Frequently when designing simple hydraulic circuits that utilize low cost solutions, system designers will often use fixed displacement pumps. One challenge associated with the use of fixed displacement pumps can be the constant flow of hydraulic oil while the machine is running, even when flow is not needed at any of the hydraulic functions. Similarly, simple low cost circuits frequently do not require the multifunctionality of high cost sectional valves, thus keeping these circuits lower cost due to the less complex nature of the product used.
When a hydraulic circuit does not require or cannot have flow to two or more functions at the same time, 3-way, 2-position spool-type solenoid valves can be very useful. When these valves are used as a selector, primarily in circuits where the system designer may want to divert flow from one leg of a circuit to another, several 3-way, 2-position valves are a cost-effective alternative while emulating a tradition directional spool valve in a customizable manifold setup. Similarly, these valves can be used as a “dump” valve when a circuit does not require flow but is being driven by a fixed displacement pump running continuously.
Parker 3-way, 2-position spool-type solenoid valves can be used in a variety of applications, machinery, and market segments that require a switching or diverting function. The design of 3-way, 2-position valves generally include a three ported design that would allow flow paths in several different configurations while only connecting two ports in any one position.
In the image below, you will find an example circuit for a blower/brush application for a piece of construction machinery. The 3-way, 2-position spool-type solenoid valve, which is circled in red, is being used as a diverter to solely supply flow to one function at a time. Function one is a lift/lower, up and down motion and function two is a tilt/swivel, side-to-side motion.
Note that all solenoid valves with this design have flow restrictions with pressure drop associated across the valve, so continuous flow will result in heat generation after a given period of time. Additionally, 3-way, 2-position solenoid valves that use a spool-type design will have a higher leakage rate than those with a poppet design, and thus would not be recommended for use in load holding applications.
Parker Hydraulic Cartridge System Division’s valves allow full rated pressure at all 3 ports with varying flow rates in industry common cavity sizes. Valve sizes of -8, -10, and -16 are available with flow ranging up to 15 GPM and pressures as high as 5,000 PSI.
Parker’s 3-way, 2 position valves are available for purchase on parker.com. Simply add products to your cart for shipment within two days for in-stock items.
Article contributed by Stephen Brunton, product manager, Hydraulic Cartridge Systems Division.
28 Feb 2019
Work can be tough, dirty and unforgiving. The last thing you need is for the machine to fail in the midst of a job. Machine failure leads to unscheduled maintenance and an increased amount of time in the field. To prevent this costly downtime, it is essential that fluids are routinely checked and replaced, namely transmission fluid.
Transmission fluid is the lifeblood of a hydraulic system. Without transmission fluid, hydraulic pumps and motors cannot perform the powerful tasks that are required for many different applications. Unfortunately, most hydraulic fluids are merely repackaged mineral oils with contaminants that reduce oil lubricity, high amounts of sulfur that accelerate corrosion and unstable chemistries that lead to phase separation and “gunked-up” gears. Coupled with a 500-hour maximum life, the current market of transmission fluids provides hassle, downtime and uncertainty.
To combat this mediocrity, Parker Hannifin’s Pump Motor Division has developed HT-1000, an engineered oil, molecularly homogenized transmission fluid with the highest starting lubricity, longest life and highest cleanliness standard on the market.
HT-1000 was developed by Parker engineers in partnership with the world’s best formulators over 18 months. The oil combines the best, state-of-the-art “know-how.” Starting with the highest quality, lowest contaminant Group II base oil, HT-1000 is formulated to unmatched molecular homogeneity and packaged to the most uncompromising cleanliness standard. Each transmission developed and built by Parker is tested and shipped with HT-1000 to promote longevity and efficiency.
"The brief going into this project was to create the best hydraulic fluid, ensure the lowest cost, maintain Parker hydraulics and spare no cost or effort in the process. We were clear from the start that we needed to engineer what was missing in the industry, if the laws of science allowed it. If we couldn't leap frog the competition, we weren’t interested. Parker formulated fluids are engineered to deliver best performance and longest maintenance intervals."
