70W continuous power from small DC motor

A continuous power rating of no less than 70 watts is offered by 30mm diameter ironless-rotor DC motors in the new 30GT range from miniature motor and gearbox supplier Portescap. These tiny motors, which are just 62mm long, combine their high power/size ratio with extended operating life, thanks to the use of high-quality graphite-copper brushgear and precision ball bearings. Portescap 30GT motors are currently offered, as standard, for use on 24V or 48V supplies.

Custom motors for other supply voltages are, however, available to order.

The typical maximum operating speed for all models is 11,000 rpm, with 24V units capable of developing continuous torques of up to 83 mNm, a figure which rises to 104 mNm for 48V motors.

All 30GT motors can operate well in excess of their rated torque for short periods.

Benefits of the Portescap ironless technology used in these new motors include low friction, low starting voltage, absence of iron losses, good thermal dissipation and a linear torque-speed characteristic.

All of these factors facilitate the use of the units in high-performance drive and servo systems.

Their high efficiency means that they are also an ideal choice for applications in battery-powered equipment.

To complement its small, but powerful, 30GT ironless-rotor motors, Portescap offers an extensive range of standard and custom miniature gearboxes.

Designed for simple and speedy attachment to the motor, these gearboxes are available in both spur and planetary versions, with a wide range of reduction ratios.

Portescap is a subsidiary of the Danaher Motion Components Group, a part of the multinational Danaher Corporation, and is a world leader in the development and manufacture of motion control products.

Conveyor upgrade is ahead of schedule

David Brown is ahead of time with its management contract to overhaul and upgrade the massive conveying system at Australia's Yallourn power station in Victoria - in turn part of a huge scheme that involves diverting the Morwell River and upgrading and modernising Yallourn mine. With the two year contract for Yallourn Energy (now called TRUenergy Yallourn) stipulating completion of 15 conveyor drive assemblies by September 2006, the company has already completed that number as well as two gearbox spares in a clear demonstration of its asset management capabilities as well as its widely recognised technical prowess. Extra work was also required following a serious fire in December 2005 that necessitated the urgent refurbishment and relocation of a number of drive conveyors in order to keep Yallourn operating.

Concurrent with this urgent work was the refurbishment of critical drive gearboxes on a large overburden dredger which was undergoing upgrade at the same time - David Brown once again pulled out all of the stops to assist Yallourn Energy at this difficult time.

Each of the 25 year old conveyor drive assemblies comprise a 370 or 610kW electric motor, gearbox, brake and fluid coupling, to absorb shock loading of the conveyors, all mounted on a base plate.

Whereas the gearboxes, of various origins, were transported from Melbourne and overhauled at David Brown's own facilities at Bulli, New South Wales, the work on motors and couplings was subcontracted.

The smooth running of the project therefore demonstrates the project management skills and QA knowledge of David Brown's management team and workforce.

Yallourn Energy had initially approached David Brown early in 2004 when the process of site visits and tendering was initiated.

On signature of the contract in the following December the real work began which required fortnightly meetings on-site to ensure the smooth running of the project.

The principal's requirements of stringent QA documentation, refurbishment to EOM standard or better, full load testing off site plus incorporation of condition monitoring devices on all refurbished equipment were challenges met by David Brown.

David Brown has also undertaken additional refurbishment works on the Yallourn overburden dredger drives, all based on the main contract terms and conditions.

'The Yallourn contract has been a very steep learning curve for us', commented David Brown Project Manager Geoff Kinniburgh.

'We were confident that we had all of the necessary experience and expertise but quite frankly we had never handled a project of this scale and importance before'.

'In completing the project successfully and ahead of time, I believe we have built a real reputation for ourselves in the field of asset management that will stand us in good stead for the future'.

In fact, as the two-year project approaches completion, David Brown is confident that it will be able to negotiate a possible extra 6-year renewal having demonstrated a much greater degree of ownership of Yallourn problems and challenges than previous asset management companies.

Yallourn W power station, located 160km east of Melbourne, provides 24% of Victoria's power and 8% of the national requirement, and the adjacent open cut brown coal mine is the second largest in Australia with available reserves sufficient to meet the projected needs of the power station until 2032.

To allow unimpeded access to the coal field a project was begun five years ago to divert the Morwell River and was recently completed on time.

