piston hydraulic pump how it works price

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Piston pumps for spray applications, irrigation, injection, variable metering work scenarios involving water, chemicals and mixtures. Piston pumps are positive displacement pumps that use a sealed chamber and cylinder strokes in repetition to generate pressure and fluid flow. They allow constant applications rates regardless of temperature, and are designed for easy, set-point adjustment of operation specs. The piston pump type has a wide range of use within residential, commercial, agricultural and industrial setting applications involving viscous and non viscous fluids. They are compatible and commonly used with agriculture chemicals, drilling and fracking fluids, manufacturing materials, oils, lubricants and paints as well as food and beverage industry ingredients. Piston pumps are also used for industrial cleaning, water jet machining, hydraulic and coolant supply systems. Piston pumps can provide a pulsating flow rate, sometimes undesired, but makes them good choices for crop field size sprinkler systems.

We provide John Blue single rate ground drive piston pumps, double rate ground drive and hydraulic drive piston pump models. Double rate pistons allow for pumping two products at different rates with a single pump. Available piston pumps are engineered for installation in pulley, belt, direct drive flexible shaft or hollow shaft systems. Standard model piston pumps are built using heavy duty cast iron metal fitted with chemically durable, synthetic o-rings and rod packings made from Buna-N and Viton. Available piston pumps for sale offer max flow rate capacities from 10 GPM to 68 GPM. Maximum pressure output ratings range up to 120 PSI. Inlet and outlet plumbing size hookups for available piston pumps range from 1” up to 2” NPT.

Press brakes, injecting molding machines, extruders—many kinds of applications that require a wide displacement range all benefit from Eaton PVM Series piston pumps. With a variable displacement from 18 cc to 141 cc (1.1 to 8.6 cu in) at operating pressures up to 315 bar (4, 500 psi) and host of advanced features, the PVM Series piston pump reduces noise levels by more than 50% for quiet, effective operation.

Piston pumps are durable and relatively simple devices. A basic piston pump is made up of a piston, a chamber, and two valves. The pump operates by driving the piston down into the chamber, thereby compressing the media inside. In a hand pump, this is usually air. Once the pressure of the air exceeds that of the outlet valve spring, the compressed media goes through the open outlet valve. When the piston is drawn back up, it opens the inlet valve and closes the outlet valve, thereby utilizing suction to draw in new media for compression.

Although somewhat expensive, piston pumps are among the most efficient types of pumps. They have an excellent pressure rating (as high as 10,000 psi), but their design makes them susceptible to contaminants. They provide an excellent solution for many high-pressure hydraulic oil pumping applications.

Axial piston pumps are positive displacement pumps that use multiple cylinders grouped around a central axis. The group of cylinders, usually containing an odd number, is called a cylinder block. The pistons within each cylinder are attached to a swashplate. The swashplate is also known as a cam or wobble plate and attaches to a rotating shaft. As the shaft turns, the angle of the swashplate changes, which drives the pistons in and out of their respective cylinders.

Since the swashplate is at an angle to the axis of rotation, the pistons must reciprocate axially as they orbit around the cylinder block axis. The axial motion of the pistons is sinusoidal. As a piston rises, it moves toward the valve plate. At this point in the rotation, the fluid trapped between the buried end of the piston and the valve plate is expelled to the pump"s discharge port through one of the valve plate"s semi-circular ports. As the piston moves back toward the valve plate, the fluid is pushed through the discharge port of the valve plate.

Axial piston pumps can be designed as variable displacement piston pumps, making them very useful for controlling the speeds of hydraulic motors and cylinders. In this design, a swashplate is used to vary the depth to which each piston extends into its cylinder as the pump rotates, affecting the volume of discharge. A pressure compensator piston is used in some designs to maintain a constant discharge pressure under varying loads. Cheaper pressure washers sometimes use fixed-rate designs.

In a typical pressure-compensated pump, the swashplate angle adjusts through the action of a valve using pressure feedback to make sure that the pump output flow is precisely enough to maintain a designated pressure. If the load flow increases, the pressure momentarily decreases, but the pressure-compensation valve senses the decrease and then increases the swashplate angle to increase the pump’s output flow, restoring the desired pressure.

Axial piston pumps can contain most of the necessary circuit controls intrinsically by controlling the swash-plate angle, to regulate flow and pressure. They are very reliable and can allow the rest of the hydraulic system to which they’re attached to be very simple and inexpensive.

