Visit the San Francisco Giants' Pacific Bell Stadium and the Monterey Bay Aquarium and you'll see impressive structures built with products from RMC Pacific Materials.

RMC, based in Pleasonton, Calif., is a key aggregate supplier in the building materials industry, manufacturing five different types of cement. Aggregate is used in RMC's ready-mix operation and marketed to other ready-mix producers and manufacturers of products such as concrete block, interlocking pavers, and lightweight roofing tiles.

Making sure aggregates are properly mixed is vital to RMC's operation. Mixing begins with mined aggregate, which is washed, crushed, and segregated into various components according to size. These are then recombined according to ASTM specifications to create products used in making concrete, asphalt, and aggregate.

The supplier recently automated its aggregate mixing operations at two of its California plants: RMC Pacific Materials in Pleasanton and Harbor Sand and Gravel in Redwood City. Using Bosch Rexroth electro-pneumatic (E/P) positioners, RMC is now able to monitor and control gate positions and protect its mixing lines from overfeeding in case of power failure or malfunction.

The mixing processes at each plant uses Rexroth E/P positioners to open and close the gates that discharge material directly onto conveyor belts, which transport the material to predefined locations within the plants. Depending on the material being produced, one to four different gates can be opened to blend ingredients.

This type of automation had never been used in aggregate mixing before. Once we tackled the size issue, we needed a 5-inch bore, which was a larger unit than we generally offer. The main challenge was the unit had to be "fail safe" in the extended position.

Maximizing tonnage

At Harbor Sand and Gravel, the E/P positioner opens and closes a gate to control the amount of material released onto a conveyor, to maximize the tonnage being transported without overloading the system. Feedback from a belt scale downstream opens or closes the gate controlled by the E/P positioner to maintain a tons-per-hour flow set by the operator.

Once the E/P positioner is given a set point by a PLC, it moves the gate to the given position and then monitors the position, making adjustments as necessary. Feedback information from the E/P positioner is monitored by the PLC, which alerts the operator if there's a malfunction.

The automated positioners have improved the reliability of the aggregate products made through the load-out system, says Tony Fuentes, of RMC's quality control department. "We've tightened our operating ranges on several products," he says. "One of the biggest benefits is that we can make changes with little or no effect to our product or operating parameters. We can also offer custom blends with more accuracy, which is a huge benefit for special projects."

The E/P positioners replaced existing air cylinders at each mixing location, making installation easier and less expensive since air was already available. A push-button station was already being used to interface with the existing air cylinders, so it was a relatively simple task to integrate the new cylinders into the system while the plant maintained normal day-to-day operations.

"Without the positioner," says Randy Mull, an engineer with Eichleay Engineers, a Concord, Calif., design and services firm, "additional I/O slots from the PLC would have been required to open and close solenoids on the cylinder to maintain the set point."

The size of the cylinders Was big enough to stop the flow of material when closing, move the gates, and control the flow of material. Typically, the actuators default to the retracted position upon signal failure, or stay where last commanded upon total loss of power.

We needed to reverse this operation because the gate closed only when the cylinder was extended. We couldn't risk leaving the chute gate even partially open, as the silo could completely empty on a stalled conveyor and create a messy, costly cleanup operation.

By reversing signal wires and plumbing lines, adjusting command signals accordingly, and adding a normally open the valve, which overrides the pilot pressure to the directional valve that extends the cylinder, the team was able to achieve the desired effect. The system is also equipped with an air reservoir to allow cylinder actuation even after a power failure stops the air compressors.

Atlas Copco South Africa Pty Ltd. has acquired the assets of Consolidated Rock Machinery Ltd. (CRM).

CRM is a distributor of surface drill rigs, portable compressors and compact equipment, as well as rig-mounted and handheld C&D equipment.

CRM manufactures its own hydraulic boom systems and a range of pneumatic tools. The company's head office is in Johannesburg, South Africa.

CRM's compact equipment business will not be included in the acquisition.

The purchase price was not disclosed, and the acquisition is subject to approval from local authorities.

Atlas Copco has a head office in Stockholm, Sweden, and U.S. operations based in Springfield, Mass. The Atlas Copco Group produces compressed air equipment generators, construction and mining equipment tools and assembly systems.

The company now provides a pneumatic cylinder package to automate productivity on rotary tables, indexers and grinders. This new air cylinder works with rotary tables, indexers and grinders. This system offers air open and air close actuation. It also offers up to 120 psi for more than 3,800 lbs of pull force.

