typical hydraulic pump efficiency quotation

Calculation of preliminary cooler capacity: Heat dissipation from hydraulic oil tanks, valves, pipes and hydraulic components is less than a few percent in standard mobile equipment and the cooler capacity must include some margins. Minimum cooler capacity, Ecooler = 0.25Ediesel

At least 25% of the input power must be dissipated by the cooler when peak power is utilized for long periods. In normal case however, the peak power is used for only short periods, thus the actual cooler capacity required might be considerably less. The oil volume in the hydraulic tank is also acting as a heat accumulator when peak power is used.

The system efficiency is very much dependent on the type of hydraulic work tool equipment, the hydraulic pumps and motors used and power input to the hydraulics may vary considerably. Each circuit must be evaluated and the load cycle estimated. New or modified systems must always be tested in practical work, covering all possible load cycles.

Hydraulic losses relates to the construction of the pump or fan and is caused by the friction between the fluid and the walls, the acceleration and retardation of the fluid and the change of the fluid flow direction.

Mechanical components - like transmission gear and bearings - creates mechanical losses that reduces the power transferred from the motor shaft to the pump or fan impeller.

Due to leakage of fluid between the back surface of the impeller hub plate and the casing, or through other pump components - there is a volumetric loss reducing the pump efficiency.

The overall efficiency is the ratio of power actually gained by the fluid to power supplied to the shaft. The overall efficiency can be expressed as: η= ηh ηm ηv(4)

The losses in a pump or fan converts to heat that is transferred to the fluid and the surroundings. As a rule of thumb - the temperature increase in a fan transporting air is approximately 1oC.

An inline water pump works between pressure1 bar (1 105 N/m2)and 10 bar (10 105 N/m2).The density of water is 1000 kg/m3. The hydraulic efficiency is ηh= 0.91.

Your final drive includes a hydraulic motor and that motor has a certain level of efficiency associated with it. Over time, that efficiency can drop -- so find out how efficiency is measured, what the source of losses are, and how to minimize them.

No system, no matter how well it’s designed, is going to be 100% efficient. High-quality, well-maintained radial piston motors are about 95% efficient while axial piston motors are about 90% efficient--which is likely why you see these two types of hydraulic motors used in the vast majority of final drive motors.

The definition of efficiency depends on what type of system you’re talking about, and even then there can be some variations. For a hydraulic motor, there are three ways efficiency can be measured or estimated: volumetric, mechanical/hydraulic, and overall efficiency.

Volumetric efficiency looks at the theoretical flow rate and the actual flow rate and provides information about leakage and wear. The theoretical flow rate is pretty easy to calculate: theoretical flow = (pump displacement per revolution) x (revolution speed).

This works much better in SI units, too. If the displacement is in cc/rev and the speed is in rpm, the results will be in liters/minute. Actual flow is then measured using a flow meter. The efficiency is then actual flow / theoretical flow x 100 to get efficiency as a percent.

Mechanical efficiency is based on actual work done and theoretical work done, both per revolution. This is based on theoretical torque and the actual torque, and in most hydraulic motors it’s about 0.9 (or 90%). Actual torque can be measured with a dynamometer, but is rarely done. The losses related to mechanical efficiency are directly tied to mechanical friction between mating parts.

Overall efficiency combines volumetric and mechanical efficiency. It"s simply the product of these two values: overall efficiency = mechanical efficiency x volumetric efficiency, and gives you an overall idea of how efficient your hydraulic motor is.

Some degree of internal leakage is normal and actually beneficial, but past a certain point it becomes a problem. Excess internal leakage most often results from wear. For example, the size of key clearances in a hydraulic motor can, over time, become larger because of abrasive wear and lead to internal leakage. That type of wear usually results from contaminated hydraulic fluid but can also result from normal wear and tear.

Friction is another major source of losses. Rough surfaces where they should be smooth cause friction issues with the hydraulic fluid, reducing the amount of power that can be transferred. There are other ways that friction can be introduced, however. For example, anti-friction bearings or plane bearings that are wearing out will be a source of friction.

One of the keys to preventing hydraulic motor losses relates to good maintenance practices, such as keeping the hydraulic fluid clean, replacing hydraulic filters, and not ignoring hydraulic leaks. It"s also important to look for symptoms of potential problems with the bearings, such as new noises, excessive vibration, and overheating.

In a condition-based maintenance environment, the decision to change out a hydraulic pump or motor is usually based on remaining bearing life or deteriorating efficiency, whichever occurs first.

Despite recent advances in predictive maintenance technologies, the maintenance professional’s ability to determine the remaining bearing life of a pump or motor, with a high degree of accuracy, remains elusive.

Deteriorating efficiency on the other hand is easy to detect, because it typically shows itself through increased cycle times. In other words, the machine slows down. When this occurs, quantification of the efficiency loss isn’t always necessary. If the machine slows to the point where its cycle time is unacceptably slow, the pump or motor is replaced. End of story.

In certain situations, however, it can be helpful, even necessary, to quantify the pump or motor’s actual efficiency and compare it to the component’s native efficiency. For this, an understanding of hydraulic pump and motor efficiency ratings is essential.

There are three categories of efficiency used to describe hydraulic pumps (and motors): volumetric efficiency, mechanical/hydraulic efficiency and overall efficiency.

Volumetric efficiency is determined by dividing the actual flow delivered by a pump at a given pressure by its theoretical flow. Theoreticalflow is calculated by multiplying the pump’s displacement per revolution by its driven speed. So if the pump has a displacement of 100 cc/rev and is being driven at 1000 RPM, its theoretical flow is 100 liters/minute.

Actualflow has to be measured using a flow meter. If when tested, the above pump had an actual flow of 90 liters/minute at 207 bar (3000 PSI), we can say the pump has a volumetric efficiency of 90% at 207 bar (90 / 100 x 100 = 90%).

Its volumetric efficiency used most in the field to determine the condition of a hydraulic pump - based on its increase in internal leakage through wear or damage. But without reference to theoretical flow, the actual flow measured by the flow meter would be meaningless.

A pump’s mechanical/hydraulic efficiency is determined by dividing thetheoretical torque required to drive it by the actual torque required to drive it. A mechanical/hydraulic efficiency of 100 percent would mean if the pump was delivering flow at zero pressure, no force or torque would be required to drive it. Intuitively, we know this is not possible, due to mechanical and fluid friction.

