AVID Technology’s eFan Micro Hybrid

Saving the planet and your pocket through electrification

Suitable for retrofitting to virtually any bus, AVID Technology’s eFan micro hybrid system promises a list of attributes including the ability to trim fuel consumption by up to 15%, reduce the time a bus spends off the road by improving its reliability, reduce its maintenance costs, cut the risk of engine bay fires and lessen noise and vibration; it even has a kerbside quiet mode. Stuart Jones went to AVID’s Cramlington headquarters to meet MD, Ryan Maughan and Sales director, Chris Waine and learn more about it, how it came to be developed and the company that produces it.

AVID Technology’s new premises on the Admiral Business Park in Cramlington

AVID Technology’s new premises on the Admiral Business Park in Cramlington


It is hard to believe that 35 year old Ryan will have been running AVID Technology, originally called Comesys, for a decade in November, because he had two previous careers. One involved touring the world tuning the engines in GT racing cars in and the other, ‘a proper job’, working for a friend’s high performance bearing company based in the North East. The break with gas guzzlers came when he met a girl, now his wife, studying at Manchester University. She questioned where he was going and it was an epiphany moment for him, after which he was determined that whatever he did was going to be a benefit to the world. He commented, ‘the green you see on the walls isn’t just for show, we take it very seriously.’ He is not a bus guy as such, but he does want to do something to help the industry.

The relationship with mechanical items started at a very early age because his father ran a plant hire and haulage company, so he grew up working on vehicles. Though the bearing business was a great one, and the company was doing well, he left because he had spotted a niche that he wanted to develop on his own. With the advance of electronic engine and emissions control, he saw an opportunity to become a leading player in the provision of control systems for heavy duty vehicles. The name Comesys was an abbreviation of control and measurement systems, and the business began, in a small way at first, developing the expertise it needed.

After a few years, they were approached by a large Asian bus manufacturer who asked them to improve the control system for their hydraulically driven cooling pack in order to improve performance and reduce fuel consumption. They looked at it and concluded that there was a better way to approach the problem. As a result they designed a new system for the vehicle, electrifying the cooling pump, the thermostat valve and the fan system. It was the start of something that has grown massively since.

It was clear there was a real opportunity to generate fuel savings and when they started talking to engineers within the industry they found that the existing hydraulic fans were top of a list of reliability issues and not infrequently the cause of hydraulic fires.

Confident that there was a need for a new product, they did a lot of work on the design and control of electric fan systems, gradually refining them. A problem was that there was not a fan you could buy that did the job they needed it to do, there were plenty that were designed for static environments and were somewhat flimsily built but none for the harsh environment of a bus engine bay, so they had no alternative but to develop one, along with the control systems and a high output alternator.

Around 2008-2009, the product they had developed started to take off in North America as a retrofit item. Systems in this market were bigger and so was the cooling need. The main drivers in this market were reliability and reducing fire risk. With fuel relatively cheap, operators were less fuel conscious, though they understandably saw reduced consumption as a useful benefit.

Early in the process, around 2004, an alliance had been formed with a well respected company called Engineered Machine Products (EMP) which handles the business in the USA. Giving an idea of the scope for the product in the US market, Ryan said, ‘it’s almost every bus. Most buses in cities have them. We have now progressed to OEM fit either as standard or an option on all buses. We are doing around 3,000-4,000 systems a year.’

Tackling the UK market, as Ryan wanted to do, was a more difficult proposition because of the grants available and the impact they had on fuel costs. BSOG made the effective price of diesel relatively low at around 30p a litre for many years. Avid started working with an established supplier of cooling products but that relationship broke down.

It forced Ryan to take a new tack and that was to set up the company’s own independent supply operation. An installation network was built up with four directly employed installation teams.

One of the first contracts won in the UK was from Blazefield who wanted to upgrade and refurbish 15 Wright bodied Volvo B7TLs for use on the Witch Way service. He recalled, ‘people were sceptical then but now all of the groups are doing it. Reliability is a big thing and our product makes a big difference to a bus. Why would you spend £15-30,000 on a bus and not do it? The cost of our system is small by comparison at around £5,000.’

