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Snapper/Ferris/Simplicity Hydro Pump 5022376 Made by Hydro Gear - The World Leader in the Manufacturing of High Performance Precision Drive Systems.

Since 1935, Muncie® Power Products has been a leading source of mobile power components to the truck equipment industry. In addition to Power Take-Offs and hydraulic motors, Muncie offers directional, pressure and flow control valves as well as system design capabilities. Call us today or visit our website for more information.

Hartmann Controls offers some of the most dependable hydraulic motors for industrial and mobile applications. Exceeding the capabilities of most other hydraulic motors, our products offer simplicity and precision for exact operations. Our superior motors can go for decades. Check out our catalog today! Our products are used by the world’s largest manufacturers and companies. Contact our company!

Planet Products Corp. is a contract manufacturer and manufacturer of various hydraulic products. Hydraulic products include motors, valves, and pumps. Planet serves mainly the defense, aerospace, machine tool, and industrial sectors and is ISO9001/AS9100 certified.

Precision Fluid Power sells new & rebuilt hydraulic motors. We also specialize in the repair of hydraulic components such as hydraulic motors, pumps, valves & cylinders. All units received for repair will be completely stripped down, cleaned and inspected, & any bad parts will be replaced. With over 150 years of experience we serve all industries, large or small. Please contact our company today!

For 40 years, Bucher Hydraulics, Inc. has specialized in hydraulic systems, including products such as hydraulic motors and hydraulic power units. Applications include concrete pumps, forage wagons, harvesters, lifting devices, recycling machines, door openers, log splitters and many others.

Danfoss has 45 years of experience offering hydraulic motor solutions. We supply hydraulic power systems for moderate to heavy load demands. Our orbital motors have speeds extending from 2,500 rpm to 600 rpm. We also have hydraulic motors that vary in size from mini to medium to large.

Established in 1966, Delta Power designs and manufactures industrial hydraulic cartridge valves and manifold systems using these valves. We also produce hydraulic motors and hydraulic power units. Contact us for cutting-edge hydraulic system designs and products.

For more than four decades, Dynex/Rivett has been manufacturing hydraulic power systems and components. Our products include hydraulic motors, hydraulic power units and variable speed motors. We serve the worldwide market with our top-quality motors and hydraulic systems.

Eaton Hydraulics designs, manufactures and markets a comprehensive line of reliable, efficient hydraulic systems and components including hydraulic motors, hydraulic power units and other hydraulic systems. We serve various markets and applications with our quality systems and accessories.

Flint Hydraulics, Inc. is dedicated to the worldwide distribution of original and replacement hydraulic pumps, hydraulic motors, and hydraulic pump replacement parts for heavy mobile and industrial equipment. We maintain a database of more than 30,000 hydraulic pumps, motors and parts by OEM part number for name brands of heavy mobile equipment such as Caterpillar, J.I. Case, John Deere, Clark-Michigan, Terex, Grove, Komatsu-Dresser, Bobcat and many more. Located in the heart of America’s distribution center, Flint Hydraulics, Inc. has grown into one of the largest suppliers of original and replacement hydraulic products in the world. Off-the-shelf availability, coupled with the distribution center advantages Memphis has to offer, give us the unique ability to provide hydraulic components across the globe, using the most efficient and economical means available. We stock substantial quantities of pumps, motors, parts and assemblies and can ship at a moment’s notice anywhere in the world. Most items are available for same or next day shipment.

Our production facility is uniquely designed for assembly and testing of various types and designs of hydraulic pumps & motors to meet the just-in-time inventory requirements of our clients. Our professionally trained staff is the most knowledgeable and schooled customer service team in the entire industry. Equipped with the latest distribution software and our own custom-tailored cross-referencing databases, our staff is able to provide instant information regarding the particular hydraulic component your client needs.

Fluidyne Fluid Power is a leading industrial power distributor and manufacturing facility specializing in hydraulic motors, components and custom-designed fluid power systems. We have an extensive product line able to provide exactly what you need. They combine fluid power expertise with a vast selection of world-class components to provide you with unsurpassed system efficiency.

Haldex is a global provider of vehicle solutions, including hydraulic pump motors, hydraulic power units, gear pumps and fan drive pumps as well as AC/DC motors. Reduce emissions and innovative diesel engines with Haldex excellent solutions and customer service. We base our decisions and actions on the customer’s best interests. Contact us today!

An employee-owned company, Hydraquip is a distributor of fluid power products, including hydraulic motors from Hydro-Gear, Hydrokraft, Rineer Hydraulics, Rotary Power, Sauer Danfoss, Ultra, Vickers and Von Ruden. Since 1951, we have been serving the fluid power industry.

Need an old cylinder swapped or remanufactured? Need telescopic cylinders, replacement cylinders or hydraulic cylinders for large industrial equipment? At Hydraulic Repair & Design, we can supply all industries with new, custom or repaired cylinders, experienced design & friendly customer service!

Hydreco® Inc. offers a wide range of hydraulic gear motors as well as hydraulic pumps and valves. We offer drive axles, gearboxes, hydraulic pumps, gear pumps and piston pumps. Contact us today for more information on our quality products.

Over 50 years, Hydro Leduc has developed more than 100 patents because of our passion for innovation in the hydraulics field. We find solutions to our customers’ most complex and demanding applications for piston pumps, hydraulic motors, hydro-pneumatic accumulators and custom hydraulic components. A complete list of available motors and features can be found on our website. Contact a representative today for any further inquiries!

Since1967, Hydrotech has provided industries with innovative solutions for their fluid power needs. Our listing of hydraulic motors are manufactured by Bosch Rexroth, Rineer Hydraulics and White Drive Hydraulics. For more information call our experienced team of technicians and sales support!

