately frees up additional money for a contractor to add more equipment to his fleet, such as a second power pack or a few handheld breakers.

Along with a higher price tag, air compressors tend to carry other associated costs that are not incurred by power packs. One such cost is license plate registration, which is generally required for towable air compressors but not for a hydraulic power pack. This type of cost may be small, but it is the type that is often overlooked when calculating the total cost of owning equipment.

Small packages

In addition to costing less, hydraulic power packs are far more compact than air compressors, giving contractors an added element of convenience. Power packs can be picked up and placed in the back of a truck or van, while comparable air compressors must be towed behind or mounted on a vehicle. Once on the jobsite, power packs can be manually wheeled or lifted into any necessary position, while compressors usually require mechanical assistance to be moved from one location to another and still could be limited in where they can physically go.

Power-packed

Not all contractors will see a need for a smaller, more convenient package, but most should have an interest in the performance advantages a hydraulic power pack can provide.

Hydraulics simply work more efficiently than pneumatics, which helps to explain how a 13-hp power pack can match the performance of a 60-hp air compressor. Compressed air has an efficiency of about 18% to 25%, while hydraulic efficiency is roughly 50% to 60%. This makes sense when considering the basics of each system.

Hydraulics operate in a closed circuit. Hydraulic oil leaves the power pack, travels through a hose to the breaker where it creates a stroke of the breaker's piston and then is returned to the power pack's oil tank. With pneumatics, compressed air is similarly delivered through a hose to a breaker. Most of the air goes to create the breaker's impact, but some of the air exits the breaker through exhaust ports, resulting in unused power.

What the more efficient hydraulic system means for a contractor in practical terms is a higher power-to-weight ratio. For example, a 40-lb hydraulic breaker usually will deliver at least the same blow energy as a 50-lb pneumatic breaker. This higher performance allows a contractor to complete more work in less time. In some cases, this is an added luxury that allows a contractor to get on to the next task or the next job. In deadline situations, it could be a critical factor in completing work on time.

Downtime reduced

In addition to accomplishing a task faster, hydraulics also can contribute to decreased downtime. Grease is a dirty word to many, not because of its grimy connotations, but because contractors are all too familiar with the work stoppages necessary to ensure that equipment is properly greased or lubricated at various intervals, along with the consequences of neglecting this task.

Fortunately for the operator of a handheld hydraulic breaker, the hydraulic oil providing the power also is supplying constant lubrication during operation, taking the task of greasing out of the operator's hands. A similar pneumatic tool would need to be regularly oiled during use. Not only does this difference maximize uptime, but it also minimizes the risk of equipment being unnecessarily damaged due to inadequate lubrication.

Hydraulics also reduce downtime on jobs during the winter. While the oil powering hydraulic tools will quickly warm to working temperature, condensation on pneumatic tools can sometimes cause the exhaust ports to freeze up in cold weather if some sort of antifreeze is not used. For all contractors, stoppages and downtime cost money.

Clear advantage

The intended applications or situations where hydraulics can be advantageous are countless. As was stated earlier, a contractor may not be overly concerned with equipment maneuverability. But the equipment weight itself could be an issue. Take the example of work on a bridge deck, where weight regulations may be a factor. Using a 150- or 200-lb hydraulic power pack rather than a 1-ton air compressor would obviously be a logical choice if the compressor exceeded the weight restriction.

Plug and play

Hydraulic tools also have the flexibility to be powered by other machines in situations where a power pack is not available. In such a case, the operator could connect the tool to another hydraulic power source, such as a tractor or backhoe loader. Power packs are more convenient because they are already rated to the proper oil flow and pressure to match the tool they are powering, but an oil flow divider could be used to regulate pressure and flow for powering a tool with a backhoe. This could come in handy in many situations, such as if a contractor owned just one power pack but wanted to run breakers in two different areas of a jobsite. The power pack could be used in one spot while the backhoe supplies hydraulic flow to a breaker in a second location.

Hydraulics also provide benefits for interior or confined-space work. Pneumatics are not a good choice under either of these circumstances, due to the exhaust ports on air-powered tools creating both dust and noise pollution. With hydraulics working in a closed circuit, exhaust fumes and sound are kept to a minimum, making work conditions much safer.

While hydraulic tools are generally friendlier from an operator's perspective, they also are environmentally friendly. Fuel consumption is drastically lower on a hydraulic power pack compared with an air compressor, which has more cylinders and requires higher horsepower to produce sufficient air to operate pneumatic tools. In some cases, air compressors will use up to eight times as much fuel as comparable hydraulic power packs, which affects the financial side of a contractor's operation in addition to the environmental aspect of the job.

To further reduce any potential environmental effects, some hydraulic-equipment manufacturers design their power packs and hydraulic tools to work with biodegradable oil. This minimizes any sort of jobsite contamination risks. It also means that no special permits are required for discarding the oil, thereby keeping the task of oil disposal simple for the contractor.

A matter of maintenance

With the number of benefits offered by hydraulics, it seems odd that they have not made a greater dent in the handheld-equipment industry. One possible reason could be that contractors have been largely scared off by an overriding beliefÑor fearÑthat for all their performance advantages, hydraulics carry with them an even greater number of maintenance headaches. One of those supposed headaches is the need for special tools unique to hydraulic equipment. In reality, hydraulic power packs and tools can be serviced with standard repair tools.

The actual maintenance work is not difficult, either. Power packs have very few wear parts, and those are easily accessible and can be serviced quickly. Hydraulic breakers and tools are based on a modular system, meaning they often can be repaired simply by changing out a defective part, rather than overhauling the entire tool.

The relative size of power packs and air compressors also comes into play in a maintenance comparison. Oil changes are faster on a power pack, since it has a smaller engine and therefore has less oil to drain than does a compressor. Eventual rebuild costs are more reasonable for a power pack than an air compressor. On a complete power pack rebuild, it is usually less expensive to purchase a new engine. But doing the same for an air compressor is not always feasible, and complete compressor replacement may be a better financial option.

The new XL 5100 III, weighing just over 55,000 lb, reflects a new Gradall design philosophy that delivers increased performance, excellent cost containment benefits and a shorter carrier for easier highway mobility and a shorter rear swing.

Unlike the XL 5100 that used two Cummins engines, the XL 5100 III uses just one Detroit Diesel Mercedes engine. Conserving fuel while producing greater horsepower, the new engine operates both the truck carrier and the upper structure and boom. The concept reduces maintenance costs with only one electrical system, one radiator, one set of filters and other non-redundant features.

While the old model required two fuel tanks-one with 86 gal and one with 50 gal-the efficient new engine is paired with a single 100-gal tank.

In the chassis cab, the operator can drive the excavator at highway speeds to one or more jobsites in a single day. From the upper structure cab, the operator uses the same engine to reposition the carrier and operate the powerful telescoping and tilting Gradall boom. New electronic joysticks replace hydraulic controls, providing optimum reliability. Using a switch in the cab, the operator can now select the Gradall, SAE or Deere joystick pattern.

Operators of the new model have greater control over their carrier positioning speed using a two-speed switch in the upper cab.