‘Another initial customer was Metroline which has 200 kits installed on its fleet of Volvo B7TLs. Now we have a good strong customer base, with Arriva, Go-Ahead, Abellio, Ipswich and Trent Barton to name a few, all being proactive and installing the AVID eFan micro hybrid system’.


On a conventional hydraulically driven fan system, air is sucked from the outside of the bus through a charge air cooler with a hydraulic oil cooler alongside and then through a jacketed water filled radiator by a large fan driven by a hydraulic motor and controlled by a hydraulic control valve. AVID say this method traps debris within the system making it less effective. The debris becomes difficult to remove and the radiators are easy to damage. The system is also prone to hydraulic leaks.

This heat exchanger removed from a bus shows how conventional hydraulic fan systems can become clogged, as well as how easily damaged the protruding fins are

This heat exchanger removed from a bus shows how conventional hydraulic fan systems can become clogged, as well as how easily damaged the protruding fins are

With the AVID eFan micro hybrid system, air flows through a bank of high performance brushless DC electric fans, cooling a charge air cooler and a water radiator. There are usually six fans, four cooling the water system and two the charge air. Cooling the charge air cooler and the water radiator independently enables their temperatures to be more accurately controlled. The electric fans used are units specially designed for vehicle applications delivering 50% more airflow than the most efficient similarly sized units available commercially. They can be run in reverse, effectively as powerful blowers, to remove accumulated debris and keep the system running cleanly and efficiently. There is no hydraulic system so it can’t leak and doesn’t need cooling.

The system is controlled by an electronic controller connected to the vehicle’s CANbus system. It monitors the water temperature through a sensor in the radiator inlet and the charge air temperature through a sensor in the charge air cooler outlet. There are three functions available to the maintenance team on each system, a reversing switch that enables the fans to be run as blowers, a diagnostic connector port and a diagnostic lamp button.

More benefits

Ryan and Chris explained more about why they believe their system is better and more fuel efficient. A major difference between the hydraulic and electric systems is the energy required, Ryan explained. When operating at full capacity, the eFan uses 3kW compared with a figure of around 20kW for a hydraulic system. On top of this, it only runs when needed and switching itself off when it isn’t. This ensures that engines operate at their optimum running temperature and also, because the fans do not operate when they are not needed in the early stages of a vehicle’s duty cycle, reduces the warm up time.

They point to the absence of hydraulic fluid as a significant safety factor because, they claim, it if often a hydraulic problem that will start an engine bay fire or exacerbate one started in another way.

Another benefit from fitting an eFan is a reduction in problems with diesel particulate filters (DPFs).  This is because additional soot is created when engines are not running sufficiently hot to optimise combustion. This soot collects in the DPF and the exhaust temperature is often not high enough to burn it off. As the eFan helps keep the engine running at its best temperature, less soot is created.

In more extreme cases of overcooling, it can be that overcooled coolant is released into the engine by the thermostat creating thermal shock which damages the power unit. Only running the fan when it is needed makes overcooling less likely and reduces instances of thermal shock.

Elucidating on the benefits of the eFan Chris said that typically, a bus radiator was designed to last a couple of years at most but the eFan was designed to last at least ten years and was essentially a fit and forget type system. He said that a robust technology called bar and plate was used because, while the traditional tube and fin construction method was OK on trucks, it was less durable in bus applications. The eFan was designed to be robust for bus applications, which was hard. He pointed out that although the eFan was more durable it was not heavier. The complete pack weighs 60-70Kg which is comparable to a conventional hydraulic pack. ‘We don’t have a heavy hydraulic fan and supporting framework,’ said Chris, adding, ‘because of this there is less vibration and less noise.’

Noise is increasingly important and here there are advantages to the eFan in two more respects. Firstly, there is a kerbside quiet feature that has been developed whereby at below 5kmh, the noise output is reduced through an algorithm that prevents overcooling. Secondly, and of local benefit to operators with residential neighbours, is the low start up noise characteristic that it gives a bus because the eFan does not activate as soon as it is turned on, only when the engine reaches a temperature at which it needs cooling. It is also quieter because it runs for less of the time.