Founded 40 years ago, Innerspace designs, develops and manufactures top-quality, efficient propulsion systems for marine vehicles. Our product capabilities include hydraulic products such as hydraulic motors and customized hydraulic systems. Check out our website for more information.

For over 50 years, MacTaggert Scott has been in the hydraulic motor business. Our radial piston hydraulic motors are used in various markets such as marine, offshore and defense. If you are looking for a hydraulic motor that runs quietly and efficiently, MacTaggert Scott is your answer. Call us today!

Our DVT Series of hydraulic motors started our hydraulic drive efficiency in the 1970s. We’ve developed more products and grown since then. Now we invite you to explore our MHA Series of heavy-duty, high-torque, low-speed, rotating shaft or rotating case hydraulic wheel motors. Check our website.

Since 1921, the world’s most demanding hydraulic control applications have relied on Oilgear high-performance fluid power solutions. We’ve met the challenge. Every time.Founded in Milwaukee, Wisconsin, Oilgear was built to bring only the most advanced engineering to our customers. Decades later, Oilgear continues to set the standard in industries requiring precise, high-performance hydraulic systems. From the depths of the ocean to the surface of the moon, Oilgear products often operate in the harshest of environments. We’re known for our robust line of pumps, but we offer so much more. No matter what your operations need, we have cartridge valves, subsea pressure control solutions and electrical embedded controllers to tackle your issues head on.

It might not seem possible, but we’re more than those products too. Oilgear is a worldwide provider of complex fluid power control system. We have a strong presence in forging and extrusion press control systems. And high-specification HPUs and high-pressure hydraulic systems.

With products operating in the toughest environments on earth, quality is Oilgear’s top priority. You can see it in our full collection of hydraulic control products and systems. We know what it takes to perform to ISO and API standards. And with an extensive history of earning certifications from institutions like ABS, DNV and Lloyds.

Parker"s Hydraulic Pump and Power Systems Division provides a broad selection of piston pumps, hydraulic motors and power units that help our customers meet their industrial and mobile application needs.

The Parker Pump & Motor Division specializes in gear pumps and motors used in a myriad of industries. With decades of experience, PMD provides the best products in the market, supplemented by best-in-class customer service, and the deepest knowledge in the industry.

The Perfection Machining Company was founded in 1964 to design and manufacture replacement parts for the mining industry. Renamed Permco 4 years later, the family-owned business developed a wide array of replacement hydraulic parts and eventually expanded its manufacturing capabilities to include cast iron parts and the resulting complete units. Today, we maintain our focus on customer service and continue a decades-long tradition of developing fluid power systems that meet each of our customer’s specific needs. Permco’s product offering now includes gear and vane pumps/motors, flow dividers, intensifiers and a variety of accessories and components. Permco offers the highest quality product possible to our wide customer base of OEMs and distributors. Because we understand that our success depends on the success of our customers, we are committed to reducing customers’ costs and increasing the simplicity of doing business with us.

Poclain Hydraulics manufactures hydraulic motors, hydrostatic transmissions and high-torque cam-lobe motors, which are used in agriculture, construction equipment, industry, marine and material handling applications. Our innovative company culture motivates us to pursue progress and excellence in everything we do. Contact Poclain today to learn more!

Established in 1979, Southwest Seal and Supply has grown to become one of the most predominant distributors of sealing, hydraulic hoses, fittings, couplings/connectors, gasketing and fluid control products in the Southwest. We offer a wide range of products including the best in selection, quality, and value-added services.

Founded in 1945, Spencer Fluid Power remains a value added distributor of hydraulic components and systems. Spencer Fluid Power continues to sell and support hydraulic components to a wide array of customer types. Small to large OEM"s, timber, mining, construction and oil & gas are just a sample of the numerous industries Spencer supports today.

Sunfab was founded by Eric Sundin in the year of 1925. Sunfab develops, produces and sells components to operate hydraulic equipment within the area of mobile vehicles. After more than 90 years, the third generation of the Sundins are still running the company in the spirit of Eric Sundin, with a family atmosphere, flexibility and innovative solutions.

Wojanis Supply Company is a total fluid power facility encompassing sales, service, design and manufacturing capabilities for a full line of hydraulic motors, pumps, valves and integrated systems for a range of applications. Additionally, we are an authorized representative for many of the top component manufacturers allowing us to fulfill your every demand.

The 2021 PTC ASIA exhibition, jointly organized by China Hydraulic Pneumatic Seals Industry Association and Hannover Milan (China) Co., Ltd., was successfully held at Shanghai Pudong New International Expo Center from October 26 to 29, 2021. The "PTC ASIA 2021 High-tech Exhibition Area@International Technology Exchange Report Conference" held at the same time of the exhibition has once again become an important technical connotation and highlight of the exhibition, attracting many guests to come to study and exchange. PTC ASIA 2021 High-tech Zone On-site Technical Report

Technical Trends and Challenges of High-speed Hydraulic Pumps in the Electrified Era——According to the report of Xu Bing, an expert from Zhejiang University

Today I am sharing with you the technical trends and challenges of high-speed hydraulic pumps in the electrification era, which are divided into four parts.

