Peter's Blog

Ergonomics

It can’t be just me who gets annoyed when stuff isn’t quite where you’d expect it. It doesn’t matter if it’s the supermarket that has shuffled the aisles or a new piece of equipment that doesn’t work in the same way as the old. Some of these really stick in your mind. Twenty years ago I drove a Austin Montego, remember those? It had electric mirrors, that was pretty spectacular back then. The trouble was you had to lean forward to reach the adjustment switch…. I’ll leave you to think that through. Another car that sticks in my mind was a Honda Legend. It had electric seats with preset buttons . The problem here, was my wife always had the seat right forward so every time I drove the car I had to stand in the rain until the seat had wurred back far enough for me to jump in. A manual seat can be banged right back in fractions of a second and adjusted in the dry.

When you’re writing a PDS you can make sure the design complies with the 95 percentile man etc but it the application that always catches you out. Back in my early Girling days I remember my boss panicking because another actuator had snapped off a Twinstop brake fitted to a Ford Transcontinental. It had sailed through it vibration test without an issue. After much heartache he discovered drivers were using it as a step to get into the cab because the steps weren’t convenient!

When you’ve finished the design there’s always a modification or cost down waiting to mess up your work.

A few years ago when my Peugeot 106 was designed the conversion to RHD involved fitting a couple of bell-cranks and a tension tube to operate the brake servo. This seems to work fine. I notice the Citroen C3 uses a torsion bar under the instrument panel. I guess this is probably cheaper but the tube is twice the diameter. Unfortunately on the Picasso version the passenger can push the operating arm with his foot and apply the brakes with a similar level of effort. Citroen are now recalling 20,000 cars to fix the problem.

I doubt very much if the PDS said “ensure the passenger cannot apply or prevent the brakes from actuation” but it will in future won’t it!

Has anybody done a crash test on a RHD car fitted with such a beam???

Is Regenerative Braking the End for Friction Bakes?

Electric cars are coming, at least it appears so at the moment. I'm still not convinced about energy storage though. My data suggests that Li-Poly batteries will give about 150W-h/kg or 300W-h/l whereas petrol gives 12300W-h/kg and 9300W-h/l respectively. Even biodiesel gives 11700W-h/kg and 8500W-h/l. It looks like we've got a hell of a way to go to get something comparable or else we need to change peoples attitudes or requirements.

Anyway back to the subject. Being able to save the energy you were going to turn to heat has to be great but that does assume you need to brake in the first place. I try to imagine the brake pedal as a hole in your trouser pocket, every time you put your hand in some more coins fall out of the bottom and if you drive like that the hole gets bigger too. Brakes are just energy dumps and using them is no different to squirting the fuel pump on the floor, except the risk of fire is slightly higher! Now if you didn't have to use the brake as much because you think ahead and coast down then you'll be better off than regenerating but it will slow your arrival time by a couple of seconds.

I'm not a battery expert but a typical car stopping at a normal rate (0.3g) from 100km/h would dump 500KJ of energy in less than 10 seconds. At 160km/h that increases to 1.5MJ and in an emergency stop that takes just 4.5 seconds. I don't know how quickly you can soak up that energy but it seems like a nice challenge. Just look at the temperature rise rates of a brake disc.

Now most customers like to be able to lock the wheels or at least get a good ABS stop on dry tarmac, that's a deceleration of about 1g however most good cars are taking 6 second to get to 100km/h so the acceleration is more like 0.5g. Assuming motor designers are looking for similar levels of acceleration, and who wants more on a bog standard Mondeo, then there's a 100% mismatch in torque requirements between accelerating and braking, unless there's some clever motor tricks I'm missing I still believe the difference will need to be done by friction braking, the new challenge will be how thin can we make the pads and disc?

Brake Fluid

OK So I haven't got a brake page on the fluids used but I keep getting asked for it so here's a bit of information....

There are 3 basic types of fluids in use today, unless you know differently :-)

well in road going vehicles anyway as I don't know too much about aviation fluids.
The main type was traditionally called vegetable based fluid but of course it's been synthetic for years. It's generally a glycol ester based liquid.
The second type is mineral hydraulic oil. It's widely used in tractors with oil immersed brakes but was also used in Citroens using the name LHM (liquide hydraulique minéral) where it is coloured green.
The third type is a silicone based oil and is used almost solely by the US military although Harley Davidson used it for several years.

Now you may well know brake fluid as DOT3 or DOT4 etc. These are codes used in the US standard FMVSS116 but they tend to be used worldwide.

