Backing

Another thing that helped me was when I GOAL I will take a few steps back at the end of the trailer to measure the distance to the dock and then do the same thing at my mirror and pick a spot on the ground to line my mirror up. I still do it to this day because I'm in gas station parking lots with a lift gate so that how I make sure I back up roughly the correct distance the first time. Sorry if that sounds stupid but it's just something that helps me.

 

You can line up with just about anything. I line up with pavement markings, other parked trucks, potholes, dumpsters, trees, grease stains, tire tracks, barrier poles and concrete blocks. Anything I can visually track. I also have a Red LED emergency flasher I can drop on the ground wherever I want for backing in poorly lit/marked locations at night or heavy weather.

If your training area has poorly marked pavement, and they do not have traffic cones, then go to Wal Mart and buy a heavy plastic frisbee. Toss it on the ground and use that for a tracking device. It should be super cheap, heavy enough not to blow away, and will survive being run over a few times.

As for what you are doing wrong, if your instructors say you are oversteering, then try to remember this.

** A combination vehicle's trailer turn rate is not constant. In a single-body vehicle, your turn rate IS constant if you keep the wheel turned and keep it turned at the same angle.

** What this means is that when you are backing or going forward, your trailer will turn faster as your tractor and trailer get closer to 90 degrees from one another.

If you start straight, with tractor and trailer in line (180 degrees), then turn the steering wheel hard and keep it that way, the trailer will start out by moving almost directly backwards. As the angle between trailer and tractor shrinks and the tractor gets closer to 90 degrees, the trailer starts to rotate faster, but move backwards slower.

If your truck can get past 90 degrees with the trailer (most standard highway trucks can get at least a bit past 90 degrees) the trailer will actually start to move FORWARD as it rotates!

If you are thinking linear turning rates, then you will always oversteer or understeer.

 

I have a suggestion for your facility, if your instructors will allow it.

Get a walking chalk marker (like what they use to mark baseball fields) and pavement marking paint.

Start a truck fully backed into the alley dock hole.

Have one of the instructors pull OUT of the hole in a clean reversal of an alley dock, with TWO steering wheel adjustments, starting in the hole, and ending up parallel to the 'street.'

Have someone else walk next to the driver side steer the whole way, making a chalk line right next to the steer tire.

Paint on the outside of the curved chalk line and let it dry.

Paint an 'x' where the tandems ended up.

Now students can pull up, put their steer on the end of the paint line and their tandems on the x.

Alley docking is exactly the same forward and back. If you keep your driver steer on the steer line, the trailer will go into the hole, as long as the tandem and 5th wheels are not adjusted.

Your instructors likely won't go for it. They will almost certainly consider it to be excessive hand-holding, but if they do, then anyone can simply watch you and tell you when your steer gets off the line.

 

It does help with conceptualizing the theory.

In your case it may not help that much.

It sounds like your issue is you are trying to drive the trailer with the steers. The steers control the tractor and the tractor controls the trailer. You need to watch 3 things as you back:

• The dot bumper
• The tandems
• The angle between tractor and trailer

The last one is where I think your problem is. You see the trailer needs to turn, so you cut the steers to the right. However the tractor is already at a 45 degree angle to the trailer so it would have turned even with the steers 1/2 turn to the left. Now the trailer is turning too fast, so you crank to the left and get the tractor in front of the trailer, which allows you to get the sight side onto the hole, but the trailer is at an angle so you try and crank around, but run out of space.

Try doing you set up then going backwards with the steers centered and no other correction.

Then reset and go backwards with one turn to the right.

The again to the left. Just see what happens.

Then start out with one turn to the right and after 10 feet get the steers pointing to the left and try and maintain the angle between tractor and trailer.

Play around and see what works and how long it takes things to respond.