The era of pure electrification is of little significance to industrial hydraulics, because it originally uses electric motors. The so-called "arrival of the electrification era" we are talking about today mainly involves non-road mobile machines (including construction machinery, agricultural machinery, forestry machinery, industrial vehicles, etc.). Non-road mobile machines are the largest user of hydraulic products and the biggest driving force for the development of hydraulic technology. Compared with industrial hydraulics, some important technical indicators of mobile hydraulic products have higher requirements. At present, the dual-carbon policy and energy-saving regulations at home and abroad have accelerated the transition from the era of internal combustion engines to the era of electric motors. It can be said that in the field of non-road mobile machines in the future, the hydraulic technology previously used in industrial equipment, especially the hydraulic technology with variable speed, will become the mainstream.

In general, non-road mobile machines should also include robots (currently a research hotspot in the field of hydraulics). There is a type of robot that carries or operates (see Figure 2). For example, it needs to carry more than tens of kilograms. At present, hydraulic pressure is still the most important driving system for this type of robot. In addition to these biological-sized robots, there is also a type of robot, we call it exoskeleton or rehabilitation machine. In fact, don’t look at it as small. So far, hydraulic pressure is also the most important drive and transmission for exoskeleton design engineers. Select, other transmission forms are relatively poor in power density ratio indicators. In the direction of prosthetic exoskeletons, the market is actually quite large. At international academic conferences and industrial technical conferences, research on compact hydraulic transmission in exoskeletons and rehabilitation machines accounts for a large part.

At present, some non-road mobile machines have begun to use electric motors as prime movers. At present, it is only a simple replacement for internal combustion engines. The hydraulic components and systems have hardly changed, but the internal combustion engine is replaced by an electric motor. This solution with relatively small technical changes is easy to enter the market quickly. . But there is a biggest problem. It does not make full use of the technical advantages of electric motors. The biggest advantage of modern electric motors over internal combustion engines is that the speed-torque characteristics are very good, and they can work continuously in four quadrants. This characteristic actually brings many opportunities to hydraulic technology. Due to the narrow high-efficiency area and poor dynamic response of internal combustion engines, many innovative hydraulic system principles and configurations cannot be applied in the era of internal combustion engines. In the era of electrification, there will be many innovations and changes in the hydraulic system configuration of non-road mobile machines.

As an example, hydraulic transmission systems are roughly divided into four categories (see Figure 3). Among them, the closed pump control system has the highest efficiency, and the motor of the pump control system can not adjust the speed, of course, it can also adjust the speed. In the future, the speed-regulated motor will definitely replace the system of non-speed-regulated motor and variable pump, because it has more advantages. It now seems that the pump control system with motor speed regulation will definitely become the future choice of non-road mobile machines, because considering the influence of distributed parasitic losses, its efficiency is much higher than the current pump control system.

Why is the distributed power mechanism in electrification so important? The main reason is that construction machinery has a very important feature. It is a single power source with multiple actuators, that is, there is only one pump source, but there are a lot of actuators. Such a system is inherently inefficient, and there is no good solution so far. There are some good technical solutions that are in the laboratory and have not been applied in the market. In the era of electrification, it is possible for "distributed drive" to replace "centralized drive". Now it seems that distributed electro-hydraulic power system will definitely become a major direction of future machines.

The "generalized" distributed electro-hydraulic control system has several configurations (see Figure 4), of which the distributed power is somewhat similar to the EHA-electro-hydraulic system that everyone is very familiar with. It is truly distributed and should be the most efficient. a type. At present, in all walks of life, especially on non-road mobile machines, everyone is building some experimental prototypes. The technology itself is very old, and it appeared on some American fighter jets fifty or sixty years ago. Now in the aerospace field, many companies are doing research in this area, which is relatively mature. Even if it is relatively mature, the challenges it faces are relatively large. In fact, the core of EHA is the hydraulic pump. So far, the design of our hydraulic pump does not consider the variable speed, because the previous source power, whether it is an electric motor or an internal combustion engine, almost does not adjust the speed. Therefore, all the designs of the pump are aimed at fixed working conditions and rated speed. When the speed changes, the design becomes very complicated.

Wide speed range. Why do you say that? Because modern speed regulating motors can maintain more than 100% speed from zero speed to rated speed, but existing hydraulic pumps cannot work in a wide speed range. Our existing commercial pumps have a minimum speed of 500-600rpm. It can"t go on, and the low speed is very inefficient or even impossible to work. Of course, there are also low-speed (tens of revolutions per minute) pumps, which are specially designed and are a niche market.

Four-quadrant work. Our existing pumps are very difficult to work in four quadrants. Of course, there are some pumps like A4VG, but they are not completely prepared for variable speed, so in the future, hydraulic pumps must have the ability to work in four quadrants.

higher revs. Why high speed? In fact, it is not that the pump needs a high speed, it is because the motor needs a high speed. If the motor speed is not high, its power density ratio index is relatively low. Therefore, in mobile machinery, if the electric motor wants to compete with the hydraulic motor, the electric motor must be above 20,000 to 30,000 rpm. Since the motor needs to be high-speed, the pump can only be high-speed. Therefore, pumps with a speed of more than 20,000rpm should be the biggest technical trend and change of hydraulic pumps in the future.

From a design perspective, what are the challenges we face? First, how to design the pump in a wide speed range; second, the pump motor working in four quadrants should take into account high efficiency and high performance under all working conditions, and it is not very good at present. Generally speaking, the working conditions of the pump are very good. The motor operating condition index is relatively poor; third, at such a high speed, many important changes have taken place in the bearings, shafting, and oil suction and discharge characteristics.

At present, in the industrial world, the speed of general-purpose hydraulic pumps on the market is below 2000rpm; the pump motor driven by the internal combustion engine of construction machinery is 2100-2300rpm; the aerospace field is special, it has pumps above 10000rpm, which are relatively small, and the same is true for motors .

