Henderson Excelsior double brake system model

Although there are no identifying marks on this lovely model, this is a demonstrator or patent model of the unique double brake system developed for the Henderson motorcycle in 1918. One brake acts on a pulley, the other a drum. The case on the other side is the chain drive mechanism. The hub on the extension arms apparently represents the front wheel. 

thanks, Rolf!

 From History of the Henderson 1918 ~ 1931 
In 1918, Both William and Tom Henderson were now employees of Excelsior.  William had taken the role of Factory Superintendent at $5,000 per annum and Tom the position of General Sales Manager at $10,000 per annum plus a one-off payment of 200 shares of stock worth $25,000 to be held by Schwinn for five years.  These would be forfeited if Tom was to leave Excelsior on unfriendly terms within this time.  Finally, Tom was receiving a royalty of $2 for every motorbike sold over the next five years or until the design was changed.  The manufacture of the 1918 Model H had been moved from Detroit and the Chicago built models were distinguished by a serial number beginning with Z rather than H.
Hendersons were still hitting the headlines.  Notably, August E. “Blick” Wolter knocked 32 seconds off the 9.3 mile Mt. Wilson Hillclimb record on a stock Henderson.  Wolter followed this some weeks later by driving his Henderson round two laps of Los Angeles’ highest rollercoaster.
The 1919 Model Z still used the Detroit designs.  Improvements included a GE generator on the Z 2 electric model.  The 4-cylinder engine now had a 70 cubic inch capacity and developed 14.2 H.P.  It sported a new Henderson logo incorporating the red Excelsior “X”.
On December 2, 1918 Tom Henderson tendered his resignation with effect from January 1, 1919 to join Melchior, Armstrong and Dessau to export Henderson and Excelsior motorcycles to Europe.  He received the $25,000 from the shares less a $62.50 interest charge.  However, the $2 royalty was stopped from December 31, 1918 due to changes in the rear hub and double rear brake.