Using mechanical energy produced by a machine’s engine, a hydraulic pump can move hydraulic fluid from the pump’s own reservoir, to a connected hydraulic motor, converting the mechanical energy to hydraulic energy. The incoming fluid/energy triggers the hydraulic motor to begin rotation, which can be used to actuate a component outside the system, such as a wheel or axle. The power of hydraulics allows for machines to do more with less, such as traversing tough terrain or lifting heavy loads.Why a piston pump?
In the world of hydraulics, the performance range of gear pumps and piston pumps overlap for low-speed, high torque applications. Being the case, why would a consumer select one over the other? What kinds of advantages and disadvantages do piston pumps have compared to gear pumps?
Piston pumps provide robust and precise performance for a myriad of applications. Compared to a gear pump, a piston pump can operate at higher pressures with the same flow performance. Typically, gear pumps are rated for around 3,000 psi, but some models reach as high as 5,000 psi. On the other hand, piston pumps can be rated to as high as 30,000 psi.
Piston pumps have the ability to produce variable displacement. Variable displacement is the act of adjusting flow during the usage of the pump, while maintaining the same motor speed. Conversely, pumps that use fixed displacement can only operate at one flow specification. By using internal controllers, like springs and dampeners, a piston pump can change displacement while maintaining the same motor speed. Gear pumps require external valving to attain this effect, which can increase the cost of the overall unit.
While a piston pump provides greater pressure ratings and flow controls, a gear pump is the more cost-effective option. The gear pump’s interlocking gear design is simpler and easier to produce on a large scale, allowing for consumers to purchase the product at a lower cost. If an application requires a lower pressure rating and is able to operate using fixed displacement, a gear pump may be the proper solution.
Parker changes the game
The engineers at Parker Pump and Motor Division have developed the HP Series of pumps, ideal for the low-speed, high torque (LSHT) applications. The HP Series is the only line of closed loop, variable displacement pumps, designed specifically for LSHT applications, with an integrated oil reservoir, filter, and cooling fan. This compact model saves an engineer space within a design, and reduces the numbers of components from 72 to 5. HP pumps are designed for superior performance and longer life; up to 20% more efficient than other pump and motor systems. They are compact and able to fit in small machine platforms where space is limited. They also easily connect to various Parker Torqmotors, providing ultimate design flexibility.
"The HP series was designed to complement our transmission technology by addressing specific customer needs. Those requirements included durability, compactness, integrated features to lessen leak points and reduced OEM assembly time. HP1 single pumps incorporate a proven design with integrated filter, reservoir and a low center of gravity pulley attachment point. HP2 dual pumps can be direct mounted to a horizontal shaft engine, so there is no need for belts and pulleys. Like the HP1, the HP2 has an integrated filter, reservoir and fan for cooling. Both units, paired with our LSHT motors, provide design versatility to better serve our customers."
Somer Malone, senior engineer, Parker Hannifin.
The Pump & Motor Division is a market leader in gear pump and low speed-high torque gerotor motors. the division continues to blaze a trail by developing new technologies, while maintaining a high level of service synonymous with the name Parker. Between two facilities in North Carolina and Tennessee, PMD employs decades of industry experience to better serve you and your application.
Article contributed by C.T. Lefler, marketing product manager, Pump & Motor Division, Parker Hannifin Corporation.
23 Apr 2019
Mobile equipment manufacturers are always striving to get the most out of their machines without over burdening the system with costly and complex mechanics. Moreover, performance expectations are not only shaping machine needs, but also safety requirements. Consequently, this has driven many engineers to design closed loop systems featuring electronic sensors as feedback devices.
For example, manufacturers of lifting equipment such as truck mounted cranes, telehandlers and scissor are all striving to provide operators with safe work environments all the while maintaining the integrity of the lifting function during operation. The choices for detecting or measuring tilting/leveling conditions are vast. They range from purely mechanical devices: tilt gauges and bubble levels for simple visual indication to basic electronic sensors offering discrete tilt switch points. While these options are typically cost effective, they offer little to no feedback for safety or performance.The Universal Tilt Sensor
Design engineers increasingly relying on sophisticated sensor technology for fast accurate feedback and diagnostics during operation. Today’s systems require something more; electronic inclinometers that offer continuous monitoring of angular position in relation to a calibrated reference planes either horizontal or vertical. The latter can best be accomplished with Parker’s Universal Tilt Sensor (UTS).
The UTS, manufactured by Parker’s Electronic Controls Division, is a MEMS technology tilt sensor designed for configurability making. It is suitable for a broad range of mobile applications. The UTS communicates via SAE J1939 protocol providing fast and reliable angular information from either two or three axes. The patented 3-point setup and low-profile housing offer ease of installation, reduced build time and maximize install possibilities. Since some applications require a balance of speed and accuracy, the UTS also offers tunable filter settings to adjust the output response on command. Three factory variations are available by catalog today:
Most vehicles with lifting booms require the chassis platform to be level with the ground before the boom and load can be elevated above a certain point and/or rotated around its base axis. This helps ensure the safety of the operator and payload. A chassis mounted UTS can continuously monitor changes in inclination during the deployment of the stabilizing actuators (outriggers and jacks) to feed the control system real time information throughout the leveling process. This feedback can insure a uniform lift even on the most challenging terrain. While a system utilizing the UTS for auto level can be made simple as a one-touch function, it can also offer continuous monitoring of the chassis as different loads and mechanical movement adjust the center of mass of the platform. The continuous feed of information can provide real-time feedback on out-of-level conditions alerting the control system and operator of potentially danger inclination. Finally, the sensor provided an operator display a real-time visualize of tip and tilt for manual adjustments where needed.
In cases where the chassis has an over extended wheel base, i.e. ladder engine or multi-axle crane trucks, two UTS sensors could be used; one in the fore and one in the aft part of the chassis. By monitoring the pitch and roll condition of the chassis in two locations simultaneously, a machine can utilize the UTS output to prevent excessive twisting along its longitudinal axis of the platform frame thus preventing costly repairs to the machine.
This is just one of many ways the UTS can be used in a close loop system to achieve optimum performance and peak safety on mobile platforms. It has been built to operate in the most demanding marketplaces including agriculture, construction, material handling and more. Learn more about Parker sensors.
Interested in trying this sensor on your own platform? Parker’s Universal Tilt Sensors 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 Marcel Colnot, regional application engineer, and Chase Saylor, product manager - sensors, Electronic Controls Division, Parker Hannifin Corporation.
Integrated ISOBUS Functions Help Agriculture Sector Plow Ahead
4 Apr 2019
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