Article - Backing Up While Turning
In the previous articles of this series, we explained why shorter trailers are harder to backup and what is going on when you backup straight. But what if the path you want to follow is not straight? What if you need to back around a bend, follow a curved driveway, or make a gradual turn?
The good news is that backing up through a curve is not a completely different skill. Backing up in a straight line is really just a special case of backing up along a path. That path might be straight, gently curved, or sharply curved. The basic idea is the same: keep the trailer on the path you want it to follow.
To backup around a curve, you steer your trailer onto a curved path and then follow it along that path. If the trailer starts to drift to one side, you steer your tow vehicle farther out to that same side to get outside of the trailer and guide it back toward the center of the path.
This is similar to a sheepdog herding sheep. The sheepdog works behind the flock to keep it moving along the desired path. If the flock starts to wander to one side, the dog moves farther out to that same side and pushes the flock back toward the center. If the flock moves to the other side, the dog does too. As the flock returns to the path, the dog returns to its position behind the flock.
Backing a trailer works much the same way. The tow vehicle is not simply pushing the trailer backward. It is constantly positioning itself behind the trailer to influence where the trailer goes next.
Steering Your Trailer by Steering Your Truck
When backing up a trailer, there are three basic steering conditions.
In the first condition, the trailer is turning faster than the tow vehicle. This is the condition that can lead to a jackknife. The hitch angle is increasing as you back up. If you do not adjust your steering, the trailer continues turning more sharply, the hitch angle grows faster, and the combination can quickly become a jackknife.
In the second condition, the tow vehicle is turning faster than the trailer. This is the condition where you prevent or recover from jackknifing. The tow vehicle is overtaking the trailer’s rotation, so the hitch angle is decreasing. Eventually, the tow vehicle catches up with the trailer and the truck and trailer become aligned again.
If the tow vehicle turns much faster than the trailer, the trailer has little time to turn before being overtaken, so its direction does not change much. If the tow vehicle turns only slightly faster than the trailer, it takes longer to catch up, and the trailer can continue turning for a longer time before it straightens.
However, there is a third condition that falls between the other two. This is when the tow vehicle and trailer are turning at compatible rates for the path being followed. The hitch angle remains approximately steady, and the trailer continues along its path.
If the path is straight, this third condition occurs when the truck and trailer are aligned and both are traveling straight backward. If the path is curved, this third condition occurs when the truck and trailer are angled relative to each other just enough to keep following the curve.
In theory, if the steering and hitch angle stayed perfectly matched, the truck and trailer could continue backing in a never-ending circle.
That is the key point: backing up straight and backing up through a curve are not really separate problems. In both cases, the trailer has an intended path. Your job is to keep the trailer on that path.
That is the key point: backing up straight and backing up through a curve are not really separate problems. In both cases, the trailer has an intended path. Your job is to keep the trailer on that path.
Backing Up Through A Curve
When backing up through a curve, the tow vehicle and trailer must form an angle that matches the curve you want the trailer to follow. Once that angle is formed, you steer the tow vehicle to maintain or adjust that angle.
If the trailer is following the curve correctly, its tires will track along the intended path. If the trailer drifts too far outside the curve, you need to steer so the trailer turns a little more sharply. If the trailer cuts too far inside the curve, you need to steer so the trailer turns less sharply or begins straightening.
This is just like backing up in a straight line. When backing straight, if the trailer drifts left, you steer to guide it back right. If it drifts right, you steer to guide it back left. The same correction idea applies on a curve. The only difference is that the centerline of the path is curved instead of straight.
Think again about the sheepdog. The dog is not trying to make the flock go straight all the time. The dog is trying to keep the flock on whatever path is intended. If the path curves, the dog still moves to the side where correction is needed and guides the flock back toward the path.
The tow vehicle does the same thing for the trailer.
If the trailer begins to move outside the intended path, the tow vehicle moves outside with it and pushes it back toward the path. If the trailer begins to cut inside the path, the tow vehicle changes position to reduce the trailer’s turn and guide it back out.
As the trailer returns to the desired path, you steer back toward the condition where the tow vehicle and trailer are turning at compatible rates. That is the third condition: not increasing the hitch angle, not rapidly reducing it, but holding the relationship needed to continue along the path.
How Do I Learn To Do This?
Developing a feel for the wheel can take time. You need to learn to recognize which side of the intended path the trailer is on. This is most difficult when the trailer is close to the path but not quite on it.
You also need to learn which way and how much to steer to bring the trailer back onto the path. That can be hard because trailer backing is delayed-action steering. What you do with the steering wheel now affects where the trailer will go next.
TowGo LLC manufactures a Trailer Backup Navigation Aid that provides real-time feedback while backing. The system displays the relationship between the tow vehicle and trailer so the driver can see whether the trailer is being directed toward the intended path or away from it.
With TowGo, the driver can see when the truck and trailer are working together to follow the path, and when the trailer needs correction. A guidance arrow shows which way the trailer will turn, and additional visual and audio cues help the driver know when the steering is in a useful correction position.
The result is not that TowGo backs the trailer for you. The driver is still in control. TowGo provides the missing feedback that makes trailer backing easier to understand, easier to practice, and easier to repeat.
The TowGo Trailer Backup Navigation Aid can easily be installed on almost any combination of tow vehicle and trailer and will have you successfully backing up your trailer in no time. For anyone who has ever struggled with backing up a trailer, this system is backup empowerment.
Dan Shepard is the Founder and CEO of TowGo, LLC, manufacturer of the Trailer Backup Navigation Aid, and is an expert on trailer backup technology.