For high-speed pumps, the most important thing is to absorb oil, how to suck the oil up. Why is there no problem in the aerospace field, because it is pressurized at the suction port, while in the civilian field, it is generally not considered not to be pressurized, and most of them need self-priming. If it only relies on self-priming to reach 20000rpm, it is not possible so far, and some auxiliary boosting measures need to be taken.

In any case, the two most important challenges for hydraulic pumps in the age of electrification are wide-ranging variable speed and four-quadrant operating capabilities.

For the industry, what kind of pump can adapt to high speed and variable speed? In principle, all hydraulic pumps can do it, but consider cost, pressure rating, simplicity, number of parts, noise, dimensions, etc.

It can be said that gear pumps are currently the most sought after. At 10000rpm, above 20000rpm, the gear pump shows good characteristics, and it is cheap, strong and reliable. Therefore, in the fuel system of aero-engine internal combustion engines, gear pumps are used a lot, and they basically run at high speed. Of course, it is mainly used for transportation, not for control. In the current mainstream gear pump motor products, the internal meshing motor speed can reach 10000rpm, so the gear pump gear motor should be a very important choice for variable speed hydraulic pressure in the future. This is mainly related to its friction pair, which has very good friction pair characteristics and is very suitable for quick start, stop and change because of its simple structure. If it is a plunger pump, the structure is too complicated. It is a complex series-parallel mechanism. If it is frequently forward and reversed, it will be a big challenge to design and manufacture.

The vane pump is also a very good hydraulic pump suitable for high speed. In the early days, the US military researched a variety of vane pump forms, some of which can reach about 15,000 rpm. Later, it was not commercialized for various reasons. In any case, the friction pair characteristics of the blade machinery are also relatively good, so it is also more suitable for the requirements of variable speed in the future. In addition, the low-speed pressure holding capacity of the vane pump is relatively strong. For example, at 30rpm, it is still relatively easy to maintain the pressure. In other pumps, an additional, expensive design is necessary to achieve this.

Piston pump is the main form of high-pressure system at present, because we must use it in high-pressure occasions, it is divided into radial piston pump and axial piston pump. In fact, the radial piston pump is a very small variety so far. There are few products in the market, and there is no high-speed product at present. However, in the 1970s and 1980s, the United States studied several radial piston pumps with special structures. At that time, the rotational speed could reach 10000rpm and 20000rpm. These pumps had very good performance, but they did not appear on the market in the end. . Therefore, the high-speed radial piston pump has no problem in principle, because its size, weight, efficiency and other indicators are very good.

The axial piston pump is what we are most concerned about, because it is the most mature research in the existing mainstream pumps, but because of its friction pair type, it limits some of its wider applications in variable speed, it is There are some problems. Until now, few people have studied piston pumps specifically for variable speed conditions. Axial piston pumps developed by Rexroth for variable speed (based on their well-known A 10 series).

In addition, there is a relatively small axial piston pump, which is a rotary valve plate. Few people produce this kind of pump, and there may be only one or two in the world, but this kind of pump has a natural advantage, because its cylinder body does not move, so it is easy to distribute flow, and it generally adopts valve distribution, and now the distribution is digitalized There are also many researches on it, so if the distribution valve adopts a continuously controlled solenoid valve, its distribution can be adjusted intelligently according to the working conditions, and the performance of the pump can be significantly improved in theory. In which fields is this pump used? In the early days of American aerospace research institutions, it was no problem to make this pump at 10,000rpm and 20,000rpm, and it was highly efficient because its distribution was valve distribution. At present, the characteristics of such pumps at low speeds are highly valued. The special pump of the swash plate researched by our Zhejiang University is mainly in the fields of water supply and drainage. It can easily be made into ultra-high pressure, which is related to its structural type. In addition, in terms of high-speed pumps, Zhejiang University has made three generations of prototypes on ultra-high-speed pumps. The indicators of the last generation of prototypes are 16000rpm and 35MPa. This is laboratory data, and it has not reached the product level. It has some special designs, mainly to adapt to high speed. For example, the structure of the sliding shoe is very unique. The sliding shoe itself has revolution and rotation, but it has no relative speed relative to the swash plate. It is stuck on the plate, and the quality of the plate is also It is relatively large, so its rotation is very stable, and the efficiency of this pump is very high.

Among the axial piston pumps, an axial piston pump, the oblique axis pump, has been despised for many years. The oblique axis pump is also very good as a high-speed pump. At present, the oblique axis pump of about 20,000 rpm is a product of a French airline. This pump is used in the aviation EHA brake unit, and its power density ratio is said to be up to 10kW/kg.

How are these hydraulic pumps designed? Structural invention is the core, but valuable inventions are too difficult, and it is difficult for most engineers to create inventions. Their more common work is to optimize on the basis of existing products, which is also very valuable work. There are tools and means for optimization, and there are many advanced analytical simulation methods at present. In the field of axial piston pump, after decades of efforts of scholars and experts at home and abroad, there have been many innovations in advanced analytical tools. From the perspective of models, after 60 years of development, these models are now relatively accurate. These models can be roughly classified into three categories: physical flow loss models, analytical flow loss models, and digital flow analysis models. Now the most accurate model is the digital flow loss model. This model has no physical meaning. It consists of dozens of polynomials. The values and coefficients of the polynomial are obtained from identification and experimental data. This model is not very popular in academia, but in industry, it is the most accurate of all models, so it has practical value. In academia, we are more concerned with physical modeling and analytical modeling. If the digital model is accurate, it is more meaningful because it is more intuitive and related to the physical nature of the components. It is conducive to engineers" understanding and future innovative designs, and each has its own advantages.

