PowerWheel USA, LLC - Trailer Tips

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SUBJECT: Moving a tandem axle trailer

An individual who owns a very large RV was trying to make a sharp turn into the intended parking spot using a powered trailer mover. Here's some specs on the RV.

In the process of parking, using the trailer mover, it became necessary to position the trailer mover at an extreme angle to the tongue of the RV, approximately 70°. He applied power and nothing happened and wondered why. It was as if he were trying to push through a brick wall.

To fully understand the dynamics of what is happening here, it is beneficial to first drop back and look at what happens when a single axle trailer is turned and exactly what is happening in the process. Let's look at a quick drawing and see if this can explain what you are dealing with.

When a trailer mover is positioned at a 90° angle to the tongue of a trailer or for that matter, 60°, 50° or even 40°, a single axle trailer simply rotates on one wheel or the pivot point (see RED X) and the opposite wheel follows the outside arc of the turning radius.

No mess, no fuss and no problem. It all happens and works in a very smooth and orderly fashion.

However the same situation, this time with a tandem axle trailer, presents a host of different problems and what was a ridiculously easy thing to do with the single axle trailer is a much more involved process. Let's look at another drawing to try and understand what is going on.

If a RV trailer had a personality it would, at this point, be a personality under great stress for you have placed it in a real quandary. Before, with a single axle, it was an easy task to decide the pivot point or "Axis of rotation".

But here, we've changed the equation significantly because neither set of inside wheels can become the pivot point and form this axis. Therefore a point somewhere in between the two axles has become the axis of rotation and we now have a war going on between the tires of one axle against the tires of the other axle. It's a no win situation!

With the trailer mover pushing in the direction of the blue arrow, this has set up a situation where the outside tire of the front axle is doing its best to follow the arc of the intended radius of movement. The culprit here becomes the rear axle. Its tires are forced to move in the direction of the red arrow and can do nothing but drag sideways along the surface. The tires of the front axle are dragging in the direction of that red arrow.

It is possible to make the trailer move given enough force being applied to the tongue but this will never be done with a small trailer mover such as those being sold in the market today. It would take the power of a truck and in all likelihood, it would apply so much force to the frame of the trailer that a tire or tires could become dismounted from the rims or at worse, the axle hubs could be bent. So this takes us to the next step.

How do you turn a tandem axle trailer with a trailer mover?

Actually, given enough space for maneuvering (and this is critical), a tandem axle RV or boat trailer can be easily turned and parked most anywhere you wish to park it. It's not a fast process however it can be done by one of two methods. (Editor's note: If someone knows of another, please send it in.)

First Method:

Generally, in most cases, a large tandem axle RV can be easily repositioned (this case a 90° turn) in one continuous movement. To do this, imagine a 100' X 100' box shaped area. Beginning in the lower left corner of the box, you can swing around to the upper right corner of the box by positioning your trailer mover handle at an angle of between 15° to 20° to the center line of the trailer tongue. Press you power switch to ON and begin moving.

In this instance, while there is still some slight drag on the tires, there is enough rotation (movement) of the tires so that you will not notice it. The tires are taking a little bit of the arc of the curve with each turn of the tire. Too much angle on the handle and the tire drag increases dramatically (as in the previous drawing example). The move is made in a sweeping giant smooth arc.

Okay . . . . so you don't have 10,000 open square feet of paved surface. What's next?

The first method was the best of all worlds solution. Now let's look at the real world.

Second Method:

Most of us park our tandem axle boat or RV in a much more confined area as we do not have a parking space rivaling that of a shopping center parking lot. However, you must have sufficient maneuvering room of almost twice the length of your RV.

Starting at your beginning point, commence a move such as you would start in the wide arching movement in the first method. It makes no real difference if you begin by pushing or pulling your trailer. Put as much angle on your mover handle so as to allow the trailer move without the tires noticeably dragging and inhibiting your progress. The tighter the turn, the better but do not overdo it! Move back about ½ the length of your RV, turning as you do.

Now, reverse the handle to the other side and push or pull the same distance placing your RV at an even greater angle to your beginning point. Repeat this process as often as necessary to end up in the direction you intended to place your trailer.

This sounds vaguely familiar to getting into or out of a tight parallel parking space.

You are right! It's simply a process of making the direction change in small incremental back and forth movements instead of one single movement.

Without going into all of the detail of the physics involved, we all know that moving a trailer up or down a hill is quite a bit different than moving a trailer over a level surface. Here is an example of what we are talking about.