The 3.5km diversion is an impressive feat of modern engineering in itself and cost Au $122 million (over GBP 50 million).

The mine upgrade and modernisation programme was also undertaken in the five year period and involved works to fixed conveyor plant and infrastructure that totalled an additional Au $50 million (GBP 20 million).

Synthetic grease for washing machine transmissions

Some washing machine manufacturers are designing new planetary gearboxes using plastic gear materials. Others maintain conventional, cut-metal, spur gear designs. However, if they rely on standard petroleum oils to lubricate those gears, they all have two things in common: leakage concerns and the added cost of seals and gaskets.

Using Nye lubricants synthetic greases can solve both problems.

Although synthetic greases may cost more than petroleum oils, it delivers large ROIs by eliminating oil seals, gaskets, silicone sealants and associated manufacturing costs - and the cost of damage control if the transmission leaks oil on a customer's brand new hardwood floor.

Nye Lubricants supplies greases for plastic gearing, cut and powered metal gears, cut metal and plastic gearing, plastic gearing and light-duty clutch mechanisms.

Newgate Simms is the exclusive UK distributor for Nye Lubricants.

Brevini integrates Posiva Drives

Designers, OEMs, and plant and process engineers are set to benefit from a wider range of solutions to their power transmission problems, following the integration into the International Brevini Group of Posiva Drives. As part of this integration, Posiva will change its name and in future will trade as PIV Drives UK. The UK incorporation follows the purchase, in 2002, of Posiva's German parent company, by Brevini Ruduttori.

It brings together the activities of Brevini UK and PIV Drives UK under the control of Guiseppe Galli, General Manager of Brevini's UK operation, which is based at a new purpose built facility in Warrington.

The partnering of the two UK companies is essentially seamless for customers as PIV is remaining at its base in Scunthorpe, Lincolnshire.

"The coming together of Brevini and PIV in the UK is good news for our customers", said Guiseppe Galli.

"The complementary product ranges offered by the two companies means that we are able to offer solutions to a wider range of industrial power transmission applications.

Moreover, our newly synergised operations mean that - more than ever - we will be able to provide the latest concepts in gear technology to solve the most complex of drive problems cost effectively for our customers".

The product ranges allied by the integration of Brevini and PIV are both top of their class in terms of quality, efficiency and flexibility.

The high torque, compact size, and low weight advantages of Brevini's planetary gearboxes mean that they are increasingly the first choice in industrial and process applications, having dominated in the mobile sector for a number of years.

The versatility in design and flexibility in the number of options available mean that Brevini's planetary range is suitable for use in a wide range of industries.

These include materials handling, water treatment, quarrying, food processing, waste disposal (crushers), marine (winches), steel, mining, agriculture, machine tools and construction.

PIV's helical, bevel helical and spiral bevel gearboxes are market leaders for design, quality, power/weight ratio and price per kilowatt.

The company' s experience is second to none and the recent introduction of the modular Posired 2 range of helical and bevel helical gears has revolutionised the market, enabling gear problems to be solved "off the shelf" with considerable savings potential for the user.

Choose the most appropriate drive for the job

Electronic servo drives are certainly in vogue. For many design engineers, they are the preferred choice for systems which synchronise and co-ordinate the movement and position of fast moving components. Clearly they have an important contribution to make but they are not necessarily the right choice for all applications.

A mechanical solution may not be as technically exciting but in many cases it can be more reliable, more accurate and far more cost efficient in the long run.

Mechanical drives are often seen as old fashioned and low tech.

In truth they are the subject of much development.

The fact is mechanical drives are increasingly getting better and those at the quality end of the scale are now able to deliver even greater accuracy and reliability.

More accurate machining of components, more durable materials, higher quality bearings, new methods of heat treatment, and heating which effectively eliminates any distortion - all these elements have contributed to the significant improvement.

The electronic drive is often sold on the basis of it being more accurate than its mechanical counterpart.

Certainly mediocre quality mechanical drives may be inferior but those at the higher end of the quality scale can far exceed the accuracy of the electronic drive.

The main benefit of a largely mechanical system - one comprising line shafts and bevel gear boxes - is that its accuracy is maintained throughout the system.

Basically, what you put in at one end, you get out the other! Within one revolution a mechanical drive will always repeat itself, it will always return to its original position.

Of course the transmission error of a geared system must be considered, but this can be measured.