Table 1. The typical overall efficiencies of hydraulic pumps, as shown above, are simply the product of volumetric and mechanical/hydraulic efficiency.Source: Bosch Rexroth

Like theoretical flow, theoretical drive torque can be calculated. For the above pump, in SI units: 100 cc/rev x 207 bar / 20 x p = 329 Newton meters. But like actual flow, actual drive torque must be measured and this requires the use of a dynamometer. Not something we can - or need - to do in the field. For the purposes of this example though, assume the actual drive torque was 360 Nm. Mechanical efficiency would be 91% (329 / 360 x 100 = 91%).

Overall efficiency is simply the product of volumetric and mechanical/hydraulic efficiency. Continuing with the above example, the overall efficiency of the pump is 0.9 x 0.91 x 100 = 82%. Typical overall efficiencies for different types of hydraulic pumps are shown in the Table 1.

System designers use the pump manufacturers’ volumetric efficiency value to calculate the actual flow a pump of a given displacement, operating at a particular pressure, will deliver.

As already mentioned, volumetric efficiency is used in the field to assess the condition of a pump, based on the increase in internal leakage due to wear or damage.

When calculating volumetric efficiency based on actual flow testing, it’s important to be aware that the various leakage paths within the pump are usually constant. This means if pump flow is tested at less than full displacement (or maximum RPM) this will skew the calculated efficiency - unless leakage is treated as a constant and a necessary adjustment made.

For example, consider a variable displacement pump with a maximum flow rate of 100 liters/minute. If it was flow tested at full displacement and the measured flow rate was 90 liters/minute, the calculated volumetric efficiency would be 90 percent (90/100 x 100). But if the same pump was flow tested at the same pressure and oil temperature but at half displacement (50 L/min), the leakage losses would still be 10 liters/minute, and so the calculated volumetric efficiency would be 80 percent (40/50 x 100).

The second calculation is not actually wrong, but it requires qualification: this pump is 80 percent efficient at half displacement. Because the leakage losses of 10 liters/minute are nearly constant, the same pump tested under the same conditions will be 90 percent efficient at 100 percent displacement (100 L/min) - and 0 percent efficient at 10 percent displacement (10 L/min).

To help understand why pump leakage at a given pressure and temperature is virtually constant, think of the various leakage paths as fixed orifices. The rate of flow through an orifice is dependant on the diameter (and shape) of the orifice, the pressure drop across it and fluid viscosity. This means that if these variables remain constant, the rate of internal leakage remains constant, independent of the pump"s displacement or shaft speed.

Overall efficiency is used to calculate the drive power required by a pump at a given flow and pressure. For example, using the overall efficiencies from the table above, let us calculate the required drive power for an external gear pump and a bent axis piston pump at a flow of 90 liters/minute at 207 bar:

As you’d expect, the more efficient pump requires less drive power for the same output flow and pressure. With a little more math, we can quickly calculate the heat load of each pump:

No surprise that a system with gear pumps and motors requires a bigger heat exchanger than an equivalent (all other things equal) system comprising piston pumps and motors.

Knowing how to right-size an electric motor for your hydraulic pump can help reduce energy consumption and increase operational efficiency. The key is to ensure the pump motor is operating at peak continuous load. But how can you know how much power is needed?

Before you can choose the correct electric motor, you must know how much horsepower (Hp) is required to drive the pump shaft. Generally, this is calculated by multiplying the flow capacity in gallons per minute (GPM) by the pressure in pounds per square inch (PSI). You then divide the resulting number by 1714 times the efficiency of the pump, for a formula that looks like this:

If you’re not sure how efficient your hydraulic pump is, it is advisable to use a common efficiency of about 85% (Multiplying 1714 x 0.85 = 1460 or 1500 if you round up). This work-around simplifies the formula to:

The above formula works in most applications with one notable exception: If the operating pressure of a pump is very low, the overall efficiency will be much lower than 85%. That’s because overall efficiency is equal to mechanical efficiency (internal mechanical friction) plus volumetric efficiency.

Internal friction is generally a fixed value, but volumetric efficiency changes depending on the pressure used. Low-pressure pumps have high volumetric efficiency because they are less susceptible to internal leakage. However, as the pressure goes up and internal fluids pass over work surfaces such as pistons, port plates, and lubrication points, the volumetric efficiency goes down and the amount of torque required to turn the pump for developing pressure goes up.

This variance makes it very important to know the efficiency of your pump if you’re using it at low pressure! Calculations that do not take low pressure into account will lead to a failed design.

If you calculate 20 GPM @ 300 PSI with an assumed overall efficiency of 89%, you would probably select a 5 Hp electric motor. However, if you calculate the same 20 GPM @ 300 PSI with the actual overall efficiency of 50%, you would know that you should be using a 7.5 Hp motor. In this example, making an assumption about the efficiency of your pump could result in installing a motor that is too large, driving up your overall operating cost.

There are many contributors to the overall efficiency of a hydraulic pump, and it pays to be as accurate as possible when choosing a motor. A best practice for proper sizing is to use published data from the pump vendor that shows actual input torque vs. pressure or overall efficiency vs pressure. Note that efficiency is also affected by RPM.

Identifying a right-sized motor for your hydraulic pump does not always ensure you are using the most efficient motor. Be sure to read Part 2 of this post to learn how RMS loading and Hp limiting can help you scale down the size of your electric motor to save money while maximizing efficiency.

Hydraulic pumps are mechanisms in hydraulic systems that move hydraulic fluid from point to point initiating the production of hydraulic power. Hydraulic pumps are sometimes incorrectly referred to as “hydrolic” pumps.

They are an important device overall in the hydraulics field, a special kind of power transmission which controls the energy which moving fluids transmit while under pressure and change into mechanical energy. Other kinds of pumps utilized to transmit hydraulic fluids could also be referred to as hydraulic pumps. There is a wide range of contexts in which hydraulic systems are applied, hence they are very important in many commercial, industrial, and consumer utilities.

