Customers always demand more performance out of their backhoe-loaders, particularly on the back end. “In North America, the backhoe end of the machine is used about 70% of the time the machine is operating, so it’s always been an area of focus for our product teams,” says Kevin Hershberger, BHL marketing, Caterpillar.
Several criteria define backhoe performance. “Consider performance specs such as digging depth, forward reach and lift height for truck loading, lift capacity and breakout forces,” says George MacIntyre, global product marketing manager, Case Construction Equipment. “Other important characteristics include machine stability while roading, boom height for transport/working in confined spaces, overall machine dimensions and visibility.”
Other considerations include how much trench you can dig without repositioning the machine, and whether you can see past the boom in the trench or as it’s swinging up and over the side of a truck. “The biggest complaint from the field is the size of the boom, as operators have to look past them into the trench or over them when loading a truck,” says Jim Blower, JCB. The JCB boom is narrow in width and depth to address this issue.
Then there is the issue of strength vs. weight. “The boom has to be able to withstand all of the digging and lifting forces while being as light as possible to get the best performance,” says Blower.
“Strength is a very important attribute when designing the boom,” agrees Jamie Wright, product manager, Terex Construction Americas. “Terex uses an 8mm-thick steel tubular design with its booms, which adds considerable strength and durability to the product. Forged steel at each pivot point reduces wear on pins and bushings.”
A box-style boom design, such as found on Volvo backhoe-loaders, can combine both rigidity and light weight. “The boom is basically a box section with a forging on the bottom and the same forging on the top. It is enclosed,” explains Marcello Bargellini, backhoe product specialist, Volvo Construction Equipment.
Keeping hydraulic lines safe is another priority on any good backhoe design. For instance, many manufacturers route hydraulic lines inside the boom so they are protected, and pay special attention to areas where plumbing has to be exposed. “To the extent that is possible, we always try to use tubes (vs. hoses) for longer life,” says Bargellini.
“Neat routing of hydraulic hoses increases visibility and reduces hose damage,” says Wright. “Visibility to both the loader and backhoe is important for overall efficient operation. A well-dimensioned boom and boom placement give the operator an excellent view into the trench at any position.”
Visibility was one of the focal points in development of Case’s N Series backhoes. “Engineering put great emphasis on making sure that any modifications to the boom design to improve performance would not interfere with the operator’s line of sight to the backhoe’s work area,” says MacIntyre. “Case engineering mapped the line-of-site visibility with new boom design concepts to better understand the impact to visibility with any potential changes to the boom design.”
2011年12月20日星期二
2011年6月22日星期三
Czech museum ends its move; elevation is next
Two weeks after the monumental move began, the National Czech & Slovak Museum & Library, 30 16th Ave. SW, was finally positioned Tuesday in front of its new home.
Gary Rozek, who leads the museum board’s building committee, said the museum rolled into place about 7:30 p.m., covering nearly 70 feet since the afternoon and 480 feet from its original spot along the Cedar River.
“Yes, we finished and everything’s perfect,” he said.
The next phase involves removing the 40 dollies – 10 of which were hydraulic and powered the move- and elevating the building with jacks and cribbing.
Rozek said the museum will be lifted about 12 feet so the building can slide onto its new foundation on top of a parking garage. That process could take another six to eight weeks.
Nearly daily downpours hampered progress by the movers, Jeremy Patterson Structural Moving & Shoring of Washington, Iowa, which started the relocation on June 8.
Here is the update from Monday:
Truckloads of rock were dumped Monday at the site of a monumental move – now heading into its 14th day – after rain again inundated the area.
Movers prepare the grounds to move the National Czech and Slovak Museum and Library on Monday, June 20, 2011. (David Scrivner/SourceMedia Group News)The gravel replaced muck to allow the National Czech & Slovak Museum & Library to continue on its move toward a new foundation.
On Saturday, Jeremy Patterson Structural Moving & Shoring of Washington, Iowa, pivoted the nearly 17,000-square-foot museum, so the side facing the Cedar River can become the front entrance.
Wheels were adjusted on Sunday to continue the move, but as has been the case since the relocation began on June 8, more rain pelted the site, leaving the road a mess, said museum spokeswoman Diana Baculis.
Baculis said the rocks were brought in to stabilize the road built for the move.
Workers hoped to move the building another 100 feet to position it in front of its new foundation on top of a parking garage, she said.
The crew connected a tow truck and a track hoe to steel beams supporting the building to provide extra traction, and the museum began moving about 4 p.m. Monday, five feet or so at a time.
Workers moved steel plates on the ground from the rear of the museum to the front to further stabilize the move.
The building progressed more than halfway to its new site before a hydraulic hose blew about 8 p.m., ending that day’s move. Weather permitting, the move will continue Tuesday.
Baculis said once the building is in place, it will be raised another 12 feet with 40 towers of cribbing – wood timbers – before it slides on top of the parking garage.
“That (cribbing) will take some time to put together,” she said. “It will be a slow process.”