They are used to power the hydraulic systems of jet aircrafts, being gear-driven off of the turbine engine"s main shaft, and are often used for automotive air conditioning compressors for cabin cooling. The design of these pumps meets the limited weight and space requirement in the vehicle"s engine bay and reduces vibrations.

Pressure washers also use these pumps, and axial reciprocating motors are used to power many machines. They operate on the same principles as axial piston pumps, except that the circulating fluid is provided under substantial pressure and the piston housing rotates and provides shaft power to another machine. A typical use of an axial reciprocating motor is powering small earthmoving machines such as skid loader machines.

This guide provides a basic understanding of axial piston pumps. To find out more about other types of pumps, read our guide here. For more information on related products, consult our other product guides or visit the Thomas Supplier Discovery Platform to locate potential sources or view details on specific products.

The type of hydraulic pump you need depends on a variety of factors, including, but not limited to, the type of hydraulic fluid used in your machinery, operating pressure, application speed, and flow rate requirements.

Two of the most common pumps used in hydraulic equipment are piston pumps and gear pumps. This article will highlight everything you need to know about each pump, including its common uses and benefits.

A piston pump is a positive displacement pump that uses reciprocating motion to create rotation along an axis. Some piston pumps have variable displacement, while others have a fixed displacement design.

A hydraulic piston pump is capable of the highest pressure ratings and is commonly used to power heavy-duty lifts, presses, shovels, and other components.

The downside of piston pumps is that they are often more expensive (especially when compared to gear pumps). Still, their improved efficiency often makes them a better investment for long-term production.

Gear pumps use gears or cogs to transfer fluids. The cogs are tightly aligned to create suction as they draw liquid in and discharge it. The gears can be internal or external, depending on the application. Gear pumps are also positive displacement pumps, but they are always fixed displacement, so you would need separate pumps or valves to control the amount of displacement.

Gear pumps are known for being reliable and durable when they are well-maintained. Compared to piston pumps, they also don’t require as much maintenance and are typically more affordable. However, these pumps usually max out at 3000 PSI. While this is enough pressure to power some machinery, it may not have the power to operate large presses and other industrial equipment. A gear-style pump also lacks the ability to vary the displacement of your system.

Gear pumps are often used in low-pressure applications where dispensing high-viscosity liquids is required. They are typically used in the food and beverage, pulp and paper, and oil/chemical industries.

The primary difference between a gear pump and a piston pump is how they are designed. While both pumps need hydraulic fluid to generate mechanical power, a piston pump uses a piston to move liquid throughout the pump valves, while a gear pump uses cogs to move fluid throughout the pump.

Gear pumps are affordable for low-pressure applications (35 to 200 bar or 507 to 2900 PSI), while piston pumps are more efficient options for high-pressure applications. A piston pump is also a better option if you’re looking for a pump with a higher discharge rate. Lastly, a piston pump will provide the most efficiency if your application is high-speed.

Founded over 25 years ago. Panagon Systems specializes in remanufacturing cost-efficient obsolete or discontinued piston pumps, motors, and replacement components from brands like Vickers/Eaton, Caterpillar, and Rexroth. All pumps we manufacture are made in-house in the United States and are guaranteed to meet OEM specifications.

If you’re looking for cost-effective and timely pump replacement options, you’re looking for us.Contact us todayfor help in selecting the right pump for your application, or to request a product quote.

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A hydraulic pump is a mechanical device that converts mechanical power into hydraulic energy. It generates flow with enough power to overcome pressure induced by the load.

A hydraulic pump performs two functions when it operates. Firstly, its mechanical action creates a vacuum at the pump inlet, subsequently allowing atmospheric pressure to force liquid from the reservoir and then pumping it through to the inlet line of the pump. Secondly, its mechanical action delivers this liquid to the pump outlet and forces it into the hydraulic system.

The three most common hydraulic pump designs are: vane pump, gear pump and radial piston pump. All are well suited to common hydraulic uses, however the piston design is recommended for higher pressures.

Most pumps used in hydraulic systems are positive-displacement pumps. This means that they displace (deliver) the same amount of liquid for each rotating cycle of the pumping element. The delivery per cycle remains almost constant, regardless of changes in pressure.