“Power transmission” alludes to the complete procedure of technologically changing energy into a beneficial form for practical applications. Mechanical power, electrical power, and fluid power are the three major branches that make up the power transmission field. Fluid power covers the usage of moving gas and moving fluids for the transmission of power. Hydraulics are then considered as a sub category of fluid power that focuses on fluid use in opposition to gas use. The other fluid power field is known as pneumatics and it’s focused on the storage and release of energy with compressed gas.

"Pascal"s Law" applies to confined liquids. Thus, in order for liquids to act hydraulically, they must be contained within a system. A hydraulic power pack or hydraulic power unit is a confined mechanical system that utilizes liquid hydraulically. Despite the fact that specific operating systems vary, all hydraulic power units share the same basic components. A reservoir, valves, a piping/tubing system, a pump, and actuators are examples of these components. Similarly, despite their versatility and adaptability, these mechanisms work together in related operating processes at the heart of all hydraulic power packs.

The hydraulic reservoir"s function is to hold a volume of liquid, transfer heat from the system, permit solid pollutants to settle, and aid in releasing moisture and air from the liquid.

Mechanical energy is changed to hydraulic energy by the hydraulic pump. This is accomplished through the movement of liquid, which serves as the transmission medium. All hydraulic pumps operate on the same basic principle of dispensing fluid volume against a resistive load or pressure.

Hydraulic valves are utilized to start, stop, and direct liquid flow in a system. Hydraulic valves are made of spools or poppets and can be actuated hydraulically, pneumatically, manually, electrically, or mechanically.

The end result of Pascal"s law is hydraulic actuators. This is the point at which hydraulic energy is transformed back to mechanical energy. This can be accomplished by using a hydraulic cylinder to transform hydraulic energy into linear movement and work or a hydraulic motor to transform hydraulic energy into rotational motion and work. Hydraulic motors and hydraulic cylinders, like hydraulic pumps, have various subtypes, each meant for specific design use.

The essence of hydraulics can be found in a fundamental physical fact: fluids are incompressible. (As a result, fluids more closely resemble solids than compressible gasses) The incompressible essence of fluid allows it to transfer force and speed very efficiently. This fact is summed up by a variant of "Pascal"s Principle," which states that virtually all pressure enforced on any part of a fluid is transferred to every other part of the fluid. This scientific principle states, in other words, that pressure applied to a fluid transmits equally in all directions.

Furthermore, the force transferred through a fluid has the ability to multiply as it moves. In a slightly more abstract sense, because fluids are incompressible, pressurized fluids should keep a consistent pressure just as they move. Pressure is defined mathematically as a force acting per particular area unit (P = F/A). A simplified version of this equation shows that force is the product of area and pressure (F = P x A). Thus, by varying the size or area of various parts inside a hydraulic system, the force acting inside the pump can be adjusted accordingly (to either greater or lesser). The need for pressure to remain constant is what causes force and area to mirror each other (on the basis of either shrinking or growing). A hydraulic system with a piston five times larger than a second piston can demonstrate this force-area relationship. When a force (e.g., 50lbs) is exerted on the smaller piston, it is multiplied by five (e.g., 250 lbs) and transmitted to the larger piston via the hydraulic system.

Hydraulics is built on fluids’ chemical properties and the physical relationship between pressure, area, and force. Overall, hydraulic applications allow human operators to generate and exert immense mechanical force with little to no physical effort. Within hydraulic systems, both oil and water are used to transmit power. The use of oil, on the other hand, is far more common, owing in part to its extremely incompressible nature.

Pressure relief valves prevent excess pressure by regulating the actuators’ output and redirecting liquid back to the reservoir when necessary. Directional control valves are used to change the size and direction of hydraulic fluid flow.

While hydraulic power transmission is remarkably useful in a wide range of professional applications, relying solely on one type of power transmission is generally unwise. On the contrary, the most efficient strategy is to combine a wide range of power transmissions (pneumatic, hydraulic, mechanical, and electrical). As a result, hydraulic systems must be carefully embedded into an overall power transmission strategy for the specific commercial application. It is necessary to invest in locating trustworthy and skilled hydraulic manufacturers/suppliers who can aid in the development and implementation of an overall hydraulic strategy.

The intended use of a hydraulic pump must be considered when selecting a specific type. This is significant because some pumps may only perform one function, whereas others allow for greater flexibility.

The pump"s material composition must also be considered in the application context. The cylinders, pistons, and gears are frequently made of long-lasting materials like aluminum, stainless steel, or steel that can withstand the continuous wear of repeated pumping. The materials must be able to withstand not only the process but also the hydraulic fluids. Composite fluids frequently contain oils, polyalkylene glycols, esters, butanol, and corrosion inhibitors (though water is used in some instances). The operating temperature, flash point, and viscosity of these fluids differ.

In addition to material, manufacturers must compare hydraulic pump operating specifications to make sure that intended utilization does not exceed pump abilities. The many variables in hydraulic pump functionality include maximum operating pressure, continuous operating pressure, horsepower, operating speed, power source, pump weight, and maximum fluid flow. Standard measurements like length, rod extension, and diameter should be compared as well. Because hydraulic pumps are used in lifts, cranes, motors, and other heavy machinery, they must meet strict operating specifications.

It is critical to recall that the overall power generated by any hydraulic drive system is influenced by various inefficiencies that must be considered in order to get the most out of the system. The presence of air bubbles within a hydraulic drive, for example, is known for changing the direction of the energy flow inside the system (since energy is wasted on the way to the actuators on bubble compression). Using a hydraulic drive system requires identifying shortfalls and selecting the best parts to mitigate their effects. A hydraulic pump is the "generator" side of a hydraulic system that initiates the hydraulic procedure (as opposed to the "actuator" side that completes the hydraulic procedure). Regardless of disparities, all hydraulic pumps are responsible for displacing liquid volume and transporting it to the actuator(s) from the reservoir via the tubing system. Some form of internal combustion system typically powers pumps.

While the operation of hydraulic pumps is normally the same, these mechanisms can be split into basic categories. There are two types of hydraulic pumps to consider: gear pumps and piston pumps. Radial and axial piston pumps are types of piston pumps. Axial pumps produce linear motion, whereas radial pumps can produce rotary motion. The gear pump category is further subdivided into external gear pumps and internal gear pumps.

