Introduction: Trailer Lock Assembly That Should Give a Thief Some Problems. About $30

A friend of mine introduced me to "the lockpickinglawyer" on youtube. I'm not a paranoid person, but this guy will make anybody think twice about what you have locked up. Basically he can open any lock in about 7 seconds sometimes with nothing more than a toothpick and tree bark. Okay, that might be an exaggeration, but it's still enough to make anyone look back over their shoulder after they have locked up something and walk away.

Now I have some trailers and I thought I had them locked up. Well this guy got some $100 trailer locks and showed how they can be bypassed/picked/removed. by little more than sneezing on them (again maybe a little more than that, but you get the idea.) Well that got me thinking, how can I make a trailer lock that would slow down someone from stealing it, and not have to pay $100's of dollars to do so? So given that I already had a decent lock, and some chain, and the knowledge of how this guy gets around locks, I set about to try and at least slow down a potential experience thief. After I post this I'll send it off to this guy and get his opinion on how well what I did would slow him down.


The BOM (bill of materials):

1 Decent lock - that gave the lockpickinglawyer at least a few seconds of trouble the Masterlock Pro 6230 I also got this super cheap from grainger as they were dumping the model (last years,) and reduced this normaly $25 lock to $6.

1 3000lb chain - I had this already as it was my runaway chain for the trailer. So its not in my budget. My other trailer has the chain welded on and my design will make use of that one as well.

1 5" diameter exhaust pipe connector - it was 8" long for $13, if I was going to make multiple of these things you can also use a 5" diameter exhaust pipe. As it happens, I have 2 trailers, so I got two of these.

1 3" diameter exhaust pipe - it was 18" and I only need about 8" it was $6

1 1"x3/16x8" piece of flat stock - I paid $7 for a 36" piece, I have plenty left over and used a bit of it to make the key longer. that will be useful later.

Step 1: The Plan

So bypassing a lock seems to take the form of one of two ways: 1) pick it. 2)smash it. In both cases easy access to the lock is the key (all puns intended,) to doing this. So my idea is to make the lock inaccessible, both physically, and make using any form of pick too awkward to use. In this way conventional tools won't allow access to the lock and as such nothing can be done to free the trailer. I have also covered up the access to the trailer hitch component so it can't be rolled away. I'm using muffler pipe parts, these are not the heaviest material, but decent enough to require at least some tools to cut them off. by locking everything with the chain taunt, the trailer hitch can't be used and slid off. to keep the lock in the center of its own 3" diameter steel tubing I've added a hasp bar/washer that slides through the 3" diameter tube to keep the lock 2-3" into the middle of the tube. This makes access to the lock very difficult. no tools can really get to it. I took some more flat stock and attached an extender arm to the key to reach into the pipe to unlock the padlock.

Step 2: The Execution.

The 5" diameter tube was shipped at 8" long, that was fine just like that. This part had to be manhandled and hammered using a 3lb mallet into the triangular shape so it just slipped around the collar and captured both the locking pin and the collar part. To hammer it, I first squeezed the pipe section into an oval in my bench vise, then inserted blocks of wood as a spacer and then starting hammering hard with the 3lb hammer shaping the thing into the triangular shape. I repeated squeezing the pipe lower on one end of the oval to make it more pointy and alternating with hammering and squeezing to get it to shape, and the required height to fit over collar and over the locking pin, Checking fit back and forth. This is by far the hardest part of this project.

The lock cover was much easier. I had to cut eye-slits into the pipe for the lock-bar such that the bar would slide through, an have wiggle room to handle the curve of the lock. I chose an "eye-slit" shape that worked out nicely for that. I bascially just drilled some holes, and then connected the holes with a dremel. The 2 holes are kinda trapeziodal shape with big parts furthest away from the two trapezoids. It kinda looks like a medieval helmet eye lists to me. They are a bit off to one side as the lock hasp will not be center either. Sand everything down so there are no sharp edges. the lock bar/washer is nothing more than 3/16x1" bar about 7" long with a hole cut in it to thread the lock through. the net result is the lock can move about an inch up and down the 3" tube, but the ends are nowhere near the mouths of the tube.

I can actually reach in with my hand to unlock the padlock, but it is much easier to make an extender for the key to reach into the tube to unlock it.

Step 3: Using the System.

so slip the the triangle cover over the ball collar and as far back as you can. You'll not on my trailer, I have an "A-frame coupler" so it widens a bit so I notched out the triangular cover a bit so I could push the cover a bit further up the A-frame.

the chain is then run through the triangular cover and looped onto itself, and where two chain links line up I thread the lock hasp through those two links. The opened lock is then fed into the 3" tube so the open end of the hasp us visible though the top eye-hole. Then put the lock bar through that top hole and the bottom then slide that bar up or down so the hole in the bar aligns with the hole in the padlock that the hasp has to pass thru. reach in from the top swing the hasp to get the open end lined up with the holes and close the lock. you will probably have to put your hand into the back of the 3" pipe to hold the padlock steady. Now everything is all locked up.

Step 4: Seems Good to Me.

Well, I hope this is a bit secure.