It is a known quantity for which compensation can be made if necessary.

In a multi-stage process driven by electronic drives, the relationship between the position of the product and various elements of the machine is fed back to the controller by a variety of peripheral sensors.

The system is therefore far more complicated and often servo motors cannot respond fast enough to achieve the required degree of accuracy.

By its very nature, an electronic drive system will only respond to where the product was in relation to the drive, not where it is.

There are however, applications where a single electronic drive offers advantages over a single mechanical drive.

If you need fast response and where the application involves changes in motion, the electronic drive is the best choice.

It is ideal for replacing cams and for applications which require high torque for fast acceleration and braking.

However, if the whole system requires high torque, the electronic drive and motor will need to be large and may be very expensive.

In this case a motor/gearbox solution will produce high torque far more cost-effectively.

Electronic drives are also limited when it comes to providing high torque at low speed; gearbox speed reduction is the only viable solution.

Electronic drives are often chosen for machines used to produce or process a number of different products.

Stored set-up data can be quickly called-up to re-set the machine with changed parameters.

But an electronic drive does not always have to be the foregone conclusion.

Speed modulation gearboxes are increasingly being used in packaging machines and in particular cartoning machines.

These gearboxes allow adjustments to be made in machine set-up to accommodate different carton sizes at a much lower cost than having all components being driven and controlled electronically.

Notably, the speed modulation gearbox offers considerable benefit over traditional systems comprising gearboxes, line shafts and chains.

Adjusting such a mechanical system would take upwards of 45 minutes.

Systems using speed modulation gearboxes, with a manual adjustment, may take just two minutes to set up.

Although the cost of servo drives is certainly reducing, they remain expensive in relation to mechanical drives.

One of the main cost penalties is the programming back-up they require.

In fairness, the majority of good servo drive manufacturers do offer this service but help is not always readily at hand in the middle of the night shift! Also when problems occur in an electronically driven system it can be difficult to know where to start.

A largely mechanical system is much more simple and user-friendly.

A problem is easier to track down.

Updated website for motor supplier

In addition, the complete range of Premotec gearboxes is also featured - with spur and planetary versions available.

Detailed data sheets can be easily downloaded on all the above product types including fully productionised, mature products in the range plus recently launched part numbers from the brushless and coreless motor families.

The site will be regularly updated as new products are launched.

Of particular interest to customers requiring long-life, simple operation and fully integrated electronic controls will be the recently extended BL58 motor family which now includes products from 35 to 70 watts in a variety of stack lengths.

The smaller, BL48 family now includes motors with or without electronic control of speed and tacho signal.

Versions are available in 8 and 12 watts.

The site is very easy to use with each page uploading quickly so that no time is wasted waiting for your valuable information to arrive.

As well as providing detailed data on the Premotec range of products, there is also an introduction to Premotec, it's products and capabilities.

Geared products have ATEX compliance covered

ATEX directive 94/9/EC (also known as ATEX 95 or ATEX 100A) and the CE Marking Directive came into force in all EC member states from 1st July, and compliance is compulsory for anyone designing, manufacturing or selling equipment for use in potentially explosive atmospheres. The directive covers electrical and nonelectrical equipment and is not only relevant to obvious industry sectors such as oil and gas and chemical manufacturing.

It also impacts on a range of other areas endangered by potentially explosive atmospheres created by the presence of flammable gases, vapours, mists or dusts.

These may include plants handling cereal, animal feed, paper, wood, coal and flour, or locations where solvents are used extensively.

David Brown, a Textron Power Transmission company, is now equipped to provide full Ex compliant badging and certification where required for its range of standard gearboxes and geared motors, through self certification as allowed by the directive.

Products that meet the requirements of the ATEX Directive are marked by the manufacturer with the CE Mark and the Ex mark, along with the name and location of the manufacturer, designation of series or type, serial number, year of construction, Ex symbol followed by equipment group and category.

David Brown standard gearboxes can be supplied against Group 2 or 3 for surface industries; ATEX defines categories of equipment specified by their protection characteristics.

It also designates the hazardous location zones where they can be used: Zones 1 and 2 for gases, vapours and mists; Zones 21 and 22 for dusts.

David Brown Engineering has for some time been supplying mechanical products to meet the ATEX requirements in anticipation of enforcement.