Jason Richardson, lead engineer on the HT-1000 project, Parker Hannifin Corporation
HT-1000 is available for purchase online in 1-quart bottles, 1-gallon jugs, 5-gallon buckets and 55-gallon drums. HT-1000 is also available in 325-gallon bulk totes and 5000-gallon tankers by special request.
The Pump and Motor Division is a market leader in gear pump and low speed-high torque gerotor motors that continues to blaze the trail with the development of new technologies while maintaining the high level of service synonymous to Parker. Between its two locations in North Carolina and Tennessee, the division employs decades of industry experience to better serve you and your application.
Article contributed by C.T. Lefler, Marketing product manager, Parker Hannifin Corporation.
18 Feb 2019
As the case is across many sectors, electronics systems are the primary drivers of innovation in today‘s agricultural industry. However, those working in this sector may have noticed that any major strides forward in past years have been somewhat hampered by a lack of compatibility between proprietary solutions from different manufacturers.
Fortunately, more recent solutions have been based on ISOBUS, bringing significant benefits to end applications and their users. And now, with the latest technology, combining HMI solutions for both ISOBUS functions and other tractor HMIs are leading to the possibility of just one, convenient, cost-effective and efficient interface for the operator.Modern ISOBUS systems
A modern ISOBUS system comprises a multitude of components, including the tractor, terminal and implement. Taking this concept a step further, an industry first from Parker’s perspective, the ISOBUS Suite Apps enable the integration of ISOBUS functionalities into the machine HMI (Human Machine Interface), via the app-based Pro Display product family.
Using the apps, ISOBUS functions can be shown on the screen. Since the display offers full flexibility and can show comprehensive information – including machine data, notifications, camera monitors, PDFs and more – no separate ISOBUS display is required.Changing the landscape
Farmers have been forced to toil with tractors, implements and machines from various manufacturers on a daily basis. The variety of proprietary solutions meant that many systems did not engage seamlessly or even at all. This disunity saw each implement and tractor requiring an individual terminal to allow data exchange and machine control – a situation that was far from ideal.
Systems based on ISOBUS and utilising tools such as Parker’s ISOBUS Suite apps are driving a shift in the agricultural landscape, making it possible to achieve higher levels of productivity with less operator fatigue.
Using these latest electronic systems, operators can now control and monitor practically every stage of the agricultural process, including tilling the soil, planting seeds, irrigating the land, cultivating crops, protecting them from pests and weeds, harvesting, threshing grain, feeding livestock, and sorting and packaging the products.How it works
In its basic form, the technology facilitating this capability is ISOBUS, an international communications protocol for the agricultural sector that offers plug-and-play functionality and – importantly – only one terminal for a large selection of implements, regardless of the manufacturer. Sounds a lot easier already. Put simply, ISOBUS standardises control settings, reduces downtime and minimises installation and interface problems.
Crucially here, a standardised plug makes it remarkably easy to connect different components, while costs are reduced because it is only necessary to buy a single terminal. Who doesn’t like cost savings? A further benefit of ISOBUS is that it improves operating efficiency and optimises timings, as data can be exchanged between the farm PC and the terminal. With ISOBUS, life on the farm is certainly a whole lot easier; but it could even better.
By utilising Parker’s UX Toolkit – an apps-based software development environment that can be used to develop HMI products for mobile machines and vehicles – and the split-screen functionality, manufacturers can display further machine data and camera monitors right next to the ISOBUS information.
Machine manufacturers can expand the functionality of a device with ease. HMI apps offer an advantage when trying to make mobile machines more efficient, when guaranteeing flexibility in terms of expanding functionalities, and when simplifying processes in the driver’s cab. Less downtime is achieved via diagnostics apps for service code protocols, data capturing and analysis, GPS tracking and geo-fencing, as well as by apps that enable mobile phone hands-free functionality, driver logbooks and operating behaviour tracking.
The UX Toolkit, together with the Pro Display family, also supports functions such as automatic steering, self-levelling suspension and weighing. In addition, the robust displays with capacitive touchscreens are equipped with multiple communications and infotainment interfaces. In short, an apps-based future looks set to enhance the agriculture industry in ways never before imagined.