An advantage that becomes increasingly important as space becomes ever more at a premium within the bus envelope, is the eFan’s packaging attributes. ‘We can split the charge air from the water and have the relevant components in different locations, which is far more difficult to do with a belt or hydraulic driven system. Also, with one big fan you have to have a big square heat exchanger but with our smaller multiple eFans you can have virtually any shape of heat exchanger.’

A newly completed e-fan at the end of the production process

A newly completed e-fan at the end of the production process

An option you don’t get on a hydraulic fan is the ability to reverse the operation of the system, at the push of the button on the left, to blow out any debris collected in the heat exchanger:radiator

An option you don’t get on a hydraulic fan is the ability to reverse the operation of the system, at the push of the button on the left, to blow out any debris collected in the heat exchanger:radiator

Having multiple smaller fans, the number depending on the cooling requirement, makes efficient packaging far easier than with a single large hydraulic fan which can only be mounted within a large square box

Having multiple smaller fans, the number depending on the cooling requirement, makes efficient packaging far easier than with a single large hydraulic fan which can only be mounted within a large square box

He continued, ‘We can fit an eFan on literally anything. Kits are offered for all leading UK models from all manufacturers. Anything post 2000 and some before.’ One of the most popular applications is on the Volvo B7TL.

Using a demonstration unit based on the system for a Volvo B7TL that readers may have seen at trade exhibitions, Ryan and Chris showed me some other strengths of the system. For example, if there is a sensor failure the bus can still limp home. Ryan demonstrated this by disconnecting the controller, whereupon it became a bit noisier but continued to operate. He also pointed out the difference between the construction of AVID‘s heat exchanger and that of a removed hydraulic unit, the AVID system having a more substantial matrix and the bar and plate system Chris had described. The fins sit behind bars within the radiator so that they are offered some protection, rather than protruding where they are more vulnerable, not only from debris damage but also over enthusiastic pressure washing.

Next month, TfL’s refurbishment specification will alter to require that if a fire suppression system is activated, the fan system should switch off immediately and automatically to prevent the fire suppression media being blown out of the engine bay and to prevent it fanning the flames. The AVID system already takes account of this.

Ryan commented, ‘There’s a lot of intelligence built in. We can monitor between five and ten functions on a bus including temperature. It helps us control some of the control algorithms for the bus if we know what has happened to it.’

‘We’re not pedalling snake oil. It’s all properly developed, validated and will work and be reliable,’ said Ryan.

Prices range from £4,500 to £8,000 but for most popular applications, the price of a brand new eFan micro hybrid cooling pack system is around £5,000. Chris Waine ran through exactly what you get for that with me. It includes a heat exchanger/radiator; electric fans; an electronic control unit (ECU); fitting by trained staff; and final two years parts and labour warranty.

In total, more than 10,000 systems are now running worldwide and sales are starting to take off in Europe. ‘We’ve probably supplied 600 systems on buses in Europe since 2005,’ said Ryan. ‘We did over 100 last year; we’ll do 300 this year and probably around 1,000 next year.’

‘Based on 40-50,000 miles a year, payback is normally between 12 and 18 months, 18 months on fuel saving alone,’ Ryan told me. ‘It takes a day to install. You can do it here at the depot or we can come and do it at your premises for £5,000. Most of what we do is big bus: Enviro400, Citaro, B7TL, B7RLE, but also Solo. With Solo it is more of a reliability thing, but it still gets good fuel results. We have done Darts and the MAN 12.240. We’ve done quite a few for MAN operators. It helps the engine out.’

Although each unit is built to order, I was told that they do try and keep some stock. ‘We try to build in advance of the required date so we can make back up stock available,’ said Ryan.


The company is planning for a long and productive future and is preparing for it. It recently moved into new premises on the Admiral Business Park in Cramlington. At 30,000 sq ft they are much larger than the previous 7,000 sq ft ones which have been retained and will, once refurbishment is complete, become a dedicated engineering centre and test laboratory. In the meantime these functions are located within the new building.