Positive-displacement pumps are grouped into fixed or variable displacement. A fixed displacement pump’s output remains constant during each pumping cycle and at a given pump speed. Altering the geometry of the displacement chamber changes the variable displacement pump’s output.

Fixed displacement pumps (or screw pumps) make little noise, so they are perfect for use in for example theatres and opera houses. Variable displacement pumps, on the other hand, are particularly well suited in circuits using hydraulic motors and where variable speeds or the ability to reverse is needed.

Applications commonly using a piston pump include: marine auxiliary power, machine tools, mobile and construction equipment, metal forming and oil field equipment.

As the name suggests, a piston pump operates through pistons that move back and forth in the cylinders connected to the hydraulic pump. A piston pump also has excellent sealing capabilities.

A hydraulic piston pump can operate at large volumetric levels thanks to low oil leakage. Some plungers require valves at the suction and pressure ports, whilst others require them with the input and output channels. Valves (and their sealing properties) at the end of the piston pumps will further enhance the performance at higher pressures.

The axial piston pump is possibly the most widely used variable displacement pump. It’s used in everything from heavy industrial to mobile applications. Different compensation techniques will continuously alter the pump’s fluid discharge per revolution. And moreover, also alter the system pressure based on load requirements, maximum pressure cut-off settings and ratio control. This implies significant power savings.

Two principles characterise the axial piston pump. Firstly the swash plate or bent axis design and secondly the system parameters. System parameters include the decision on whether or not the pump is used in an open or closed circuit.

The return line in a closed loop circuit is under constant pressure. This must be considered when designing an axial piston pump that is used in a closed loop circuit. It is also very important that a variable displacement volume pump is installed and operates alongside the axial piston pump in the systems. Axial piston pumps can interchange between a pump and a motor in some fixed displacement configurations.

The swivel angle determines the displacement volume of the bent axis pump. The pistons in the cylinder bore moves when the shaft rotates. The swash plate, in the swash plate design, sustain the turning pistons. Moreover, the angle of the swash plate decides the piston stroke.

The bent axis principle, fixed or adjustable displacement, exist in two different designs. The first design is the Thoma-principle with maximum 25 degrees angle, designed by the German engineer Hans Thoma and patented in 1935. The second design goes under the name Wahlmark-principle, named after Gunnar Axel Wahlmark (patent 1960). The latter features spherical-shaped pistons in one piece with the piston rod and piston rings. And moreover a maximum 40 degrees between the driveshaft centre-line and pistons.

In general, the largest displacements are approximately one litre per revolution. However if necessary, a two-litre swept volume pump can be built. Often variable-displacement pumps are used, so that the oil flow can be adjusted carefully. These pumps generally operate with a working pressure of up to 350–420 bars in continuous work

Radial piston pumps are used especially for high pressure and relatively small flows. Pressures of up to 650 bar are normal. The plungers are connected to a floating ring. A control lever moves the floating ring horizontally by a control lever and thus causes an eccentricity in the centre of rotation of the plungers. The amount of eccentricity is controlled to vary the discharge. Moreover, shifting the eccentricity to the opposite side seamlessly reverses the suction and discharge.

Radial piston pumps are the only pumps that work continuously under high pressure for long periods of time. Examples of applications include: presses, machines for processing plastic and machine tools.

A vane pump uses the back and forth movement of rectangle-shaped vanes inside slots to move fluids. They are sometimes also referred to as sliding vane pumps.

The simplest vane pump consists of a circular rotor, rotating inside of a larger circular cavity. The centres of the two circles are offset, causing eccentricity. Vanes slide into and out of the rotor and seal on all edges. This creates vane chambers that do the pumping work.

A vacuum is generated when the vanes travel further than the suction port of the pump. This is how the oil is drawn into the pumping chamber. The oil travels through the ports and is then forced out of the discharge port of the pump. Direction of the oil flow may alter, dependent on the rotation of the pump. This is the case for many rotary pumps.

Vane pumps operate most efficiently with low viscosity oils, such as water and petrol. Higher viscosity fluids on the other hand, may cause issues for the vane’s rotation, preventing them from moving easily in the slots.

Gear pumps are one of the most common types of pumps for hydraulic fluid power applications. Here at Hydraulics Online, we offer a wide range of high-powered hydraulic gear pumps suitable for industrial, commercial and domestic use. We provide a reliable pump model, whatever the specifications of your hydraulic system. And we furthermore ensure that it operates as efficiently as possible.