Tommi Forsman, principal engineer, Parker Hannifin, Electronic Controls Division
9 Jan 2019
Hoover Dam -- one of the most impressive engineering feats of the 20th century – generates hydroelectricity for millions of homes and businesses across the Southwest, and it’s a constant challenge to keep the vital power source running smoothly. Recently, a team of innovative engineering experts wrapped up a massive multi-year retrofitting and refurbishing project to make the dam safer and more operationally efficient.
Project scope and challenges
The challenge was to overhaul and upgrade a series of 50-foot-tall pressure-relief valves on turbines in the dam’s powerhouse and to convert them to a hydraulic control system. The contract for the project was awarded to Precision Machine & Supply, Inc., (a division of Andritz Hydro), which had been working with Hoover Dam since the 1990s.
“Because of the sheer complexity and logistics involved, this has been the most challenging thing I've ever done. It was complicated to get the old equipment out and put the new equipment in, especially with all the restrictions operating in a concrete structure at the bottom of Hoover Dam.”
Dan Wenstrom, president, Precision Machine & Supply, Inc.
Subcontractors for the complex assignment included Parker Hannifin (led by Greg Paddock, hydraulic territory manager; Regional Manager Steve Camp; and Jeff Sage, product manager for Parker’s Accumulator and Cooler Division) and Controlled Motion Solutions, Inc., (Comoso). The Comoso team was led by Joe Oloffo, Southwest regional manager / systems integrator; Director of Engineering Matt Schoenbachler; and Jeff Geyer, fluid systems manager.
Parker was tasked with designing and manufacturing a series of compressed-gas accumulators, and Comoso was responsible for providing engineering and sourcing the hydraulic components.
Upgrading an engineering marvel
Hoover Dam is often called one of the modern wonders of the world. Standing over 700 feet tall and containing more than 3,250,000 cubic yards of concrete, the magnificent structure spans the Colorado River between Nevada and Arizona, forming the 247-square mile Lake Mead reservoir behind it.
The dam generates more than 4 billion kilowatt-hours of electricity each year by taking diverted river water from the lake, under extremely high pressure, and channeling it into giant turbines at its base. The water to drive the turbines is fed by gravity through a series of large pipes called penstocks, which narrow (from 30 feet to 13 feet) as they descend to increase the pressure on the water being forced through. When the incoming water reaches this point, its pressure is 250 psi.
At the bottom of the penstocks, the water then enters the turbine through large steel wicket gates, each over six feet tall and weighing 1,500 pounds. The gates work like Venetian blinds, opening and closing to control the volume of water going into the turbine. As water rushes through the wicket gates, it passes over blades that spin the turbine and drive a rotor inside a generator, which then creates a magnetic field to produce electricity.
Hoover Dam has 17 turbines, each weighing about 700 tons, with generator shafts rotating at 180 rpm. While a turbine is spinning, energy is constantly being created and fed through power lines. However, if there is a sudden break or fault in the line – also called a load rejection – the turbine needs to stop as quickly as possible.
When a rejection takes down a primary line – which can be caused by a lightning strike or actual physical damage to a transmission wire -- there’s no place for that newly generated electricity to go. If that happens, the spinning turbine tends to overspeed, which can cause serious damage to the mechanism. Therefore, the water driving it has to be immediately shut off at the gates and simultaneously diverted around the turbine. However, that necessity comes with problems of its own.
First, if the high-pressure water flow is stopped too abruptly, it results in a powerful “water hammer” effect when the backed-up pressure suddenly and violently slams into an obstruction. (Imagine trying to bring a fast-moving train to an immediate stop.) The water delivery system at Hoover Dam contains kinetic energy to reduce the life of the penstocks.
Diverting the flow and relieving pressure
To avert the dangers of those sudden load rejections, the original designers of Hoover Dam installed large pressure-relief valves (PRVs) which could quickly reroute incoming water to bypass the turbines, thereby taking the generators offline. The first PRVs utilized water head pressure to drive large pistons to close tulip valves.
In recent years, though, questions arose about the original PRVs’ functional consistency and ability to protect the aging water lines. Installation of the turbines at the dam began in 1936, so the equipment and infrastructure inside the power plant were naturally affected by time and use.
