Tandems will not slide help

Ok.

You sit still with your tractor trailer. Set the parking brakes right? Brakes set.

Pick a low gear and gently try to drive off with the parking brakes on. She aint going no where right? She might even stall on you.

Now.

If you repeat the exercise this time with the TRACTOR BUTTON IN, parking brakes OFF the tractor and LEFT ON IN THE TRAILER, should you try to gently drive off you should be skidding your trailer wheels. That tells me your parking brakes back there are doing what they are supposed to do.

ANY rotation in your trailer wheels with the parking brakes or trolley applied full back there tells me your brakes are out of a adjustment.

Remember the basic DOT rules. You must have a parking brake able to hold that rig on any grade that is free from ice and snow. If it rolls it's not holding.

Take the whole thing to a shop have them go over the entire brake system with a eye towards adjusting everything so when you do set the parking brakes all over she will stay right there and not move a wheel.

That is what you want when sliding tandems. Rolling trailer wheels mean you are NOT going to have the friction you need (Anchor) to slide on those rails under the floor.

EDIT.

Get under your rails and eyeball straight down front to back under there. If there is any flex, twist, out of line or tandems crooked you are not going to be sliding them today.

Check all 4 of your pins when you pull the widowmaker bar. Make sure all your pins are in as in all the way in free to slide all around.

 

Sounds like weak springs in the brakes. When you say "brakes are set", I assume you mean the red button is pulled, at the same time all the pins are fully retracted?

Do you have air assist pins or a pull lever system? If pull lever system, then maybe using the trolly brake might give you more holding power (red button in, fully charge air system, then apply maximum air to trailer brakes, then try to slide) Note: You can't do this with an air pins system because as soon as you press the red brake button in, you activate the pin lock function.

If so, then maybe ask a flatbed driver if you can borrow one or two of his 4x4's and place them immediately in front or back of the trailer tires, then see if this will help stop the trailer from rolling.

 

Slack adjusters. most likely out of whack causing the brakes to go out of adjustment. I went through this on my fontaine and on a drive axle of my Columbia.

After replacement,.. no more adjustment problems.

Hurst

 

I pulled a trailer that had the brakes adjusted correctly, but when I tried to slide it, it rolled. I used a chick, and the next time I slid that trailer, I was much lighter, and slid find.

I agree with @STexan , the springs have gotten weak. If it has manual pin unlock and trolly, then charge the trailer, and hold it with the trolly. If air operated pins or no trolley, you'll have to find checks or a curb.

 

Or an older model where they aren't automatic.
Tell him to chock up 1of his wagon wheels. Depending on which way he needs to slide.
THEN GET THE #### BRAKES FIXED

 

Unhook the air hoses to your trailer and try sliding it.

 

The biggest mistake I see when watching someone try to slide bogies is the tractor is not straight with the trailer. If not, you are trying to slide a trapezoid and are increasing resistance. The air brakes have much better holding power than spring brakes do. If they wont slide from a stop the roll out and pull the spike down, they should slide then.