Gary Rozek, who leads the museum board’s building committee, said the museum rolled into place about 7:30 p.m., covering nearly 70 feet since the afternoon and 480 feet from its original spot along the Cedar River.
“Yes, we finished and everything’s perfect,” he said.
The next phase involves removing the 40 dollies – 10 of which were hydraulic and powered the move- and elevating the building with jacks and cribbing.
Rozek said the museum will be lifted about 12 feet so the building can slide onto its new foundation on top of a parking garage. That process could take another six to eight weeks.
Nearly daily downpours hampered progress by the movers, Jeremy Patterson Structural Moving & Shoring of Washington, Iowa, which started the relocation on June 8.
Here is the update from Monday:
Truckloads of rock were dumped Monday at the site of a monumental move – now heading into its 14th day – after rain again inundated the area.
Movers prepare the grounds to move the National Czech and Slovak Museum and Library on Monday, June 20, 2011. (David Scrivner/SourceMedia Group News)The gravel replaced muck to allow the National Czech & Slovak Museum & Library to continue on its move toward a new foundation.
On Saturday, Jeremy Patterson Structural Moving & Shoring of Washington, Iowa, pivoted the nearly 17,000-square-foot museum, so the side facing the Cedar River can become the front entrance.
Wheels were adjusted on Sunday to continue the move, but as has been the case since the relocation began on June 8, more rain pelted the site, leaving the road a mess, said museum spokeswoman Diana Baculis.
Baculis said the rocks were brought in to stabilize the road built for the move.
Workers hoped to move the building another 100 feet to position it in front of its new foundation on top of a parking garage, she said.
The crew connected a tow truck and a track hoe to steel beams supporting the building to provide extra traction, and the museum began moving about 4 p.m. Monday, five feet or so at a time.
Workers moved steel plates on the ground from the rear of the museum to the front to further stabilize the move.
The building progressed more than halfway to its new site before a hydraulic hose blew about 8 p.m., ending that day’s move. Weather permitting, the move will continue Tuesday.
Baculis said once the building is in place, it will be raised another 12 feet with 40 towers of cribbing – wood timbers – before it slides on top of the parking garage.
“That (cribbing) will take some time to put together,” she said. “It will be a slow process.”
Tenneco's Kinetic Suspension, the Anti Anti-Roll Bar - Tech Dept
The lowly damper (a.k.a. shock absorber) is the unsung hero of any car’s suspension system. Ride and handling specialists sweat untold hours over them, and engineers have painstakingly improved shocks with friction-reducing seals, gas pressurization, electronic valving, and even magnetic fields. While it’s hard to argue with a 3-series BMW’s poise or the comfort strides Ferrari has achieved of late, the damper’s best days may lie ahead. Credit Australian Chris Heyring for inventing a superior means of controlling wheel and body motion and Tenneco for developing that technology into its Kinetic suspension system.
Conventional shocks use calibrated orifices restricting the oil flow through a moving piston to produce damping effects that manage some very complicated, often contradictory forces—wheel impacts (the so-called bump force) want a soft response; body heaves (roll) demand a stiffer one. The Kinetic setup keeps the piston stroking in sync with wheel motion inside an oil-filled cylinder at each corner just as in a conventional shock, but it adds some embellishments. To diminish the usual trade-offs between ride and handling, the creation and manipulation of damping forces are moved outside these hydraulic units in a manner far beyond the electronic valves and remote reservoirs employed before. A network of hoses connects all four units to two hydraulic accumulators (sealed devices containing pressurized nitrogen and oil separated by a membrane). In the most exotic version of the Kinetic system, there’s also a pump to adjust the pressure inside the accumulators.
Heyring’s brainstorm was a scheme for interconnecting the eight chambers inside the four suspension units. The top chambers on one side of the vehicle are hydraulically linked to the opposite side’s bottom chambers, and vice versa [see schematic above].
When a one-wheel bump is encountered, the resulting suspension motion pumps oil into one chamber and out the other side of the piston at that corner of the car. To minimize the disturbance at the other corners, both accumulators regulate this flow. Damping forces are produced as the oil passes through calibrated restrictions (orifices) built into the hydraulic hose attachments.
When the car negotiates a corner, the cross-plumbing arrangement yields a response dramatically different from the one-wheel reaction. Now the outbound flow of oil from all four hydraulic units rushes into just one accumulator. The contained nitrogen acts as a spring to resist that flow. As a result, there’s no need for anti-roll bars or stiff suspension coils to keep the body from listing excessively in a bend.
Because the bump and roll modes act independently, the Kinetic system can be tuned to provide a controlled response over potholes, supple ride motions over dips, and firm resistance to body lean in sweeping bends. Adding electronically adjustable orifices allows the damping to be keyed to car velocity and the driver’s moods. Pumping extra oil into the hydraulic veins raises the accumulator pressure—and roll stiffness—to provide a handy track-day setting.
