Industrial hydraulics users are assured of the compliance of Rexroth products with the technical documentation and the requirements laid down in the EU Directive.

Rexroth, a supplier in the field of industrial hydraulics, produces and delivers its product range with strictest observance of ATEX directive 94/9/EC. Since the beginning of July 2003, equipment that has been or is newly employed in potentially explosive atmospheres as well as the associated documentation must comply with EU Directive 94/9/EC, the so-called ATEX 95. Rexroth's processes guarantee the users of industrial hydraulics the compliance of products with the technical documentation and the requirements laid down in the EU Directive.

Many hazardous applications require equipment and systems that conform with ATEX.

Rexroth is a known supplier of components and systems in the field of industrial hydraulics.

Rexroth hydraulics offer not only individual products that comply with the EU Directive, but also complete systems.

This increases safety of man and machine in the sectors concerned, such as in applications with hazardous escaping gases (foundry equipment or core-shooting machines).

Rexroth products and systems in accordance with the new ATEX Directive are also required for plant in which hazardous vapours may occur (drilling rigs, tank systems or chemical plants) or for installations with a dangerous formation and accumulation of dust (plastics processing machines, wood processing machines).

The Business Unit Industrial Hydraulics eliminates risks and hazards at the design, production and operational stages right from the start through timely and precise risk analyses and conformity assessment procedures.

'As a result of this, our product solutions for industrial hydraulics meet the stringent safety and health requirements of Directive 94/9/EC.

The services provided by us result in a real added value for our global customers,' says Dr Lutz Zimmermann, Chief Technical Officer of the Business Unit Industrial Hydraulics.

The product range according to the ATEX Directive comprises a comprehensive and application-oriented assortment of on/off, servo, proportional and high-response valves, hydraulic power units and hydraulic cylinders.

In close cooperation with the customer Rexroth also develops complete drive and control solutions for industrial hydraulics in accordance with the ATEX Directive.

To ensure this high standard, the Business Unit implemented processes in line with ATEX in the production sequence or optimized existing processes.

This includes quality assurance with process representation, ensuring the traceability of products and parts, the issue of a declaration of conformity and Ex marking.

The customer gets operating instructions for components, equipment and power units.

The design documentation as well as required type tests are presented to notified bodies.

Moreover, the Business Unit Industrial Hydraulics of Rexroth appointed an explosion protection officer.

A further integral part of the ATEX Directive is the comprehensive documentation.

For this reason, Rexroth's industrial hydraulic components always come with a comprehensive documentation package.

This includes written operating instructions in four languages, a CD-ROM in all EU languages for standard parts and in the national language of the final customer for individual orders (power units, systems).

In addition, the customer obtains general information about the use of Rexroth components in potentially explosive atmospheres as well as a product data sheet and product-specific instructions with the compulsory declarations of conformity.

The required technical product data sheets are, of course, also available online.

Servicing and repair of equipment according to the old Directive is still permitted in the EU and worldwide.

xA new range of multi-function cartridge valves, designed for use in integrated hydraulic circuits and perform duties normally requiring two or more cartridges, has been introduced by Integrated Hydraulics of Warwick, UK. These screw-in hydraulic cartridge valves from Integrated Hydraulics, '4CKKT50', offer the machine designer the potential of condensing the majority of a machine's hydraulic controls into a single hydraulic integrated circuit (manifold block), or incorporating valves into the body of other hydraulic components, such as cylinders. This reduces installation time and space requirement whilst minimizing leak paths, facilitating servicing and improving performance.

The 4CKKT50 valves are dual pilot operated check units with thermal relief and are rated at 300 bar with 25 litre/min flow.

They are ideal for small to medium size stabilizer cylinder applications, simplifying their design by eliminating the need for three cavities and a series of cross holes previously demanded.

The valve will hold the stabilizer legs in both extended and retracted positions, with the relief element preventing over pressurization of the cylinder due to thermal expansion of the oil.

In operation, pressure on the valve port causes the poppet to lift against the spring force, allowing flow to the cylinder port.

Reverse flow is prevented by the poppet reseating.

Pressure applied to the pilot port will overcome the cylinder port pressure and lift the poppet from its seat, allowing flow from the cylinder to valve port.

In dual pilot check valves, each pilot section is cross connected to the opposite line, giving automatic pilot operation in both directions.

