Picture this, you\u2019re cruising down State Highway 1, your favourite roadtrip tunes on blast, when you see a bright flash out of the corner of your eye. What was that? D\u2019oh, of course it was a speed camera!<\/p>\n\n\n\n
You quickly check your speed, gently heading up towards the 120km\/h mark. Yeesh! You start to slow down, but the damage is done. It mightn\u2019t be damage done to your vehicle, but no doubt there\u2019ll be a bit for your bank balance to contend with.<\/p>\n\n\n\n
To state the obvious, speedometers are remarkably handy fixtures in any car. I\u2019ve actually been on a road trip from Raglan back to Auckland one summer when my friend\u2019s speedometer stopped working. Like, literally just stopped. Needless to say it was a rather tense ride home as we tried to navigate the speed limit \u2018by feel\u2019.<\/p>\n\n\n\n
The original speedometers on cars were analog, controlled by a cord.<\/p>\n\n\n\n
This cable was directly connected to the back of the instrument cluster and was either attached to the gearbox or down near the wheels. The speed of the vehicle would directly influence the reading on the speedometer. There was none of this speed sensor business!<\/p>\n\n\n\n
The cable would spin faster or slower depending on the wheel speed using electromagnetism (today’s buzzword).<\/p>\n\n\n\n
The speedo needle was attached to a magnet, and the cable’s rotation created a magnetic field that controlled the needle.<\/p>\n\n\n\n
Speeding up would increase the magnetic field, making the needle float upwards, and lowering itself when the speed drops.<\/p>\n\n\n\n
Admittedly it does sound a little bit complicated.\u00a0 Believe it or not, this was actually the simpler system when compared to modern standards! \u00a0 The cable\/cord system began to be phased out in the 90s as the auto world welcomed anti-lock braking (ABS) and wheel speed sensors.<\/p>\n\n\n\n
Because these sensors monitor wheel speed in real time and give a digital signal to the engine control unit (ECU), they provide a far more precise speed reading.<\/p>\n\n\n\n
After that, the signal is sent to the instrument cluster.<\/p>\n\n\n\n
Sure, It may seem straightforward, but there\u2019s a little more than meets the eye here.<\/p>\n\n\n\n
Magnets are also<\/em> used in this system, which are attached to the driveshafts or wheel bearings. They spin at different speeds, and specialised sensors (also known as hall sensors) pick up this movement as an electrical pulse. <\/p>\n\n\n\n This pulse is then sent up to the ECU via a wiring harness. The speed is then shown on an analog or digital display, according to the parameters inputted by the car\u2019s manufacturer. <\/p>\n\n\n\n This speed is then shown on either an analogue speedometer (with a needle to indicate speed) or a complete digital readout in more recent cars.<\/p>\n\n\n\n This device also maintains track of wheel rotation and delivers your vehicle’s odometer readout. Simply explained, the wheels turn, a signal is sent to the computer, and the speed is shown.<\/p>\n\n\n\n Now, it\u2019s worth paying attention to one aspect mentioned above. And that is, a vehicle\u2019s speedometer\u2019s parameters are set by the manufacturer, which goes some way to explaining why, if everyone on the highway is travelling along at 100km (they are, right?) – there\u2019s generally a bit of leeway between vehicles.<\/p>\n\n\n\n In some cases, this means some drivers can narrowly avoid speed cameras, and in some cases it means they get flashed when truly unaware of their driving speed.<\/p>\n\n\n\n So, our advice is to play it safe when it comes to speed, and be aware of what\u2019s happening on your speedometer. Know the speed limit, stay well inside of it. <\/p>\n","protected":false},"excerpt":{"rendered":" Picture this, you\u2019re cruising down State Highway 1, your favourite roadtrip tunes on blast, when you see a bright flash out of the corner of your eye. What was that? D\u2019oh, of course it was a speed camera! You quickly check your speed, gently heading up towards the 120km\/h mark. Yeesh! You start to slow […]<\/p>\n","protected":false},"author":10,"featured_media":3889,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[3],"tags":[388,385,387,386,390,384,389],"post_folder":[],"class_list":["post-3888","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-education","tag-drive-shafts","tag-dshboard","tag-ecu","tag-magentic","tag-sensors","tag-speedometer","tag-wheel-bearings"],"acf":[],"_links":{"self":[{"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/posts\/3888"}],"collection":[{"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/users\/10"}],"replies":[{"embeddable":true,"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/comments?post=3888"}],"version-history":[{"count":1,"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/posts\/3888\/revisions"}],"predecessor-version":[{"id":3890,"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/posts\/3888\/revisions\/3890"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/media\/3889"}],"wp:attachment":[{"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/media?parent=3888"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/categories?post=3888"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/tags?post=3888"},{"taxonomy":"post_folder","embeddable":true,"href":"https:\/\/myautoshop.co.nz\/info\/wp-json\/wp\/v2\/post_folder?post=3888"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}