In the 3rd article of Jim Whitton's machinery series, he explores the development of commercial mower electrical systems over the last three decades. He looks at what is state of the art now and has a glimpse of what the future might bring.
I will get off the fence straight away with this one, and say electronic systems on current mowers are far too complicated and add unwelcome elements of unreliability, and unpredictable ownership costs. They are often added just because they can be, and many systems don't add any tangible benefits to the actual mowing process. There are, of course, notable exceptions which I will cover later in the piece.
When I first started in the groundscare machinery industry, seat switches, operator presence controls (OPCs) and solid state controllers or ECUs had yet to be invented. The most complicated electronic control was the bit of spring metal that was used to ground the spark plug to the engine cylinder head to stop the engine! The only safety precaution was to make sure one's hands were dry in order to avoid an attention getting "belt" off the ignition system. How things have changed. This was the era of belt and chain drives operated by simple levers or pedal controls, where a 6.25hp single cylinder petrol engine would drive a 6ft cut ride-on cylinder mower all day on a couple of litres of fuel. Before you ask, yes, you could also buy 3 stone of monkey nuts and still have change out of a farthing as well, but I digress! Seriously though, a similar hydraulic machine today would struggle on 25hp! My question is; have we really made any progress, especially with regard to saving the planet? Making sure the machine was safe to start or to get off was down to common sense, something that seems sadly lacking today.
Don't get me wrong, I'm all in favour of safety and I have seen too many accidents caused by a simple momentary lapse of concentration. This is where the electronic safety system offers the greatest benefit. However, as with many safety inventions it takes legislation to drive change across an industry. And so it was with early safety systems such as OPCs on mowers.
The problem for machine manufacturers developing compliant new systems was the availability of electrical components that could live and be reliable in the harsh environment of the mower. Electrics and mowers was not a happy marriage. Moisture, vibration, temperature extremes and corrosion were typical issues that led to high failure rates in early systems. To most operators, these breakdowns were just a nuisance which spawned the very first electrical system "special tool". Called the "jumper wire", this state of the art emergency device became essential kit in many operator tool boxes and could be used most effectively on dark Saturday mornings when trying to mow golf greens on a "task and finish" basis and the mower broke down. Its use was of course strictly illegal and obviously not best practice, but it did get the operator home before "the match kicked off"!
It took a considerable time for component manufacturers to develop their switches and connectors to be able to deal with this application and, most importantly, be reliable enough to be depended upon in a safety system. These early systems were based on simple mechanical switches, basic unsealed connectors and crude wiring harnesses. Let's call these systems 1st Generation.
The 2nd generation mower electrical system evolved in response to changes in mower design. As more functionality was required and higher currents were needed to power the likes of electro-magnetic blade drive clutches, and solenoid operated hydraulic valves, simple switches were just not up to the job. Enter the relay based systems.
The relay was basically a remote control heavy duty switch. A light duty switch was used as the operator interface to control the relay. The heavy contacts in the relay were capable of operating much higher currents over many more cycles without burning out. It was a great solution, and one that is still reliable and simple today. The relay system is simple to fix, and diagnostics require only basic tools such as a cheap multi-meter. Because most relays were standard ISO units, "Get you going" field fixes could be as easy as swapping a relay from one circuit in the machine to another. Above all, they were very cheap to replace.
For the majority of mowers, even sophisticated ones, the 2nd generation system (pictured left) was perfectly acceptable, and in my view no further development was needed except for further improvement to the sealing on connectors and ensuring that the wiring harnesses were integrated into the machine design, rather than being an untidy afterthought!
Any electrical system is only as reliable as its weakest link. In a lot of cases, the weak link was the connector, or even the wire itself. Poor or high resistance connections rank high on the list of root causes of the dreaded transient or intermittent electrical fault. I often wonder why it is that when a technician arrives to troubleshoot an intermittent fault, the machines works faultlessly until he drives away back to the depot. I think it's probably due to sods law, or whatever the electrical equivalent is.
The quality of automotive wiring connectors has improved immensely over that last decade. They began to be designed to an IP (ingress protection) rating, which is essentially a measure of how resistant they are to contamination such as moisture. A good quality connector for mower use for example, would be IP67. These connectors have proper integrated seals and, although expensive, they are very reliable unless you pressure wash them! They would handle being underwater to a certain depth, but pressure washing is a different ball game.
Switches have also been improved, with many now having no moving parts at all. These sensor type switches are tricky to test compared with conventional ones, but some manufacturers have kindly integrated a test LED in the switch body. This makes diagnostics easy.
3rd Generation systems
This is where it gets too complicated. By now, we have moved forward to the glory years of the grounds maintenance industry. The market was buoyant and machine designers were all looking for "an edge" over the competition. Electronic component and systems suppliers were offering "off the shelf" programmable digital controllers and fully compatible operator information displays and joysticks. This provided machine designers with very cost effective digital control systems, with very little development cost. This was too much to resist for some manufacturers' designers and they became carried away with adding electronic gadgets to machines, in some cases, simply because they could.