“The turbines and all their plumbing are vintage – 80 years old in some cases – with a lot of wear and tear on them. So the Hoover people were very concerned about pressure spikes and the resulting negative impact they could have on the equipment.”
Greg Paddock, territory manager, Parker Hydraulics
“Over the years, those pressure-relief valves became corroded, agreed Wenstrom. "Also, the original valves were mechanically actuated and water-operated, because that's all the technology they had in the 1930s.”
Developing the solution
Aware of the critical need to optimize the reliable performance of the older pressure-relief valves, the operations team at Hoover Dam launched a long-term project to upgrade them. The main objective was to make the PRVs more responsive and functionally efficient when a power line break would necessitate a generator shutdown.
The initial plan called for overhauling the existing valves by taking them apart and restoring worn components to like-new condition. The scope of the challenge – plus the restriction of not being able to shut down multiple turbines at the same time – meant the work would inevitably require many years to complete. Hoover’s plant personnel and Precision Machine began the first remedial work on the valves in 1998 and 1999.
While that work was underway, Wenstrom came up with a unique design concept to standardize operation of the PRVs and make them digitally controlled. The dam’s original generating equipment was built by various manufacturers and installed over a long span of years, so it was far from consistent. There are five separate turbine designs in operation at Hoover Dam. Even units built by the same manufacturer several years apart had differences.
“We showed Hoover a design that would make the units fully compatible with their existing electronic control system that operated and controlled the generators. We proposed converting all PRVs to be operated in the same way and all controlled by hydraulic cylinders.”
Dan Wenstrom, president, Precision Machine & Supply, Inc.
The decision was made to go with hydraulic-driven pressure-relief valves which could provide very precise control and extremely fast response. The system would also reduce the number of false pressure relief valve operations that often occurred with the old mechanically operated PRVs. Wenstrom brought in Comoso to engineer and supply the hydraulic power unit and manifold that mounted to the hydraulic cylinder.
Auxiliary power needed
The hydraulic controls also required accumulators for energy back-up. Parker's Accumulator and Cooler Division -- a world leader in the development of customized accumulator applications -- was given the assignment to design the best units for Hoover Dam’s unprecedented requirements. Working closely with Comoso and Precision, Parker was able to implement an ideal, cost-effective solution. An accumulator enables a hydraulic system to respond quickly to a temporary demand, using a less powerful pump.
“Think of the accumulators as very large batteries with high levels of energy to operate the PRVs. The accumulator stores hydraulic energy until it’s needed for immediate use.”
Jeff Sage, product manager, Accumulator and Cooler Division, Parker Hannifin Corporation
Supplemental power from the accumulators is necessary because of how Hoover’s hydroelectric equipment is configured. Ironically, available electricity is very limited inside the huge power-generating facility.
“Where the PRVs are located in the dam, there isn’t much access to electrical power, said Camp. "The dam puts out 185,000 horsepower per turbine, but we only had the equivalent of ten horsepower in the area where we worked.”
The power that's available inside the dam itself comes from two smaller separate generators called “house units” in the powerhouse. The little units simply wouldn't have the energy capacity to operate multiple high-pressure, high-horsepower hydraulic oil pumps to drive the cylinder when a PRV trips.
“The accumulators instantaneously allow 750 to 900 horsepower, so we have the energy we need at the drop of a hat to operate the valves. It opens the bypass very quickly.”
Steve Camp, regional manager, Parker Hannifin Corporation
Each pressure-relief valve at Hoover Dam now utilizes one compressed gas piston accumulator with pressurized oil (180 gallons under 2,750 psi) and two large nitrogen-gas bottles. The accumulators have a 20” bore and an outside diameter of 23 5/8”. They’re 200" long and have a dry weight of 8,653 lbs. A total of seventeen accumulators and thirty-four nitrogen gas bottles have been installed.
“It was a huge challenge, and not many manufacturers can build accumulators of this size,” Paddock noted, “but Parker Hannifin was up to the task.”
“As the upgraded PRVs are designed, we now get shaft movement typically within less than a tenth of a second after the signal is received that the generator is going into emergency shutdown,” said Paddock. “As quickly as the (water intake) gates are closing, the PRV has to open to bypass the same amount of water that was otherwise going through the turbine. That’s within ten seconds. And then the most critical aspect of it is once the PRV is fully open, it has to slowly reclose so that no water hammer is created.”