Assume you have a slope beginning at your garage going down your driveway. In deciding if a powered trailer mover is right for you, it is necessary to determine the slope and compare this to the weight of your trailer.

Let's assume you have the following:

Your trailer weighs a total of exactly 2,000 pounds. This is not the empty weight. This is the total weight of what you pull behind your towing vehicle whether it is a RV, boat, or whatever.

1. The distance from the driveway edge of your garage floor (where you park your trailer) to the low point of your driveway (where you would begin to move your trailer) is 35 feet or 420 inches.

2. The low point of your driveway is 21 inches below the level of your garage floor. This means that in a run of 420 inches, there is a drop of 21 inches. How do we accurately determine this?

It used to be complex to accurately determine this as you would need a surveyor's transit but technology has given us a very inexpensive device to get this done. It's called a laser level and a stick and we'll tell you how to get one cheap.

Let's look a quick drawing to see the setup. Excuse any lack of artistic skill.

Make sure the bubble in your laser level is centered in order to project a level beam. If necessary, place something under the front or rear to raise it to a level position.

Step 1. Measure and record how many inches up the beam (red dot) is from the bottom of the stick .

Step 2. Measure the distance from the edge of your garage floor to the low point (where the stick was) and convert this to inches.

In the foregoing example, you have determined that the falloff is 21 inches over 420 inches (or 1.75 feet over 35 feet).

Now the computation of what effect this has on the effective weight of your trailer going up this grade gets a little complex in that you must first determine the degree slope and then apply that to the weight of your trailer. For purposes of this computation, we assume a constant movement speed and we do not factor in the coefficient of friction and all of those other scientific things. A NASA engineer might take exception to this method.

However for this purpose, the degree slope is approximately 2.86 degrees and the "effective" or perceived weight of your trailer is approximately 2,979 pounds as far as the trailer moving machine is concerned. That's a 50% increase in weight.

The whole point of this is just to just show the effect of grade on the ability of a trailer mover to move a load up a slope. If you were to purchase a trailer mover rated at 2,500 pounds thinking it will be sufficient for your particular circumstance, you would very quickly find that you have a problem when you begin up this grade. This is why we always recommend in your selection process that you purchase a machine with excess capacity so that you can handle the variables you will encounter from place to place.

You can perform this same computation right here online once you have determined the following.

Distance from parking spot to lowest point of beginning ________ (in inches) THE RUN
Difference in elevation between the two points ________ (in inches) THE RISE
Weight of your trailer you are moving ________ (in pounds) TOTAL WEIGHT OF TRAILER

We have now included access to an online computation of this data to give you an approximate indication of the effect on your trailer's weight moving up a grade.

* * * * * Click Here to Use Our Online Calculator * * * * * *

OK . . . Here is where you can purchase a laser level. The one that we use at Power Wheel USA was purchased at Lowe's Building Supply for around $49.00. It's an aluminum frame Lasermark but you do not need to spend this kind of money. For your purposes, it does not have to be a sophisticated device. Just project a reasonably accurate laser beam.

Your can go to Google and search for "LASER LEVEL". You will sometimes see on the right hand side of the screen "Laser Levels on Ebay". Or you can search on Ebay direct. Here you can many times find them for as low as around $12.00 - $15.00 and many of the companies offer "Purchase Now Option" for a couple of bucks more. We've recently seen laser levels as low as $5.99 at Harbor Freight Tools.

Click above link and keyword search "Laser Level"

This is not a wasted purchase in that you will find numerous uses for do it yourself projects around the house.

Regardless of whether or not you purchase a machine from Power Wheel USA or our competition, we want you to make a fully informed purchase and to be sure what you are purchasing will get the job done for you. An expenditure of as little as $20.00 (with shipping) for a laser level and a little time invested on your part will assure that you do not make a $1,000 or more mistake. Don't order a machine, discover it will not get the job done, and face the cost of shipping it back for a refund after you have paid the cost of having it delivered. That can cost as much as $250.00.

Our goal is to make sure you get it right the first time. Your safety and satisfaction is our primary concern

Please contact us if you need any further explanation in determining your slope.

Bill Fambrough
President
Power Wheel USA, LLC
4140 JVL Industrial Park Drive
Unit 207
Marietta, GA 30066
Toll Free 1-866-770-3740

The foregoing represents the personal opinions of the editor and contributors. Safe moving of your trailer with a powered trailer mover is your personal responsibility. Nothing presented herein is represented to be applicable or similar to your own unique situation. Always practice Safety First.