In the industrial world, there are some small specialized software currently in use, which are not commercially available. For example, there is special software in the design of the distribution plate. Why do you want to do this? If the pump is regarded as a rigid object, you do not need advanced analytical methods, but modern products have entered the stage of refined design. The core of the friction pair of the plunger pump is embodied at the microscopic level (micron-scale friction interface), the oil film at the interface and the solid The coupling of boundary structural deformation determines the performance, reliability and life of the plunger pump, and the information of structural deformation is also reflected in the oil film. Therefore, without advanced calculation and digital analysis software tools, it is impossible to analyze and understand the physical field information of the friction pair oil film, and it is impossible to optimize the design of the friction pair structure. The friction pair structure design of modern plunger pump products has undergone some changes. For example, the plunger pair is traditionally a cylindrical pair. Now we can design various non-cylindrical friction pair structures. Through advanced numerical analysis and analytical tools, Optimize these structures. Otherwise, it can only rely on trial and error, and the cost is too high.

The test discussed here is not the test of the macroscopic parameters of the hydraulic pump, but the test of the physical parameters of the interface oil film of the friction pair, which is very difficult. Let me introduce you to the test of the high-speed pump. In the test plan of Zhejiang University to study high-speed pumps, there is a very important test item: stirring loss. Generally speaking, the hydraulic pump below 2000rpm does not need to consider this problem, but above 10000rpm, the stirring loss will become very important, and the stirring loss will reach 10% to 20% of the total loss, which will seriously affect the efficiency of the pump. We have done a lot of valuable work in recent years. The first is how to measure it, and the other how to analyze it. Is the plunger pump agitation loss caused by the cylinder block or the plunger? It is generally believed that the plunger should be stirred more, but in fact the cylinder is the largest source of stirring loss (see Figure 5), we have a very good test set to more accurately test the stirring loss. So how to suppress it? There are various methods, but the most practical method is to add an embedded cover structure on the surface of the cylinder. We give this method a name, called regular flow. Why does the cylinder block produce such a large loss? Because the interface flow field has changed a lot, if we regularize the flow field, this loss will drop significantly. A fairing we designed on the cylinder block reduces the loss very significantly. In addition, the friction coefficient is reduced by the surface coating of the cylinder block, and the comprehensive effect of a wide speed range can be obtained.

The testing equipment for the microscopic parameters of the friction pair oil film is relatively expensive, and the design and analysis are very difficult. Zhejiang University has been engaged in the testing and research of the micron-level oil film of the friction pair of hydraulic pumps. It is used for the research and development of pumps and motors for aerospace companies. We provide some equipment for testing the oil film. At present, most of this test equipment is based on simulation, not real working conditions, but it is better than simulation, so it can be used by engineers in the industry, and most of the experiments are relatively simple, which can reduce costs. Taking a slipper pair and a plunger pair as an example, we can measure the friction force of the slipper pair, as well as the position and motion of the three degrees of freedom of the slipper pair; we can also measure the friction force of the plunger pair, which can support the structural Optimized design. In addition, we also test the friction pair of the sliding shoe. It is difficult to measure the interface parameters of the friction pair of the sliding shoe. Until now, we still cannot accurately know the changing law of the rotation of the sliding shoe. We currently have a set of experimental devices. The design is more precise and delicate. Compared with similar foreign devices, we measure more parameters in range and quantity.

The other is to measure the distribution pair. Everyone thinks that the distribution pair is relatively simple, because the distribution plate is not moving, then it is enough to add three tiny displacement sensors to the end cover, but this method is difficult to reflect the multi-free movement state of the piston pump cylinder. . Recently, we proposed a method. The basic idea is: the drive shaft of the piston pump cylinder is in the form of time-varying repetitive deflection motion, then the posture of the cylinder body directly maps the overturning state of the distribution pair. An eddy current sensor is installed at intervals of 120°, so that the position and posture change of the cylinder can be measured truly. Compared with the scheme of measuring the angle between the valve plate and the cylinder, the new method is obviously more intuitive, and the measured data can reflect the cylinder. More information on body assignments.

The EHA technology in the aerospace field has led the development of high-speed pumps, but once it enters the population, this problem is more troublesome, because the population is concerned with the combination of performance and cost. But in any case, the research of high-speed and variable-speed hydraulic pumps is a very important direction in the future, whether in industry or academia.

At present, in the field of electrification of non-road mobile machines, the industry mainly considers electric motors to replace internal combustion engines, and cares about new components and systems such as batteries/capacitors, and does not think much about changes in hydraulic components and systems. In recent years, many new configurations of the hydraulic system have come out, making full use of the four-quadrant working ability of the electric motor, and it is easy to recover energy. At this time, the accumulator has become very important. As a hydraulic energy storage element, there are some technical bottlenecks in the hydraulic accumulator, so a very important focus of the accumulator research is how to improve the energy density and reduce the weight.

In the field of non-road mobile machines, there is still a long way to go for electric motors to replace internal combustion engines. At present, electromechanical actuators are still difficult to adapt to harsh working conditions and environments like hydraulic actuators. The performance tradeoff, if you don"t take this into account, no matter how good the technology is, it will not be applied in practice.Editor/XingWentao

The historical region now known as China experienced a history involving mechanics, hydraulics and mathematics applied to horology, metallurgy, astronomy, agriculture, engineering, music theory, craftsmanship, naval architecture and warfare. Use of the plow during the Neolithic period Longshan culture (c. 3000–c. 2000 BC) allowed for high agricultural production yields and rise of Chinese civilization during the Shang Dynasty (c. 1600–c. 1050 BC).multiple-tube seed drill and the heavy moldboard iron plow enabled China to sustain a much larger population through improvements in agricultural output.