When pressure is applied to port 3, the poppet in line 2,1 opens allowing return flow and vice-versa.

The direct acting relief valve is located in the poppet controlling flow in ports 3,4.

When the pressure in port 4 rises above the setting of the relief valve, the relief valve will open, allowing flow to port 3, relieving pressure on the cylinder.

Integrated Hydraulics' new 4CKKT50 cartridge fits in the same cavity as the company's series 5 solenoid valves so requires no additional tooling.

Internal leakage past the poppet valves is 0.3ml/min in one line and 0.5ml/min in the other.

Overcentre valves give static and dynamic control of loads by regulating the flow into and out of hydraulic actuators and will stop runaway in the event of a hose burst.


A new 120 litre valve has been added to Integrated Hydraulics' range of Overcentre valves. It has been introduced to compliment the company's existing 30, 90, 140 and 300 litre valves and enables the company to more accurately match valves to specific motion control application requirements. Overcentre valves are designed to give static and dynamic control of loads by regulating the flow into and out of hydraulic actuators.

When installed close to, or within an actuator, these valves will stop runaway in the event of a hose burst or allow thermal expansion relief of the hydraulic fluid where open centre directional control is used.

The NEW valve, the '1CE120', is based upon the company's tried and tested 120 litre balanced and zero differential variants.

It has the spring chamber connected to the valve port, which provides extra stability because of the dampening chamber created behind the poppet.

Pulses produced by bouncing booms etc are eliminated by the highly evolved component design.

In order to minimise its size, the 120 litre capacity cartridge uses a differential area design, whereby the pressure in the cylinder acts over only an annular area on the nose of the poppet.

This reduces the force transmitted to the poppet and consequently the size of the springs required to control it.

This design also provides an excellent flow path, therefore improving a system's efficiency.

It is designed for load induced working pressures to 270 bar, with a maximum relief setting of 350 bar and for flows up to 120 litres/min.

Internal leakage is only 0.3 ml/min.

The adjustment range of Integrated Hydraulics cartridges is particularly wide, simplifying development because one cartridge can be set to give the best results for any given system.

In operation a check section allows free flow into the actuator then holds and locks the load against movement.

The pilot assisted relief valve section will give controlled movement when pilot pressure is applied.

The relief section is normally set to open at a pressure at least 1.3 times the maximum load induced pressure but the pilot pressure required to open the valve and allow movement depends on the pilot ratio of the valve, 3.5:1 for the 1CE120.

The Overcentre cartridge is ideal for mounting directly into a cavity machined in the body of the cylinder, motor or rotary actuator.

The cartridge can also be mounted directly to the ports via a specifically machined body, as part of a Hydraulic Integrated Circuit (manifold block), or contained within a standard line body.

Single overcentre valves are normally used when the load is unidirectional, for example an aerial platform or crane and dual overcentre valves are used for controlling loads in both directions for motor applications or for cylinders going over centre.

Integrated Hydraulics offers an extensive range of Overcentre valves designed to overcome almost any motion control problem that may arise.

Existing valves in this constantly expanding range include: Standard, Balanced, Part Balanced, Counter Balanced and Zero Differential designs.

Low cost particle counter is designed to help companies reduce the cost of machinery maintenance and system downtime caused by contamination of hydraulic oils.

A new, low cost version of an innovative portable particle counter has been launched by Parker Hannifin. Called the Classic Laser LCM, the new particle counter is less than half the price of many existing devices and is designed to help companies throughout industry reduce the cost of maintenance and system downtime caused by contamination of hydraulic oils in manufacturing and process systems, and in mobile plant and machinery. It is estimated that at least 80% of all hydraulic systems failures are caused by contamination, mainly in the form of dirt and debris that enters the system during installation, maintenance or repair, or through damaged or worn parts, such as cylinder and valve seals.

Particulate contamination will affect the operating efficiency of both the oil and sliding parts, cause valves to stick and, in the worst case, can lead to sudden component failure.

In each case, the result will be costly system downtime and increased maintenance.

These problems can, however, be overcome by regularly monitoring the level of contamination using Parker's Classic Laser LCM, which has been developed to make sampling quick, simple and cost effective.

The unit is compact and lightweight and produces extremely accurate results within a simple two minute test cycle, with connection to the hydraulics system by means of a dedicated in-line sensor or a single point sampling device.