Johannes Kepler invented the gear pump around year 1600. Fluid carried between the teeth of two meshing gears produces the flow. The pump housing and side plates, also called wear or pressure plates, enclose the chambers, which are formed between adjacent gear teeth. The pump suction creates a partial vacuum. Thereafter fluid flows in to fill the space and is carried around the discharge of the gears. Next the fluid is forced out as the teeth mesh (at the discharge end).

Some gear pumps are quite noisy. However, modern designs incorporating split gears, helical gear teeth and higher precision/quality tooth profiles are much quieter. On top of this, they can mesh and un-mesh more smoothly. Subsequently this reduces pressure ripples and related detrimental problems.

Catastrophic breakdowns are easier to prevent with hydraulic gear pumps. This is because the gears gradually wear down the housing and/or main bushings. Therefore reducing the volumetric efficiency of the pump gradually until it is all but useless. This often happens long before wear causes the unit to seize or break down.

Can hydraulic gear pumps be reversed? Yes, most pumps can be reversed by taking the pump apart and flipping the center section. This is why most gear pumps are symmetrical.

External gear pumps use two external spur gears. Internal gear pumps use an external and an internal spur gear. Moreover, the spur gear teeth face inwards for internal gear pumps. Gear pumps are positive displacement (or fixed displacement). In other words, they pump a constant amount of fluid for each revolution. Some gear pumps are interchangeable and function both as a motor and a pump.

The petrochemical industry uses gear pumps to move: diesel oil, pitch, lube oil, crude oil and other fluids. The chemical industry also uses them for materials such as: plastics, acids, sodium silicate, mixed chemicals and other media. Finally, these pumps are also used to transport: ink, paint, resins and adhesives and in the food industry.

Mathematical calculations are key to any type of hydraulic motor or pump design, but are especially interesting in the gerotor design. The inner rotor has N teeth, where N > 2.  The outer rotor must have N + 1 teeth (= one more tooth than the inner rotor) in order for the design to work.

When you need to choose a hydraulic pump solution for a hydraulic system, it is important to decide what type of pump you will require. You must also understand the basics of how pumps work and hydraulics.

All hydraulic systems rely on pressurized fluid to create force in order to perform work that is accomplished by transforming mechanical energy into hydraulic energy inside hydraulic pumps and creating a positive displacement downstream. For example, a forklift needs to raise and lower pallets—which would be the desired work.

You must also choose between a ‘closed-loop’ or ‘open-loop’ system. In a ‘closed-loop’ system, the fluid passes from the pump directly to the motor before returning to the pump. In an ‘open-loop’ system, the pump draws the fluid from a reservoir or tank, and then pumps it to a control valve from where it is directed to the services being operated before returning to the tank.

Fixed-displacement pumps are well suited to a wide range of functions where the amount of pressure required to perform work is the same each and every time. For instance, if the pump is rated as a 30 cc pump, it will pump 30 ml of hydraulic fluid through the system for every single rotation.

The pressure and flow rate will not change, no matter how the pump is operated or what occurs elsewhere in the system. If you need a lower flow rate, then you will have to divert the excess flow or use a variable displacement pump.

Two common types of fixed-displacement pumps you can use are the bent axis piston pump and the gear pump. The bent axis piston pump provides the added benefit of normally having a higher pressure capability than a gear pump.

Aside from flow rates being directly proportional to pump drive speeds, fixed-displacement hydraulic pumps have several key benefits over variable displacement pumps, including:

Unlike fixed-displacement pumps, variable displacement pumps are able to increase or decrease the fluid flow rates electronically, manually, or hydraulically. The method used will depend on the flow required and the type of pump being used, such as a vane pump, axial piston pump, etc.

Furthermore, the method of displacement changes based on the pump’s internal structure. For example, a variable displacement piston pump is determined by the bore area of the pistons and the stroke length. The stroke length can vary to help regulate the flow rates as shaft rotation turns and moves the pistons inside the pump.

The control piston inside the pump also helps regular pressure and, essentially, functions as a relief valve. When pressure increases above the desired pressure compensator setting, the control piston moves outwards and slows the travel distance of the other pistons.

