Article – Taking Control of Jackknife Turns

In the previous article, we explained that backing up through a curve is much like backing up in a straight line. In both cases, the trailer has an intended path, and the tow vehicle is used to keep the trailer on that path.

But what if the path is not a gentle curve? What if you need to make a sharp 90-degree turn into a driveway?

That is where the idea of a controlled jackknife becomes useful.

The word “jackknife” usually sounds bad, and for good reason. An uncontrolled jackknife happens when the trailer turns faster than the driver can manage. The hitch angle grows too quickly, the trailer folds toward the tow vehicle, and the driver may run out of room to recover.

But an increasing hitch angle is not always a mistake. Sometimes, for a sharp turn, you need the trailer to rotate significantly relative to the tow vehicle. The key is control.

A controlled jackknife is a deliberate maneuver. You allow the hitch angle to increase so the trailer can be placed onto a sharper path, but you manage that angle before it becomes excessive. You are not letting the trailer fold uncontrollably. You are using the hitch angle to aim the trailer. This takes skill that comes with a lot of practice.

When a driver reacts a little late or corrects a little too hard, the trailer can start backing along a serpentine path. The first correction may bring the trailer back to the intended path, but the trailer may reach that path slightly crooked. On the next correction, that small crookedness combines with another late or overly strong steering input, so the trailer crosses the path even more crooked than before. Each swing builds on the last. Before long, the trailer is no longer following one clean curve. It is snaking back and forth in wider and wider arcs until the driver has to pull forward and straighten out, or risk hitting objects on either side.

Why a Sharp Turn Needs More Hitch Angle

When a trailer backs through a turn, it is not simply “turning left” or “turning right.” It is following an arc.

That arc has a radius. A large radius is a broad, gentle turn. A small radius is a tight turn.

A gentle curve may only require a small hitch angle. The trailer does not need to rotate very much relative to the tow vehicle because the path changes slowly.

A tight driveway turn is different. The trailer has to get onto a much smaller-radius path. To do that, the trailer must rotate more sharply. That means the hitch angle has to increase.

This is the reason for the controlled jackknife. You are creating enough hitch angle to put the trailer onto the sharper turning path.

Choosing the Cornering Radius

A helpful way to plan a sharp backing turn is to think about the center of the curve.

Imagine the trailer is going to follow part of a circle as it backs from the road into the driveway. The center of that circle is not usually marked, but you can often estimate it from something nearby.

For example, a mailbox post, signpost, tree, or other fixed object near the corner may be close to the center of the curve you want to follow. If the object is roughly the same distance from the center of the driveway as it is from your starting point in the road, it can give you a useful visual reference for the cornering radius.

You do not need to measure it exactly. This is just a practical way to picture the turn.

If the radius is too large, the trailer will swing wide and may miss the driveway. If the radius is too small, the trailer will cut too sharply and may jackknife or strike the inside edge of the turn. The goal is to choose a radius that fits the available space and then guide the trailer onto that path.

The trailer’s path is mostly determined at the trailer axle. So when you are watching the trailer, pay attention to where the trailer tires are going. The tires tell you whether the trailer is following the intended arc.

Getting Onto the Sharper Path

To begin a sharp turn, you first need to make the trailer turn toward the driveway. That usually means allowing the hitch angle to increase.

At this stage, the trailer is turning faster than the tow vehicle. That is what creates the angle. If you keep allowing the hitch angle to grow without correction, the maneuver can become an uncontrolled jackknife. But if you manage the angle, it becomes useful.

The goal is to increase the hitch angle enough to point the trailer onto the desired cornering radius.

Once the trailer is on that path, your steering job changes. Now you are no longer just trying to make the trailer turn more sharply. You are trying to control whether the trailer continues tightening, holds the curve, or begins to straighten.

A useful way to think about it is this:

If the trailer is swinging too wide, it needs a tighter radius.
If the trailer is cutting too sharply, it needs a wider radius.
If the trailer tires are following the intended arc, you want to manage the hitch angle so the trailer stays on that arc.

This is where the controlled part matters. The trailer may need a fairly large hitch angle to enter the driveway, but once it is aimed correctly, you usually need to slow the increase, hold the angle, or begin reducing it.

Recovering From the Turn

A sharp turn is not finished when the trailer starts entering the driveway. You still need to recover.

As the trailer becomes aimed down the driveway, you steer the tow vehicle so it begins to catch up with the trailer. The hitch angle decreases, and the truck and trailer gradually move back toward alignment.

If you recover too early, the truck and trailer may end up in line, but positioned at a crossing angle toward the far side of the driveway. Too late and the alignment will be angled toward the near side of the driveway.

That is why sharp backing turns are difficult. The driver has to create the angle, use the angle, and then recover from the angle — all while moving backward.

What TowGo Adds

TowGo helps by showing the driver what is happening between the tow vehicle and trailer in real time.

The system uses a sensor on the steering wheel and a sensor at the hitch. The app displays the relationship between steering and hitch angle so the driver can see not only where the trailer is, but also what it is about to do.

For a sharp turn, this is especially helpful. The driver can create a controlled hitch angle to put the trailer onto the desired radius, then use the guidance to manage that angle before the trailer folds too far.

The guidance arrow shows which way the trailer will turn. It turns green when the trailer is being directed toward the target path. TowGo’s prediction display helps the driver understand the result of the current steering position before the trailer has already moved too far.

Flash & Beep™ provides an additional cue when the steering reaches the useful correction point. This allows the driver to keep eyes primarily on the mirrors and surroundings while still receiving clear feedback from the system.

Features such as Angle Lock and Align Assist further support real-world backing situations. Angle Lock helps the driver hold a selected trailer path, while Align Assist helps guide the driver back toward a straight truck-and-trailer alignment when needed.

The result is that a sharp driveway turn becomes easier to understand. Instead of guessing whether the trailer is turning too much or not enough, the driver can see whether the trailer is being guided onto a tighter radius, a wider radius, or back toward alignment.

The Big Idea

A controlled jackknife is not a mistake. It is a tool.

For a gentle curve, you may only need a small hitch angle. For a sharp driveway turn, you may need a larger hitch angle to get the trailer onto a smaller cornering radius. The skill is knowing how much angle to create, how long to hold it, and when to recover.

TowGo gives the driver feedback during each part of that process: creating the turn, following the radius, and recovering toward alignment.

For anyone who has struggled with sharp backing turns, understanding cornering radius and controlled jackknife maneuvers can make trailer backing much less mysterious.

Dan Shepard is the Founder and CEO of TowGo, LLC, manufacturer of the TowGo Trailer Backup Navigation Aid, and is an expert on trailer backup technology.

by Dan Shepard