Conventional blasting is becoming more tightly regulated, more expensive and more challenging in many locales due to encroaching urbanization. So manufacturers of hydraulic rock breakers have stepped up the pace of product development in a race to reach the triple crown of breaker technology — superior impact energy, fewer moving parts, less recoil and vibration.
The increased selection of models, coupled with higher performance and greater reliability, has enabled quarry operators to expand the role of rock breakers as a stationary, pedestal-mounted support implement to a flexible production tool. Rock breakers are available to match up with almost any size carrier. And many of the larger breakers can be used to replace or supplement blasting in situations such as breaking rock on the periphery of a property to avoid blast effects in nearby communities or handling smaller jobs that don't warrant the expense and effort of blast preparation and monitoring.
Rock breaker versatility has been bolstered by the proliferation of suitable carriers — including beefier skid loaders and hydraulic excavators in a wide spectrum of weight classes. Rock breakers come in sizes that range from handheld versions up to massive 8-ton units; the latter typified by Atlas Copco Construction Tools' HB 7000. Atlas Copco marketing manager Torsten Ahr explains some of the challenges involved in designing and selling such a large unit.
“Our sales expectations were quite modest at the time, because at the beginning of the '90s there existed only a few suitable carrier units worldwide,” Ahr says. “Moreover, the use of hydraulic rock breakers as production units in quarries was little known at the time. No one had the experience, one could not bank on reliable data and there were only a few potential users willing and able to invest in heavy hydraulic rock breakers for direct mining.
“The HB 7000's development engineers had … to harness and produce in a reliable manner a single-impact energy, which was never achieved before. In achieving this, they also had to ensure that the breaker would not destroy itself by the sheer power produced by the impact mechanism. The kinetic forces inside the breaker are enormous, more than 600 tons acting on the tool with every impact, which can be compared with the weight of a fully loaded Airbus A380. The chisel alone weighs 430 kilograms (950 pounds) and has a diameter of 210 millimeters (8.25 inches).”
Ahr says, “Work [on the HB 7000] really started as the first prototypes were delivered to the customers. The breaker reached its physical limits, partially exceeded them and new ways had to be found to turn the prototypes into a real product. No other product has ever yielded such a close cooperation between the product management, sales and marketing departments, dealers, service, logistics and end users.”
Because of the growing interest in rock breakers, Atlas Copco has stepped up its pace of development, introducing a handful of new breakers and opened a new hydraulic implement service center in Texas. Many of the other dozen or so top breaker suppliers also have unveiled new models to meet customer demands and fill gaps in their product lines.
At the upper end of the size range, Atlas Copco has added two models to its heavy-duty HB series — the year-old HB 4200 and the recently introduced HB 2500. The 4200, with a service weight of more than 4 tons, is designed for mounting on carriers in the 45- to 80-ton range. The unit delivers an impact rate of up to 530 blows per minute, with maximum hydraulic flow of 84 gallons per minute and at 2,610 pounds per square inch of pressure. It offers two major productivity features: Atlas Copco's AutoControl that controls the impact rate on startup to prevent tool slippage and then matches the rate to the density of the material being worked on; and StartSelect that keeps the unit's hydraulic oil circulating at all times but won't allow the hammer to fire unless there is down pressure on the tool, thus preventing potentially damaging blank firing. This feature also allows an operator to warm the hydraulic system before starting work in cold weather.
The smaller HB 2500 weighs 2.25 tons, delivers an impact rate of up to 550 blows per minute and is suitable for carriers weighing 32 to 45 tons. It also comes standard with AutoControl and StartSelect, and features an additional system — PowerAdapt — which will automatically shut down the breaker if it senses excessively high oil pressure from the carrier. This provides protection against internal damage that can happen when a breaker is used on multiple carriers with different hydraulic systems.
Both the 2500 and 4200 are equipped with an energy-recovery system that is claimed to prevent damage from piston recoil on extremely hard materials. The system consists of a shuttle valve that detects piston rebound and a high-pressure accumulator that stores energy from piston recoil. The stored energy is used on the succeeding strokes to make them faster and harder.
Caterpillar says its new H160Ds hammer is suitable for mounting on carriers in the 77,000- to 98,000-pound class, such as Cat's 330C and 345B II hydraulic excavators. The hammer measures 116.2 inches from top plate to tool tip and has an operating weight of almost 7,000 pounds. According to Cat, this model incorporates a number of new or improved features including automatic shut-off, which turns the hammer off when no material is present to avoid blank firing; an accumulator design that allows the user to check and recharge the accumulator without removing the hammer from the machine; a screw adjustment for the pressure-control valve without removing it from the hammer power cell; and full-length wear plates, with visual wear indicators, on all four sides of the inner housing. Cat also says that the new hammer has more power and higher blow frequency, offering improved productivity over the previous model.
Hydraulic hammer manufacturer Breaker Technology Inc. also has developed the MBS mounting systems for use with rock breakers on portable aggregate and recycle plants. The new MBS models can remain on the plant due to a low-profile design that allows the boom to be lowered flat onto the feeder, below the height of the flywheel for road transportation. These units are designed to be installed or retrofitted to new or existing wheeled- or track-mounted crushing plants. They can be mounted to the side of track-mounted crushing plants or between the drive and the jaw on portable plants. It also can be designed without a pedestal base to give it a smaller footprint in confined spaces.