As can be seen, fixed-displacement pumps and variable displacement pumps have their own benefits, depending on your specific needs. For further assistance in choosing the right pump or for other hydraulic system solutions, please feel free to contact White House Products, Ltd. at +44 (0) 1475 742500 today!

The radial piston pump type R consists of valve-controlled pump elements arranged in star form around an eccentric. For large flow rates, up to 42 pump elements can be ...

... axial piston pump type V60N is designed for open circuits in mobile hydraulics and operate according to the swash plate principle. They are available with the option of a thru-shaft for ...

The K3VG series are swash-plate type axial piston pumps which give excellent performance in high flow industrial applications in a compact and cost-effective package.

... Parker’s hydraulic truck pump series F1 featuring high self-priming speed and high efficiency and is one of the leading truck pumps in the market. The F1 pump provide ...

... Piston Pumps provide fixed-displacement power in a unique miniature design. Engineered for open-circuit systems, they bring flexibility to your operation. Compact Piston ...

Parker P2/P3 High Pressure Axial Piston Pumps are variable displacement, swashplate piston pumps designed for operation in open circuit, mobile hydraulic ...

Closed circuit axial piston pumps are used as hydrostatic transmission components in self-propelled machines and for rotary drives in both fixed and mobile equipment of all kinds.

... and very compact for easier and inexpensive installations. Bent Axis pumps-motors will mount directly to virtually any Bezares PTO in our extensive line.

... displacement bent axis piston pumps were developed with spherical head pistons. This provides extremely high performance and high pressure ratings on a long life span unit. Flow rates ...

Sophisticated technology in the smallest space - this is what our Alfra electro-hydraulic pumps stand for. Due to the compact design, the powerful drive units also find room when things ...

Our hydraulic cylinder with a quick coupling has a performance up to 11 tons pressure – with a deadweight of only 2,5 kg. The SKP-1 is compatible with the ALFRA foot pump. Your advantage: Your hands are ...

... our ALFRA hydraulic cylinder SKP-1. In a team with the hydraulic pump DSP-120 it is capable to take a variety of challenges – because the SKP-1 working with a maximum operating pressure ...

... alkitronic hydraulic pumps with electric or pneumatic drive provide fast operating speed, reliability, and safety. They are designed for permanent operation. Our hydraulic ...

With their unique design, PA-PAC pumps offer a robust and durable solution to the high pressure needs of truck applications. Combining the automatic dual direction of rotation, high operating pressure (up to 500 bar peak), ...

Bent axis XPi pumps are specially designed to meet the needs of truck equipment. Their compact design allows a direct flange-mounting on the PTO. All models are of 7 piston design to ...

Lightweight two-speed hand-pump. Low hand force required at max. operating pressure. Pump housing from malleable cast iron, oil reservoir from aluminium. With pressure relief valve, factory set at max. ...

Ideal for powering single-acting cylinders and portable hydraulic tools, the Power Team PA9 series pumps are easier to operate than a hand pump, designed for efficiency. Built to be economical ...

Precision-matched cylinder and pump set for wide range of applications. Four styles of cylinders within the CPS/RPS Series with each set featuring single or two-speed hydraulic hand pumps. ...

The Power Team P-Series hand pumps come in a variety of configurations to meet the requirements of your application. Along with various oil capacities and flow rates, you can choose from the following options:

... time. Stage 1 allows rapid piston travel under no load or light load conditions. The pump automatically switches to stage 2 when the piston is loaded and a higher force is required from ...

Introducing the Axial piston hydraulic pump by Atos are designed for superior pressure application on industrial operation . It features its reduced noise operation capacity having a ...

Like all the pumps of the HP Series, it is suitable for any hydraulic application which require very high hydraulic output pressures and a moderate and controllable oil flow, to ensure ...

Air hydraulic pump, double pneumatic motor, double effect, foot operated with lock-up function, lever distributor valve (4/3), 10L tank, oil flow 8.5 / 0.26 l / min

The HP-AP pump, like all HP Series pumps, can be installed in any hydraulic applications which requires high working pressures and moderate and controllable oil flow. Our HP Series air-hydraulic ...

The displacement of a pump is defined by the volume of fluid that the gears, vanes or pistons will pump in one rotation. If a pump has a capacity of 30 cm3, it should treat 30 ml of fluid in one rotation.

In axial piston variable pumps, the flow is proportional to the drive speed and the displacement. The flow can be steplessly changed by adjusting the swivel angle. Axial piston variable ...

