Kevin,

After reading your theory about egg-shaped metric hitches my anal
retentive engineering mind kicked in. I rushed to get my digital
calipers and measured the ball dimensions on the 20-year old Mercedes
we brought to this country once. I measured an incredibly precise
50.01 mm at any point of the (machined) surface of the ball. (This is a
removable hitch, it lives in the trunk)
There are lots of egg-shaped objects in this world but the European
hitch ain't among them! BTW, when towing with said Mercedes I notice
that the ball has (of course) noticable play in the imperial size
American tongue part of the hitch.
John is right in saying that a 2" ball will likely bind in a finely
made metric 50mm receptacle.

Herb, J7

wrote:
Metric hitches are designed with a different shape, more egglike, than
imperial types. This is why you must always use the proper ball, even
though sizes are soo close.

2c
Gary Emerson wrote:
ContestID67 wrote:
I needed to move a Blanik L23 trailer over the weekend. Using my 2"
tow hitch ball and I had a heck of a time disconnecting the two. I
knew that the Blanik trailer has what I assume is a 50mm tongue.

I was kind of surprised that my 2" ball (which works out to be 50.8mm)
would be a problem disconnecting. 8/10's of a millimeter difference
doesn't seem like enough to worry about.

What is the tolerance on a 2" setup? Is it so close that 0.8mm can be
a problem?

Thanks, John


How sure are you that it was a 50mm hitch on the trailer? Did the
trailer get imported with the glider? Usually you can find 2" stamped
somewhere on the trailer if it's english. I'm sure we could fill the
newsgroup many times over with people's stories of having a hard time
either connecting or disconnecting trailers even when they are a correct
match.

With that said, the following link shows a picture of a bulldog coupler
(made by HammerBlow). I've only used this on one trailer, but it was
awesome when it came to hooking and unhooking the trailer. It looks
ugly, but it always dropped on with a snap and the way it pops loose by
swinging the jaw open when you're ready to unhook make it a piece of
cake every time. I'll convert any future trailer to this style as a
result. Don't knock it until you've tried it.

http://www.etrailer.com/mm5/merchant...y_Code=COUPLER