With the installation of each new pressure-release valve, a commissioning team – including representatives from Hoover Dam, Precision Machine, Comoso, and Parker Hannifin – conducts a very detailed testing process.
“To do the commissioning, we bring the generator up to speed and then trip it to simulate an emergency shutdown, Wenstrom explained. "Recording devices with transducers on the turbine side and the PRV side precisely measure the hydraulic pressures, the strokes, and the time it takes the cylinder to respond to the emergency closure signal. Then we measure the amount of time it takes the pressure-relief valve to open and to reclose. The whole idea is that these PRVs have to open very quickly, as soon as the wicket-gate starts to close, to avoid a water hammer.”
In addition to dramatically improving the functionality and reliability of the PRVs, the hydraulically driven system provides a solution to a new problem at Hoover Dam: Quagga mussels.
An invasive species of Quagga mussels had made its way into the Colorado River and Lake Mead, and by 2009 the mussels actually started plugging up water passageways in the dam’s control valve system. They clog PRVs by clinging to the rods that open and close the valves, and in some cases even prevented them from opening.
“Dan’s design to modernize the PRVs ensured they would operate regardless of any fouling factors such as the Quagga mussels,” said Paddock. “The hydraulic-driven PRV could basically just plow through any obstruction in its path, by brute force. The impetus of the conversion to the hydraulic design wasn't the mussels, but it turned out to be a great secondary benefit.”
The entire process of upgrading the pressure-relief valves and associated equipment has been an extraordinary team effort representing a lot of combined brainpower. Ultimately taking twenty years from start to finish, the scope and uniqueness of the project seem appropriate for such a magnificent historic facility.
“There are many long-term benefits to this whole project, from operational efficiency to safety and more,” said Paddock. “Parker is grateful to have been part of it.”
Other related articles for you:
7 Jan 2019
A massive engineering and design collaboration have brought the vision of world-renowned Spanish architect Santiago Calatrava Valls to life in Lakeland, Florida. The new Innovation, Science and Technology (IST) Building at Florida Polytechnic University will serve as the central building for the campus of Florida’s newest state institution, dedicated to a curriculum of science, technology, engineering, and math. It houses classrooms, auditoriums, administrative offices, common areas and a number of cutting-edge laboratories; including a Supercomputer and Student Data Center, a Visualization and Technology Collaboration Lab, and a Rapid Application Development Makerspace Lab with 3D printing capabilities. The $60 million, two-story building also includes a system of 94 louvered arms that raise and lower to track the sun above a glass roof.
Each louver is manipulated by a Parker Series 2HB Mill-Type hydraulic cylinder. The custom application required five different sized cylinders, with larger cylinders for the longer louvers at the center of the roof and smaller cylinders for the shorter louvers at the ends.
“We are pleased to have supported this highly customized cylinder application with full integration capabilities and precise engineering,”
Tad Brown, cylinder application engineer, Parker Hannifin Cylinder Division
Specifying assembly to design
Specified by Parker distributor Atlantic Hydraulic Systems, based in Shirley, N.Y., each cylinder was assembled with integrated cartridge valves on a manifold, which was bolted to the cap and plumbed to the head end of the cylinder. Further, a spherical rod eye was installed at the rod end, and the entire cylinder was painted to match the remainder of the structure. This full integration, along with special pressure decay testing, was all accomplished within Parker’s Cylinder Division in Goodland, Indiana.
The cylinders act independently from one another and can manipulate the louvers to provide shade and artistic motion. The louvers were designed to eventually accommodate a system of photovoltaic tape to generate power for the campus. Each louver arm is engineered with the capability of a maximum upright position of 65 degrees above the horizontal plane and a maximum lowered position of 48 degrees below the horizontal plane. Traveling the full 113-degree distance takes about 10 minutes.