AVID have only recently moved to the new premises. They are far bigger than their previous ones which are being retained and will become a research and development centre after refurbishment

AVID have only recently moved to the new premises. They are far bigger than their previous ones which are being retained and will become a research and development centre after refurbishment

One of the team of design engineers working on a new system

One of the team of design engineers working on a new system

At present the company employs 35 people but that is set to increase. The four installations teams will be increased in number to eight so Ryan is recruiting for qualified installation technicians. He is also looking for design engineers to join the strong engineering department of ten people. He told me that the main driver for this recruitment was OEM business.

Aside from the offices and research department, the main shop floor is divided into two with three van loading bays and three installation bays in a workshop area to the left and the production area to the right. There is also a considerable degree of space devoted to the storage of obsolete units removed during upgrades, much of which will eventually be scrapped once all recyclable parts have been removed. ‘This is where hydraulically driven fan systems come to die,’ he joked. All are properly recycled and disposed of.

The eFans are produced in an inverse production cell in the middle of the production area. This has a work station in the centre and the pallets containing the various components required situated around the outside of a square. There is also a wire harness assembly cell at one side of the plant along with a coolant pump cell. Ryan told me that £20,000 had just been invested in additional production equipment to expand harness manufacture that would be delivered shortly. A 100% test on all systems is conducted before they are shipped out.

To look at the factory at present the considerable interior space looks somewhat under utilised but this will gradually change because by the end of the year AVID is to transfer in from America the production of the fans used within its systems, as demand has reached the point at which it makes sense to do so. The relationship is being maintained with EMP, which hitherto produced them.

New products

‘We are always looking at ways to improve the performance of the bus. Our expertise is in rotating electrical machines and their control and we are now developing other products to electrify the other ancillary loads,’ said Ryan. ‘It will give us a full retrofit package that electrifies everything and combines it with a very efficient generator. There is a trend towards electrification in the bus industry. We are currently working with leading OEMs as well as engine manufacturers. We already supply a number of OEMs with equipment for full hybrids but the demand and interest goes far beyond this. People want to improve diesel buses because the cost of a full hybrid is significant. We can electrify anything conventionally driven off a belt drive.’

One product currently under development will be several years before it is released. The company is not afraid to work on long term projects for which the payback period is some way off. ‘We’ve just started a project for equipment for which the prototyping stage is three years,’ he told me, ‘We’re delivering sustainable technology solutions.’

It isn’t only new products that are being developed; attention is also being paid to developing the UK network. Ryan explained, ‘We are currently looking to appoint four or five installation partners as installation centres. They will be able to fit the systems while other refurbishment work is being done. It’s about cost and capacity. We will have them in place by the end of the year.’ The move is prompted by the growing importance being placed on preventative maintenance with refurbishment becoming more commonplace. Working in this way an upgrade to fit an eFan can be undertaken at the same time as a refurbishment without the need for the bus to spend more time off the road.

‘We see the future for retrofits of technology to improve vehicle performance increasing dramatically because of fuel costs, financial pressure and Government legislation. We also see the OEM market developing as well as a result of direct pressure from operators. It means that with some things we are working with the bus manufacturers but with others we are working with the engine manufacturers as well.

He stressed, ‘It’s really important to work with people who share the same values in terms of wanting to do a good job. It’s quite a technical product and you need the right skills to install it.’

Last word

It’s always good to go somewhere and be really impressed and you cannot fail to pick up the buzz that Ryan’s enthusiasm for more efficient vehicles generates. That enthusiasm is tempered with a determination to ensure that everything produced performs as it should and he sounds sad rather than gloating when he shows you the after effects of a system he has removed that does not perform as efficiently.

Ryan may not be in to fast cars these days but he still drives a BMW 5 Series. When I mentioned it he said, ‘It’s because BMW was the first to fully electrify the engine ancillaries. It’s one of the reasons why their diesels are so good.’





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