Trailer brake and relay

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Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=59978
Printed Date: May 29, 2024 at 2:00 AM

Topic: Trailer brake and relay

Posted By: logager
Subject: Trailer brake and relay
Date Posted: July 24, 2005 at 3:18 PM

I have seen some alarm systems out there for enclosed trailers, and know that they use a relay or two to lock up the brakes on the trailer so the thief can't drive off with out it. I'm a tight wad. If I buy a car alarm with a shock sensor, and a door pin, can I add a relay somehow to lock up the trailer brakes?

Thanks for your help!

Replies:

Posted By: ff-mike
Date Posted: July 29, 2005 at 5:37 PM

Yep

Put a relay in as an extension of the alarm, and give 12 volts to the trailer brakes. I would only activate 1 pair of brakes max, as they suck some serious power to lock them up. The laws generally do not require the battery to be able to hold for more than 15 minutes though

Posted By: hotwaterwizard
Date Posted: August 09, 2005 at 12:12 AM

What good would that do if they unplug the trailer wire?

Why not put some hydraulics on the trailer that lowers it to the fenders when not in use.

-------------
John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: ff-mike
Date Posted: August 09, 2005 at 8:16 AM

Generally newer trailers that are equipped with brakes use electric brakes, and it is standard now (and law depending on size/jurisdiction) to have a breakaway device on the trailer, so there is a battery onboard the trailer to activate the brakes for a minimum of 15 minutes if the trailer reakaway is activated. Seeings it is a simple on-off circuit, we should be able to use a stand alone alarm on the trailer running off of that battery, and use a relay in parallel with the breakaway switch to activate the brakes on an alarm condition

Posted By: logager
Date Posted: August 09, 2005 at 8:23 AM

OK, got it figured.

I can use the poser from the horn when it is sounded to activate the brakes.

Thanks all. Just got to how to wire.

Posted By: ff-mike
Date Posted: August 09, 2005 at 10:12 AM

Glad to be of assistance