I fianly had a chance to take a better look at the rear chain on the HEAVY DUTY trike.... The chain was OK.

I acquired this trike second hand, the previous owner said he had one of the rear axles replaced. Because it broke on him(I'm still trying to figure out how he did that to a 3/4 inch shaft) he had a local bike shop do the work.... They installed the rear cog backwards, causing a chain misalignment
Which is why the chain popped off. On this trike there are two set screws on the rear cog. The cog is the stop that prevents the axle from walking out of the axletube, they use spacer washers between the cog and the inner bearing. With the cog on backwards the axle could walk as Much as 3/4" . once again contributing to said cog misalignment. It is fixed now... FYI. The chain on it is one of the heavyist bike chains I have ever seen....