The company has undertaken a programme of risk assessment and product evaluation in preparation for the ATEX enforcement as part of a wider TPT initiative, with special attention devoted to the installation and maintenance protocols.

Commercial Manager for Standard Products Richard Irons, who has been closely involved with the ATEX programme, explains: "Safety is a vital element in the design and manufacture of all our products, and as a matter of course we pay particular attention to critical areas such as lubrication and surface temperatures.

Service factors are an additional consideration to maintain the ATEX standard, so we insist that maintenance schedules and installation procedures, such as electrical grounding, are followed precisely

Marine gearbox is affordable alternative

The PRM 1750, Newage Transmissions' highest capability marine gearbox to date, will form the centrepiece of the company's joint presentation with its distributor, Albatross Marine, on Stand 31 at the Seawork 2005 international boat show - to be held in Southampton between 14th and 16th June. With a maximum torque capacity of 1750Nm, the PRM 1750 is suitable for engines rated at up to 457kW and is available in both shallow or deep gearcase configurations, with standard ratios from 1.22:1 to 4.90:1. Units also have integral SAE housings and can be supplied with trolling valve and clutched power take-off (PTO) options, enabling them to meet the widest variety of commercial and pleasure workboat applications.

The new transmission has been developed as an affordable and reliable alternative to twin disc, self changing gears, capitol and other drop centre gearboxes.

It features a twin countershaft design that is compatible with both left or right hand propeller rotations, making the transmission equally suitable for single or twin engine installations.

The PRM 1750 also uses maintenance-free, self-adjusting, oil-operated multiple-disc clutches for reliability and in-service performance, and allows maximum input torque to be transmitted continuously in either direction at speeds of up to 2500rev/min.

The use of lubricating oil of the same viscosity as the engine eliminates the need for automatic transmission fluid and ensures rapid response to control movements.

The gearcase is manufactured from high grade cast iron, which is internally ribbed for extra rigidity and strength, and the gearbox's operating lever has a positive neutral detent for use with proprietary single lever remote control operating systems.

In addition, the PRM 1750's oil pump and hydraulic control valves are mounted externally for easy access and servicing.

Further Newage gearboxes for commercial fishing vessel and work boat applications to be featured at Seawork 2005 will include PRM 500, 750, 1000 and 1500 models.

These are suitable for engines from 245 to 500hp and, in common with other Newage marine gearbox designs, have output shafts that can be rotated continuously in neutral, eliminating the need for a propshaft brake when running with an engine shut down.

As an additional safeguard, they also incorporate a mechanical lockup device that will enable the vessel to be brought safely back to port in the unlikely event of hydraulic failure.

Harmonic Drive sets up shop in the UK

Harmonic Drive has been a leading manufacturer and supplier of precision gears and actuators for more than 30 years in Europe. The company's core competences lie in the development, production and marketing of gear component sets, servo actuators, gearboxes or custom-made motion control systems which are manufactured at its facility and headquarters in Limburg (near Frankfurt), Germany. For many years the Heason Technologies Group was Harmonic Drive's sales partner in the UK and responsible for the sales and marketing of its products.

However, the continuous expansion of the company and its product range, coupled with positive UK business development, has necessitated the foundation of a new sales subsidiary, enabling Harmonic Drive to provide its specific knowhow directly to UK customers.

The company's new office is located at the Staffordshire Technology Park in Stafford, close to the M6 motorway between Manchester and Birmingham, at the heart of the UK manufacturing industry.

This is the first of a number of major investments in both personnel and facilities by Harmonic Drive over the coming months.

As a 100% daughter of Harmonic Drive AG, the UK company can now offer direct customer support by a local UK sales team.

"Customer care, short reaction time and intensive engineering support are the most important objectives for us", says Graham Mackrell, Sales Director of Harmonic Drive UK.

"Harmonic Drive UK aims to offer an improved level of services to all customers, now having the benefit of direct contact to specialist staff at our manufacturing plant in Germany".

"We will also try to offer customers some cost savings and shorter delivery times, where possible, associated with the purchase of products directly from the manufacturer", adds Mackrell.

Gearbox options make for flexible gearmotors

Following the launch of the new generation of helical geared motors from Leroy Somer, Industrial Motors and Gears is stocking inline, right angle and shaft mount gearboxes. Designed to exceed the demands of today's industrial applications, the new 3000 range consists of modular helical-geared motors. The CB3000 range is already in stock for same-day build an delivery.

