I found a bunch of Pat Pend LEGO in a thrift shop. Among all the goodies there are two black smooth 2x4 bricks with train wheels attached to them.
Their characteristics are as followed:
- They are studless.
- Have a closed bottom.
- On one of the long sides there is a half moon like cut-out with a sort of flat hook thing.
- On the short sides there are detachable train wheels with ten spokes.
- The wheel axles are made of yellow brass.
- The logo on top is the old LEGO logo with the letter "O" being open.
- The logo is quite large.
Can anyone help me identify these parts?