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Post by c64 on Jan 25, 2013 17:12:31 GMT
Not sure about other states, but CT DOT regs say that any trailer over 2500 lbs requires: (1) electric brakes & (2) single-sided sway (stabilizer) bar. Over 4000 lbs requires (1) hydraulic brakes & double-sided sway bar (or other stabilizer rig). ≤700kg no brake required >700kg overrun brake required, usually a spring which becomes compressed by the pushing trailer and a pulley which operates the brakes. |
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Post by the light works on Jan 26, 2013 2:41:23 GMT
12 pins? what do you do with all those connections?
here, they don't specify what kind of brakes are required. rental trailers tend to have inertial braking systems (AKA surge brakes) but trailer built to be towed by non-commercial vehicles tend to have electric brakes. big commercial trailers run off the truck's air brake system.
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Post by the light works on Jan 26, 2013 2:49:54 GMT
electric brakes are a lot more proactive than surge (overrun) brakes. most even have adjustable brake bias so you can fine tune it.
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Post by c64 on Jan 26, 2013 8:30:16 GMT
12 pins? what do you do with all those connections? here, they don't specify what kind of brakes are required. rental trailers tend to have inertial braking systems (AKA surge brakes) but trailer built to be towed by non-commercial vehicles tend to have electric brakes. big commercial trailers run off the truck's air brake system. Without the need to look it up, the old 7-pin was: 1 (top): Turn signal left 2 (clockwise looked on socket or clamps inside plug): Fog light or B+ (permanent 12V) for fridge and lights. (You need to take out the fog light bulb if the car is wired for caravans) 3: Ground 4: Turn signal right 5: Right tail light, all position lights and license plate lights (Cars usually have this on their left circuit) 6: Brake lights 7 (center): Left tail light I would need to look up the modern 12-pin plug which became standard in the 90s. I am pretty sure the pin numbers are identical but I don't know the layout. But I know the additional features: Backup lights B+ (so the fog light is always the fog light on pin 2) "Klemme 30" (Circuit #30, on when the ignition is on but not the starter) 2 Additional grounds for supplying gadgets on B+ and #30 Input to let the car know it has a trailer |
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Post by c64 on Jan 26, 2013 8:36:06 GMT
electric brakes are a lot more proactive than surge (overrun) brakes. most even have adjustable brake bias so you can fine tune it. The passive system works fine, you may not pull trailers which are too heavy for the vehicle anyway. The total weight of the trailer is printed in the cars documents and is far less than the weight of the vehicle. It simply can't fail caused by a loose wire or when the driver forgets to plug in the trailer. Usually the trailers have two independent pulley systems for left and right or connected diagonally if you have a twin axis. There's also a safety wire with a noose you put on the hook which tightens the manual brake lever to activate the brakes when you loose your trailer. |
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Post by the light works on Jan 26, 2013 9:14:38 GMT
here, (I'm not going to try to track the order) you have left rake/turn, right brake/turn, running lights, electric brakes, backup lights, +12V and ground. a trailer with elecric brakes has an onboard battery - if the safety lanyard is pulled out, it shorts the brakes to full on.
our surge brakes are hydraulic instead of cable pull - and the lanyard pulls out a block which releases a spring to push the piston.
still, if your trailer starts tailwagging with electric brakes, you can manually apply the trailer brake to slow the vehicle without making it worse.
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Post by c64 on Jan 26, 2013 9:52:59 GMT
still, if your trailer starts tailwagging with electric brakes, you can manually apply the trailer brake to slow the vehicle without making it worse. No problem, just brake your vehicle hard and the mechanical system will also brake the trailer and take away the energy of tail-wagging. Unfortunately the myth is that you need to floor the accelerator to "straighten things out" which has the opposite effect. Even professionals think that. I've seen a DHL truck toss its trailer over a 15ft high anti-noise dam that way. I was lucky since I was about to pass the truck when it started tailwagging and flooring MY accelerator was good for me. Watching the huge yellow box fly away looked real cool in my mirrors. I had even seen the puff of derbies coming from behind the dam since my right side mirror is a (not quite legal) panoramic mirror. I had expected a puff of mail like in the cartoons when a mailbox explodes but it was mostly dust and maybe trailer bits. |
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Post by silverdragon on Jan 26, 2013 10:06:47 GMT
Trailer tail wagging.... Oh you are in a LOT of trouble right there.....
Experience will win in that situation.
My only advice is take the foot off the gas right now, and get a GOOD Religion.....
(Do NOT pump the brakes at this point... the trailer will overtake.....)
If you ever get it stopped, start thinking, WHY was it wagging?... if the trailer is rated at 50 and you was doing 60, give yer head a wobble.
If its loaded all wrong and you have too much weight at one end or the other, get it sorted.
If you have a cross-ply on one wheel and a radial on another, and yes, I have been given a car trailer to pull just like that, go kick the (holy deleted batman) outa the guy that gave you the trailer....
Mostly, when pulling a trailer, "Feel" the trailer... as in drive through the seat of your pants....
