I have purchased several books and eBooks from RVbookstore.com, but I can’t find the answer to my burning question. In your eBook The Complete Guide to Dinghy Towing you say to never back up a motorhome when pulling a dinghy. My question is: You see many motorhomes pulling boats. If you can’t back up a toad, how do boaters back up to launch their boats? --Jim Walker
Dear Jim,
The reason you can back a boat trailer, but not a dinghy (car or other vehicle), is that the boat trailer doesn't have a set of steering front wheels.
A while back an engineer at Blue Ox experimented backing several towed vehicles. The results weren't good. One person would drive the motorhome and another would attempt to steer the front wheels of the toad. The problem was, in every test, the front wheels would unexpectedly turn drastically to one side making the steering wheel violently spin out of control. If a person has their hands or arm caught in the steering wheel the results could be a broken finger, hand or arm. Even when they attempted to back straight back the wheels would turn, and it was with other manufacturers tow bars too. You should never attempt to back a toad!
Here is how the engineer explained it:
"The reason this happens is not the tow bar but rather the caster angle in the front end of the towed vehicle. Caster is the forward tilt of the steering axis versus vertical. It provides steering stability, steering returnability and cornering ease. In reverse, the caster angle makes the wheels want to turn around the other direction like "casters" on your office chair or shopping cart. We all know they can't turn all the way around on a car, but they will turn off to the side as far as the steering mechanism will let them.
This is virtually undetectable from the driver's seat in the motorhome making this a very scary situation. If you continue to back up, after the wheels have turned, the tires "scrub" or slide sideways causing damage to the tires. Other things caused by this are; severe stress to the steering components, suspension and towing system components."
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5 comments:
Finally, an explanation that makes sense! Thank you.
With your explantion in mind, would it then be possible to back up a car on a towing dolly provided the front wheels are the ones up on the dolly?
Yes, backing a car on a dolly is doable; I've done it with no unusual behavior.
I wonder if you can carefully pull the mororhome back by starting the tow vehicle and pulling the motorhome back eith the tow vehicle (dinghy)? The motorhome would have to be in neutral (running) and someone steering it following the tow vehicle backwards. ????
Peggy,
I would not recommend trying to back a tow dolly either. When you attempt to back up the tow dolly will turn but the vehicle on the dolly will try to stay in a straight line. The results are the tow dolly fender hitting and damaging the side of the vehicle on the dolly.
Mark Polk
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