Now if you are at all concerned go and download the standard from here

This standards defines 'brake fluid' as a liquid compatible with SBR, EPR, CR and NR rubbers and a hydraulic system mineral oil as a liquid NOT compatible with SBR, EPR or NR rubbers. So that leaves type 1 & 3 as 'brake fluids' and type 2 as a 'hydraulic system mineral oil'

The standard doesn't define the base chemical only it's compatibility with certain rubber types so you can't assume that DOT 4 and DOT 5 can be mixed only that they will work with the same rubber types.

The main difference in the standard grades is the wet and dry boiling points and the viscosity.

What's wet boiling point I hear you shout!

Well, glycol ester based fluids absorb and chemically convert water over time. This is absorbed through the cap, hoses etc and after a year or so it will boil at a lower temperature, the wet boiling point.
Of course mineral oils and silicone fluids are much better behaved but if water gets into the system, run off from the windscreen or washer bottle are favourites, you'll find it sinks to the lowest point. If there’s a bend in a pipe it'll rust out and if it's the brake it'll boil at 100C, because it's still water! Leaving you with no brakes!

Now, of coarse the higher the number the better the spec, obvious eh? Well yes and no. Certainly the measured parameters are better but as an engineer you know there's no such this as design without compromise.

You may find the higher spec fluids have inferior lubricating properties and in the case of silicone inferior compressibility.
So what's this odd ball DOT 5 silicone fluid, SBBF as it's called?

Well if you want to deploy your vehicles to the Arabian Gulf at 45C and Northern Europe at -50C without stripping and rebuilding the brake system than SBBF could be for you.
If you want to change your brake fluid and drip it all over your custom paint job without damaging it, then SBBF could be for you. (Of course silicone on metal work prevents paint adhesion and is difficult to clean off)

If you don't fall into the above categories then it's probably better to avoid it.

If you can live with the spongy pedal feel at high temperatures and don't bottom the master cylinder out, are happy with it's poor lubrication properties and are prepared to strip and clean all the components, give it a try but be very careful pouring it in as it is prone to collecting tiny air bubbles.

Now this is where it gets complicated. Originally glycol based fluids couldn’t meet the low temperature viscosity requirement so DOT 5 was only SBBF but now it can so to avoid confusion it’s been called DOT 5.1. What a great numbering convention this is!!!

So you know all about brake fluid now and are going to fill your racing bike or car with DOT 5.1 because it’s the highest spec and is much less compressible than SBBF ah! there’s one more thing to consider. What if you could create a glycol brake fluid that had an excellent dry boiling point, much better than 5.1 but it didn’t have a good wet boiling point. To certify it for road use it may only be a DOT 4 fluid but providing you change the race fluid often the wet boiling point may be of no concern.

Racing fluid may only be DOT 4 but read the small print. What’s really important for you?

Brake Recalls

According to Auto Industry News BMW motorcycles are recalling 6600 bikes because of hose failures, (again) though it doesn't appear on the VOSA website

http://www.autoindustry.co.uk/news/21-05-10_3

http://www.dft.gov.uk/vosa/apps/recalls/default.asp?tx=VOSA

It's easy to speculate on the cause but I've experienced the different ways in which hoses from different manufacturers behave when bent.

Clearly the task is, get it right at the prototype and pre-production phase and don't change it to save money!

During my time at Honda we spent a disproportionate time studying Maru W (wiring and piping). Maybe there's another Japanese lesson to be learnt?

Blogger is Dead! Long live the Blog

Well you may know Blogger decided to terminate FTP publishing so I've not been able to post for a while.

Well it's now fixed thanks to Thingamablog. I've republished all the old stuff and am getting fired up to start writing again!

Environment

I’ve just heard a new word today ‘greenwashing’. It was in response to an electricity company sending out loads of free long live light bulbs to their customers, irrespective of whether they needed, wanted or could use them.

I, along with many others think we should start by reducing waste…

On the same news bulletin was a family who recycled almost all their packaging waste. No mention about how they reduced waste but to be successful I’m sure they purchased low packaging products. My bin seems to be full every week despite recycling everything we’re asked and putting most paper waste in the log burner.

Now that’s enough of personal crusades and the likes, in many cases there is a financial benefit to thinking about the environment. When I started working for Honda in 1996 all components sourced from the EU were delivered in returnable plastic boxes. Yes, the boxes were plastic but in most cases they outlasted the supplier! I figure if the supplier is delivering full boxes, he can usually return with empty boxes at no additional cost.

On the other hand JCB received most components in cardboard boxes, in itself recyclable but often boxes were damaged, fell off of pallets, got punctured of squashed, causing rework, late deliveries and general heartache.

Of course how you package the product isn’t the only thing to be concerned with, what about the product itself?

One lesson I learned was don’t compromise the design for ‘green’ benefits, the customer won’t thank you and at the end of the day the product life will be reduced loosing the green battle anyway.