The complete package includes a 6" or 9" air cylinder, drawtube, adapter plates, filter, lubricator, regulator, hand-lever actuator and hoses with quick connect valves.

The Cretelock System is a new and innovative pneumatic tailgate for concrete trucks. It provides positive shut-off to the concrete mixer at the feed hopper, and prevents concrete from spilling into the chute- Shut-off at the point of discharge is achieved through a replaceable wear liner, allowing the drum to turn against the CreteLock. It uses a modular bolt-together construction, which requires no welding and is pneumatically operated with a hand switch inside the cab of the truck and a light to verify if the gate is opened or closed. The product by Mix USA prevents costly spills and allows ready-mix trucks to carry full loads, even in hilly terrain or with high-slump mixes.

A single pass filter kit shows lower pressure drops and higher efficiencies and dirt holding capacities, resulting in cleaner oil, longer element life, and less downtime.

Schroeder Industries, a recognized leader in filtration and fluid conditioning products, announces the addition of the 3K9 single pass filter kit to its offline filtration products line. The 3K9 is composed of three Schroeder K9 filters mounted in series as a single assembly, providing either in-line single pass staged filtration or a combination of particulate and water filtration. Each K9 medium pressure filter is rated at flows of up to 100 gal/min (380 litre/min) and pressures up to 900 lb/in2 (60 bar).

The 3K9 accepts HF4 spec elements, and double and triple stacking of K-size elements can be replaced by single KK and 27K elements.

Testpoints can be supplied in either the cap or block, allowing the user to record pressure readings or take fluid samples.

The 3K9 is furnished with Schroeder Excellement (Z) media, the latest in a long line of premium filter media for the fluid power industry that outlasts, outperforms and excels in every measurable benchmark.

Excellement media show lower pressure drops and higher efficiencies and dirt holding capacities, resulting in cleaner oil, longer element life, and less downtime.

* About Schroeder Industries - Schroeder Industries designs, manufactures and markets filtration products for the fluid power industry.

Schroeder is a leader in filtration and fluid conditioning.

Their expertise in filtration technology, superior filter and element manufacturing capabilities, and dedication to customer service and product support are the reasons Schroeder is considered 'The Filter Company'.

Catalogue brings together an expanding, diverse range of pressure and vacuum operated switches used in hydraulic, pneumatic, instrumentation, manufacturing and scientific applications.

A new catalogue bringing together their expanding range of pressure and vacuum operated switches has been published by hydraulic system Products of Wakefield, West Yorkshire, UK. The range is diverse in order to meet the needs of a wide range of applications including hydraulic, pneumatic, instrumentation, manufacturing and scientific. HSP switches are all based on well proven design principles with models for actuation by rising pressure, falling pressure, differential pressure or vacuum.

These are diaphragm type switches operating in various ranges typically starting at 0.2 bar for the low pressure models and going up to 420 bar for the higher ranges.

The actuation point can be set anywhere within the specified range either at the factory prior to shipping or by the user in the field.

Proof pressures are commensurate with the maximum system pressure, normally one and a half times, to ensure a high degree of safety not only for the switch body but also for the actuating diaphragm and mechanism.

Switching is via high quality 5A snap action micro-switches using 12/24V DC or 120/240V AC electrics.

Electrical connections are 500mm flying leads, DIN plug or DIN cable clamp.

Standard body material is steel which is zinc plated and passivated for excellent environmental protection.

316 stainless steel is optional.

Differential pressure switches have aluminium bodies.

Medium connection is either 1/8'in BSPF or 1/4'in BSPF male thread.

Standard diaphragm material is Nitrile with EPDM or Viton options for media compatibility.

Rugged construction, vibration resistance and IP65 protection are standard features for all switches.

A series of hydraulic rack and pinion rotary actuators - completely enclosed - offer high levels of strength and torque, with a long, trouble-free operating life.


The latest HTR Series hydraulic rack and pinion rotary actuators from Parker Hannifin offer high levels of strength and torque, with a long, trouble-free operating life. HTR actuators are suitable for use in the most demanding production systems including those used in the mining, off-shore, power generation, automotive, commercial marine and metals processing sectors. HTR actuators convert fluid power into rotary motion by using the piston in a conventional tie rod cylinder to move an output shaft via a through-hardened, chrome-alloy steel rack and pinion.