Each type of hydraulic pump, regardless of piston or gear, is either double-action or single-action. Single-action pumps can only pull, push, or lift in one direction, while double-action pumps can pull, push, or lift in multiple directions.

Vane pumps are positive displacement pumps that maintain a constant flow rate under varying pressures. It is a pump that self-primes. It is referred to as a "vane pump" because the effect of the vane pressurizes the liquid.

This pump has a variable number of vanes mounted onto a rotor that rotates within the cavity. These vanes may be variable in length and tensioned to maintain contact with the wall while the pump draws power. The pump also features a pressure relief valve, which prevents pressure rise inside the pump from damaging it.

Internal gear pumps and external gear pumps are the two main types of hydraulic gear pumps. Pumps with external gears have two spur gears, the spurs of which are all externally arranged. Internal gear pumps also feature two spur gears, and the spurs of both gears are internally arranged, with one gear spinning around inside the other.

Both types of gear pumps deliver a consistent amount of liquid with each spinning of the gears. Hydraulic gear pumps are popular due to their versatility, effectiveness, and fairly simple design. Furthermore, because they are obtainable in a variety of configurations, they can be used in a wide range of consumer, industrial, and commercial product contexts.

Hydraulic ram pumps are cyclic machines that use water power, also referred to as hydropower, to transport water to a higher level than its original source. This hydraulic pump type is powered solely by the momentum of moving or falling water.

Ram pumps are a common type of hydraulic pump, especially among other types of hydraulic water pumps. Hydraulic ram pumps are utilized to move the water in the waste management, agricultural, sewage, plumbing, manufacturing, and engineering industries, though only about ten percent of the water utilized to run the pump gets to the planned end point.

Despite this disadvantage, using hydropower instead of an external energy source to power this kind of pump makes it a prominent choice in developing countries where the availability of the fuel and electricity required to energize motorized pumps is limited. The use of hydropower also reduces energy consumption for industrial factories and plants significantly. Having only two moving parts is another advantage of the hydraulic ram, making installation fairly simple in areas with free falling or flowing water. The water amount and the rate at which it falls have an important effect on the pump"s success. It is critical to keep this in mind when choosing a location for a pump and a water source. Length, size, diameter, minimum and maximum flow rates, and speed of operation are all important factors to consider.

Hydraulic water pumps are machines that move water from one location to another. Because water pumps are used in so many different applications, there are numerous hydraulic water pump variations.

Water pumps are useful in a variety of situations. Hydraulic pumps can be used to direct water where it is needed in industry, where water is often an ingredient in an industrial process or product. Water pumps are essential in supplying water to people in homes, particularly in rural residences that are not linked to a large sewage circuit. Water pumps are required in commercial settings to transport water to the upper floors of high rise buildings. Hydraulic water pumps in all of these situations could be powered by fuel, electricity, or even by hand, as is the situation with hydraulic hand pumps.

Water pumps in developed economies are typically automated and powered by electricity. Alternative pumping tools are frequently used in developing economies where dependable and cost effective sources of electricity and fuel are scarce. Hydraulic ram pumps, for example, can deliver water to remote locations without the use of electricity or fuel. These pumps rely solely on a moving stream of water’s force and a properly configured number of valves, tubes, and compression chambers.

Electric hydraulic pumps are hydraulic liquid transmission machines that use electricity to operate. They are frequently used to transfer hydraulic liquid from a reservoir to an actuator, like a hydraulic cylinder. These actuation mechanisms are an essential component of a wide range of hydraulic machinery.

There are several different types of hydraulic pumps, but the defining feature of each type is the use of pressurized fluids to accomplish a job. The natural characteristics of water, for example, are harnessed in the particular instance of hydraulic water pumps to transport water from one location to another. Hydraulic gear pumps and hydraulic piston pumps work in the same way to help actuate the motion of a piston in a mechanical system.

Despite the fact that there are numerous varieties of each of these pump mechanisms, all of them are powered by electricity. In such instances, an electric current flows through the motor, which turns impellers or other devices inside the pump system to create pressure differences; these differential pressure levels enable fluids to flow through the pump. Pump systems of this type can be utilized to direct hydraulic liquid to industrial machines such as commercial equipment like elevators or excavators.

Hydraulic hand pumps are fluid transmission machines that utilize the mechanical force generated by a manually operated actuator. A manually operated actuator could be a lever, a toggle, a handle, or any of a variety of other parts. Hydraulic hand pumps are utilized for hydraulic fluid distribution, water pumping, and various other applications.

Hydraulic hand pumps may be utilized for a variety of tasks, including hydraulic liquid direction to circuits in helicopters and other aircraft, instrument calibration, and piston actuation in hydraulic cylinders. Hydraulic hand pumps of this type use manual power to put hydraulic fluids under pressure. They can be utilized to test the pressure in a variety of devices such as hoses, pipes, valves, sprinklers, and heat exchangers systems. Hand pumps are extraordinarily simple to use.

Each hydraulic hand pump has a lever or other actuation handle linked to the pump that, when pulled and pushed, causes the hydraulic liquid in the pump"s system to be depressurized or pressurized. This action, in the instance of a hydraulic machine, provides power to the devices to which the pump is attached. The actuation of a water pump causes the liquid to be pulled from its source and transferred to another location. Hydraulic hand pumps will remain relevant as long as hydraulics are used in the commerce industry, owing to their simplicity and easy usage.

12V hydraulic pumps are hydraulic power devices that operate on 12 volts DC supplied by a battery or motor. These are specially designed processes that, like all hydraulic pumps, are applied in commercial, industrial, and consumer places to convert kinetic energy into beneficial mechanical energy through pressurized viscous liquids. This converted energy is put to use in a variety of industries.

Hydraulic pumps are commonly used to pull, push, and lift heavy loads in motorized and vehicle machines. Hydraulic water pumps may also be powered by 12V batteries and are used to move water out of or into the desired location. These electric hydraulic pumps are common since they run on small batteries, allowing for ease of portability. Such portability is sometimes required in waste removal systems and vehiclies. In addition to portable and compact models, options include variable amp hour productions, rechargeable battery pumps, and variable weights.

