Vintage Tinplate GAMA Fire Truck w/ Pumper Trailer Ladder US Zone Germany Key

This fire truck and pumper were found in a box of toys.  

I am including the key, but I am not sure this is the correct key. 

I believe there is something missing on the bottom because I cannot wind it nor 

figure out where a key would go.  The back wheels have resistence when turned

so they seem like they would work.

There are some missing pieces on the truck and pumper.  I cannot get the ladder

to stay in place, so it is not attached.

Please see the pictures.  All sides are pictured. You will receive the exact items pictured.