All engineers with an ear to the ground will be aware of the problems caused by lead free solder; the Xbox 360 is a well documented example.

http://en.wikipedia.org/wiki/Xbox_360_technical_problems

The use of trivalent chrome in the zinc plating process has also caused many issues, inconsistent performance due to handling damage, torque differences in fasteners and the likes. Of course it can be done properly for a price but the learning curve can be expensive.

I also remember a plastic trim part that was made from recycled plastic, unfortunately it soon became damaged by the seat belt clip, try explaining that to your customer…

Remember, I didn’t say don’t try out these new ideas, not that you often have a choice, but DON’T compromise the design. If it’s a new process make sure you fully understand it and have tested it thoroughly.

Energy Consumption

In the West we never consider how much energy a product uses until you don’t have enough of it.

When we tried to run a compressor from a generator and couldn’t start it, the size of the motor became obvious.

I spent a couple of years living in a caravan (14’ 6” touring van) whilst working away from home. Now the choice of a tourist site in Cirencester or a little farm in Minety was an obvious one to me but electric hook-up wasn’t available. It wasn’t a problem as the heating, water, oven and hob were all gas but lighting and TV all consumed electricity. I fitted a 12V inverter to run my satellite receiver and had a small B&W TV. I had a company car so hooking up a good battery was a quick job each night but by the morning it was pretty low. Power consumption suddenly became a real issue, leave the light on OR have a shower in the morning. I don’t know if LCD TV’s are any better, I suspect not.

It seems like the government are finally starting to realise that our old nuclear power stations really need to be shut down but they don’t have the guts to make a decision on the future.

They’ve just about banned traditional light bulbs, to save energy but my new super efficient house appears to be full of 12V 50W spotlights, 300W in the kitchen alone! Why are they still available and promoted? Maybe they think 12V electricity is more efficient? They produce poor lighting and shadows too so one 4’ fluorescent tube would win on all counts, except style.

I remember when Sky TV first launched their Digibox, the engineering magazines were all moaning about having to leave them in standby. Now of course Sky are a ‘carbon neutral’ company (not including the Digibox)!!! and they run adverts telling customers to switch the box into standby. Why can’t they design a box with an off switch like most digital receivers? Sadly, for them, I’m no longer a customer.

I bought a nice AAA rated washing machine but it uses so little water the silicone door seal keeps going mouldy and a replacement is expensive and time consuming.

We burn carbon neutral wood at home instead of sulphur laden coal but now the roof is covered in moss and has to be scrapped off every couple of years.

Anyway when you design a product you really ought to consider how much power it will require and take steps to minimise it, you’ll be thanked in the end.

I do have one proviso though; consider the whole system lifecycle costs and KISS, Keep It Simple Stupid. I guess I’m a bit of a Luddite but don’t add £500 of complex equipment to save £100. Hybrid cars are probably a good idea but step one ought to be to reduce the basic complexity and mass, my 13 year old Peugeot 106 does 60 mpg (UK) diesel and doesn’t have an electronic controller at all. In fact it ran for 3 weeks with a failed alternator one summer. If a Toyota hybrid system was fitted in a 106 without all the crappy TV screens, electric windows, seats and other rubbish then it could be a useful design but bogged down in customer comfort features it won’t suit me so I’ll sit the scrappage scheme out if you don’t mind.

I think I might just expand this section and let you have my thoughts on solar water heating next time, it’s a bit of a diversion but it should be said…..

Disposal

When you’re designing a product you don’t need to worry about disposal do you? In the car industry it’s easy; just make sure a certain percentage of the plastic bits have the correct recycling mark and the jobs done!

I for one will be a little unhappy when all the supermarkets stop giving away free plastic bags.

Why….

because we always reuse them. Mainly as kitchen waste bin liners, but also to keep stuff dry in our rucksacks or canoes or inversely to prevent our wet swimming towels wetting everything else.

Cynically I’d suggest supermarket bin liner sales have increased in line with the reduction of free bags.

We’ve just got a new Morrisons supermarket and the plastic carrier bags are about 2cm bigger than Sainsburys but so much easier to pack resulting in far fewer bags being required…..

I remember a brake friction chemist saying that at one time all bar four or five solid materials that exists in the ‘real’ world were used in friction materials, when in came to deleting Lead and Antimony on health grounds all they needed to do was miss them out!!!

(They’ll all tell you Asbestos gave a better brake than we’ve got today but as they all retire, we’ll forget).

When it comes to it, I think you need to consider reuse first, followed by remanufacture and recycling but don’t forget the obvious question; Do we actually need the product or all it’s features? If I have to repair another plastic toy within 1 day of purchase I’ll go mad, that’s real waste.

