This latch is made to be used on an off road metal dump trailer such as one pulled behind  ride-on lawn mowers.  This latch will lock into position on it's own when the dump body is returned to the "down" position because of the spring and the long taper of the latch itself.

     On the drawing, (A) shows an inside look at the latch, with one of the outside posts removed, and also shows most of the dimensions as well. (B), on the top right side, shows the complete finished latch, and a top view. The stop, shown in black, is also pictured here. (C) has the finished latch actually installed on a trailer as seen from the side view of the trailer. The last part of the drawing, (D), is a bit different in that the latch is not shown. This view shows the trailer while looking at it from the front. It is meant to better show where the angle iron is fastened to the front of the trailer, and the shape of the guides.

     To clarify things a bit, you will note that in the drawings of the latch, there appears to be two fastening pins. This is not the case. Only one pin, the top one on the latch, is a pivot pin which is what the latch will ride on while moving in and out of position (shown by "travel" and the two black arrows). The bottom hole in the latch is for a safety pin only. This will allow the trailer dump body to be secure in the "down" position and will prevent accidental release of the latch which in turn would cause the trailer to dump. To dump the trailer, this pin would obviously have to be removed.

     The angle and guides are from a single piece of  angle. The bottom leg of the angle is measured for the width of the tongue. An additional 1" per side is allowed for each guide. The remainder of the bottom of the angle is cut out and removed. The angle is heated and bent as shown in (D). 

    Before you install the latch onto the tongue of the trailer, place the angle iron into the installed position and tack weld it fast to the front body of the trailer. After doing that, then place the latch in place on the tongue and tack weld it. Once this is done, check that the arm will freely move back and forth and will pass over the angle as intended. The latch should clear the angle iron by about 1/16" to 1/8". Make adjustments as needed to allow the latch to be fitted snugly and still operate freely.