The entire unit is completely enclosed, avoiding the need for external protection and preventing contamination of moving surfaces.

The pinion and shaft are manufactured as a single piece and are supported in high capacity tapered roller bearings, eliminating the need for additional external bearings for the corresponding machine member.

The gear housing is manufactured from high strength ductile iron and, on larger capacity models, the rack is supported by heavy duty bronze bearings.

This construction results in an extremely robust system which produces uniform torque in both directions of rotation and which is capable of withstanding high radial and thrust loads even in applications with high cycle rates.

In addition, the latest HTR rotary actuators are designed to deliver a long operating life and to be both easy to install and maintain.

For example, the single-piece steel pistons are fitted with self-compensating polyurethane seals and durable PTFE wear rings as standard, which can be inspected and replaced with the actuator in-situ.

HTR rotary actuators are rated for working pressures up to 210 bar, and are available in a range of sizes with output torque ratings of 100 to 68,000Nm.

Shaft rotations of 90 deg, l80 deg and 360 deg are available as standard while up to five full rotations or more are possible.

Options include a choice of port positions, cushioning for progressive deceleration of piston speeds, different seal materials, feedback devices and position sensors.

Tank top mounted return line filters have dual port filter heads, allowing more cost effective use of the filters and enables improved ease of use, as the second port can be used for filling.

The Hydraulic Filter Division of Parker Hannifin has introduced the latest versions of its TTF and BGT tank top mounted return line filters that can now be supplied, as standard, with dual port filter heads, allowing more cost effective use of the filters. The dual port also enables improved ease of use, as the second port can be used for filling or connecting another return line to the filter head, for example. Additionally, the nominal flow capacity of the TTF is increased from 300 up to 500 litre/m, while the BGT has been increased from 2000 up to 2400 litre/min.

Parker Filtration has also advanced its filter technology still further by extending the life cycles of their elements, by introducing patented Low Environmental Impacts (LEIF), which offer considerably higher flow rates than competing products, enabling the operating life of each filter to be significantly extended.

In addition, Parker LEIF filters reduce the cost of purchasing replacement filters, disposal and the associated downtime with filter changes.

This is due to the LEIF reusable element sleeve, that, depending on the application, results in only the expired filter requiring disposal, as opposed to the entire filter, reducing replacement costs by up to 50%.

LEIF filters are guaranteed to high standards of filtration or particulate removal, and meet ISO14001 standards.

In addition, the TTF and BGT filters can be supplied with a metal diffuser that contributes to an optimal filtered oil entry path inside the reservoir.

By comparison with other filters using plastic type components, this ensures that the amount of static electricity that is generated is significantly reduced.

Needle type flow control valves are installed in hydraulic system pressure lines to provide infinitely variable flow control and each model is available in four sizes.

These flow control valves are additions to the range of hydraulic valves manufactured by hydraulic system Products of Wakefield, West Yorkshire, UK. They are installed in hydraulic system pressure lines to provide infinitely variable flow control. Two versions are manufactured: Model HSP2810, allows infinitely variable controlled flow in either or both directions.

Model HSP2818, has an integral check valve to allow infinitely variable controlled flow in one direction and free flow in the opposite direction.

In both models the flow rate is varied by a tapered valve which passes through a fixed orifice.

A threaded stem with a hand wheel controls the height of the valve and a locknut is provided on the threaded stem to lock the flow setting.

The valves are designed for in-line mounting and each model is available in four sizes having port connections of 1/4in, 3/8in,1/2in and 3/4in NPTF or BSPF.

The largest sizes offer variable controlled flows up to 80 litre/min.

The check valve in Model HSP2818 has a cracking pressure of 0.20 bar and permits free flow up to 110 litre/min for the largest size.

Maximum operating pressure is 350 bar for all valves.

The steel bodies are zinc plated and passivated for maximum protection against environmental conditions and the stem is stainless steel with viton seals.

Overall height with the stem fully open is 104mm for the largest sizes of both models.

Lengths port to port for the largest sizes are 72mm and 90mm for models HSP2810 and HSP2818 respectively.

Typical applications would include limiting the maximum speed of a cylinder movement in either meter-in and/or meter-out circuits or in a test rig to apply infinitely variable and progressive back pressure on the test piece.

Interchangeable and environmentally friendly hydraulic filter elements have been designed to eliminate the problems of equipment downtime and failure caused by fluid contamination.