While non rechargeable alkaline 12V hydraulic pumps are used, rechargeable ones are much more common because they enable a continuous flow. More considerations include minimum discharge flow, maximum discharge pressure, discharge size, and inlet size. As 12V batteries are able to pump up to 150 feet from the ground, it is imperative to choose the right pump for a given use.

Air hydraulic pumps are hydraulic power devices that use compressed air to stimulate a pump mechanism, generating useful energy from a pressurized liquid. These devices are also known as pneumatic hydraulic pumps and are applied in a variety of industries to assist in the lifting of heavy loads and transportation of materials with minimal initial force.

Air pumps, like all hydraulic pumps, begin with the same components. The hydraulic liquids, which are typically oil or water-based composites, require the use of a reservoir. The fluid is moved from the storage tank to the hydraulic cylinder via hoses or tubes connected to this reservoir. The hydraulic cylinder houses a piston system and two valves. A hydraulic fluid intake valve allows hydraulic liquid to enter and then traps it by closing. The discharge valve is the point at which the high pressure fluid stream is released. Air hydraulic pumps have a linked air cylinder in addition to the hydraulic cylinder enclosing one end of the piston.

The protruding end of the piston is acted upon by a compressed air compressor or air in the cylinder. When the air cylinder is empty, a spring system in the hydraulic cylinder pushes the piston out. This makes a vacuum, which sucks fluid from the reservoir into the hydraulic cylinder. When the air compressor is under pressure, it engages the piston and pushes it deeper into the hydraulic cylinder and compresses the liquids. This pumping action is repeated until the hydraulic cylinder pressure is high enough to forcibly push fluid out through the discharge check valve. In some instances, this is connected to a nozzle and hoses, with the important part being the pressurized stream. Other uses apply the energy of this stream to pull, lift, and push heavy loads.

Hydraulic piston pumps transfer hydraulic liquids through a cylinder using plunger-like equipment to successfully raise the pressure for a machine, enabling it to pull, lift, and push heavy loads. This type of hydraulic pump is the power source for heavy-duty machines like excavators, backhoes, loaders, diggers, and cranes. Piston pumps are used in a variety of industries, including automotive, aeronautics, power generation, military, marine, and manufacturing, to mention a few.

Hydraulic piston pumps are common due to their capability to enhance energy usage productivity. A hydraulic hand pump energized by a hand or foot pedal can convert a force of 4.5 pounds into a load-moving force of 100 pounds. Electric hydraulic pumps can attain pressure reaching 4,000 PSI. Because capacities vary so much, the desired usage pump must be carefully considered. Several other factors must also be considered. Standard and custom configurations of operating speeds, task-specific power sources, pump weights, and maximum fluid flows are widely available. Measurements such as rod extension length, diameter, width, and height should also be considered, particularly when a hydraulic piston pump is to be installed in place of a current hydraulic piston pump.

Hydraulic clutch pumps are mechanisms that include a clutch assembly and a pump that enables the user to apply the necessary pressure to disengage or engage the clutch mechanism. Hydraulic clutches are crafted to either link two shafts and lock them together to rotate at the same speed or detach the shafts and allow them to rotate at different speeds as needed to decelerate or shift gears.

Hydraulic pumps change hydraulic energy to mechanical energy. Hydraulic pumps are particularly designed machines utilized in commercial, industrial, and residential areas to generate useful energy from different viscous liquids pressurization. Hydraulic pumps are exceptionally simple yet effective machines for moving fluids. "Hydraulic" is actually often misspelled as "Hydralic". Hydraulic pumps depend on the energy provided by hydraulic cylinders to power different machines and mechanisms.

There are several different types of hydraulic pumps, and all hydraulic pumps can be split into two primary categories. The first category includes hydraulic pumps that function without the assistance of auxiliary power sources such as electric motors and gas. These hydraulic pump types can use the kinetic energy of a fluid to transfer it from one location to another. These pumps are commonly called ram pumps. Hydraulic hand pumps are never regarded as ram pumps, despite the fact that their operating principles are similar.

The construction, excavation, automotive manufacturing, agriculture, manufacturing, and defense contracting industries are just a few examples of operations that apply hydraulics power in normal, daily procedures. Since hydraulics usage is so prevalent, hydraulic pumps are unsurprisingly used in a wide range of machines and industries. Pumps serve the same basic function in all contexts where hydraulic machinery is used: they transport hydraulic fluid from one location to another in order to generate hydraulic energy and pressure (together with the actuators).

Elevators, automotive brakes, automotive lifts, cranes, airplane flaps, shock absorbers, log splitters, motorboat steering systems, garage jacks and other products use hydraulic pumps. The most common application of hydraulic pumps in construction sites is in big hydraulic machines and different types of "off-highway" equipment such as excavators, dumpers, diggers, and so on. Hydraulic systems are used in other settings, such as offshore work areas and factories, to power heavy machinery, cut and bend material, move heavy equipment, and so on.

Fluid’s incompressible nature in hydraulic systems allows an operator to make and apply mechanical power in an effective and efficient way. Practically all force created in a hydraulic system is applied to the intended target.

Because of the relationship between area, pressure, and force (F = P x A), modifying the force of a hydraulic system is as simple as changing the size of its components.

Hydraulic systems can transfer energy on an equal level with many mechanical and electrical systems while being significantly simpler in general. A hydraulic system, for example, can easily generate linear motion. On the contrary, most electrical and mechanical power systems need an intermediate mechanical step to convert rotational motion to linear motion.

Hydraulic systems are typically smaller than their mechanical and electrical counterparts while producing equivalents amounts of power, providing the benefit of saving physical space.

Hydraulic systems can be used in a wide range of physical settings due to their basic design (a pump attached to actuators via some kind of piping system). Hydraulic systems could also be utilized in environments where electrical systems would be impractical (for example underwater).

By removing electrical safety hazards, using hydraulic systems instead of electrical power transmission improves relative safety (for example explosions, electric shock).

The amount of power that hydraulic pumps can generate is a significant, distinct advantage. In certain cases, a hydraulic pump could generate ten times the power of an electrical counterpart. Some hydraulic pumps (for example, piston pumps) cost more than the ordinary hydraulic component. These drawbacks, however, can be mitigated by the pump"s power and efficiency. Despite their relatively high cost, piston pumps are treasured for their strength and capability to transmit very viscous fluids.