The Orthobloc series (delivering its output via helical bevel gears) will be introduced over the next month to further extend the range.

The Poulibloc PB range of shaft mount speed reducers is also available 'off the shelf'.

Whatever the version, the advanced design of the 3000 range delivers up to 30% more torque than similar-sised competitors.

Dust and damp ingress protection has been improved, and a redesigned removable panel gives easy access for inspection and preventative maintenance.

A variety of mounting options are available for maximum versatility, including MI mounting with integral motor, MU universal mounting using a standard B5 IEC motor and AP input shaft with optional AP/AD antirunback.

A key feature of the 3000 range is its modularity: a unique integral mounting allows the same MI motor to be used on all three gearbox series, reducing the number of spare parts required.

The same Leroy-Somer integrated motors can also now be used across the entire 3000 range, making them the ideal choice for a wide variety of applications including ATEX dust, ATEX gas, variable speed, food and beverage and many others.

A wide variety of mounting configurations combine with various drive options for maximum versatility.

Mechanical help for steppers and servos

Total Motion Systems can supply a range of mechanical equipment to complement its stepper and servomotor systems. A series of high precision planetary gearboxes with ratios from 3:1 to 400:1 gives torque outputs up to 3500Nm from input speeds of up to 6000rev/min. Backlash options range from 30 down to 1arc-min, and the gearboxes can be fitted with flanges to suit almost any motor.

Linear actuators and tables are available with ballscrew and belt driven variants.

These can be fitted with stepper or servomotors to give accurate linear positioning.

The ballscrew electric cylinder range is available in ISO frames 32, 50, 80, 100 and 125 and can produce thrusts of up to 44.5kN and variable speeds up to 2m/s.

Positioning tables are available with strokes up to 2m, and can move payloads up to 1000kg at up to 0.5m/s.

Higher loads and longer strokes are available in a range of high payload linear actuators.

All these linear products can be used as single-axis systems, or can be linked together to produce multi-axis gantries.

The TMS mechanical range is further enhanced by a series of stepper-motor-driven rotary tables.

Among their features are indexing repeatability to 12arc-sec, load capacities to 90kg and 360-degree continuous travel.

Table diameters up to 305mm are available.

Also available are linear and rotary manually driven tables and slides.

The linear slides range in size from 11 to 150mm wide with travels up to 305mm and have load capacities from 25g to 100kg.

Rotary tables have load capacities up to 90kg and diameters up to 305mm.

Harmonic Drive sets up shop in the UK

Harmonic Drive has been a leading manufacturer and supplier of precision gears and actuators for more than 30 years in Europe. The company's core competences lie in the development, production and marketing of gear component sets, servo actuators, gearboxes or custom-made motion control systems which are manufactured at its facility and headquarters in Limburg (near Frankfurt), Germany. For many years the Heason Technologies Group was Harmonic Drive's sales partner in the UK and responsible for the sales and marketing of its products.

However, the continuous expansion of the company and its product range, coupled with positive UK business development, has necessitated the foundation of a new sales subsidiary, enabling Harmonic Drive to provide its specific knowhow directly to UK customers.

The company's new office is located at the Staffordshire Technology Park in Stafford, close to the M6 motorway between Manchester and Birmingham, at the heart of the UK manufacturing industry.

This is the first of a number of major investments in both personnel and facilities by Harmonic Drive over the coming months.

As a 100% daughter of Harmonic Drive AG, the UK company can now offer direct customer support by a local UK sales team.

"Customer care, short reaction time and intensive engineering support are the most important objectives for us", says Graham Mackrell, Sales Director of Harmonic Drive UK.

"Harmonic Drive UK aims to offer an improved level of services to all customers, now having the benefit of direct contact to specialist staff at our manufacturing plant in Germany".

"We will also try to offer customers some cost savings and shorter delivery times, where possible, associated with the purchase of products directly from the manufacturer", adds Mackrell.

Gearbox is crucial to satellite success

The recent successful launch and subsequent solar array deployment of the Eur 2 billion (GBP 1.2 billion) Envisat satellite depended on a 4in-diameter gearbox, created by David Brown Engineering. The gearbox controlled the deployment of the satellite's crucial power-generating solar array. The Envisat environmental monitoring satellite is the largest satellite yet launched by ESA (the European Space Agency).