The Filtration Division of Parker Hannifin, the world's largest manufacturer of motion and control technology, has introduced its latest range of hydraulic filter elements that have been designed to eliminate the problems of equipment downtime and failure caused by fluid contamination. Perhaps most importantly, the new environmentally friendly ParFit elements are interchangeable with products from all other suppliers, giving end users the option of sourcing all filter elements from a single, high quality manufacturer; this approach can reduce stock levels and, as the ParFit elements are manufactured to the highest standards, can significantly extend operating life and reduce overall costs. Ideal for use in a wide range of applications including industrial and mobile plant, test rigs, aircraft ground support equipment, steel and paper mills, the new ParFit elements have been developed to allow both system designers and end users to meet current and future environmental regulations.

In particular, the ParFit filter system uses a standard metal housing and replaceable element, which is quick and simple to change during routine maintenance, leaving the housing in place, and dramatically reducing both waste disposal and element replacement costs.

In addition, ParFit filter elements can be used as a direct replacement for competing products and are manufactured to stringent quality standards, ensuring that every unit is produced to extremely tight tolerances, with features including corrosion resistant end caps and fully bonded construction for maximum strength.

John Botley, marketing services manager for Parker Filtration, explained that, 'To date, users of hydraulically powered systems have had to source replacement filter elements from either the OEM or the filter manufacturer, often at a premium price or with a delayed delivery'.

'The alternative has been to find a third party supplier; although these companies may have been able to offer a low cost option this has generally been of inferior quality.' He said: 'Now, with our ParFit range, we can offer customers a high performance range of fully interchangeable filter elements that are suitable for use in almost all applications, yet are available at extremely competitive prices and immediate delivery.' The new Parfit elements conform to international ISO standards, governing collapse and burst resistance, fabrication integrity, material compatibility and flow fatigue characteristics, as well as to the internationally recognised multipass test, and are available through Parker's nationwide UK network of ParkerStores and authorised distributors.

Motion and control company has issued a handbook that makes it easy for factory, plant and maintenance engineers to choose a replacement hydraulic filter element from an extensive range.

Parker Hannifin, the world's largest manufacturer of motion and control technology, has produced a new handbook making it easy for factory, plant and maintenance engineers to choose a replacement hydraulic filter element from its extensive ParFit range. Until now, users of hydraulically powered machinery have been forced to buy replacement filter elements from either the machinery OEM or the filter manufacturer. Parker now offers engineers the opportunity to source replacement elements from a single trusted source, at the right price, regardless of the original equipment manufacturer.

The importance of hydraulic filtration should not be underestimated.

Designers and users of hydraulic and lubrication systems have proven that over 85% of system failures are caused by contamination.

The cost of such system failures, resulting from production downtime, unscheduled maintenance, and the need to replace components and fluids, has made engineers increasingly aware of the need for high quality, correctly matched filtration.

ParFit elements are manufactured to the highest standards, significantly extending operating life, reducing costs, and often surpassing the efficiency of the original elements.

Every unit conforms to all relevant ISO standards and is produced to extremely tight tolerances, with corrosion resistant end caps and fully bonded construction for maximum strength.

They are ideal for use in a range of applications including industrial test rigs, aircraft ground support equipment, steel mills, paper mills, and industrial and mobile equipment.

John Gilks, product manager for Parker's Hydraulic Filter Division Europe, confirmed, 'The new ParFit handbook has been produced with the user in mind.

They can now select a replacement filter element quickly and easily, saving time and money, and with the confidence that they can rely on the high quality products for which Parker is known.

There is a ParFit element to fit almost any size and make of OEM filter, allowing engineers to reduce stockholdings and cut costs.' For ease of use, all products in the handbook are listed in alphanumeric sequence, with the manufacturer part number alongside the ParFit equivalent item number.

The pneumatics Division of Parker Hannifin has introduced its latest Moduflex Miniature Vacuum Generator, which has been developed to offer a compact, lightweight solution for use in a variety of automation and product handling applications, ranging from component pick and place in the electronics and semiconductor industries, to paper, foil and carton handling in the print and packaging sectors. Perhaps as importantly, the Moduflex Vacuum Generator incorporates a number of innovative features, including a standard blow-off facility, and can be positioned remotely from the control valve, directly onto a valve island, or mounted in-line close to vacuum cups to minimise space requirements. The Moduflex Vacuum Generator uses proven Venturi technology, where the kinetic energy from a compressed air jet can be harnessed to create a vacuum or suction force, reaching up to 90% vacuum.