Although the new particle counter has been launched as a low cost device, it incorporates advanced laser technology, with an opto-mechanical, continuous wave single point source laser (SPSL).

In addition, the Classic LCM features a hands free 300-test cycle logging via LCD handset; an RS232 serial port computer interface; and a wide range of optional extras such as a barcode swipe wand to allow quick handset data loading.

Data can be printed immediately, including graphical representations of results to support predictive maintenance, from the integral 16-column printer.

The Classic LCM is IP55 rated with a protective cover to enable it to be used both in production environments and on outdoor sites, as it is resistant to contamination by particles and other airborne matter.

It is therefore ideal for use in a wide variety of demanding indoor and outdoor environments, such as general and heavy industrial, agricultural, mobile, military and marine applications.

In addition, a dedicated aggressive fluids version is available, suitable for monitoring corrosive fluids such as phosphate ester based lubricants in commercial aviation.

The Classic LCM is accredited to US Standards and has full ISO certification and calibration to the latest ISO Medium test dust standards.

One of the least understood hydraulic circuit components is one of the most important, as it can bring many benefits to hydraulic applications, say Andrew Lindgren and Bernd Killing.

One of the least understood components within hydraulic circuits is also one of the most important, as it can bring a raft of benefits to virtually all hydraulic applications, whether they be stationary or in motion. The authors take a 'back-to-basics' look at accumulators and discuss how virtually all those that employ the features of fluid-based systems can use them. Using the simple interaction of an inert gas (nitrogen) on one side of a moveable barrier and a hydraulic fluid on the other, accumulators are very simple in operation but tremendously effective in what they achieve.

Used to moderate and maintain hydraulic circuits, their method of operation is not 'rocket science' although tight specifications must be determined prior to use to get the very best out of them.

Put simply, accumulators are used to both store and deliver hydraulic potential whenever a system experiences a peak or trough in pressure.

'When correctly specified, accumulators can be used for a variety of functions to enhance system efficiency,' explains Lindgren.

'These include: reducing the shock effects generated by inertia or external mechanical forces; system pressure maintenance; compensation for leakage; and as a back up power supply when system demands are higher than the pump can deliver.' Three common types exist, all of which exhibit specific features that make them more suitable to different applications.

The first, bladder-type accumulators, employ a gas filled bladder contained within a vessel that is attached to the hydraulic circuit.

As the hydraulic pressure increases, hydraulic fluid enters the vessel and compresses the bladder, which, in its 'resting state', is at a known pressure or precharge.

Fluid will continue to compress the bladder until equilibrium is reached, i e, until the gas and hydraulic fluid are at the same pressure - this is why the precharge pressure is important.

Once the system pressure starts to fall, the gas under pressure, acting like a spring, forces hydraulic fluid back into the system until the pressures balance.

The second type of accumulator, widely used in mobile and off-road applications, uses a piston instead of a bladder to contain the gas in the closed end of a cylinder.

As with the bladder accumulator, the device is tailored to the application by selection of size and volume of the accumulator, and by means of precharge pressure adjustment.

The third and final variant is the diaphragm accumulator.

Instead of a bladder, it used a rubber diaphragm to separate the gas and liquid in the two halves of a vessel.

Its method of operation is essentially identical to the other two types.

As mentioned earlier, each accumulator variant exhibits operational features and constraints that make them more or less suitable to particular applications.

Bladder accumulators offer quick response times, hysteresis-free operation and good tolerance to contamination of the system fluid.

However, they only offer a limited compression ratio (up to 4:1) and limited flow rates when compared to piston accumulators.

The failure mode of bladder accumulators is immediate - there are no warning signs - a valuable feature in industrial applications where a consistent product is required, as a reduction in quality is immediately apparent and waste product can be avoided.

Piston accumulators offer extremely high flow rates, a wide operating temperature range, high compression ratios (up to 10:1) and resistance to external forces.

They also offer virtually unlimited size availability, large gas ports for use with gas bottles, position monitoring of the piston and more versatile mounting possibilities.

On the 'down side' they require a higher level of fluid cleanliness than bladder types, have lower response times at low pressures (p<35 bar) and exhibit hysteresis.

Their 'non-catastrophic' or progressive failure mode makes them particularly suitable for mobile steering and braking applications as early warning of deteriorating performance is easily identified.

