Quote Originally Posted by safeman View Post
Chubby, the 1920's heavy Ratners - List 6 & 7 and later the Grade 7- were offered with 2 keylocks plus the option of the Ratner Letter Lock to close off the keyway. On the Grade 7 (below right) the 3 horizontal arrows show the live 'Safety Bolt' at the top and 2 dead 'Safety Bolts' on the left. The vertical arrow shows part of the servo bar from the letter lock. As far as I know Ratner was the first to use an anti-explosive device - the dead one in 1913 and the live one in 1918. I daresay the Letter Lock was superceded by the 1930's.
Those Ratners List 6 and 7s are amazing, way above the model I was referring in response to chubby's question but clearly on par with Chatwood's top offerings.

Come on Tom lets see some pics over Xmas hols.