Supplementary braking system?
Supplementary braking system?
(OP)
Hello all,
I'm Paul from Manchester England and have an interest in Automotive engineering. Although I'm not too savvy on certain subjects,for example pneumatic components.
I'm trying to devise an auxiliary braking system to my car that can suit an A-frame,or a brakeless trailer. What I have configured in my minds eye,is an pneumatic actuator fitted to the drivers footpedal,where the rod from the actuator will be already protruding,will be forced in when the brake pedal is depressed. From the actuator will be an airline going to the rear of the car,attached to another actuator which will send the rod out of the actuator to another secondary pedal,built on a frame. For the compressed air to be in the system,I supect that a fill & chuck valve would be needed.
Your opinions most welcome,and perhaps,notice any flaws in my contraption
regards
Paul
I'm Paul from Manchester England and have an interest in Automotive engineering. Although I'm not too savvy on certain subjects,for example pneumatic components.
I'm trying to devise an auxiliary braking system to my car that can suit an A-frame,or a brakeless trailer. What I have configured in my minds eye,is an pneumatic actuator fitted to the drivers footpedal,where the rod from the actuator will be already protruding,will be forced in when the brake pedal is depressed. From the actuator will be an airline going to the rear of the car,attached to another actuator which will send the rod out of the actuator to another secondary pedal,built on a frame. For the compressed air to be in the system,I supect that a fill & chuck valve would be needed.
Your opinions most welcome,and perhaps,notice any flaws in my contraption
regards
Paul





RE: Supplementary braking system?
Cheers
Greg Locock
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RE: Supplementary braking system?
Regards
Pat
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RE: Supplementary braking system?
Please just go to a local trailer shop and have one of the many commercially available trailer brake systems installed before you kill someone.
RE: Supplementary braking system?
Around here, you can get the electric wheel brake assemblies for about $45 each and the electric brake controller for around say $100. It's simply retarded to mess around with a cobbled together contraption to build a safety critical trailer braking system.
RE: Supplementary braking system?
If he had the brains to come consult the experts on eng-tips forums I am sure he also has the brains to know when to stop working on a flawed design.
Adriaan.
I am an Engineer/part time student (Mechatronics) from South Africa.
Advice from lecturer: "Be warned - when you go into industry your boss will give you a thousand things to do and he wants them done yesterday!" So far he is right...
RE: Supplementary braking system?
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Supplementary braking system?
The big problem with using air in the manner described, is that air is compressible.
Automotive braking systems use hydraulics because hydraulic fluid is (substantially, for the purpose that we are talking about here) incompressible.
Transport-truck braking systems use compressed air, but it operates differently than described. The driver's foot is not the source of pressure in the system. The driver's foot is more like an input to a servo system, in which the pressure is generated by an engine driven compressor, and the driver's foot only operates what amounts to a valve that tells how much pressure to pass into the rest of the system.
Automotive / light truck trailer braking systems are of two types, electric, or "surge". The parts for making both such systems are readily available quite cheaply. Electric brakes are easier to implement (when the vehicle's brake lamps come on, the brakes get turned on) but are "on/off" and are not proportional to how much deceleration the driver wants. Surge brakes are hydraulic, but instead of the driver's foot pushing the brake pedal which pushes the master cylinder, the mechanism that attaches to the tow vehicle's hitch ball actuates the master cylinder (on the trailer). The harder the tow vehicle brakes, the more force is transmitted, the stronger the brakes are applied. Reversing uphill with the trailer could be tricky. I don't actually know how they handle that.
And on those notes ... I'm with everyone else on this. Buy something that does what you want it to do.
RE: Supplementary braking system?
There is also an obsolete vacuum operated system that was very effective, but it was operated by a separate hand control lever.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Supplementary braking system?
@GregLocock,you do have a point regarding insurance issues when not properly equipped to avoid an accident.
I do deem myself a responsible motorist,so safety has priority. It was mainly for A-frame application,as A-frames are illegal for long distance in the UK.
@patprimer,thanks for the options. The vacuum setup is probably similar to this http://www.smart-tow.com/braking.htm
And I've also engine searched other varities.
@Mintjulep,thanks for being blunt,"lack of fundamental engineering knowledge" is about correct,that's why test casing a gadget is part of learning.
@LionelHutz,so it's a cobbled contraption. The electric wheel brake would suit a trailer with existing brakes,if I am not mistaken.
@Bithkits,thanks for the support. I do have a couple of brain cells to rub together *GRIN* to now realise it is a total flop.
My system was a mixture of the smart-tow and the metal cable from the surge systems.
Thanks all again.
regards
Paul
RE: Supplementary braking system?
Posting "A-frame, or brakeless trailer" just isn't very clear. "brakeless trailer" just sounds like you have a trailer with no brakes on it.
Some transport trucks run hydraulic front axle brakes and air on the rest of the axles so I guess it could be possible to duplicate that with an actuator running the pedal in the tow vehicle...
You'd need an onboard air tank and compressor that will keep up with repeated braking though, none of this fill and chuck valve stuff will cut it.
RE: Supplementary braking system?
A 12 VDC linear actuator connected via a spring could also be mounted to the brake pedal, and operated by a conventional electric brake controller it the trailer lights being used on the towed car. But as was said before, it would be an on/off system.
But cars on towbars are very hard to back up. I think if it was something I would be doing regularly, or for a long distance, a trailer would be optimal.