Construction of the 162,000 square foot IST building took 28 months and was completed by Skanska USA. Headquartered in New York, Skanska USA is one of the largest construction and development companies in the country with expertise in construction, civil infrastructure, public-private partnerships and commercial development initiatives in select U.S. markets. Florida Polytechnic welcomed students for the inaugural day of classes on August 25, 2014. The University offers six undergraduate degree programs with 19 unique areas of concentration and two masters degree programs in the College of Engineering and the College of Innovation and Technology.
The 2HB cylinder design in long-stroke industrial applications is an engineering breakthrough that is expected to extend service life, reduce downtime, increase throughput and ultimately increase the profitability of industries requiring stroke lengths over five feet. For OEMs incorporating cylinders into heavy-duty industrial equipment and machines or into apparatus where design aesthetics are important, the 2HB Series of non-tie-rod cylinders offer several differentiating benefits for competitive advantage.
Learn more about the benefits of non-tie-rod hydraulic cylinders and how they can improve performance in your heavy-duty, long-stroke industrial applications - download our Long-Stroke Industrial Cylinder Performance white paper.
For more information on the award-winning IST building and the new Florida Polytechnic University, visit their website.
Article contributed by Bruce Kohlmeyer, engineer manager, Parker Cylinder Division.
Related, helpful content for you:
12 Dec 2018
Industrial OEMs and end users rely on traditional tie-rod cylinders to deliver power to industrial presses, mills, foundries, power generation, oil and gas exploration and other extreme, heavy duty applications.
As the workhorse of the industrial cylinder market, tie-rod cylinders perform reliably and offer tremendous flexibility including several mounting options, cushions, position feedback, etc. However, tie-rod cylinders do have some limitations, particularly in longer strokes. Serviceability can be a concern, due to the added complexities of assembling and torquing long tie rods. And for some design-sensitive applications, the visible tie-rod profile can be aesthetically disruptive.
For operations where such concerns are an issue, the introduction of a new class of heavy-duty, non-tie-rod cylinders will be welcome news.
Improved performance and serviceability
For applications with longer strokes, our 2HB and 3HB non-tie rod cylinders offer reduced complexity and weight versus comparable tie-rod cylinders. Parker’s 2HB and 3HB Series of cylinders are available in 1½" to 14" bores sizes and are dimensionally interchangeable with their tie-rod counterparts, since they adhere to the same industry standard - ANSI/(NFPA) T3.6.7R3 – 2009.
Tie-rods are eliminated through an innovative design which utilizes flanges threaded onto both ends of the cylinder body. The head and cap are bolted to the threaded body flanges with SHCS’s with a small gap between. That gap allows for the head & cap to be preloaded against the end of the cylinder body when the SHCS’s are torqued.
The resulting configuration presents a cleaner, more aesthetically pleasing design. Perhaps most importantly, 2HB and 3HB cylinders enable industrial users to achieve current levels of performance while eliminating tie-rod-related fatigue and maintenance concerns. These non-tie-rod cylinders meet NFPA fatigue tests for reliable performance using standard, field-proven components. They are built to a design safety factor of 4:1 on burst.
To learn more about the benefits of using non-tie rod cylinders for your long stroke industrial applications, download our Long-Stroke Industrial Cylinder Performance white paper.
Raising standards in performance, durability and trouble-free operation
Improving hydraulic cylinder performance in long-stroke applications is a challenge for industrial OEMs and operators alike. For their heavy-duty industrial applications, replacing traditional tie-rod hydraulic cylinders with non-tie cylinders can extend service life, reduce downtime, increase throughput and ultimately increase the profitability of applications requiring stroke lengths over five feet. For OEMs incorporating cylinders into heavy-duty industrial equipment and machines or into apparatus where design aesthetics are important, non-tie-rod cylinders offer several differentiating benefits for competitive advantage.
Tie-rod cylinders will remain the workhorse of the industrial world, but for those applications demanding long-stroke performance, there is now a viable alternative capable of meeting the high-performance expectations of extreme-duty environments.
To learn more about using non-tie rod cylinders for your long stroke industrial applications, including a university architectural application case study, download our Long-Stroke Industrial Cylinder Performance white paper.
Article contributed by Bruce Kohlmeyer, engineer manager, Parker Cylinder Division.
Related, helpful content for you:
7 Dec 2018