trailer brakes

You want the gain set so that the trailer brakes are in balance with the truck brakes, i.e. the trailer hitch isn't being slammed forward or yanked backward when braking. You want both the truck brakes and the trailer brakes sharing the braking load or else you will have excessive wear on one or the other as well as poor to dangerous handling.

What did you find on the truck's GCRW? I seem to recall that this trailer was well over your trucks capacity if fully loaded, and close to capacity with the trailer empty. This is not something to screw around with, especially if you are commercial.

Towing a camper that is a couple percent over your GCRW isn't likely to be a problem, but something that is considered commercial and is substantially over GCRW will get you in a lot of trouble. That trailer will put you over into the 26,000#+ commercial range without a lot of cargo on it, and at the same time put you over your GCRW by 4,000#+.

I would start with setting it low, and then increasing it so that when you hit the brake, the trailer pulls back, but gently. Note that everything depends on how hard you brake also. I have electric brakes on my trailer. I figured that for empty it should be 1.4, for 1.5-2k lbs it should be 2 or so, for 4000 lbs it should be 3.4 or so.

In other words, just go by feel. I guess i figured that's the only way.

Karl

Yep, this is a back road only unit if I'm up to what the tires can carry without popping. But I do want to run the highways when hauling only a forklift or payloads under 10,000. You're like Iggy's advice, "Go by feel". I was hoping for a bit more, but I guess I'm not surprised.

Karl

Ok, install a load cell on the hitch assembly so you can measure the forces on it during braking and then adjust it so there is between zero and a small negative force on it during braking (trailer brakes leading).

Karl sez: In other words, just go by feel. I guess i figured that's the only way.

Good call, Karl ! As in most mechanical endeavors, one is usually well guided by his own intuition..

Bob Swinney

Karl

I diddle with mine until it "feels right".

My trailer's brakes are odd, in that they start normal, then wind up harder and harder, so I have to pulse the truck brakes if I'm trying to stop gently. So "feels right" is a quite perceptible difference from the trailer brakes at first, but no smoke from the tires unless I've been on the brakes for several seconds. With better brakes on the trailer, "feels right" would be an attempt to nicely balance the brakes between truck and trailer.

It's easy to do once you've done it a few times -- I wouldn't spend much time coming up with an algorithm for it.

What I described is not exactly go by feel, it is a procedure.

Do you have a dirt road to practice on? Maybe have someone with a cell phone watch and tell you which wheels lock up first.

jsw

Do you have a dirt road to practice on? Maybe have someone with a cell phone watch and tell you which wheels lock up first.

jsw

Good suggestion. i like it.

Looks like I get the acid test next week. They just scrapped out a 20,000 lb. commercial laser where my son works. He gets to take it home.

For this much weight, I'll have a follow car with flashers. I'm pretty sure max gain won't be too much.

Karl

I hope you have class A CDL to drive that trailer. It is an articulated vehicle over 18,000 lbs. and falls in the same category as a tractor trailer.

John

What's that Lassie? You say that Karl Townsend fell down the old rec.crafts.metalworking mine and will die if we don't mount a rescue by Mon, 21 Jun 2010 06:12:07 -0500:

Are the trailer brakes proportional to the tow trucks breaking force?

If it is, then I would try going down a hill, and riding the brakes as you turn up the gain until you feel the slack in the coupler get taken up. You should be able to adjust the gain above and below the balance point and feel the coupler slack chatter back and forth.

Ooh, ooh, tell us (ok, me :-)) more! What kind of laser, what shape is it in, is he going to try to get it running?

----- Regards, Carl Ijames

His company was running "lights out" with this machine. There was a fire and the control wiring burnt up. As the machine was slated for replacement in a year, they scrapped it out.

Somebody has to help get rid of this monster laser, might as well be us. the laser itself is only for 4x10 sheets up to 3/8 thick, but it includes a material handling system to feed off a stack of input and send the finished parts and scrap down a conveyor to a part pick and place unit.

Karl

Oh man, Karl. That is going to be the all time best gloat - ever!

Sounds exciting. What are you going to do with it? Part out?

"The Kid" says it won't take me long to get it running again. He's always generous with my time. I haven't seen it yet, and I'm sure the key is if the head itself can be saved. The fire was not near this part. I should be able to get a laser running for less than you have in your CNC mill after selling off the handling system and Mazatrol control parts

Karl

Sounds cool. Without the handling system, it is just a glorified XY table moving a torch, right?

I am slowly progressing with the mill, adding 220v 1 phase wiring, VFD etc. My kids are really generous with my time also, I am only free after putting them to bed at 10:30pm.

Aye, but you only need the CDL if your driving commercially. If wanted, any bloke could go out and buy a semi with a trailer and as long as it was for personal use only there is no need for a CDL.

Scary eh? heh