It boosts Europe's capacity to take part in the study of the Earth and its environment by supporting critical research programmes on global warming and climate change issues.

The satellite depends for power on a giant solar array capable of generating up to 8kW of electricity.

The solar array design was termed 'flatpack', because it was folded away during the launch.

Once the satellite was stationed in orbit the Flatpack was deployed using a battery operated electric motor in combination with a cable pulley system, with power routed through the David Brown Engineering gearbox.

Control is effected by an epicyclic gear train of a two stage sun and triple planet wheel arrangement giving an overall ratio of 38:1.

Fokker Space, the contractor for the solar array has a 100% record of successful solar array deployments and chose David Brown as a partner in the confidence that the gear specialist would help maintain this record.

Phil Dalton, Technical Sales Manager for David Brown Engineering said: "The small gearbox only had to operate once but it had to work with absolute certainty in a harsh environment and following the stresses imposed by a rocket launch.

In space, on a satellite orbiting at this distance above the earth, there are, of course, no opportunities for repair and servicing!".

Every component on the satellite is critical in terms of its weight and size.

An extra gram of weight on a mechanical component means one less gram for the satellite's monitoring equipment, likewise components and equipment must be balanced millimetre for millimetre.

The gearbox therefore had to produce the maximum power to weight ratio with the lowest possible space envelope.

David Brown engineered a gearbox which can be held in the palm of a hand, and yet was entirely capable of deploying the 70m2 solar array from its position folded within the body of the satellite to full deployment and 'snap-locked' into position.

On behalf of Fokker Space, Wim den Haak, Product Assurance Manager said: "I congratulate David Brown on the successful deployment of the solar array which was possible thanks to the co-operation between our companies during the development and manufacturing of this complicated solar array".

Phil Dalton of David Brown Engineering said: "This contract is a major success for David Brown, showing, as it does, the capability the company possesses to manufacture bespoke gearboxes capable of producing maximum torque in the most challenging environment and with absolute reliability.

It also demonstrates the underlying strength of the David Brown portfolio, encompassing gearboxes used in everything from military vehicles and ships, to power plants and industrial machinery".

The gearbox was originally designed by Alvis Transmissions, a company which David Brown purchased in 1998.

Development continued during the handover period.

David Brown is supplying similar gearboxes to another European Space Agency project, this being the METOP series of weather and climate monitoring satellites, the first of which is scheduled for launch in 2005.

Workshop looks at latest gearbox diagnostics

Cranfield University, together with its industrial partners, is hosting a half-day workshop on 'New technology for in-service early differential vibration diagnostics of local tooth damage in gearboxes'. Cranfield University in collaboration with three leading UK industrial partners and funded by the DTI, has experimentally adapted and validated a new condition monitoring technology which will substantially improve gearbox manufacturing, reliability and safety, provide significant reduction of maintenance costs and maintain gearbox quality. The technology is relevant to many applications, such as spur gears, bevel gears, helical gears etc.

It is of high benefit across a number of sectors: defence, aerospace, railway, automotive, power, shipbuilding, oil, gas, food, agricultural, mechanical and civil engineering.

Attendance at the workshop is subsidised by the DTI Basic Technologies for Industrial Applications (BTIA) technology transfer Programme and therefore costs just GBP 25 per delegate.

Choose the most appropriate drive for the job

Electronic servo drives are certainly in vogue. For many design engineers, they are the preferred choice for systems which synchronise and co-ordinate the movement and position of fast moving components. Clearly they have an important contribution to make but they are not necessarily the right choice for all applications.

A mechanical solution may not be as technically exciting but in many cases it can be more reliable, more accurate and far more cost efficient in the long run.

Mechanical drives are often seen as old fashioned and low tech.

In truth they are the subject of much development.

The fact is mechanical drives are increasingly getting better and those at the quality end of the scale are now able to deliver even greater accuracy and reliability.

More accurate machining of components, more durable materials, higher quality bearings, new methods of heat treatment, and heating which effectively eliminates any distortion - all these elements have contributed to the significant improvement.

The electronic drive is often sold on the basis of it being more accurate than its mechanical counterpart.

Certainly mediocre quality mechanical drives may be inferior but those at the higher end of the quality scale can far exceed the accuracy of the electronic drive.