Handling hydraulic liquids is messy, and repairing leaks in a hydraulic pump can be difficult. Hydraulic liquid that leaks in hot areas may catch fire. Hydraulic lines that burst may cause serious injuries. Hydraulic liquids are corrosive as well, though some are less so than others. Hydraulic systems need frequent and intense maintenance. Parts with a high factor of precision are frequently required in systems. If the power is very high and the pipeline cannot handle the power transferred by the liquid, the high pressure received by the liquid may also cause work accidents.

Even though hydraulic systems are less complex than electrical or mechanical systems, they are still complex systems that should be handled with caution. Avoiding physical contact with hydraulic systems is an essential safety precaution when engaging with them. Even when a hydraulic machine is not in use, active liquid pressure within the system can be a hazard.

Inadequate pumps can cause mechanical failure in the place of work that can have serious and costly consequences. Although pump failure has historically been unpredictable, new diagnostic technology continues to improve on detecting methods that previously relied solely on vibration signals. Measuring discharge pressures enables manufacturers to forecast pump wear more accurately. Discharge sensors are simple to integrate into existing systems, increasing the hydraulic pump"s safety and versatility.

Hydraulic pumps are devices in hydraulic systems that move hydraulic fluid from point to point, initiating hydraulic power production. They are an important device overall in the hydraulics field, a special kind of power transmission that controls the energy which moving fluids transmit while under pressure and change into mechanical energy. Hydraulic pumps are divided into two categories namely gear pumps and piston pumps. Radial and axial piston pumps are types of piston pumps. Axial pumps produce linear motion, whereas radial pumps can produce rotary motion. The construction, excavation, automotive manufacturing, agriculture, manufacturing, and defense contracting industries are just a few examples of operations that apply hydraulics power in normal, daily procedures.

Power is consumed by a pump, fan or compressor in order to move and increase the pressure of a fluid. The power requirement of the pump depends on a number of factors including the pump and motor efficiency, the differential pressure and the fluid density, viscosity and flow rate. This article provides relationships to determine the required pump power.

The hydraulic power which is also known as absorbed power, represents the energy imparted on the fluid being pumped to increase its velocity and pressure. The hydraulic power may be calculated using one of the formulae below, depending on the available data.

The shaft power is the power supplied by the motor to the pump shaft. Shaft power is the sum of the hydraulic power (discussed above) and power loss due to inefficiencies in power transmission from the shaft to the fluid. Shaft power is typically calculated as the hydraulic power of the pump divided by the pump efficiency as follows:

The motor power is the power consumed by the pump motor to turn the pump shaft. The motor power is the sum of the shaft power and power loss due to inefficiencies in converting electric energy into kinetic energy. Motor power may be calculated as the shaft power divided by the motor efficiency.

There are several other pump and drive features which will increase the power requirement to achieve a particular fluid transfer, these include:Gearboxes

Variable speed drives (VSDs)Each of these components will have their own efficiency ratings, which must be factored into the power delivered by the motor.

The table below provides some typical efficiency values which may be used for power requirement estimation for a selection of pump types. These values are for correctly sized pumps, if a pump is oversized or poorly designed its efficiency may be much lower than the values quoted below, this is particularly common in small pumps.

There are important considerations when evaluating published pump performance and different testing options to achieve performance levels acceptable for an application. Guarantee point efficiency, part-load efficiencies, motor efficiencies, drive efficiencies and control strategies all come into play when determining the energy required to operate a system from a pumping standpoint.

Just like the materials of construction, the seal type and the impeller trim have an impact on pump performance. Even if a performance test is requested in accordance with Hydraulic Institute/American National Standards Institute (HI/ANSI) 14.6 for a specified guarantee point, if the actual test grade is not specified in the order/quote, the manufacturer will likely apply the default test grade for the intended service. It is important to review the current revision of HI/ANSI 14.6 to understand the default acceptance grades per application and shaft power along with the current grades and their associated test bands. It will be easier and more economical for the manufacturer to comply with requests that align with published standards as opposed to a custom specification developed for a specific project or user.

A reasonable assumption is that a pump would perform closely to its currently published curve. But many curves, whether published in a booklet or displayed on selection software, do not specify the intended service or what grade they would certify to. Why is this important? Many factors influence how close to the published curve a pump will actually perform.

According to HI, variations in hydraulic performance are the result of manufacturing tolerances, testing instrument fluctuations and accuracy, driver (motor) variation, and the inherent instabilities in the pumped media near the pump suction and discharge. The magnitude of these variations will vary directly with the degree of precision applied to manufacturing processes, the test equipment and test procedures. The higher the precision used in manufacturing and testing, the smaller the expected variations in test results. The published curve will likely represent an average of the historical performance of similar units.

If a pump is specified as requiring compliance to a grade higher than what the manufacturer assumed in its published curve, a quote from the manufacturer may come with a trim that is different from the published curve used to make the original selection. In fact, if the specified duty point falls on the maximum trim for a pump, the manufacturer’s quote may come with a different pump or motor than originally specified in order to achieve the guarantee point at the tighter performance tolerance. This is different from a scenario where no performance tolerance was specified, and the pump was either not tested or was tested to a general standard in the case that the manufacturer was not specifically informed about the type of application and, therefore, standard to apply.

Even if a performance test and grade are specified, it should be noted that many only ensure testing of head and flow to that grade at the specified guarantee point. The testing standard is specific and should be consulted to understand what will be included in a normal test and what must be additionally specified. Power or efficiency may not be guaranteed without being additionally specified. Another consideration is that some grades may have a bilateral (positive and negative) tolerance or a unilateral (positive only) tolerance for head and flow.

It is important to understand what aspects of pump performance will be most critical for the application and match requirements accordingly. Will the pump be operated with a variable speed drive (VSD)? Is maximum pressure or maximum horsepower a concern? Is the net positive suction head available (NPSHa) a concern?

The good news is that there are steps that can be taken to ensure future pumps satisfy requirements. While every project cannot justify the additional cost of a certified performance test to the tightest tolerance band on pump flow, head and efficiency, it does not mean that users cannot ensure that the application requirements are met.

