Noise control in hydraulic systems

Noise Control

Many designers have long accepted leaks as inherent to hydraulic systems, even though advances in technology should have eliminated hydraulic leakage a long time ago. Hydraulics suffers a similar identity crisis when it comes to noise. Noise certainly cannot be eliminated, but a number of products and techniques exist to at least bring noise down to an acceptable level.

Sources of noise

A hydraulic system’s greatest contributor to noise is the power unit, Figure 1. Noise not only emanates directly from the electric motor and pump, but also is caused by pressure fluctuations in the hydraulic fluid and by components. This results from these pressure fluctuations or from physical vibration.

Electric motor noise comes from bearings, the rotor and stator assembly (the characteristic hum), and, especially, the fan. A standard electric motor contains a fan with blades designed to provide cooling whether the motor shaft rotates clockwise or counter-clockwise.

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Loader Backhoe Maximizes Resources

Case Construction Equipment’s Backhoe

Case Construction Equipment, Racine, Wis., recently unveiled its N series backhoe loaders with maintenance-free Tier-4 Final engine. The newest addition to the series is the 580N EP, which is powered by a 207 in.3 (3.4 l) diesel engine that puts out 74 gross hp (55 kW) at 2,200 rpm. The engine powers a mechanical drivetrain and a Parker Hannifin P330 single-section gear pump for backhoe, loader, and other hydraulic functions. The pump’s maximum output is 28.5 gpm at 3,350 psi (107.9 lpm @ 231 bar).

Backhoe Functions

Hydraulic fluid is filtered to 7 microns, and a warning light comes on when the filter goes into bypass mode. This alerts the operator that the filter element needs to be replaced.

The loader function is controlled by two- or three-spool open-center valves through a single lever manual control. The lift lever has a positive hold float position and a return-to-dig feature.

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Can the U.S. really go frack-free?

Earlier this month, both candidates for the Democratic Party nomination for president took shots at frack free — hydraulic fracturing, the process that extracts oil and natural gas by using high-pressure liquids to break through shale rock formations.

In a March 6 debate, Hillary Clinton said, “By the time we get through all of my conditions, I do not think there will be many places in America where fracking will continue to take place.”

“My answer is a lot shorter,” Sen. Bernie Sanders, D-Vermont, said. “I do not support fracking.”

All three Republican candidates for president support hydraulic fracturing.

The presidential race amplifies a debate that’s more complex than the typical struggle between industry and the environment.

On a warming planet, does fracking keep the nation’s energy mix chained to fossil fuels and further delay a future where clean energy sources dominate? Critics say it does.

However, the fracking boom also is largely responsible for utilities’ accelerating shift from coal-fired power plants to cleaner-burning natural gas generators. Meanwhile, there’s fierce debate about potential threats to ground water and methane leaking into the atmosphere.

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How To Configure Hydraulic Conductors For Noise Reduction

Noise reduction in hydraulic systems

This often involves isolating the pump/prime-mover assembly using flexible mounts (isolators). In these cases, the use of hose is necessary to maintain the isolation between the pump/prime-mover and the rest of the system.

The flip-side to this though is, although long lengths of hose can reduce structure borne noise, hose is actually an efficient radiator in the frequency range where most of the energy is generated, typically around 600, 900 and 1200 Hertz.

In terms of vibration and noise conductivity, a long length of pipe or tube is the worst configuration. A long length of hose is better than pipe or tube, but still bad. A better configuration is one section of pipe or tube connected to one section of hose. And the best configuration for noise reduction is one section of pipe or tube with a section of hose either side, that is: hose > tube >hose.

Two other negatives of hose are: its length changes with pressure, and when it is bent through a radius, it acts like a Bourdon tube; it tries to straighten as pressure increases. Both of theses dynamics produce forces which act on connecting structures. For these reasons, the best way to control noise when making bends with hose is to use a solid bend (90° or 180°) with a hose section on either side.

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Kubota Introduces the SVL95-2s

Kubota’s New Technology

Kubota Tractor Corporation’s SVL95-2s compact track loader offers greater multi-tasking capabilities, more powerful hydraulics and more comfort upgrades than ever. The SVL95-2s takes the place of the SVL90-2 compact track loader in the Kubota product line-up.

“Kubota is raising the bar with the introduction of our new SVL95-2s. This new compact track loader offers a heightened level of performance and convenience features,” said Jorge De Hoyos, Kubota senior product manager.

Stronger Hydraulics: Five-Way Adjustable, Triple Duty-Capable

With five hydraulic presets available for the operator to choose via an in-cab control, the SVL95-2s, when equipped with the optional high flow, is ideal for jobs that require running more than a single attachment. At the heart of the SVL95-2s is its new, more powerful high flow hydraulic system, which can be programmed and instantly adjusted at the push of a button to adjust flow rates from as little as 5 to as much as 40 gal. (19 to 151 Lpm) per minute — a 19-percent improvement over previous models — and at line pressures of 3,553 PSI.

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Hydraulics Pointers

There has been a cloud of mystery around tractor hydraulic systems that scares collectors away from restoring them. And for good reason. Just the pumps alone are complicated mechanisms with seemingly hundreds of small parts and tighter-than-engine tolerances.

