Help Requested Identifying Automobilia

[iansp]

Does anyone know if this is related to a specific car or motorcycle maker.
I have made the assumption it is automobilia related and it was found during a family house clearance but a google image search was unsuccessful.
I think it is made of brass and it weighs approx. 500g and measures approx. 220mm width and the sprocket is approx. 152mm diameter.
Any information much appreciated.