You should start to feel "something wrong" before the trailer starts to dance if you get the knack.....
And watch your mirrors.
If you cant see your trailer in your mirrors, you have the wrong mirrors, or they are incorrectly adjusted.
You MUST be able to see your trailer by some means at all times, that way you can see when something starts to go adrift....
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Post by c64 on Jan 26, 2013 10:21:55 GMT
I drove farming tractors for years. If your trailer has good brakes, braking your tow vehicle relative hard does the trick in making the trailer behave. I never had any trailer related accident on public roads. Inside dense forests with or without road or trails is another story  And one trailer I almost crashed on purpose. My race car was street legal so why not making good use of a super strong engine and attach a trailer hook? And then there was this old rusty little trailer belonging to the owner of a race track… Now I wonder why there is a trailer speed limit of 80kph. You can triple that just fine on a straight piece of road. But 150kph in a tight corner feels real ugly and causes a lot of sparks and noise! |
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Post by silverdragon on Jan 26, 2013 12:30:01 GMT
I have never in all my years got that far?.....
Perhaps its luck, I know its probably more caution because of the way I drive, but I never had a trailer get out of hand in normal driving conditions....
This of course doesnt include emergency braking and jack-knife situations.
I have always "felt" the trailer starting to miss-behave and slowed down to a more appropriate speed?....
Is it just experience here or blind luck?... I have no idea, and I have no experience of real problems that getting off the throttle slightly has not corrected..........
But then again, I always drive a trailer with extreme caution.
Even when I had a car-trailer towing a RIB boat in slightly gusty winds....
Maybe I am too cautious?... I dunno.
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Post by privatepaddy on Jan 26, 2013 14:52:59 GMT
A couple months ago I traded in my '05 Chevy Trailblazer (loved it, but didn't love the gas consumption...) for a '10 Mazda CX-9 AWD. [Background info: I have a pop-up (tent) camper with a dry weight of 3250 and is equipped with electronic friction brakes.] The Trailblazer came with a frame welded hitch that allowed it to tow up to 6500 lbs (GCWR 10,000+). I had the brake controller & wiring added (had it installed). With the CX-9, I have to start from square one. Need to add-on the hitch, controller & two separate wiring harnesses: 1) 4-pin plug & play wiring harness 2) 4-pin to 7-pin wiring adapter (requires hardwiring) I could definitely install the hitch myself and the 4-pin harness doesn't seem too complicated. Performing these as DIY would save about $175 in labor at the local dealer. My question is about installing the controller & 7-pin adapter. I could possibly do it myself, but is the piece of mind of having a tech install it worth $150? What are your thoughts? You can go with option 3(TLW) or build the wiring harness yourself if you feel confident. If your skills are greater than twisting two wires wires together and using insulation tape to "insulate" the join then by all means defer option 3 and build the wiring harness your self. You may require specialist crimp tools to actually crimp wires into the pins of the connector. Long term using pliers to crimp wires is not a viable option, they tend to work themselves lose. If you are using existing wiring, solder joints are a preferable option but not the only option. Satisfactory results of solder joints with the appropriate size heat shrink insulation can be achieved. Heat shrink should be shrunk to fit neatly over solder joints with a heat gun (paint stripper) although a soldering iron match or cigarette lighter can be used the later two can leave a trace carbon on the insulation. Another option is the commercially available "crimp" connector "barrel" terminal, red, blue or yellow depending on the size of the conductor. Most likely red or blue in this situation (Aus CC) with once again the appropriate "crimp" tool pliers again preferably not. There is no reason why a properly constructed wiring harness cannot give you years of trouble free motoring if properly constructed. It really comes down to how much time and effort you are willing to put into such a project V the cost of a Chinese made item of equal quality. |
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Post by the light works on Jan 26, 2013 15:14:56 GMT
one more option on the tailwagging: if the low forehead types at the tire center couldn't hear you properly when you told them, "and make sure the tires are at full pressure, because I will be towing a trailer 1000 miles" and thought you said, "make sure the tires are only at half the recommended pressure; because I don't need sidewall integrity"
but now, knowing that all you have there is surge brakes, I can see why you advocate that particular technique, which we, in the land of brakes that are controlled by the tow vehicle think is alarmingly risky. here, if it gets frisky, or if, for some reason, you feel the imperative need to shed, say 5MPH without anyone noticing brake lights, you simply give it a bit of trailer brake, and it lines up and slows down beautifully.
it's kind of like the difference between letting off the throttle or tapping the brake when the rear end is getting loose in a RWD car.