For the purposes of this list, inventions are regarded as technological firsts developed in China, and as such does not include foreign technologies which the Chinese acquired through contact, such as the windmill from the Middle East or the telescope from early modern Europe. It also does not include technologies developed elsewhere and later invented separately by the Chinese, such as the odometer, water wheel, and chain pump. Scientific, mathematical or natural discoveries made by the Chinese, changes in minor concepts of design or style and artistic innovations do not appear on the list.

Philon of Byzantium (3rd or 2nd century BC)chain drive and windlass used in the operation of a polybolos (a repeating ballista),chain pumps which had been known in China since at least the Han Dynasty (202 BC – 220 AD) when they were mentioned by the Han dynasty philosopher Wang Chong (27 – c. 100 AD),clock tower built at Kaifeng in 1090 by the Song Chinese politician, mathematician and astronomer Su Song (1020–1101).

Escapement, hydraulic-powered (use in clock tower): The escapement mechanism was first described for a mechanical washstand by the Greek Philon of Byzantium who also indicated that it was already used for clocks.Yi Xing (683–727) of the Tang Dynasty (618–907) for his water-powered celestial globe in the tradition of the Han dynasty polymath and inventor Zhang Heng (78–139), and could be found in later Chinese clockworks such as the clock towers developed by the military engineer Zhang Sixun (fl. late 10th century) and polymath inventor Su Song (1020–1101).striking clock.pendulum resting and releasing its hooks on a small rotating gear wheel, the early Chinese escapement employed the use of gravity and hydraulics.waterwheel (which acted like a gear wheel) would be filled one by one with siphoned water from a clepsydra tank.

air conditioning, the Han Dynasty craftsman and mechanical engineer Ding Huan (fl. 180 AD) invented a manually operated rotary fan with seven wheels that measured 3 m (10 ft) in diameter; in the 8th century, during the Tang Dynasty (618–907), the Chinese applied hydraulic power to rotate the fan wheels for air conditioning, while the rotary fan became even more common during the Song Dynasty (960–1279).Georg Agricola (1494–1555).

archaeological site in Anatolia (Kaman-Kalehoyuk) and is about 4,000 years old.East Africa, dating back to 1400 BC.Falcata were produced in the Iberian Peninsula, while Noric steel was used by the Roman military.cast iron from the late Spring and Autumn period (722–481 BC), produced steel by the 2nd century BC through a process of decarburization, i.e. using bellows to pump large amounts of oxygen on to molten cast iron.Liu An (179–122 BC). For steel, they used both quenching (i.e. rapid cooling) and tempering (i.e. slow cooling) methods of heat treatment. Much later, the American inventor William Kelly (1811–1888) brought four Chinese metallurgists to Eddyville, Kentucky in 1845, whose expertise in steelmaking influenced his ideas about air injection to reduce carbon content of iron; his invention anticipated the Bessemer process of English inventor Henry Bessemer (1813–1898).

pestle and mortar to pound and decorticate grain, which was superseded by the treadle-operated tilt hammer (employing a simple lever and fulcrum) perhaps during the Zhou Dynasty (1122–256 BC) but first described in a Han Dynasty (202 BC – 220 AD) dictionary of 40 BC and soon after by the Han dynasty philosopher and writer Yang Xiong (53 BC – 18 AD) in his hydraulic power, which the Han dynasty philosopher and writer Huan Tan (43 BC – 28 AD) mentioned in his Xinlun of 20 AD, although he also described trip hammers powered by the labor of horses, oxen, donkeys, and mules.waterwheels were made in subsequent Chinese dynasties and in Medieval Europe by the 12th century.Pliny, Roman Empire by the 1st century AD.

Lewis, Michael (2000b), "Theoretical Hydraulics, Automata, and Water Clocks", in Wikander, Örjan,Handbook of Ancient Water Technology, Technology and Change in History, 2, Leiden, pp. 343–369 (356f.), ISBN 90-04-11123-9.

Hydraulic systems continue to offer advantages to designers of industrial machinery. Power density is a major benefit, and hydraulics also offer control accuracy, simplicity, safety, reliability and cost-effectiveness. At the heart of any hydraulic system is a pump but how do you decide which type to use for your application? This article provides practical guidance on pump selection.

Specifying a hydraulic pump for an industrial application can be a daunting task. Moreover, you cannot consider the pump in isolation, as you need to take into account the operating cycle, system components, what will power the pump, the type of hydraulic fluid and maintenance issues.

Factors to think about include the type of hydraulic circuit (open- or closed-loop), power, flow rate, pressure, noise, the type of hydraulic fluid, the operating conditions and how the pump will be powered.

There are two main types of hydraulic circuit:Open-loop: This covers approximately 75 per cent of applications and is the most common type for industrial hydraulic systems. Hydraulic circuits are configured with return lines open to atmosphere. Open-loop systems provide flexibility for multi-axis applications and scope for future upgrades.

Closed-loop: Most commonly used on mobile plant and winches/cranes, closed-loop systems have return lines piped directly back to the pump inlet. This avoids the need for control valves and provides accurate, compact control. Closed-loop systems are best suited to rotary type actuators but can also be used with cylinders for applications such as steering.

Start by determining the flow rate required for the application, then factor-in the inevitable loss of efficiency due to component wear and leakage in system components. This gives a required flow rate for the pump.