When creating a pump specification, make sure to include that the pump must perform to a specified grade at a minimum and all submittals should include a curve to meet that grade. If the order contains a certified test requirement, be explicit in the test specification for head, flow and/or efficiency. It is up to users as the specifiers to include this information in the specification. As an alternative, a tighter tolerance for head and flow can be specified, with a lower tolerance for efficiency.

If users are concerned about overloading the motor, consider specifying a maximum horsepower and flow range to be evaluated. If users are going to be operating the pump with a VSD, the duty point may be achieved at other than the typical motor test speed. Remember to either specify the reduced test speed or provide a guarantee point that will fall on the constant speed curve of the pump.

A tighter performance specification or additional test requirements typically equate to additional costs for the pump. It can also extend lead times as the manufacturer takes additional steps to ensure compliance and schedule the testing. Balance these short-term issues with the longer-term issues of pump performance. Understand exactly what is needed to make the project successful and then specify the requirements precisely.

The possibility of using a hydraulic ram pump (HRP) as a means of utilizing its energy to produce high head for pump has been investigated. To make such a system economically competitive, it is necessary to improve the performance of HRPs. To achieve this improvement, it is also necessary to understand the parameters that marked out the design of conventional HRPs. The performance is presented in dimensionless terms as the head ratio or discharge head to drive head and flow-rate ratio or discharge flow rate to drive flow rate. The experiments on HRPs were conducted by which each of the following factors could be varied independently: (a) supply head, (b) air chamber pressure, and (c) waste valve beats per minute. An increase in the supply head tends to increase the supply flow rate, delivery flow rate, delivery head, and the overall efficiency of the pump. An increase in air chamber pressure tends to decrease the overall efficiency of the pump. However, there was no significant difference on the HRP performance over a wide range of flow conditions when air chamber pressure was varied. An increase in waste valve beats per minute tends to decrease the supply flow rate, delivery flow rate, and delivery head. But it tends to increase the head ratio, the flow-rate ratio, and the overall efficiency of the pump. The experimental data reveal that the HRP characteristics are functions of the waste valve beats per minute and the supply head.

The concept of hydraulic ram pump (HRP) was developed 200 years ago. In a HRP, no external powers are required to drive water. Water is pumped from a particular head at a high flow rate and comes out with a higher head but at a lesser flow rate because of the water hammer effect. The system consists of a drive pipe, waste valve, discharge valve, air (pressure) chamber, and delivery pipe (Figure 1). The only moving parts of the system are the waste valve and the discharge valve which operate from the fluid dynamic actions of the pumping cycle [1].HRP is one of the simplest and the most environmentally friendly devices for domestic or agricultural use [2, 3]. There are a lot of people in a lot of countries that build and use this kind of pump. Details of these are given by Watt [4, 5], Schiller [6], Browne [7], and Inthachot et al. [8].

There are a number of studies which have been done to improve the design of HRPs by experimental, theoretical, and numerical approaches. A short description of the function and history of HRPs can be found in Basfeld and Miiller [9]. Experimental and theoretical investigations on HRPs were done by Lansford and Dugan [10] to determine the rate of pumping and wasting for any conditions of operation. The dominant factor controlling the functioning of the HRP is the velocity in the drive pipe necessary to cause the waste valve to start closing, and its value is fixed by the waste valve setting. They also reported that the maximum efficiency varied little with various adjustments of the waste valve, except perhaps for extremely high values of velocity in the drive pipe, at which the efficiency was somewhat lower. Details of the HRP working cycle are also described.

Iversen [1] carried out a comprehensive investigation to identify the features of the HRP; the drive head and flow, the discharge head and flow, the cycle frequency of the HRP, and the system efficiency. The expected performance is presented in a generalized form of the head ratio or discharge head to drive head and the flow rate ratio or discharge flow rate to drive flow rate. He reported that performance features of the head ratio and the flow rate ratio relate directly to cyclic frequency.

CFD analysis of opening and closing condition of a hydraulic pump can be found in [13, 14] . The height of the waste valve and the height of the pressure chamber have significant effect on the outlet flow of the pump [15].

Numerous attempts to analyze the complex behavior of a HRP system have been made in the past. Many variables are involved in the operation. Investigations on the performance and its factors have been widely carried out. The available literatures aim to present a generalized design methodology for HRPs covering design parameters and the design procedure along with the mathematical relationship used for the design work. It has been found that design parameters and their effect on the performance of the HRP were not fully studied. The influence on the rate of pumping and wasting for any conditions of operation and performance in HRPs are therefore investigated in this study.

A HRP is shown in Figure 1. The pump utilizes the energy from a supply head, Hs with a large quantity of water, Qs to a delivery head, Hd which is higher than the supply head with a small quantity of water, Qd by rapid closure of the waste valve. The operation is continuous with no other external input and the flow is intermittent. The power used to drive the pump is

We can expect that the flow-rate ratio is high by reducing water loss at the waste valve (Qw), and the head ratio is high by increasing the momentum of the water flow in the supply pipe. For this purpose, the effect of waste valve opening and closing on pump performance is investigated in order to reduce water loss at the waste valve and increase the pumping pressure. A HRP working cycle has been relegated to Appendix.

The experiment was performed in the HRP test rig (Figure 2). The pump was made of PVC pipe and fittings. The HRP has a drive pipe of a nominal pipe size of 25 mm (1 inch). The drive pipe is connected to a supply tank with a slope of 45°, as shown in Figure 2.

Before starting the pump, trapped air in the inlet to the drive pipe must be flushed out with water by opening the waste valve. The HRP will pump water to the delivery tank at most settings of the waste valve. The water flow rate can be varied quite easily by adjusting the turning of the control valve at the delivery line. However, if the control valve at the drive line is used instead, the waste valve must be adjusted, especially of valve beats for each flow rate.

The effect of supply head on the HRP performance was studied in this case. For each supply head condition, the HRP was tuned to pump the greatest amount of water to the delivery tank at approximately the same number of waste valve beats per minute. It was found that the valve beat of 285 times/min is for Hs = 2.5 m and that of 282 times/min is for Hs = 2.0 m. The variations of the supply flow rate, Qs, and delivery head Hd with delivery flow rate, Qd, are shown in Figures 3 and 4, respectively. It reveals that an increase in supply head Hs, tends to increase the delivery head Hd, delivery flow rate Qd, and supply flow rate Qs. Therefore, we can expect higher power added to the water at a higher supply head.

