That is a very interesting story and great job about troubleshooting a field failure with an uncooperative customer...it is also a great reminder to inquire as to any modifications that a customer may have made that can introduce problems that they are blaming on the original design!
It was good of the vendor to offer a solution to the customer's modification. Good vendors will help as long as safety is not concerned. As a teen, I was working on an old Chevy loosening a bolt that was too close to the frame to reach with a standard box wrench, so I ground some off of the OD which promptly broke. I then took the Craftsman wrench back to Sears who said that it had been modified, but it should have been tough anyway and gave me a replacement.
The Sherlock Ohms stories never fail to amaze me. I never would have considered adding a ground strap between the wagon body and axle frame. Engineers -- especially those who submit our Sherlock Ohms stories -- are an amazingly clever bunch.
Hi Chip--great story. It is always challenging supporting customers in the field. You were lucky to get the parts back.
Once I was involved with design, production, and then support of an antenna module for commercial telematics. It consisted of an amplified GPS patch antenna integrated to a cellular omnidirectional antenna printed on an FR4 PCB. There was a long cable pigtail to allow the installer to locate the antenna in a good but hidden place in vehicles. Most often, it was placed under the dash on top of wire bundles or air ducts etc.
Two support challenges were memorable. I don't need to give all the details, just the solutions. Case 1: "We recommend you do not locate the antenna inside the glove box as the antenna won't perform well inside of a metal enclosure". Case 2: We added a label "This Side Up" to ensure the GPS patch was facing the sky, not the ground.
On the subject of ground straps, I've seen missing ground straps on motor vehicles, and what often happens is the cranking current for the starter motor will go through the next best conductor, often the driveshaft U-Joints, fries them pretty well.
I remember that story, Jenn. I liked it for two reasons. First, it was a clever solution. Second, instead of coming up with some costly, convulted solution, they simply stopped testing their phones when a frieght train would pass.
This is an interesting example of one of the problems that will pop up when the efforts to keep low level signals in the low level realm are inadequate. I can understand that it was cheaper to simply glue the strain gauge to the axle, but the shiels of the cable should have been connected to that axle, or another conductor, if not the shield. MY reasoning is that aside from the voltage build up, the conductive axle is a good candidate to pick up a lot of noise and couple it to the strain guage. I learned all about the coupling of undesired signals while working with a non-strain-gage pickup as part of a product development project. Compensating cor the mount material potential is vital.
The two solution options would have been to either ground the axle to the input circuit, or to float the input circuit from all other potentials, but that would be difficult and expensive.
Good point William, in practice the load cells were never attached to the shield because of problems with ground loops. Some of the load cells were trailer hitches or physical links between the wagon body and wagon frame. Tail lights, alarm horns and other accessories would wreak havoc with the signal if the shields were terminated.
By experimenting with the photovoltaic reaction in solar cells, researchers at MIT have made a breakthrough in energy efficiency that significantly pushes the boundaries of current commercial cells on the market.
In a world that's going green, industrial operations have a problem: Their processes involve materials that are potentially toxic, flammable, corrosive, or reactive. If improperly managed, this can precipitate dangerous health and environmental consequences.
With LEDs dropping in price virtually every year, automakers have begun employing them, not only on luxury vehicles, but on entry-level models, as well.
From Dell / Intel® New Paradigms in Design Work Scott Hamilton, vertical market strategist for Dell Precision workstations, 5/2/2013 3
Early in my career, I worked as a draftsman and remember the days of drawing on vellum with numbered pencils and Mylar with plastic lead. This was a fun experience in the sense that I ...
I've been using workstations for more than 10 years and love finding ways to get more performance from my system. With demanding professional applications that require more power each ...
A lasting memory from my first job as an engineer in an auto assembly plant is standing on hard concrete at six in the morning, vending-machine coffee clutched in hand, listening to ...
A quick look into the merger of two powerhouse 3D printing OEMs and the new leader in rapid prototyping solutions, Stratasys. The industrial revolution is now led by 3D printing and engineers are given the opportunity to fully maximize their design capabilities, reduce their time-to-market and functionally test prototypes cheaper, faster and easier. Bruce Bradshaw, Director of Marketing in North America, will explore the large product offering and variety of materials that will help CAD designers articulate their product design with actual, physical prototypes. This broadcast will dive deep into technical information including application specific stories from real world customers and their experiences with 3D printing. 3D Printing is
To save this item to your list of favorite Design News content so you can find it later in your Profile page, click the "Save It" button next to the item.
If you found this interesting or useful, please use the links to the services below to share it with other readers. You will need a free account with each service to share an item via that service.
Tweet This
3 