The MBS series comes in two major configurations — the MBS and the MBS-H. The MBS is the lighter of the two styles and is designed for recycle and light quarry applications for hydraulic breakers up to 1,100 foot-pounds. The MBS-H is designed for hard-rock applications for breakers as large as 3,000 foot-pounds. The MBS13H has a vertical reach of 13 feet and 200-degree swing rotation.
Both Caterpillar and Bobcat have launched new models in the lower size ranges for mounting on skid-steer loaders or mini-excavators, The Bobcat HB1180 hydraulic breaker falls into the 750-foot-pound impact energy class and can be used on Bobcat skid-steer loaders (models S220 through S300), compact track loaders (models T250 through T300), the A300 all-wheel steer loader, and compact excavators (models 337, 341 and 435). A major improvement on the HB1180 is the auto-power feature, which is an automatic pressure regulator that ensures maximum performance of the hydraulic breaker, regardless of tool carrier hydraulic flow variations or changes in outdoor temperature. This feature also limits excessive pressure at the time of start-up. As a result, the energy chamber diaphragm is protected, allowing for longer service life. According to Bobcat, the energy chamber on the HB1180 allows nitrogen pressure to remain constant so periodic recharging is unnecessary, thus making the breaker virtually maintenance-free.
Cat's H55Ds 500-foot-pound hydraulic hammer features a higher blow rate and 25% more power for production from a 436-pound work tool. Recommended carrier weight is 5,500 to 9,900 pounds. The new hammer is compatible with the Caterpillar pin grabber quick coupler system. Principal features include an enclosed housing that protects the power cell and reduces noise, recoil isolation, high- and low-pressure accumulator, a one-piece body that eliminates rods and nuts for better reliability, and integral mounting that doesn't require brackets on the excavator.
Atlas Copco's 1,210-pound PB 530 Penta Series hydraulic breaker is designed for use with skid steers, backhoes and mini-excavators in the 20,000- to 35,000-pound weight class. The breaker delivers an impact rate of up to 1,100 blows per minute and accepts a maximum hydraulic flow of 26.4 gallons per minute at 2,175 pounds per square inch of pressure. The PB 530 comes with the standard VibroSilenced damping system, which controls the breaker's sound and vibration during operation. Elastic elements between the percussion mechanism and box enclosure provide acoustic insulation, reducing noise by up to 10 decibels compared with similar guide systems. The unit's one-piece, field-replaceable slip-fit bushing is pinned in place by the working steel. This allows the operator to replace both the steel and bushing by removing the pin, as opposed to dismantling the entire breaker.
Sandvik Mining & Construction added the Rammer G88 heavyweight breaker to its line-up. This 3-ton unit is larger than the Rammer G80 and is designed for use on excavators in the 30- to 45-ton weight range. As with the other hammers in the Rammer line, the G88 is equipped with a seal system around the tool to keep dust and dirt out. The unit also features idle stroke protection, an integrated lubrication system and advanced side-bolt engineering. According to Sandvik, this results in a hammer that is more durable, reliable and, therefore, profitable than its predecessors.
The G88 has an impact cell with advances in seal technology as well as a reduced number of components. At the front end of the hammer, the G88 has a simple and reliable tool retaining system and a longer guidance arrangement for the tool while the lip bushing is removed. The Rammer G88 is offered with tools that have been designed with a larger diameter at the lower tool bushing for improved durability. Although Sandvik's announcement of the G88 didn't include operating specs, the G88 falls into the range of its G80 and G90 series of hammers which provide impact rates from 300 to 630 blows per minute, depending on the model, and operate on 42 to 82 gallons per minute of hydraulic flow.
Stanley Hydraulic Tools markets a line of mountable breakers that range in size from 1,250 to 8,800 pounds (with bit). The MB EXS Stealth series extends from the smallest model — the MB20EXS, with 1,500 foot-pounds of impact energy — to the 12,000-foot-pound MB100EXS, which is 128 inches long, has a tool diameter of 6.9 inches and is intended for mounting on carriers sized between 80,000 and 130,000 pounds. An optional auto-lube kit is available for all models in the series and is mounted directly on the breaker.
Indeco's line of hydraulic breakers covers all applications from skid-steer loader-mountable units up to the HP-16000. It's a 17,000-pound hammer that uses a 9-inch-diameter tool and is suitable for mounting on excavators with operating weights up to 130 tons. Impact rates provided by the 16,000-foot-pound HP-16000 ranges from 240 to 550 blows per minute.
In the medium-size class, Atlas Copco introduced two new models, the MB 1200 and MB 700. Weighing just over 1.5 tons, the 1200 can be mounted on carriers weighing 15 to 30 tons and delivers up to 680 blows per minute. The 1,650-pound, 800-blow-per-minute MB 700 has only two moving parts and doesn't require a high-pressure accumulator, reducing the unit's maintenance needs and increasing its reliability. In addition to AutoControl and StartSelect, these units feature a VibroSilenced damping system for reduced noise and vibration, and Atlas Copco's ContiLube II, an automatic lubrication system mounted directly on the breaker.
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