Using the head ratio, , and the flow rate ratio, , as parameters, the relationship of the two parameters reduces the amount of data scatter. Its head ratio, , decreases with the flow rate ratio, (Figure 5). At high , the value of decreases rapidly. A high (in this study  > 1) means that Hd is increased, and a high (in this study  < 1) means that water loss Qw is decreased. This curve shows that a HRP can pump high flow for low lift, but as the lift increases, the flow decreases.

Figure 6 illustrates the HRP efficiency for the two different supply heads. The result shows that its efficiency reaches a peak near the maximum for each supply head. It should be noted that, when the supply head increases, the velocity and momentum of water in the drive pipe also increases. The result shows that the increase in the supply head increase the pump flow rate, Qd, waste valve beats per minute, delivery power, and pump efficiency. Therefore, we must then try to make the supply head as large as possible. However, if the supply head is high and the drive pipe is long, the momentum of water in the drive pipe will be very high and the pump will be damaged. In this case, a large air chamber and air volume may be necessary to absorb the increased water hammer pressure that will occur in the HRP.

Figures 8 and 9 illustrate the variations of the head ratio and efficiency as a function of the flow-rate ratio at different pressures inside the air chamber, Pc = 1, 2, and 3 bar. As seen from the figures, an increase in air chamber pressure tends to decrease the overall efficiency of the pump. However, there was no significant difference on the HRP performance over a wide range of flow conditions. The main function of the air chamber is to absorb the water hammer pressure that will occur in the HRP. Water continues to flow into the air chamber until the unbalanced force caused by the difference between supply and delivery pressures reduces the velocity to zero. The kinetic energy after the water hammer is gradually transferred to potential energy by compression of the air in the chamber and then transferred to water in the ascending pipe by expanding the volume of air. Water can thus be pumped to a considerable height by periodically opening and closing the waste valve. The pressure in the air chamber is the delivery pressure. Due to the low compressibility of water, if little or no air is present in the chamber, the energy is immediately transferred to the entire ascending pipe system, and the air chamber may burst. Therefore, in practice, adjust air pressure in the chamber so that pulse in the pipe is at a minimum. The pressure is then used to lift water to a point higher than where the water originally started with the least energy expenditure.

The variations of the supply flow rate, Qs, with delivery flow rate, Qd, are shown in Figure 11. It may be seen that an increase of waste valve beating decreases both flow rates. Figure 12 illustrates the variations of the delivery head Hd with a delivery flow rate for different valve beatings. The delivery head seems to decrease when valve beats per minute was increased. However, there was not much difference over a wide range of flow conditions when waste valve beats per minute was varied. It should be noted that with an increase in waste valve beats per minute, the time required to close the waste valve decreases. Thus, an increase of waste valve beats per minute decreases the quantity wasted per cycle. Figures 13 and 14 illustrate the variations of the head ratio and efficiency as a function of the flow rate ratio at different valve beats per minute, fb = 208, 244, and 285 times/min. The results from this study show that an increase of waste valve beats per minute will increase , , and pump efficiency. Therefore, we must then try to make the waste valve beating as fast as possible. However, if the waste valve beating is too high, there will be no build up of the powerful hammer pulse, and the flow through the waste valve is stopped.

The influence of any conditions of operation and performance on the rate of pumping and wasting in a HRP has been investigated in this study. The experiments on a HRP were conducted by which each of the following factors could be varied independently: (a) supply head, (b) air chamber pressure, and (c) waste valve beats per minute. Performance curves for variation of the head ratio, flow rate ratio, and pump efficiency at each condition have been determined.

It may be seen that the supply flow rate Qs, the delivery flow rate Qd, the delivery head Hd, and the pump efficiency η increase with increasing the supply head Hs. Using and as parameters, the performance curves facilitated an understanding of its operation. Though the points are somewhat scattered, it can be seen that the flow-rate ratio at which the maximum efficiency occurs becomes higher as the supply head increases. It is also apparent that an increase in the supply head, decreases water loss at the waste valve (Qw). Under the action of the supply head, Hs, the water in the drive line is accelerated. As the flow velocity increases, the disc of the waste valve rises due to the drag of the plate. The closure will be very rapid.

An increase in waste valve beats per minute tends to decrease the supply flow rate, delivery flow rate, and delivery head. But it tends to increase the head ratio, the flow-rate ratio, and the overall efficiency of the pump. It must be pointed out that there is only a limited range of waste valve beating values for each particular HRP system.

The dominant factors controlling the functioning of the HRP are the waste valve beats per minute and the supply head. A good waste valve design and proper adjustment are very essential for smooth and efficient HRP operation. For a given supply head, the HRP is tuned to pump the greatest amount of water possible, and this normally occurs when the waste valve beats per minute value is maximum. A more detailed analysis of the specific applications and the corresponding economic factors would be necessary to identify completely the relative merits of a HRP. Furthermore, work is in progress to study the technical feasibility for increasing lift of a conventional pump using a HRP.

The waste valve will close at some flow velocity. The closure will be very rapid. Thus, the flow through the waste valve is stopped, but since the water in the drive pipe has a considerable velocity, a very high pressure wave will be created. This pressure is larger than the static supply pressure. This pressure opens the discharge valve, which permits the flow of the water to continue by passing into the surge tank or air chamber. This tank is filled partly with water and partly with air. Water continues to flow into the surge tank against the pressure which exists there with decreasing velocity. There is also some energy stored in the surge tank due to air compression. The inertia of the flowing mass of fluid in the drive line maintains the flow. During this interval, the flow in the drive line is decelerated. The waste valve is closed and the discharge valve is opened. This is a pumping period (Figure 16).

(i) The experiments on HRP were conducted to determine its operation and performance. (ii) Supply head, air chamber pressure, and waste valve beat rate were considered. (iii) Increase in the supply head will increase the flow rate, delivery head, and efficiency. (iv) Air chamber pressure was not a significant effect on the HRP performance. (v) Increase in the waste valve beat rate will increase the head ratio, flow-rate ratio, and efficiency. (vi) The HRP characteristics are functions of the waste valve beat rate and the supply head.