Brake Over Travel Switch

[Gerard87]

Hey, I'm currently building a single seater racer as a college project, Formula Student. My main area of the build is Braking System Design. I am having problems with the design of a brake overtrave switch/ Circuit.

B7.3.1 A brake pedal over-travel switch must be installed on the car. This switch must be installed so that in the event of brake system failure such that the brake pedal over travels, the switch will be activated and will stop the engine from running. This switch must kill the ignition and cut the power to any electrical fuel pumps.

B7.3.2 Repeated actuation of the switch must not restore power to these components, and it must be designed so that the driver cannot reset it.

B7.3.3 The switch must be implemented with analog components, and not through recourse to programmable logic controllers, engine control units, or similar functioning digital controllers.

I have been told to use a latching relay to brake the circuit, with a reset switch away from the driver. I am unsure where to start so any advice would be greatly appreciated.

[A13EX_f]

B7.3.3 The switch must be implemented with analog components, and not through recourse to programmable logic controllers, engine control units, or similar functioning digital controllers.

pretty sure a relay isn't analog,

you will need to use something like a cable operated kill switch

[countersteer]

McMaster-Carr (the big yellow book) and Newark Electronics.

You can review their websites but I strongly suggest you keep a copy of the Mc-Carr catalogue around.

You can find all kinds of switches and relays in here that will get you thinking about what you're trying to accomplish, even if you don't buy anything from them.

Always helped me when I was trying to solve a problem.

[Jersey Tom]

Toggle switch is all you need, dude

[A13EX_f]

http://www.streetperformance.com/part/f ... r1013.html

[Tim.Wright]

http://www.streetperformance.com/part/f ... r1013.html

Thats waay to big. Jersey Tom nailed it. We also used a toggle switch. It was connected to the ignition and fuel pump relay.

Tim

[DaveKillens]

I would suggest you use a relay, designed so that with power off, the contacts are open. The relay is held closed by power coming from the electric fuel pumps. The brake overtravel switch, when closed would activate the relay to open the circuits for the ignition and pumps. There would be a bypass switch that would close the circuit for the fuel pumps, thus allowing the relay to close again.

This design is fail-safe.

[donskar]

I would suggest you use a relay, designed so that with power off, the contacts are open. The relay is held closed by power coming from the electric fuel pumps. The brake overtravel switch, when closed would activate the relay to open the circuits for the ignition and pumps. There would be a bypass switch that would close the circuit for the fuel pumps, thus allowing the relay to close again.

This design is fail-safe.

Simple, light, cheap, reliable -- the essence of elegant engineering.