Diaphragm variants will withstand compression ratios of up to 8:1 and exhibit the same advantages as bladder types.

They can suffer from gas permeation across the diaphragm and, like bladder accumulators, their failure mode is immediate.

'When selecting an accumulator for a particular application, both system and performance criteria should be considered,' says Killing.

'To ensure long and satisfactory service life, many factors should be taken into account.' The factors Killing is alluding to include failure mode, output volume, flow rate, fluid type, response time, shock suppression, high frequency cycling, mounting position, external forces, sizing information, certification and safety.

All of these can have an effect on the optimum operation of the accumulator and, in most cases, external expertise is the best option.

With this fact in mind, Lindgren is keen to point out that potential users do not need to worry about performing these calculations as Parker's engineers are used to bespoke specification and will happily design the optimum system for a user's application.

'We find ourselves acting as consultants for the majority of our customers,' he explains.

'With so much knowledge of the hydraulic market we are more than happy for customers to take advantage of our expertise in these types of applications.' One of the most critical factors in the operation of an accumulator is precharging.

Correct precharging involves accurately filling the gas side of an accumulator with pure nitrogen before admitting fluid to the hydraulic side.

It is important to precharge an accumulator to the correct specified pressure as the precharge pressure determines the volume of fluid held in the accumulator at maximum and minimum system pressures.

In an energy storage application, a bladder accumulator is typically precharged to 80% of minimum system pressure, and a piston accumulator to 7 bar below, or 90% of, minimum system pressure.

The ability to correctly carry out and maintain precharging is an important factor when choosing the type of accumulator for an application.

Accumulator failure is often defined as the inability to accept and exhaust a specified amount of fluid when operating over a specific system pressure range.

Failure often results from unwanted loss or gain of precharge pressure.

Correct precharge pressure is the single most important fact in prolonging the life of the accumulator.

It is for this reason that Parker supplies complementary equipment to ensure that precharge pressure can be maintained at its optimum level.

This equipment includes a remote charging and gauging block, (Note well - this is more for the industrial than the mobile sector) which enables operators to pre-charge a newly installed accumulator and to check and adjust the pre-charge of an existing unit.

Initial filling of the gas pre-charge and adjustment where necessary can be carried out using Parker's UCA charging and gauging assembly.

A huge amount of accumulator options are also available to engineers.

Piston, bladder and diaphragm variants come in a variety of sizes and volumes and all can be supplied pre-charged to the customer's specification.

Piston accumulators, due to the nature of their construction and operation, are the most flexible in design.

Indeed, massive early examples were used to store energy within London's Tower Bridge for raising and lowering of the two halves of the roadway.

Accumulators can also be ganged into multiple groups to act as an emergency power reserve in case of system delivery failure.

Application-specific, pre-fabricated hydraulic circuit solutions and controls for specific motion tasks reduce the engineering effort for manufacturers of machine tools.

Application-specific, pre-fabricated hydraulic circuit solutions and controls by Rexroth reduce the engineering effort for manufacturers of machine tools. At EMO 2005, Rexroth will present package solutions for specific motion tasks. The function groups that are made up of standard components simplify the modularization of machines and thus shorten the time required for engineering and commissioning.

Rexroth completes these modules to provide a complete hydraulic control taking into account the size of the machine, the field of application and customer requirements.

With electro-hydraulic axes, the manufacturer can combine the advantages of decentralised automation structures with the specific benefits of hydraulic drive physics.

By offering these function modules that are optionally semi-finished or ready for operation, Rexroth promotes the standardisation of hydraulic drive units for specific movements.

These standard solutions improve the modularisation of machine concepts and contribute to an increase in the lifecycle value.

They are based on the use of standard components from the comprehensive Rexroth hydraulic product range and allow almost infinite scaling.

Depending on the task at hand, the complete power units can be used for continuous or intermittent operation.

Various valve combinations cover the specific motion tasks.

The modular IH control plate system of segment design significantly reduces the piping effort and allows the integration of all clamping and handling functions in one complete hydraulic control.

With electrohydraulic axes, Rexroth opens up new dimensions and allows highly dynamic movements to be performed with a positioning accuracy in the order of microns.

The drives that are provided with internal or external closed-loop control electronics fit seamlessly into Rexroth's modular hydraulic product system and consequently into the function modules.