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Post by the light works on Jan 26, 2013 15:15:53 GMT
A couple months ago I traded in my '05 Chevy Trailblazer (loved it, but didn't love the gas consumption...) for a '10 Mazda CX-9 AWD. [Background info: I have a pop-up (tent) camper with a dry weight of 3250 and is equipped with electronic friction brakes.] The Trailblazer came with a frame welded hitch that allowed it to tow up to 6500 lbs (GCWR 10,000+). I had the brake controller & wiring added (had it installed). With the CX-9, I have to start from square one. Need to add-on the hitch, controller & two separate wiring harnesses: 1) 4-pin plug & play wiring harness 2) 4-pin to 7-pin wiring adapter (requires hardwiring) I could definitely install the hitch myself and the 4-pin harness doesn't seem too complicated. Performing these as DIY would save about $175 in labor at the local dealer. My question is about installing the controller & 7-pin adapter. I could possibly do it myself, but is the piece of mind of having a tech install it worth $150? What are your thoughts? You can go with option 3(TLW) or build the wiring harness yourself if you feel confident. If your skills are greater than twisting two wires wires together and using insulation tape to "insulate" the join then by all means defer option 3 and build the wiring harness your self. You may require specialist crimp tools to actually crimp wires into the pins of the connector. Long term using pliers to crimp wires is not a viable option, they tend to work themselves lose. If you are using existing wiring, solder joints are a preferable option but not the only option. Satisfactory results of solder joints with the appropriate size heat shrink insulation can be achieved. Heat shrink should be shrunk to fit neatly over solder joints with a heat gun (paint stripper) although a soldering iron match or cigarette lighter can be used the later two can leave a trace carbon on the insulation. Another option is the commercially available "crimp" connector "barrel" terminal, red, blue or yellow depending on the size of the conductor. Most likely red or blue in this situation (Aus CC) with once again the appropriate "crimp" tool pliers again preferably not. There is no reason why a properly constructed wiring harness cannot give you years of trouble free motoring if properly constructed. It really comes down to how much time and effort you are willing to put into such a project V the cost of a Chinese made item of equal quality. the expression I use for that is "consider how much you charge yourself per hour" |
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Post by privatepaddy on Jan 26, 2013 15:18:01 GMT
I never charge family  |
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Post by the light works on Jan 26, 2013 15:26:21 GMT
That's a poor policy, because they will take terrible advantage of you.
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Post by GTCGreg on Jan 26, 2013 15:40:46 GMT
Depending on the vehicle and trailer, sometimes it's a lot more complicated wiring up the lights than just adding or building a wiring harness and connecting up to the regular tail lights.
Sometimes the problem is the car or truck has separate turn and stop lights and the trailer may use one bulb for both. There is also usually some type of lamp failure warning system to alert the driver that a turn signal bulb is out. In the old days, it was that the mechanical flasher was matched to the lamp load and if a lamp was out, it wouldn't flash or would flash very rapidly. Often, adding a trailer just required replacing the flasher with a "heavy duty" unit. Most newer vehicles now use some type of solid-state module for controlling the stop and turn signals. You often can not add lamps to the circuit without really messing things up.
My truck came with a factory installed trailer package. The trailer lighting (run, stop and turn) is powered from separate power supply fuses through relays. It takes a lot more than just a wiring harness.
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Post by GTCGreg on Jan 26, 2013 15:41:46 GMT
That's a poor policy, because they will take terrible advantage of you. And they expect a lifetime warranty. |
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Post by c64 on Jan 26, 2013 15:55:48 GMT
but now, knowing that all you have there is surge brakes, I can see why you advocate that particular technique, which we, in the land of brakes that are controlled by the tow vehicle think is alarmingly risky. Big trailers as for farming tractors and semi trucks are air braked and controlled by the vehicle. They also have ABS and ESP now. I had a training with a big tanker truck with "training wheels" on the trailer. There were stripes painted on them and whenever you saw them turn in your mirror, you did something seriously wrong since an ordinary trailer would have tripped over. First, the ESP was deactivated, a certain turn could only be managed at 50kph. With ESP the instructor said I should take the turn at top speed (80 kph), the deceleration was pretty intense and came very suddenly but the training wheels were not turning! I've never driven any tanker truck afterwards but I learned a few things. Here's a video of a similar system for car trailers: There is also a shock absorber in the spring to avoid sudden brake and release action while tailwagging. The brake has g-force sensors and receives its power from the car, but since it can only apply the brakes, it doesn't matter munch if it fails since the brake is still activated mechanically. No need to control the trailer brake by the driver. And just for the laughs, what kind of driver would work for minimum wage? |
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Post by the light works on Jan 26, 2013 16:00:12 GMT
my truck has separate leads for all the trailer lighting features. there's a 20 pin wiring harness connector right in front of the trailer plug location - the trailer plug just connects to a tap point on that connector.
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Post by c64 on Jan 26, 2013 20:12:10 GMT
The funny thing is that if you have a broken light, you get a ticket because you are supposed to check all lights before you start driving. But how can you check the brake lights? So I made a little gadget which plugs right into the trailer outlet. It hotwires the lights and beeps when one of the circuits won't take enough current.
If it beeps, how do you know which circuit had failed the test? I didn't bother to add LEDs to the plug so I came up with a real clever way to let you know, it flashes the lights on the problem circuit - guess how often I use this thing? I am so proud of my little invention that I have burried it under a ton of junk in my cellar since I have never bothered to fix that issue.
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