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Hi, I'm (re)building a MATLAB simulation of longitudinal vehicle dynamics and want to sanity check my handling of tyre rolling resistance power losses: For the Drive case (RWD), I am calculating front tyre rolling resistance losses (P = FV where F = CrrN) only and modelling rear tyre losses as...

Hi, Is anyone aware of a public-domain vibration standard suitable for a circuit board of the type that might be housed within an ABS module? Something the board could be submitted to, to validate the mechanical integrity. Thanks, Ian

Just speculating on the likely shortest engine for a given performance (based on equal swept volume & maximum revs): V4 would have 2x larger bore diameter vs. 3x smaller bore diameter for V6 V4 would need shorter stroke to achieve similar revs to V6, so slightly larger bore again 'lost' length...

Hi, FWD cars often seem to use a clamp-on or spline-on torsional damper. Some seem to be simple masses, others have an elastomer component too. Can anyone point me to a calculation of how these dampers work, and what their capabilities are? Google just throws up countless references to parts...

Hi, What are the challenges of combining the output of two alternators, running at different speeds, to charge one 12V battery? In particular, one or other alternator could be stationary while the other is rotating. I don't really see how this is different to a single alternator charging a...

Hi, I thought this might be a good place to ask a question about a specific design of electric machine. Trying to search online for information is difficult if you don't know the right terminology. For example, I could not easily search for information on matrix converters until I knew they...

Hi, I think this forum has many knowledgable members, compared to many... We need some software to manage & document our FMEAs (Design & Process). At the moment we use Excel templates, which are time-consuming to manage. Can anyone recommend a dedicated FMEA software package we should...

Hi, Does anyone know of a suitable cut-off switch that can be used to detect a serious impact and cut off a hydraulic system? The ideal switch would be normally closed and latching open in the event of an impact. It would power a normally-open solenoid valve connected to the hydraulic...

I saw a press release on the new Porsche turbo and one of the new technologies listed was a variable displacement oil pump to reduce parasitic torque at high rpms. I Googled a bit but could not find any info on how it works. There is mention of axially displacing gears in the press release...

I've seen a lot of research literature on AC/AC matrix converters but actual products seem hard to find. Do they exist yet? Our application is a test rig with two permanent magnet 3-phase motors. Currently we use 2 inverter drives with a DC link between them. We'd like to build a new rig and if...

Hi, I'm looking for an approximate value for the heat rejection to ambient air of a typical transmission casing. Watts/surface-area for an aluminium casting in free air would be a good starting point. I need to calculate the size of the oil cooler, but want to subtract the heat rejection of...

How does an ABS system or a rear brake proportioning valve reduce pressure in a caliper line without causing a 'soft' pedal? All the mechanisms I can think of require some hydraulic flow, which would eventually result in the pedal hitting the floor... Thanks, Ian

I'm looking to do some analysis for transmission options that include both transverse and longitudinal configurations. I.e. with and without a 90deg bevel gear set. At this stage there is plenty of design flexibility in the longitudinal case, such as performing the main reduction at a set of...

A lot of cars now use electric pumps to power conventional hydraulic PAS systems. Feel can be made speed sensitive, less parasitic losses on the engine, etc. Is there a good primer anywhere on the details of the technology? Questions that spring to mind are: Who are the usual suppliers? What...

Hi, We have a need for a brushless DC motor controller that can peak at 100A for a nominal 12 to 14V automotive supply. The motor drives a hydraulic pump, so the duty is not continuous. Roughly 50A average. None of the industrial drives I've found so far will run down to 12V supply, it's...

What's the maximum yaw rate a vehicle is likely to see during an extreme situation such as a spin or J-turn? (Something that a vehicle can recover from undamaged, not during a collision situation). I know that the Bosch ESP yaw rate sensor (for example) tops out at 100deg/s, but is that just...

I've been researching available hydraulic valves for a transmission control application. The need is for proportional (PWM) control of pressure in a clutch slave cylinder. It's not a standard clutch, instead the springs keep the plates apart and hydraulic pressure clamps the clutch. This is so...

I'm putting together a simulation of the energy budget for a car driving the NEDC and FTP-75 emission drive cycles. I need to incorporate the effect of warmup enrichment for gasoline and diesel powertrains. As a first approximation, I plan to simulate a simple heat capacity model of the engine...

We have 2 very similar model cars, just one model year difference between them. They have the same size tyres. One steers normally at all speeds, the other when making parking manouvres has a 'steer onto lock' characteristic whereby the steering's self centreing reverses beyond a certain amount...

Is there a simple way to estimate the peak pneumatic trail of a tyre? I need to calculate some likely peak steering forces without any tyre data. I can estimate the contact patch length, would e.g. taking the trail to be 75% of the way along the patch length be OK? Thanks, Ian