Following the launch of the ZU electric pumps for the construction market, Enerpac has just released the new ZE series 700bar hydraulic pumps for industrial applications.

Following the launch of the ZU electric pumps for the construction market, Enerpac has just released the new ZE series 700bar hydraulic pumps for industrial applications. In the Z-Class range of electric pumps, Enerpac said that it has used the latest metallurgical, bearing and seal technologies. According to the company, by reducing the number of moving parts, improving flow dynamics and decreasing friction, Z-Class pumps will stay on the job longer, require less energy to operate and when needed, have lower service costs.

The design of the ZE electric pump has higher oil flow and by-pass pressure, runs cooler and requires 18 per cent less current draw than comparable pumps said Enerpac.

The totally enclosed, fan-cooled electric motor supplies extended life and stands up to harsh industrial environments.

The multiple valve and reservoir configurations provide application specific models to match the most demanding industrial applications.

The optional LCD readout provides a number of diagnostic and readout capabilities never before offered on an industrial pump.

The ZE pumps are available in four flow ranges and single and two-stage models, to provide the optimum cylinder and tool performance for almost any industrial application.

Available in four oil flow groups of 0.55, 0.82, 1.64 and 2.73 litres per minute at 700bar.

Motor sizes include 0.75, 1.12, 2.24 and 5.60 kW models.

A list of accessories is available, including heat exchanger, roll bars, pressure transducer and level and temperature switches to allow complete pump control over a range of industrial applications.

The use of valves that control pressure proportional to an input signal, is an effective solution to the problem of providing ever more subtle and fine control demanded by the end user.

The use of valves that control pressure proportional to an input signal, is an effective solution to the problem of providing ever more subtle and fine control demanded by the end user, according to Integrated Hydraulics. The company added that striving to improve controllability is driven by the need for continued improvements in productivity and safety, so Integrated Hydraulics has designed a new pressure reducing cartridge valve that is said to be simple but effective and accurate. Typical applications for the cartridge valve will be provide a proportional pilot pressure to a directional valve or transmission, raising or lowering of a sweeper brush, or cooling fan control circuits.

The proportional pressure reducing valve, designated PPD2 2 is of simple, robust, spool type design and makes use of tried and tested components and technology.

With no current applied, the regulated port is connected to tank.

As the current increases the pressure in the regulated port will rise to balance the increasing solenoid force.

Pressure in the regulated port acts on the spool tending to close it against the force of the solenoid.

As pressure in the regulated port increases (with a constant current applied to the solenoid) the spool will shift, restricting the inlet, equilibrium is then achieved and a reduced constant outlet pressure held.

Varying the current will alter the force applied to the spool and hence the pressure in the regulated line.

The cartridge has a maximum inlet pressure of 210bar and a maximum regulated pressure of 28bar (when fitted with a 29 watt coil).

It benefits from having no dynamic seals, reducing hysterisis and prolonging service life.

The armature is oil immersed and the coil and stem sealed to avoid atmospheric corrosion.

A manual override is provided to help set-up and to operate the valve in the event of power failure.

PWM (Pulse Width Modulation) is preferred with a frequency of 200Hz to minimise the hysterisis.

The coil is interchangeable with those used on their S5 Series valves, reducing spares inventory.

It uses the same cavity as other valves in the pressure reducing valve range, so no new tooling is required.

Due to excellent design and close manufacturing tolerances, internal leakage is minimal at 50ml per minute at 210bar pressure differential.

Robust range of quick couplings for high pressure hydraulic tools combine a positive and secure locking mechanism with a long operating life.

Parker Hannifin, the world's largest manufacturer of motion and control technologies, has released a new and robust range of quick couplings for high pressure hydraulic tools and rescue equipment, where safety and reliability are crucial. Called the CL/CM range, the new couplings have been developed to combine a positive and secure locking mechanism with a long operating life and quick and easy installation, to save engineers time and money while ensuring safe and dependable hose connections. The new couplings offer consistently strong connections for use with high pressure hydraulic jacks, rams, clamping devices, torque wrenches, cable cutters and spreaders.

The products are exceptionally robust, with the CL series able to withstand a maximum working pressure of 1,000 bar (100MPa), while the CM series, designed for even higher pressure applications, can withstand a maximum of 1,500 bar (150MPa).

