I have used the Master Lock that slides over the lip around the trailer
hitch coupler and is painted hammer finish brown. The key lock opens and
closes a hole through which the key, an Allen (1/8"?) wrench, reaches up
through to tighten the lock plug. The one I have fits 2" coupler.
$35-$40. I think it is made for 2 5/16" also. 4-pin plug.
Hidden Hitch has a similar lock, Gorilla Guard - $50
hitches4less.com/gorguarcoupl.html
Hidden Hitch Guardian - $33.30
www.hidden-hitches.com/trailer_couplers.htm
I have one of the new Master chrome plated locks that has a swiveling
plunger lock. The one I have fits 2" coupler. $25. I think it is made
for 2 5/16" also - $38.89
www.masterlock.com/cgi-bin/class_search.pl?class_id=CA_TS_03
Cheap disk tumbler plug. Can be broken by driving a big square shaft
screwdriver into the key slot and turning with a wrench. Or just whack
the projecting part that contains the plunger with a big hammer - the
body of the lock is zinc alloy ("pot metal").
Some of these locks appear physically strong but use 4-pin lock cores
that anyone with a little practice can pick. The Abus "Diskus" padlock is
a 4-pin core lock also.
My trailer that has a 2 5/16" coupler has a sawn-off old scored 2 5/16"
ball with a screw threaded into the sawn-off part for a handle. It is
inserted into the coupler, the latch closed and a padlock used to lock
the latch.
Blaylock has models that will fit most couplers. Unfortunately the body
is made of aluminum, which can be sawn off rather easily, particularly
with a cordless "Sawz-All." $30
www.mrlock.com/eshop/locks/mfg/blaylock/index.html
In every case a thief can hitch up with a chain and tow the trailer off
to a secluded place where he can saw or break any lock off.
If you have an electric tongue jack you can put a switch inside the
trailer and route a wire in series with the jack motor wire to the
switch. Unfortunately the electric jacks I've seen have the wire to the
motor head exposed, so all one would have to do would be to hot-wire it.
It would slow them down, which tends to discourage thieves.
To prevent towing, use wheel locks. The ones that jam between the tires
are not security locks, but are simply parking brakes to keep the trailer
from jouncing around while parked. I know, I drove off and forgot to
remove them. The tires spit them out, breaking the hook screws.
This kind of lock clamps over the wheel, nuts and around the back of the
wheel like those horrible things the parking police put on cars when they
don't pay the meter. Some models on the market don't work on brake
equipped wheels.
About the only way I can think of to really give determined thieves a
serious problem (other than an armed guard living in the trailer) is to
cut the A-frame off and set it up for bolting to the trailer frame.
Pretty drastic, especially since most of our trailers have equipment
mounted on the A-frame: LP tanks, batteries, fuseboxes, and the tongue
jack.
You can put the axles on jackstands and remove the wheels. A lot of
trouble each time you park.
Or you can jack it up and remove the hubs or even axles. A lot of heavy
work.
Parking it in a locked garage inside a secure storage facility with 24
hour security is probably the best way to keep one's trailer. The
security fence and guards keep others away and the lock on the garage
keeps the guards and fellow renters out of your trailer.
Or, just have such an old ratty beater of a trailer that no one wants to
steal it. Make sure it's watertight and fix up the interior real nice but
leave the exterior dented and hailstoned.
Al Grayson