The quality and ease by which complex systems could be constructed using these industrial, modular units was very impressive. Mowers now had CANBUS based electronics! The CANBUS offered functionality not possible with conventional relay based systems. But was this actually needed on mowers? Probably not.
The main attraction of the micro-controller was that lots of wiring and connections, as well as most of the system relays, could be eliminated and replaced by solid state components within the controller. It's nice and neat, but if one of the internal components fails, the only solution is to replace the whole unit at considerably more cost than an individual relay. Operator diagnostics on these systems is very limited to a few "slow" fault codes flashed by an LED on the controller case. More detailed diagnostics requires a dealer computer interface tool which, although excellent, is expensive. The programmable system allows software updates, so if a change in functionality is required, it's a relatively easy job to squirt in a new programme. I don't believe any of this complication is needed on a mower, but of the various digital systems available, this is by far the best.
Some manufacturers adopted bespoke, non-programmable controllers. These offered enhanced operator diagnostics with an array of input and output LED lights mounted on the controller case. These are very easy to use and generally don't require computer interfaces for diagnostics, but again, if just one internal component fails, or the magic black smoke escapes, I'm afraid it's a new box at considerable cost.
This is where things have definitely gone too far. You can't argue that true hybrid drives do offer some step change benefits such as eliminating the possibility of spilt oil on greens, lower fuel costs and unrivalled cutting consistency. The evidence is there
to be seen and is tangible. However, you have to ask the question, at what cost? I don't just mean the initial cost of the machine, but the whole cost of ownership. Some machines run complex CANBUS electronic systems with 5 or more ECUs communicating on a network. The reliability is good but, when things do go wrong, diagnostics can be complicated, and often very time consuming and expensive. Depending on the machine, some have fairly comprehensive operator fault code displays and audible alarms. This can help narrow down the cause of the fault, but as with most DTCs (diagnostic trouble codes), they are quite vague. Dealer diagnostic equipment is not as helpful as the equipment available for the common rail diesel engines discussed in my last article, and some dealers are still not up to speed with using it either. It's a shame that the dealer diagnostic tool was not developed to the same extent as the engine system tools. It would have been a great help to technicians and boosted their confidence in this type of product as well.
If you are tempted by the real benefits of a hybrid mower, then in my opinion, the only way to take advantage of the benefits and protect yourself from unpredictable, costly failures is to contract hire the machine and purchase the longest possible factory extended warranty available. At the end of the contract, hand it back and start again. So that's about where we are currently.
What then does the future hold?
I think since the financial crash, manufacturers are looking more closely at what the customer actually needs, rather than what's possible to make. Any future innovations would need to fill an "unmet need" before capital could be justified for development. The technology is already out there in other industries that could easily by adapted to the groundscare market, but the problem is, I don't think the market is ready for most of it.
Here are some examples:
1. Telematics: Already used in the construction and agricultural equipment market, this is one technology I actually do see as offering some real benefits. Remote machine health monitoring happens via a live link and is communicated directly back to the dealer and / or the users service facilities. Any fault codes (DTCs) logged by the machine are sent by text to the dealer's service department. Often the first thing the user knows about the problem is when the dealer phones to ask if they require a technician to be despatched to fix the problem. With this system, expensive repairs can be avoided, and operator misuse or abuse can be detected immediately.
2. Precision guidance: Again, already used worldwide in the agricultural industry, this technology can provide 2cm self-steer precision using a combination of GPS (Global Positioning System) and ground based correction stations known as RTK (Real Time Kinematics). The machine would auto-steer to a very accurate path guided by satellite. In theory, this could be used on mowers used in wide area applications to optimise overlaps and increase productivity. It could also be used when visibility is limited, for example, when mowing early morning or late evening.
3. Autonomous Mowers: This may not be as much Sci-Fi as you might think. But I doubt it will ever be cost effective for commercial mowers.
4. My prediction for future golf green mowers: I could see a small autonomous mower based at each green, solar powered, with a backup charge station landscaped into the green surround. The mower, much like some domestic robotic mowers, would pop out
constantly when the green was not occupied, thereby ensuring a perfectly manicured playing surface at all times. When the green was approached by players, it would pop back into its discreet charge cave! Who knows? The technology to make these things happen is already out there, but there needs to be a demand for manufacturers to justify the cost of development.
In reality, I think the smart money is on quality "back to basic" machines with simple, reliable relay based electrical systems that can be easily diagnosed when faulty. They will be economical to repair without the need for specialist knowledge or fancy computer diagnostic equipment. That's what I would be looking for in a future machine!
Look out for the next article in the series from Jim in future issues