Both the CL and CM ranges are manufactured from Chromium-6 Free plated steel, in compliance with the latest EU directives, offering excellent corrosion protection and extremely solid construction in even the toughest of operating environments.

All of the couplings are easy and simple to fit, with positive ball locking mechanisms, while a flat faced poppet feature reduces spillages, keeping workplaces clean and reducing the risk of harm to the environment.

Hardwearing plastic dust caps and plugs protect the couplings when not in use and prevent damage through mishandling, reducing the costs associated with repairing and replacing components.

The couplings are ideally suited as upgrades for existing components in high pressure hydraulic systems, being fully compatible with similar products on the market, and are widely available through Parker's global network of sales offices and distribution partners.

Brochure for Parker E-Series filters high performance filters for hydraulic oils and lubrication systems shows how to cut waste costs.

he Hydraulic Filter Division Europe part of Parker Hannifin, the world's leading motion and control company, has published a new brochure to promote its innovative E-Series range of high performance filters for hydraulic oils and lubrication systems.

Designed to help OEMs and end users cut the cost of waste disposal and to comply with ISO 14001, the E-Series filters feature reusable filter sleeves and central cores, and provide exceptionally high levels of filtration efficiency in applications operating between 10 and 420 bar and with flow rates of up to 2400 litre/minute.

By employing Parker's calibration service, users of crimping equipment for hydraulic hose are assured of full compliance to ISO9000, and Health and Safety assurance.

As a direct result of the continuing popularity of Parker Hannifin's Hose crimping equipment (Karrykrimp, Parkrimp, and Variable crimpers), the company has now launched a new calibration service. By employing Parker's fully trained and qualified technicians, end users of Parker crimping equipment are assured of full compliance to ISO9000, and peace of mind regarding Health and Safety issues. The service, which is recommended on an annual basis, is carried out by an experienced technician who will also verify pressure, and check for leaks using a pressure sensing device, check all fixings, fittings as well as wear and tear on the machine and dies, and, if required, will provide training on the safe use of crimping machines and hose fittings.

At the same time customers are able to discuss repairs and benefit from advice regarding new equipment.

Parker crimping machines encompass the latest technology, with PLC devices.

The machines are simple to operate, enabling leak-free, factory-quality hose assemblies to be produced quickly and cost effectively, either in high volumes in the factory or on-site assembly for repairing mobile equipment.

For example, the rugged Parkrimp produces hose assemblies that meet or exceed EN requirements, has no gauges to set and features colour coded die trains for easy identification.

The machine automatically aligns the fitting during crimping and adjusts the crimping diameter making it fast and easy to use.

In addition, the die crimp gives 360 deg degree gripping power for greater impulse life, and when used with the unique Parkalign, positions the fittings perfectly, even with bent hose fittings.

More importantly, this system ensures that fittings bite through the hose cover and grip the wire reinforcement for maximum integrity.

For a cost effective, portable, field alternative, the Karrykrimp range, series 1 and 2, offers crimping of Parker No-Skive hose and fittings, for example from 1 and 2 SN hose up to DN32, 1 and 2 braid compact up to DN25, through to 1 SN hoses to size -16, 2 SN hoses to size -20.

1 and 2 layers compact to size -20, plus many others.

The Parker range of crimping machines offers fast, easy, and safe crimping of hydraulic fittings and hoses; now, with the introduction of the new service, end users have the added assurance of an annual calibration facility that meets all health and safety requirements now, and in the future.

Proportional flow control valve that is small and simple provides reliable, accurate and affordable pressure compensated proportional flow control.

A new Proportional Flow Control Valve that gives engineers reliable, accurate and affordable pressure compensated proportional flow control has been introduced by Integrated Hydraulics. This small, simple, valve compliments the company's proportional pressure compensated flow control circuits and other proportional and manually operated cartridges. It is designed to give pressure compensated flow control for flows up to 28 litres/min, working at 210 bar.

The valve makes innovative use of flow forces within the spool to achieve a fine level of pressure compensation in a very simple and cost effective cartridge.

The NEW proportional flow control valve, designated PFR24A, is of simple two port, spool type design and makes use of tried and tested components and technology.

With no current applied, the spool blocks the ring of holes in the nose of the cartridge, preventing flow to the outlet port.