A pump does not create pressure, it only creates flow. It generates flow with enough power to overcome pressure induced by the load at the pump outlet. If the outlet is connected straight back to tank there will be no pressure; if connected to a cylinder, it will generate the pressure required to lift the load. The maximum operating pressure varies between different types of pump. For example, the nominal pressure for a vane pump might be 100 bar whereas a radial piston pump could be rated at 700 bar.

Hydraulic power is defined as flow multiplied by pressure. It is best to calculate the power required by the hydraulic system. Beware of guesstimating the pump’s power by looking at a pump on a similar application, as that pump may have been over-specified.

Different types of hydraulic pump have higher or lower operating speeds. For example, the maximum speed of an external gear pump might be 4000 RPM but a bent-axis piston pump might only operate up to 3000 RPM. Running a pump at a lower speed than its optimum rated speed usually results in reduced efficiency, so care needs to be taken to ensure the pump’s speed and flow rate match the application’s requirements. Note that the efficiency of the driving unit, whether an electric motor or internal combustion engine, will also depend on the speed.

A pump’s purchase cost is only one element of its total cost of ownership (TCO). Maintenance is important to avoid performance degradation as well as preventing premature failure, unplanned downtime and spiralling TCO. Furthermore, correct maintenance ensures worn parts are replaced before the pump sustains more extensive damage. However, some types of pump are more expensive to maintain. It is therefore important to consider the utilisation, ease of maintenance (due to accessibility) and system design life.

The fluid must be compatible with the pump, so the optimum fluid should be selected at the same time as deciding which type of pump to use. Options include:Conventional hydraulic fluid: Most pumps work well with these fluids based on mineral oil, which have good lubricity and a high boiling point.

Phosphate ester: These synthetic fluids benefit from high thermal stability, good lubricity and antiwear properties. Phosphate ester fluids are typically used in high-temperature applications where there is a risk of fire. They are less viscous, however, and can be chemically aggressive, so care is required when specifying seals and coatings. Hydraulic systems with phosphate ester fluid can cost more to maintain.

Biodegradable fluids: Environmentally-sensitive applications such as agricultural machinery and marine equipment often use biodegradable hydraulic fluids to reduce contamination risks. These fluids may be based on vegetable oils and they typically have high lubricity and are inherently anticorrosive. However, they can oxidize quickly and degrade if contaminated with water.

Pump data sheets usually state a maximum viscosity for the hydraulic fluid and it is important to adhere to this. A viscosity that is too high or low can reduce efficiency and introduce further problems. The environmental conditions and operating temperature due to the pump duty cycle will have an effect on the temperature and hence viscosity of the fluid. Therefore, the designer may need to consider using heating or cooling to maintain the desired operating viscosity.

Pumps are classified as positive displacement or non-positive displacement. Most hydraulic pumps are positive displacement types as outlined below. With non-positive-displacement pumps, the flow rate varies in response to the pressure exerted on the outlet, which is usually undesirable for hydraulic systems.

Gear pumps can be subdivided as follows:External gear pump: Meshing gears within a close-fitting casing force hydraulic fluid to travel in the voids between the gear teeth and the casing. Where the gear teeth come out of mesh, a volume expands, creating an area of lower pressure that draws in fluid via the inlet port. Conversely, where the teeth come into mesh, the volume between the teeth deceases, pressure rises and the fluid flows out of the outlet port. External gear pumps can operate at high speeds and are relatively quiet and inexpensive.

Internal gear pump: These have an inner gear with teeth facing outward to mesh with inwards-facing teeth on an outer gear. The two gears are located so they mesh on one side; on the opposite side, a crescent-shaped barrier fills the space between them. Where the gear teeth come out of mesh, an area of lower pressure is created, which draws in fluid via the inlet port. Where the teeth come into mesh, an area of higher pressure is created. Hydraulic fluid is carried in the gaps between the gear teeth. Compared with external gear pumps, internal gear pumps produce smooth flows with little pulsation. However, internal gear pumps are more costly to manufacture.

In vane pumps, the rotor has radial slots in which vanes slide. The rotor is offset in the bore of the casing cavity so, as it rotates, the vanes move in and out to remain in sliding contact with the cavity wall. Fluid is trapped in the chambers created by pairs of vanes and is transported from the inlet port to the outlet port.

Vane pumps come in fixed- or variable-displacement types, both of which are characterised by low operating noise levels. Variable-displacement vane pumps benefit from high repetition accuracy but they are relatively low-pressure, low-speed units.

Piston pumps are available in axial and radial types:Axial piston pumps: A circular array of pistons operate in a cylinder block, with an angled swashplate controlling the piston strokes. As the cylinder block rotates, the pistons move axially, drawing fluid in when the pistons are at the inlet port and pumping it out when they are at the outlet port. In variable-displacement axial piston pumps, the angle of the swashplate is altered to change the piston’s stroke and displacement – and, consequently, the flow rate.

Bent-axis piston pumps: These are similar to swashplate axial piston pumps but the axes of the drive shaft and cylinder block are at a fixed angle relative to each other. The pistons are caused to move in and out by a drive flange.

Radial piston pumps: Radial piston pumps have three or more radial pistons in fixed cylinders. As the drive shaft rotates, a cam causes the pistons to move along their axes. Each cylinder is fitted with inlet and outlet ports and non-return valving. Radial piston pumps benefit from high efficiency, smooth flow, low noise levels, high reliability and can operate at high pressures.

As we have seen above, some types of pump are available as fixed-displacement units while others can be fixed or variable-displacement. While variable-displacement pumps tend to cost more to purchase, they enable the flow rate to be varied without altering the pump’s speed. For simple applications where movements are always the same, fixed-displacement pumps are usually preferred, whereas variable-displacement pumps are better for applications where motions are less predictable.