In common with all products in the Moduflex range, the Vacuum Generator offers users a choice of mounting and positioning options: for example, remotely with the vacuum cup directly mounted on the generator for fast response times; with centralised control on a valve island to save space at the point of suction or in rugged environments; and in-line, with the suction cup being positioned remotely, again to save space at the point of use, while allowing easy access to the vacuum generator.

Depending on the application, the Moduflex Vacuum Generator can be controlled by either single or double 3/2 electrically or pneumatically actuated valves and can also be supplied with an optional vacuum sensor for connection to machine monitoring systems.

Other options include push-in straight, elbow, and double main union connectors, and an exhaust silencer.

The latest Moduflex Vacuum Generator are lightweight, with the standard unit weighing just 30g, and have a robust construction, with a polyamide bodies, nitrile poppets and brass nozzles.

A wide range of hydraulic oils includes biodegradable hydraulic oils, based on rapeseed and synthetic base stocks and food machinery lubricants that are food safe.

Gulf lubricants UK are now offering their customers one of the broadest ranges of hydraulic oils available in the market. In addition to their well known Harmony AW (Anti-Wear) grades, Gulf also offers HVI (High Viscosity Index) multigrade hydraulic oils which cover wider operating temperatures, plus zinc-free products for equipment with silver components. The Gulf range also includes biodegradable hydraulic oils, based on rapeseed and synthetic base stocks.

Gulf Food Machinery Lubricants include Food Safe Hydraulic Oils, gear and chain lubricants and greases.

For Industrial customers, Gulf also offers special fire resistant hydraulic fluids, turbine oils, and special new technology water contamination resistant hydraulic oils that resist the formation of oil / water emulsions.

This enables water contamination to be isolated and separated out, extending the life of the oil, and preventing damage or increased wear to hydraulic equipment.

High pressure transducer and transmitter can measure very high pressures from 1000 bar (15,000 lb/in2) up to 5,000 bar (75,000 lb/in2) in high pressure testing and machine hydraulic systems.

The TPH High Pressure Transducer and the TPHA High pressure transmitter can measure very high pressures from 1000 bar (15,000 lb/in2) up to 5,000 bar (75,000 lb/in2) in applications which include high pressure testing, hydraulic fatigue testing, burst testing, destructive testing, machine hydraulic systems such as water cutting machines, diesel injection testing and ultra-high pressure sterilization for the food industry. The sensing technology of the TPH and TPHA High pressure sensors incorporate an extremely reliable 15-5ph stainless steel diaphragm with proven photo engraved metal leaf strain gauges formed into a four arm Wheatstone bridge circuit to provide a robust pressure sensing assembly which performs well in systems which exhibit high over-pressure spikes and cavitations. The standard ranges available for the TPH and TPHA are 1000bar, 1500bar, 2000bar, 3500bar and 5000bar and the sensor can be scaled to any range from 1000 bar to 5000 bar as a special execution.

The accuracy for all ranges is 0.3% of full scale including linearity, hysteresis and repeatability.

For high dynamic response applications the TPH pressure transducers unamplified output signal of 2mV/V makes full use of the frequency response of the measurement diaphragm which ranges from 18 to 80kHz at full scale pressure.

The TPHA electronics package offers zero and span adjustment for fine tuning the pressure transmitters amplified voltage or current output signal which are easily accessible via the two fixing screws which are located along the body of the sensor.

There is also an integral calibration signal that can be selected for simulating an applied pressure when scaling or calibrating an instrument for use with the TPH or TPHA.

The flexible electronics design provides a variety of output signals of 4-20mA, 0-10V, 0-5V, 1-5V.

Due to the very high pressure range of the TPH and TPHA only two pressure connections are offered which are the F-250-C (9/16-18UNF) female autoclave fitting and the M16x1.5 female.

As standard a DIN43650 plug (IP65), Bendix military style electrical connector (IP66), or integral cable can be selected for the electrical interface to suit the environment in which the sensor will be used.

The TPH and TPHA family of High Pressure Sensors has been developed solely for the measurement of very high hydraulic pressures and has all the necessary product features that you would expect for hydraulic applications such as high dynamic response, durable and reliable diaphragm, and high integrity mechanical construction.