As the current increases the increasing solenoid force acts on the spool to open it against the force of the spring, progressively uncovering the radial holes and permitting flow through the valve.

If down stream pressure should fall, the flow rate would increase, but, due to some clever detail design, the increase in flow reduces the pressure behind the spool.

The resulting pressure imbalance on either end of the spool creates a force that is added to the force of the spring, against which the solenoid is acting.

This change in forces causes the spool to shift, restricting the flow path through the radial holes, thus maintaining near constant flow for any given input signal.

Varying the current will alter the force applied to the spool and hence the flow through the valve.

These valves compensate in both directions and are ideal for use as bleed off valves in systems using a fixed pump, providing proportional flow control at working pressure instead of full system pressure.

The valve has an hysterisis of better than 4% with PWM at a cycle rate of 200-400 Hz and 6% without PWM.

It benefits from having no dynamic seals, which reduces hysterisis and prolongs service life.

Response time is 300ms and internal leakage 200 millilitre/min.

For systems requiring lower leakage, Integrated Hydraulics has developed a proportional poppet type flow control valve that gives an internal leakage of just 0.7 millilitre/min.

The armature is oil immersed and the coil/stem sealed to avoid atmospheric corrosion.

Installation and commissioning costs are minimised as a manual override is provided to help set-up (and to operate the valve in the event of power failure).

Also, an innovative feature is the addition of an air bleed valve on the solenoid tube of the cartridge which greatly assists in the initial commissioning of the system.

Air trapped in the tube can cause instability and a reduction in the performance of proportional valves.

The coil is interchangeable with those used on Integrated Hydraulics S5 Series valves, reducing spares inventory and it uses one of their standard cavities so no new tooling is required both of which reduce the overall cost of using the product.

An 'extended' specification range of hydraulic accessories includes plugs and dipsticks, as well as dome-shaped level indicators.

Elesa (UK) have a knack of producing just the right standard parts for wide ranges of industrial applications. Their new 'extended' specification hydraulic accessories fully confirm this point. New additions are plugs and dipsticks, as well as dome-shaped level indicators which compliment recently introduced high pressure/high temperature level indicators, a rapid mounting kit for column level indicators and a set of blanking plugs/filler plugs with dipstick.

Column level indicators now include the HCZ lens effect units at especially competitive prices for oil/fluid tank fitment, with the HCZ/T which also incorporates an integral thermometer to monitor the working range - maximum 90 deg C.

Two sizes are available - 76mm and 127mm mounting centres.

For the HCX and HCX/T (thermometer) range there is now a quick fit mounting kit which allows fully external fitment - only requiring two holes in the side of the tank.

HCX series come with mounting centres of 76mm, 127mm and 254mm to suit most hydraulic reservoir requirements.

For those difficult high pressure reservoirs Elesa now offer the HGFT oil level window capable of withstanding up to 3 Bar.

Where high temperature is also a consideration then the HGFT.HT.PR will withstand both 140 deg C and up to 7 Bar tank pressure.

This is especially important in high back-pressure systems such as those with high reflow.

High grade plastics technology using polyamide technopolymer viton seals ensures the extended performance of these standard components.

Elesa also offer TN series low cost blanking plugs for those high volume, low cost applications, such as transmission gearboxes on industrial machinery and equipment such as conveyors.

Their range of working temperature, up to 130 deg C with peaks to 180 deg C and low cost/ex-stock supply, makes them an attractive alternative to steel or brass.

Thread styles of BSP and metric are shared with the TCD oil fill plugs, which have a moulded-in symbol for oil fill identification and can have a custom specified dipstick.

For use in low pressure hydraulic systems, insert filters offer high capacity and flow rates with extended filter element life, leading to significant savings in space and costs.

Parker Hannifin has introduced three new elements to its range of IN-AGB insert filters, for use in low pressure (LP) hydraulic systems. These new filters have been developed to offer high capacity and flow rates with extended filter element life, leading to significant savings in both space and costs. The new filters are ideal for use in a wide variety of applications, such as commercial and agricultural vehicles, construction equipment and materials handling and waste management plant.

The new AGB-2-400 and AGB-2-500 filters have nominal flow capacities of 400 and 500 litre/min respectively, and form part of the IN-AGB 2 series of Low Environmental Impact Filters (LEIF).