As a general rule, if the hydraulic pump on the machine you are restoring is on the fritz, then you would be best advised to find a hydraulic professional to take on the job. It’s not that hydraulic pumps are impossibly complicated to rebuild compared with, say, a diesel injection pump. No, the reasoning behind this advice is that professionals have the specialized tools necessary for the repair. Unless you are hankering for a challenge, you may be better off hiring the work done.

Replace all seals

Luckily, hydraulic systems on older tractors are often in workable condition and don’t need repair – 
unless they’re leaking like a sieve. In this case, you’ll need to replace any gaskets, 
O-rings, and packings to stop oil from ruining a paint job. This is certainly a job a restorer with some experience can take on since it doesn’t require disassembly of the internal working mechanisms.

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Hydraulic Integrated Circuits Provide Big Payoffs

Hydraulic Integrated Circuits

Even though the effects of hydraulic integrated circuits (HICs) are not as dramatic as those in the world of electronics, they still can substantially reduce the size, complexity, and overall cost of hydraulic systems. Furthermore, HICs exhibit additional advantages that go beyond these benefits.

An HIC consists of a manifold containing multiple pressure-, directional-, and even proportional-control valves. In extreme cases, an HIC may even contain pumps, filters, actuators, or any combination of these to form a completely self-contained hydraulic system. Most HICs, however, consist of a manifold containing inlet and outlet ports, cartridge and subplate mounted valves (or both), and a network of internal passages that route hydraulic fluid through branch circuits of the hydraulic system.

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The Evolution of Down Force Tech

Down Force History

For years, down force has been supplied by springs on individual row units. While better than no down force, springs struggle to maintain a consistent pressure and are difficult as well as time consuming to adjust.

“In the past, the typical scenario was to have a manual spring setting on the back of the planter, but it wasn’t an easy adjustment,” says Nathan Paul, On-Farm Network. “You would have to get out of the tractor cab and adjust springs that would have different weights across the width of the planter. With the weight of the seed itself or the additional bags being carried, you would have rows putting too much pressure on the seed. When that row would go across the ground, it would compact the seed wall. If you didn’t have enough pressure on the row, you ran the risk of planting too shallow.”

Down Force Technology

As technology progressed, a pneumatic (air bag) system was developed, which uses a compressor to inflate/deflate air bags across the planter as it calculates down force.

“The air bag system became popular because you could adjust down force on-the-go,” explains Paul. “The system slowly adjusted the weight across the entire width of the planter based on field conditions, which were preset and monitored from the cab.”

Although this was an improvement over past practice, the pneumatic system can struggle to keep up because it takes anywhere from 15 to 20 seconds to inflate or deflate air bags to match conditions. In a field with varying soil types, the air bag system may continually be trying to catch up, which can still cause inconsistent seed depth or unnecessary soil compaction.

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McCormick Plans to Offer Higher Horsepower Tractors

Higher Horsepower Tractors

Since 2005, McCormick hasn’t offered tractors above 225 hp. in the North American market. That will change next year when McCormick jumps back into the higher horsepower market with the X8 series. The X8 tractors, which made their debut at Agritechnica in late 2015, will be available in three models with 265, 286, and 310 hp.

“McCormick wants to get back into the row-crop market,” explains Taylor Grout with McCormick. “The X7 is the current flagship for this movement and with the X8, we will continue building on this.”
X7 Series

Introduced in 2014, the X7 series includes five models from 143 to 212 hp. The two smallest models in this range are powered by a 4.5-liter, four-cylinder engine while the three largest run on a 6.7-liter, six-cylinder engine. Both BETAPOWER turbocharged engines feature multivalve technology, electronic common rail fuel injection, and advanced SCR emissions control systems.

To transfer power to the ground, the tractors come standard with a 24-speed powershift transmission, featuring electro-hydraulic range shifting and a power shuttle control. The electro-hydraulically engaged rear PTO offers 540, 540 eco, 1,000, and 1,000 eco rpm PTO speeds with interchangeable flange-type shaft. The system incorporates PTO headland management to eliminate implement driveline damage when raising rear-mounted implements. The closed-center hydraulic system has a standard flow rate of 32.5 gpm available to the implement system with up to five rear remotes. Maximum lift capacity comes out at 20,500 pounds.

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Tips for Maintaining Hydraulic Hoses

Maintaining Hydraulic Hoses

Hydraulic excavators need their hydraulic hoses working properly. If there’s a cut, break or hole in one of them, the digger is done.

Hydraulic hoses do not last forever; eventually they break down and need to be patched or replaced. But here are a few tips to help extend hose life and keep hydraulic excavators operating longer and more efficiently.

There are three factors that can create hydraulic hose failure: (1) external damage, (2) wear and tear from hours of use, and (3) corrupted oil in the hydraulic system.

Hydraulic hoses on excavators are exposed. They can be struck, severed or crushed by outside objects, such as sharp pieces of metal, concrete or rebar. Excavators working in hostile environments such as building demolition, scrap yards and harsh rough excavation job sites are at greater risk of sustaining damage.

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