The main benefit of a largely mechanical system - one comprising line shafts and bevel gear boxes - is that its accuracy is maintained throughout the system.

Basically, what you put in at one end, you get out the other! Within one revolution a mechanical drive will always repeat itself, it will always return to its original position.

Of course the transmission error of a geared system must be considered, but this can be measured.

It is a known quantity for which compensation can be made if necessary.

In a multi-stage process driven by electronic drives, the relationship between the position of the product and various elements of the machine is fed back to the controller by a variety of peripheral sensors.

The system is therefore far more complicated and often servo motors cannot respond fast enough to achieve the required degree of accuracy.

By its very nature, an electronic drive system will only respond to where the product was in relation to the drive, not where it is.

There are however, applications where a single electronic drive offers advantages over a single mechanical drive.

If you need fast response and where the application involves changes in motion, the electronic drive is the best choice.

It is ideal for replacing cams and for applications which require high torque for fast acceleration and braking.

However, if the whole system requires high torque, the electronic drive and motor will need to be large and may be very expensive.

In this case a motor/gearbox solution will produce high torque far more cost-effectively.

Electronic drives are also limited when it comes to providing high torque at low speed; gearbox speed reduction is the only viable solution.

Electronic drives are often chosen for machines used to produce or process a number of different products.

Stored set-up data can be quickly called-up to re-set the machine with changed parameters.

But an electronic drive does not always have to be the foregone conclusion.

Speed modulation gearboxes are increasingly being used in packaging machines and in particular cartoning machines.

These gearboxes allow adjustments to be made in machine set-up to accommodate different carton sizes at a much lower cost than having all components being driven and controlled electronically.

Notably, the speed modulation gearbox offers considerable benefit over traditional systems comprising gearboxes, line shafts and chains.

Adjusting such a mechanical system would take upwards of 45 minutes.

Systems using speed modulation gearboxes, with a manual adjustment, may take just two minutes to set up.

Although the cost of servo drives is certainly reducing, they remain expensive in relation to mechanical drives.

One of the main cost penalties is the programming back-up they require.

In fairness, the majority of good servo drive manufacturers do offer this service but help is not always readily at hand in the middle of the night shift! Also when problems occur in an electronically driven system it can be difficult to know where to start.

A largely mechanical system is much more simple and user-friendly.

A problem is easier to track down.

Given the right application, there is no longer any reason for an electronic drive to be dismissed on the grounds of unreliability.

They are certainly becoming more reliable.

However, if maintained properly, a mechanical system can be highly reliable and maintain the same level of accuracy over many years.

Again, we need to remember that a mechanical drive will always accurately repeat itself per revolution and that its accuracy can be measured.

This assurance allows an OEM to predict its own product accuracy with full confidence.

So, what of the future.

Will the electronic drive grow in popularity?

Gearless systems may sound Utopian but are they realistic?

The astute design engineer will recognise that whilst the electronic drive has its merits, so does the mechanical drive and a combination of the two in most multi-stage systems is certainly the best bet.

Even in the traditional printing press where the mechanical drive is king, servo drives could certainly play their part.

A typical system could comprise a single drive motor, a line shaft and gearboxes to branch off for all the colours.

A mechanical system is ideal here as print stations can require register accuracies down to less than 0.05mm.

This is well within the capability of a good mechanical drive system.

However, additional processes such as unwind or rewind could benefit by being driven electronically.

Motorised gearbox has flexible configurations

Ondrives has launched a new DC motorised worm and wheel reduction gearbox into its 2005 product range. They are fitted with high end 24V DC motors which when operating at 12V DC ensure good torque and speed characteristics. They are available in ratios from 10:1 to 120:1 as standard with fitted motors.

Thanks to the quality of the motors, Ondrives is able to offer variations on this, including encoders and brakes fitted to these motors.

This allows Ondrives to offer gearboxes tailored to more specific applications, capable of moulding their products to specific needs.

The gearboxes and motors are also available to purchase as separate components, allowing total flexibility for customers' applications.

Ondrives can also design and supply the gearboxes to accept customers' motors.

Suitable applications include medical and pharmaceutical industries, scanning machines and general OEM work.

They are always available to purchase in small or large volume quantities. Request a free brochure from Ondrives/Rino Industries....

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