Bosch Rexroth is a world leader in the design, manufacture and supply of hydraulic pumps. For more information about Bosch Rexroth, please visit: https://www.boschrexroth.com/en/xc/products/product-support/hydraulic-fluids/index

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The hydraulic contour plate does not cause any problems in pump operation since the hydraulic fluid passes easily through the contour plate holes. However, a process contour plate, required by traditional disc diaphragm liquid ends, places limitations on the types of process fluids the pump can handle (such as slurries) since the process fluid must also pass through contour plate holes. The process contour plate also creates a pressure loss which raises the NPSH requirement of the liquid end.

The MARS System The MARS System eliminates the need for a process contour plate by assuring that the hydraulic fluid can only be refilled when the diaphragm has traveled all the way back to the hydraulic contour plate. The diaphragm presses against the MARS valve, which only then permits a poppet valve to open from the vacuum created by insufficient hydraulic fluid.

Hydraulic overfill is therefore impossible. With the process contour plate gone, the straight through path of the process liquid makes the HPD a perfect choice for slurries and viscous materials. It also lowers the NPSH requirements of the pump, since pressure loss through a process contour plate is eliminated.

The MARS system also simplifies HPD start-up. Unlike other hydraulic liquid ends, the refill valve does not need adjustment. Additionally, since the HPD hydraulic fluid cannot be overfilled, there is no need to perform delicate procedures to synchronize hydraulic fluid balances (a difficult task required for tubular and other double diaphragm liquid ends). With the HPD, you just fill the reservoirs, and turn it on.

In this article I would like to throw in my modest opinion about non-original spare parts - a frequent discussion topic among folks involved in the business of hydraulic pump and motor overhauling.

Although workshops can"t repair pumps without spare parts, they can choose where to buy the spares, and this choice is the key factor that defines how much money they make and how much "overhauling quality" they deliver. With so many suppliers and resellers of non-genuine replacement parts for hydraulic pumps and motors popping up every day, choosing the right "economic" supplier has become all but an easy task involving trial and error overhauls, pissed-off mechanics, pissed-off customers and even forever lost contracts and clients.

A mechanic, for example, being the person who shoves the parts into them pumps and motors, will always prefer genuine replacement parts over any aftermarket ones for one simple reason - they are easy to work with, they always fit and require no "finishing touches" - ergo his work is faster and simpler. Genuine parts last long and are hardly ever faulty, which makes the testing and adjustment procedures safer and reduces the risk of having to re-open overhauled units to a minimum. A mechanic doesn"t care about how much they cost because he"s not the one paying for them.

The truth lies, as always, in the golden middle, and I, personally, came to the conclusion that although most of the times you do get what you pay for, this doesn"t mean that you can"t get a bargain for a penny every once in a while, so a sound overhauler keeps his eyes and mind open and uses both genuine and aftermarket parts in a combination defined by his trial an error experience and the pump/motor application demands. This approach is sound because even in pre-recession years there were hydraulic equipment owners who actually preferred aftermarket to genuine in the pursuit of cutting down overhaul expenses. So, some clients will want the genuine quality, and some will want the lower price - and in order to satisfy both you, naturally, have to be able to serve both, but - if your goal is to deliver quality repairs, aftermarket part suppliers should be chosen with a cool head and on the basis of quality, not price!

OK, you say, so I am a hydraulic equipment owner, and I"ve got this excavator pump to repair, how do I know if I am going to be scammed with them Chinese spares? Well, there is no simple answer to this question...There is an opinion that if an overhaul is backed up by warranty than you"re on the safe side, no matter what parts were used - this, unfortunately, is not entirely true, because if you"re the unlucky hydraulic pump owner caught in the "error" stage of the new supplier trial and error validation process, you can get two different answers and two very different bills depending on how honest the company you are dealing with is. An honest workshop will admit their fault and try to correct the mistake as fast as they can, and if you are not the first-time customer you might even get the - "sorry about that, dude, the parts"re all **cked up..." confession, while a less candid workshop will give you the standard "commission errors committed by non-qualified personnel plus hard particle contamination in conjunction with the inappropriate oil temperature and deficient system design" excuse, and make you pay for their poor part supplier choice. So I"d say that warranty alone isn"t a guarantee, and would cast my vote for warranty combined with transparency - if a workshop has good experience with their non-genuine spare parts supplier - they won"t be ashamed to admit that the parts are not original.

Now, a separate word must be said about Chinese suppliers of spare parts for hydraulic pumps and motors. There are hundreds of companies in China that will sell you spare parts for almost any existing brand, with the quality ranging from superb to unacceptable and even ridiculously unacceptable. However with most suppliers (and especially resellers) the fact that you have received a batch of supreme quality spares doesn"t guarantee that you will get the same quality in the next batch. So if you ever decide to "go oriental" - be prepared for nasty surprises! (At least that was the situation at the moment of writing - December 2011).

My calling is more technical than commercial, therefore I am mainly interested in the quality of the spares rather than their price or where they come from - so please, don"t bother asking me for a list of "unofficially approved" Chinese suppliers of cheap yet extremely high quality spare parts for hydraulic pumps and motors - I won"t provide it because I frankly don"t have it! We do use some aftermarket spares from China, we did have our share of mishaps and disappointments with Chinese made parts, and our initial "Hurrays" got eventually replaced by "Boos" for most of them. Since our policy has always been to never let a client pay for a breakdown caused by a low quality part, a couple of lessons "learned the hard way" taught us that in most cases (not all, though) using Chinese spares in hydraulic pumps and motors is like using bathroom soap for filling cakes - looks and smells nice, yet still tastes like crap...