... axial piston pump type V60N is designed for open circuits in mobile hydraulics and operate according to the swash plate principle. They are available with the option of a thru-shaft for operating additional ...

Variable displacement axial piston pumps operate according to the bent axis principle. They adjust the geometric output volume from maximum to zero. As a result they vary the flow rate ...

... piston pump type V30D is designed for open circuits in industrial hydraulics and operate according to the swash plate principle. They are available with the option of a thru-shaft for operating additional ...

... circuit axial piston pumps are used as hydrostatic transmission components in self-propelled machines and for rotary drives in both fixed and mobile equipment of all kinds.

Axial piston twin flow pump. With a very high performance in all job conditions. Due to its twin flow configuration this pump allows a great variety of solutions in different job applications.

Air hydraulic pump, double pneumatic motor, double effect, foot operated with lock-up function, lever distributor valve (4/3), 10L tank, oil flow 8.5 / 0.26 l / min

... customer system options for mechanical, hydraulic and electric input solutions are available. Further special regulating features like torque control and pressure cut-off are also available. The reliable ...

... needs of truck hydraulics, the TXV variable displacement pumps with LS (Load Sensing) control allow flow regulation to suit the application requirements. The pump ...

... rev. displacements, these pumps are designed to operate in both directions of rotation (clockwise or counter-clockwise). Only one reference regardless of direction of rotation. The TXV indexable pumps ...

... PVG is a variable-displacement axial-piston pump designed to take on your most demanding applications. It offers high-pressure, superior performance in a compact design ...

Variable displacement pumps in closed loop; 3 basic design units and 8 max. displacement sizes of 14, 18, 21, 28, 35, 46, 56, 64 cc/rev; various control options; max. ...

Compact Design, Economical Conception. High Power Density, High Overall Efficiency, High Rotating Speeds. High Output Pressure. Simple Change of Direction of Rotation, For Industrial & Mobile Market. Splined or Keyed ...

Parker P2/P3 High Pressure Axial Piston Pumps are variable displacement, swashplate piston pumps designed for operation in open circuit, mobile hydraulic ...

... Series pump offers variable displacement axial piston pumps for open-circuit applications. Featuring a compact footprint and continuous operating pressure ...

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Piston design - Solid, hollow, or with piston rings. The design and weight of the pistons will have a major effect on pump efficiency. The Parker F11 design with its lightweight head and retained balls can reach significantly higher speeds than swashplate pumps with their longer, heavier pistons.

Some pumps and motors can run over-centre, which means they can provide flow or rotate their drive shaft in both directions. These are commonly used in closed circuit, mobile vehicle drives systems.

Bent axis designs tend to have much heavier duty shaft bearings than swashplate pumps. This is because they are more commonly used as motor drive units and have to take the wheel loads against their shaft. Swashplate pumps, on the other hand, tend to be driven through flexible couplings that will remove any side loads, so the internal bearing is sized just to take the internal loads from the dynamic and pressure loading forces.

Noise level can be an issue with piston pumps. The noise is generated by the discontinuities in the flow e.g. as the pistons move forward and backward they create a pulsating flow that passes into the complete hydraulic system and vibrates or radiates from other components further down the circuit. This flow discontinuity is further complicated by the supply port which connects and disconnects each piston as it rotates. The timing of the opening and closing can create other, higher frequency flow discontinuities. Often different timing plates are available for different operating conditions e.g. fixed speed or variable speed applications.

Case leakage line pressures are critical for controlling the pressure balance of the slipper against the suction pressure. Care should be taken with some pump controllers as the valves exhaust into the pump casing and can create dangerous pressure spikes. Make sure case drain lines are sufficiently sized. One possible solution may be to use a more compliant, clear plastic hose for the case leakage line which will have the effect of damping out these peaks before damage the slippers. Case leakage line temperatures are also a good way of monitoring the health of the pump as discussed in the vane pump section.

If you are in doubt about the most appropriate pump to use in your application then always talk to manufacture or distributor who should be able to offer the most appropriate pump range and advise the expected service life.

- A hydraulic piston pump is a circulating pump that moves and pressurizes fluids by using one or more return pistons. It is usually driven by an electric motor via a crankshaft and connecting rod.There are 2 types of piston pumps that we often encounter: lift pump and force pump, both of which can be controlled manually or by themselves moving.

