homebuilt ABS controller

Sounds like he home brewed an ABS controller and servo actuator.

Maybe he was curious or had some spare time. Anyhow it's hardly new or groundbreaking engineering.

...you could just go down the truck factors and buy a Wabco, Bendix or Bosch system off the shelf and plug it all together for under a grand.

Not able to open the link as it wont let me login at the minute.
Loads of stuff on U-Tube about ABS all interesting and can be a lot more involved than you would first think.
I'll have a wee look later ................

I don't doubt it. Took a while for the big boys to perfect it. Wasn't until advent of microelectronics that it became accurate, reliable and cheap enough to mass produce.

Not sure why you'd be motivated to DIY it though, other than coz you can.

Pheasant Surprise said:

Not sure why you'd be motivated to DIY it though, other than coz you can.

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The journey, a very good engineering project.
Some off the shelf kits have issues working at low speed, so he might have addressed limitation like that.
I'd get tired just thinking about it.
Hydraulic only, not that I now off .....
Back in the day Ford had a mechanical one on the MK3 Escorts, sensors/control valves were belt driven I believe off the driveshafts.

aidan said:

thus I guess it needs an electricity supply, could you have one that operates on hydraulics only

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Mostly electronics now, really a small computer, called a microcontroller (a CPU with some memory, and other computer bits and bobs in one package) that runs a dedicated program. Basically it reads the wheel sensors and works out when a wheel/axle is locking or about to lock up, momentarily releasing the pressure (hydraulic or air) on the brake actuator.

The 'trick' is knowing when and how long to release as maximum braking happens just on the point of lockup.

It sounds simple but is actually pretty complex, there are other factors including weight and weight distribution which need to be taken into account.

Car based systems are even more sophisticated as the ABS program is actually part of a larger suite of dynamic handling control programs.

@Dr Dunc is an ex chassis development mechanical engineer so probably can shed way more light on the intricacies.

I would have thought putting in a basic load sensing valve would do nearly the same job
http://www.wabco-auto.com/wabcoindi...products/valves/automatic-load-sensing-valve/

Yes just with the ABS you have a feedback loop from the wheel.
So the brakes can be applied right up to the point of lockup (max efficiency) then as soon as the wheel stops, the pressure is released. This can happen a few times a second.
With the load sensing valve there is no feedback from the wheel. So for a given load if it isn't braking to the max, or locking up there is nothing that can be done. Its a compromise, that in some applications is adequate and cost effective.