These filters offer significantly higher flow rates than competing products, enabling the operating life of each filter to be dramatically extended, while reducing the costs of purchasing replacement filters, disposal and the downtime incurred while filters are changed.

In addition, Parker LEIF filters have a re-usable element sleeve, so that only the expired filter inserts need to disposed of, rather than the entire filter; depending on the application, this can reducing replacement costs by up to 50%.

LEIF filters also feature patented elements, with a guaranteed quality of filtration or particulate removal, and meet ISO 14001 standards.

Parker has also introduced an addition to the IN-AGB 4 Series, the IN-AGB-4-2400, with flow rates that have been increased from 2000 litre/min to 2400 litre/min.

The IN-AGB-4-2400 features an optimised design of pleat packing that allows customers to take advantage of the greater flow capacity filters without changing the size of the insert.

As a result, the IN-AGB-4-200 filters can be used in applications where space is at a premium.

All Parker IN-AGB filters are high performance return line filters with Microglass III filter media and bypass construction with low hysteresis, magnetic pre-filtration and a high dirt-holding capacity.

Marco van Boven, product manager for Low Pressure Filters, says, 'The new filters will help customers improve the performance and reliability of their hydraulic systems'.

'In particular, the IN-AGB filters can significantly extend operating life, increase flow capacity and reduce lifetime costs, while helping to reduce environmental damage by minimising the disposal of elements.'

Hydraulic components manufacturer in the USA has launched a 'Rapid Response Program' that guarantees orders will ship on time or the supplier will pay a substantial penalty.

Prince Manufacturing Corporation, a hydraulic components manufacturer headquartered in North Sioux City, SD, USA, has launched an industry leading program that guarantees orders will ship on time or Prince will pay a substantial penalty. The Prince Rapid Response offer is the first of its kind in the hydraulic components industry. Prince guarantees that 'Standard Delivery' for orders on custom products will be ready to ship on time or they will pay a 10% penalty per day.

The offer also guarantees that 'Express' and 'Urgent' orders will be ready to ship on time or Prince will pay a 50% penalty for the first day late and 10% per day there after until the order is free.

By establishing these substantial penalties, Prince is letting the market know that they are serious about meeting their scheduled deliveries.

Express orders are half the standard lead-time and urgent orders are one forth the standard lead-time.

Rhea Geary, president of Prince Manufacturing said: 'The Prince Rapid Response program was developed after an analysis of the challenges facing the manufacturing marketplace and supply chain'.

'Prince found that long lead times and unreliable delivery have the greatest impact on the manufacturers'.

'These challenges cost money'.

'Not getting products when needed causes disruptions and lost opportunities'.

'Manufacturers are forced to carry larger inventories or reschedule production'.

'A lack of flexibility results in missed sales opportunities'.

'All of these problems have a negative impact on the bottom line'.

'Prince determined that the solution must guarantee reliable delivery, faster delivery if needed, increase flexibility to changes and have a positive impact on the bottom line.'

To better serve their customers' needs, Kurt Hydraulics has increased its inventory to include over three million feet of Hydraulic Hose ready for immediate delivery.

To better serve their customers' needs, Kurt Hydraulics has increased its inventory to include over three million feet of Hhdraulic Hose ready for immediate delivery. Products include SAE 100 R1, R2, R4, R5, R12, R13, R16, R17, 4SH, Jack Hose, Teflon Hose and Refrigerant Hose. Positioned as the 'new alternative source in the hydraulics industry'.

Kurt hose products and its complete line of couplings are directly interchangeable with other popular brands and crimping systems.

For fast referencing and ordering, all hose products are indexed at on the Kurt website by part number and recommended application.

Also included for each hose product are individual hose cover type, sizes, minimum bend/inches, minimum burst/lb/in2and temperature range.

Kurt hydraulic hose is manufactured to the highest quality for both industrial and commercial applications including construction, agricultural, mining and plant maintenance equipment.

With over 35 years experience manufacturing hydraulic connector and components, Kurt provides responsiveness to all needs including long term, high volume requirements.

To complement its hose products with single source solutions, Kurt Hydraulics also provides couplings in hundreds of configurations and sizes.

These include metric hose couplings, R2 reusable couplings, spiral hose couplings, JJ R13 couplings and Teflon, R5 and beadlock couplings.