- The hydraulic piston pump can also be operated single or double. Double acting pump delivers two sets of check valves and fluid on both sides of the piston, this allows the piston to complete the pump"s full cycle by moving in one direction.

- So the pump works by moving into the cavity, so compressing the facilities inside a pump instead is usually air. Once the excess air pressure of the spring occurs, the compressed medium is passed through the outlet valve. When the piston is pulled back, it closes the inlet valve and closes the exit valve thus using suction to attract additional means of compression.

- Axial piston pump contains a number of pistons attached to a cylindrical block moving in the same direction as the center line of the block. The majority of flow and pressure control circuits can be included internally allowing for reliable operation and simple design of the hydraulic system involved.

This type of pump has a piston placed parallel to the pump shaft and is transmitted by a joint or inclined disc. The piston is always close to the surface of the inclined disc, so it participates in the reciprocal movement of the piston and participates in the rotation of the rotor.

An axial piston pump is a positive displacement pump that has a number of pistons in a circular array within a hydraulic motor or an automotive air conditioning compressor.

An axial piston pump has a number of pistons (usually an odd number) arranged in a circular array within a housing which is commonly referred to as a cylinder block, barrel. This cylinder block is driven to rotate about its axis of symmetry by an integral shaft that is, more or less, aligned with the pumping pistons (usually parallel but not necessarily).

Mating surfaces. One end of the cylinder block is convex and wears against a mating surface on a stationary valve plate. The inlet and outlet fluid of the pump pass through different parts of the sliding interface between the cylinder block and valve plate. The valve plate has two semi-circular ports that allow inlet of the operating fluid and exhaust of the outlet fluid respectively.

Protruding pistons. The pumping pistons protrude from the opposite end of the cylinder block. There are numerous configurations used for the exposed ends of the pistons but in all cases they bear against a cam. In variable displacement units, the cam is movable and commonly referred to as a yoke or hanger. For conceptual purposes, the cam can be represented by a plane, the orientation of which, in combination with shaft rotation, provides the cam action that leads to piston reciprocation and thus pumping. The angle between a vector normal to the cam plane and the cylinder block axis of rotation, called the cam angle, is one variable that determines the displacement of the pump or the amount of fluid pumped per shaft revolution. Variable displacement units have the ability to vary the cam angle during operation whereas fixed displacement units do not.

Reciprocating pistons. As the cylinder block rotates, the exposed ends of the pistons are constrained to follow the surface of the cam plane. Since the cam plane is at an angle to the axis of rotation, the pistons must reciprocate axially as they precess about the cylinder block axis. The axial motion of the pistons is sinusoidal. During the rising portion of the piston"s reciprocation cycle, the piston moves toward the valve plate. Also, during this time, the fluid trapped between the buried end of the piston and the valve plate is vented to the pump"s discharge port through one of the valve plate"s semi-circular ports - the discharge port. As the piston moves toward the valve plate, fluid is pushed or displaced through the discharge port of the valve plate.

Effect of precession. When the piston is at the top of the reciprocation cycle (commonly referred to as top-dead-center or just TDC), the connection between the trapped fluid chamber and the pump"s discharge port is closed. Shortly thereafter, that same chamber becomes open to the pump"s inlet port. As the piston continues to precess about the cylinder block axis, it moves away from the valve plate thereby increasing the volume of the trapped chamber. As this occurs, fluid enters the chamber from the pump"s inlet to fill the void. This process continues until the piston reaches the bottom of the reciprocation cylinder - commonly referred to as bottom-dead-center or BDC. At BDC, the connection between the pumping chamber and inlet port is closed. Shortly thereafter, the chamber becomes open to the discharge port again and the pumping cycle starts over.

Variable displacement. In a variable displacement pump, if the vector normal to the cam plane (swash plate) is set parallel to the axis of rotation, there is no movement of the pistons in their cylinders. Thus there is no output. Movement of the swash plate controls pump output from zero to maximum. There are two kinds of variable-displacement axial piston pumps:

direct displacement control pump, a kind of axial piston pump with a direct displacement control. A direct displacement control uses a mechanical lever attached to the swashplate of the axial piston pump. Higher system pressures require more force to move that lever, making direct displacement control only suitable for light or medium duty pumps. Heavy duty pumps require servo control.linkages and springs and in some cases magnets rather than a shaft to a motor located outside of the pump (thereby reducing the number of moving parts), keeping parts protected and lubricated and reducing the resistance against the flow of liquid.