One of my previous employers got a bit upset when a few companies started remanufacturing their new brake caliper. I can understand that, as they still had the original name on the castings, however testing these dubious parts came as a bit of a shock. Some, not all, were better than the originals. The use of Stainless Steel slide pins was prohibitive at OE prices but perfectly acceptable at aftermarket prices and volumes. Providing the parts are remade with care and understanding then it’s got to be good for society and the world. If the OEM gets upset about it they should catch the copying bug rather than crying about all the development costs and the likes. If the original lasted the life of the vehicle there would be no market anyway.

The CUSTOMER

Many years ago we took a brake that had been designed and was in series production in Germany to a Swedish company in the hope of persuading them to buy the same kit.

We were laughed out of the place.

“If you take the cover off you needed 23 very thin fingers to reassemble it.”

“How is a truck repairer meant to rebuild it?”

In Germany, we replied, “The brake housing is a replacement part and not serviceable…”

“but it costs £1500” (1990)

The German truck makers were very happy with the product but the Swedes (and me) would not consider it as it stood and a serious redesign was ordered.

I guess they were happy with the redesign, eventually:-

http://www.itsdocs.fhwa.dot.gov/jpodocs/repts_te/14349.htm

So who really knew their CUSTOMERS?

Well I suspect they both did, to a point. In Germany, German truck makers were king but in Sweden the Swedish manufacturers ruled.

The problem comes when trying to sell outside their comfort zone. European truck makers never really succeeded in the USA until they started buying the companies and likewise US companies in the EU. We’ve still not seen a world car that’s been successful worldwide.

The key to good design is to really understand the customer and if the market is very wide to customise the product to offer different variations in different regions.

Of course you can force the market if you’re big enough.

Does nobody want a kettle that last more than a couple of years?

The UK is full of shops selling cheap tat, we’ve just got another one in Oswestry. So much so that you couldn’t buy a good kettle if you could recognise one.

Recognising a good product is also difficult, I almost bought an expensive cake mixer until I found out everybody I knew who had one had had problems.

Putting a big price tag and a Union Jack doesn’t necessarily bring in repeat customers.

Sochiro Honda was full of wise words like all good company founders I suspect, but one I remember was called ‘Sangen Shugi ‘

Study the actual place, the actual part, the actual situation.

How many times have you spent weeks discussing something only to find you solved it within 30 seconds of seeing the actual situation.

YOU CAN’T SECOND GUESS THE CUSTOMER, GET UP AND FIND OUT WHAT THEY REALLY WANT!

Understanding the Competitors Design Process

We’ve all heard about reinventing the wheel and no doubt I’ll come to it again when we come to the patent section – but do you REALLY know who your competitors are and how they tick?

In the information age you don’t need to go to the library and trawl through Kelly’s to find similar companies, the internet can produce a whole lot of information in a very short time.

Before you start designing your new product spend a day on the net studying the competition. You WILL discover new competitor all set to steal your market. You may find someone already doing it in a different part of the world.

I discovered a company I’ve been working with had a fringe competitor in New Zealand who had some product in use here in the UK – a phone call and visit produced an excellent learning opportunity.

Since both you and you competitors are both in business one would assume the product has customers and makes money, that’s a bit more difficult to find out but use you imagination, it isn’t impossible. Why do customers buy from you competitors? What can they do that you can’t?

It’s not always design related it could be price (cost is a design issue), service support, delivery etc.

How do these competitors market the product? Do they have features or options you can’t supply? Do they integrate better with other systems?

Of course you’d like to wipe out your competitors but that’s unlikely to happen so designing more openly could give an advantage forcing competitors to design components to suit your basic architecture.

Study their design carefully; there will be a reason for everything they’ve done. Why spend your precious design resource on areas that have already been solved successfully, don’t be too proud to copy their best features, (legal issues aside).

I’m a great fan of Geomag but I hope they know their competitors. My kids have some of the real stuff and some cheap copies. As an adult into serious construction the original is superior, better moulding shapes, stronger magnets etc. BUT it’s twice the price and the kids spend more time rolling it round the floor than actually building so they don’t really care.

Take a look on the Amazon website, 220 pieces of Geomag for £44.99

http://www.amazon.co.uk/Geomag-41034-Panels-220/dp/B0002CYT9E/ref=sr_1_2?ie=UTF8&s=kids&qid=1244022128&sr=1-2

or 240 pieces of Supermag for £19.99

http://www.amazon.co.uk/Supermag-Classic-Set-240-pieces/dp/B000FP30YI/ref=sr_1_8?ie=UTF8&s=kids&qid=1244022128&sr=1-8

I don’t know if we have Supermag or some other brand and I’m not suggesting Supermag is inferior but with that huge price difference one would assume they are not really competing for the same customers.