Conventional shocks use calibrated orifices restricting the oil flow through a moving piston to produce damping effects that manage some very complicated, often contradictory forces—wheel impacts (the so-called bump force) want a soft response; body heaves (roll) demand a stiffer one. The Kinetic setup keeps the piston stroking in sync with wheel motion inside an oil-filled cylinder at each corner just as in a conventional shock, but it adds some embellishments. To diminish the usual trade-offs between ride and handling, the creation and manipulation of damping forces are moved outside these hydraulic units in a manner far beyond the electronic valves and remote reservoirs employed before. A network of hoses connects all four units to two hydraulic accumulators (sealed devices containing pressurized nitrogen and oil separated by a membrane). In the most exotic version of the Kinetic system, there’s also a pump to adjust the pressure inside the accumulators.
Heyring’s brainstorm was a scheme for interconnecting the eight chambers inside the four suspension units. The top chambers on one side of the vehicle are hydraulically linked to the opposite side’s bottom chambers, and vice versa [see schematic above].
When a one-wheel bump is encountered, the resulting suspension motion pumps oil into one chamber and out the other side of the piston at that corner of the car. To minimize the disturbance at the other corners, both accumulators regulate this flow. Damping forces are produced as the oil passes through calibrated restrictions (orifices) built into the hydraulic hose attachments.
When the car negotiates a corner, the cross-plumbing arrangement yields a response dramatically different from the one-wheel reaction. Now the outbound flow of oil from all four hydraulic units rushes into just one accumulator. The contained nitrogen acts as a spring to resist that flow. As a result, there’s no need for anti-roll bars or stiff suspension coils to keep the body from listing excessively in a bend.
Because the bump and roll modes act independently, the Kinetic system can be tuned to provide a controlled response over potholes, supple ride motions over dips, and firm resistance to body lean in sweeping bends. Adding electronically adjustable orifices allows the damping to be keyed to car velocity and the driver’s moods. Pumping extra oil into the hydraulic veins raises the accumulator pressure—and roll stiffness—to provide a handy track-day setting.
2011年6月12日星期日
Gold rush another blight to ailing Amazon jungle
A gold rush that accelerated with the onset of the 2008 global recession is compounding the woes of the Amazon basin, laying waste to Peruvian rain forest and spilling tons of toxic mercury into the air and water.
With gold's price soaring globally as the metal became a hedge against financial uncertainty, the army of small-scale miners in the state of Madre de Dios has swelled to some 40,000. The result: Diesel exhaust sullies the air, trees are toppled to get at the sandy, gold-flecked earth and the scars inflicted on the land are visible on satellite photos.
"Extracting an ounce of gold costs from $400 to $500 and the profit is $1,000 per ounce," notes Peru's environment minister, Antonio Brack. In just a decade, gold has more than tripled in value.
The situation in the southeastern state of Madre de Dios, which borders Brazil and Bolivia, is mirrored in dozens of the countries where gold is similarly mined, and where the desperately poor often end up working for the most unsavory of opportunists.
Government controls are mostly futile.
As the industry has grown, heavy machinery has moved in bearing Caterpillar, Volvo and other international trademarks into a state the size of Maine or Portugal, whose remotest reaches are believed inhabited by uncontacted Indian tribes.
In February the Peruvian navy dynamited 13 dredges which, working in violation of a government ban, were choking the Madre de Dios river with silt, killing plants and destroying habitats. Protesting laborers blockaded Madre de Dios' only highway, and at least three people were shot and killed by police sent from Lima.
"One of the big hydraulic dredges we destroyed could easily harvest a kilogram (worth about $45,000) of gold a day," said Brack.
Rather than try to evict the thousands of protesting informal miners, the government decided to work to "formalize" their operations, which have denuded well over 180 square kilometers (70 square miles ) of jungle in Madre de Dios.
With gold's price soaring globally as the metal became a hedge against financial uncertainty, the army of small-scale miners in the state of Madre de Dios has swelled to some 40,000. The result: Diesel exhaust sullies the air, trees are toppled to get at the sandy, gold-flecked earth and the scars inflicted on the land are visible on satellite photos.
"Extracting an ounce of gold costs from $400 to $500 and the profit is $1,000 per ounce," notes Peru's environment minister, Antonio Brack. In just a decade, gold has more than tripled in value.
The situation in the southeastern state of Madre de Dios, which borders Brazil and Bolivia, is mirrored in dozens of the countries where gold is similarly mined, and where the desperately poor often end up working for the most unsavory of opportunists.
Government controls are mostly futile.
As the industry has grown, heavy machinery has moved in bearing Caterpillar, Volvo and other international trademarks into a state the size of Maine or Portugal, whose remotest reaches are believed inhabited by uncontacted Indian tribes.
In February the Peruvian navy dynamited 13 dredges which, working in violation of a government ban, were choking the Madre de Dios river with silt, killing plants and destroying habitats. Protesting laborers blockaded Madre de Dios' only highway, and at least three people were shot and killed by police sent from Lima.
"One of the big hydraulic dredges we destroyed could easily harvest a kilogram (worth about $45,000) of gold a day," said Brack.
Rather than try to evict the thousands of protesting informal miners, the government decided to work to "formalize" their operations, which have denuded well over 180 square kilometers (70 square miles ) of jungle in Madre de Dios.
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