Pressure. In a typical pressure-compensated pump, the swash plate angle is adjusted through the action of a valve which uses pressure feedback so that the instantaneous pump output flow is exactly enough to maintain a designated pressure. If the load flow increases, pressure will momentarily decrease but the pressure-compensation valve will sense the decrease and then increase the swash plate angle to increase pump output flow so that the desired pressure is restored. In reality most systems use pressure as a control for this type of pump. The operating pressure reaches, say, 200 bar (20 MPa or 2900 psi) and the swash plate is driven towards zero angle (piston stroke nearly zero) and with the inherent leaks in the system allows the pump to stabilise at the delivery volume that maintains the set pressure. As demand increases the swash plate is moved to a greater angle, piston stroke increases and the volume of fluid increases; if the demand slackens the pressure will rise, and the pumped volume diminishes as the pressure rises. At maximum system pressure the output is once again almost zero. If the fluid demand increases beyond the capacity of the pump to deliver, the system pressure will drop to near zero. The swash plate angle will remain at the maximum allowed, and the pistons will operate at full stroke. This continues until system flow-demand eases and the pump"s capacity is greater than demand. As the pressure rises the swash-plate angle modulates to try to not exceed the maximum pressure while meeting the flow demand.

Designers have a number of problems to overcome in designing axial piston pumps. One is managing to be able to manufacture a pump with the fine tolerances necessary for efficient operation. The mating faces between the rotary piston-cylinder assembly and the stationary pump body have to be almost a perfect seal while the rotary part turns at perhaps 3000 rpm. The pistons are usually less than half an inch (13 mm) in diameter with similar stroke lengths. Keeping the wall to piston seal tight means that very small clearances are involved and that materials have to be closely matched for similar coefficient of expansion.

The pistons have to be drawn outwards in their cylinder by some means. On small pumps this can be done by means of a spring inside the cylinder that forces the piston up the cylinder. Inlet fluid pressure can also be arranged so that the fluid pushes the pistons up the cylinder. Often a vane pump is located on the same drive shaft to provide this pressure and it also allows the pump assembly to draw fluid against some suction head from the reservoir, which is not an attribute of the unaided axial piston pump.

Another method of drawing pistons up the cylinder is to attach the cylinder heads to the surface of the swash plate. In that way the piston stroke is totally mechanical. However, the designer"s problem of lubricating the swash plate face (a sliding contact) is made even more difficult.

Internal lubrication of the pump is achieved by use of the operating fluid—normally called operating temperature, limited by the fluid, of about 120 °C (250 °F) so that using that fluid as a lubricant brings its own problems. In this type of pump the leakage from the face between the cylinder housing and the body block is used to cool and lubricate the exterior of the rotating parts. The leakage is then carried off to the reservoir or to the inlet side of the pump again. Hydraulic fluid that has been used is always cooled and passed through micrometre-sized filters before recirculating through the pump.

Despite the problems indicated above this type of pump can contain most of the necessary circuit controls integrally (the swash-plate angle control) to regulate flow and pressure, be very reliable and allow the rest of the hydraulic system to be very simple and inexpensive.

Axial piston pumps are used to power the hydraulic systems of jet aircraft, being gear-driven off of the turbine engine"s main shaft, The system used on the F-14 used a 9-piston pump that produced a standard system operating pressure of 3000 psi and a maximum flow of 84 gallons per minute.

Automotive air conditioning compressors for cabin cooling are nowadays mostly based around the axial piston pump design (others are based on the scroll compressor or rotary vane pump ones instead) in order to contain their weight and space requirement in the vehicle"s engine bay and reduce vibrations. They"re available in fixed displacement and dynamically adjusted variable displacement variants, and, depending upon the compressor"s design, the actual rotating swashplate either directly drives a set of pistons mated to its edges through a set of hemispherical metal shoes, or a nutating plate on which a set of pistons are mounted by means of rods.

Axial reciprocating motors are also used to power many machines. They operate on the same principle as described above, except that the circulating fluid is provided under considerable pressure and the piston housing is made to rotate and provide shaft power to another machine. A common use of an axial reciprocating motor is to power small earthmoving plant such as skid loader machines. Another use is to drive the screws of torpedoes.