Harley's Machine Gun Flathead

Here is Harley's answer to the US Military's desire for a motorcycle mounted machine gun.  This prototype is based on a 1940 model UL.  The UL was powered by a 74" side valve motor, commonly referred to as a flathead.  This was the big twin model, not to be confused with the smaller 45" side valve motor which powered the WLA during WWII.  The motor was mated to a tank-shifted four-speed transmission that drove the rear wheel via a chain.  Mechanically, it's basically your standard issue UL, but to make it battle hardened, Harley added some interesting options.

The most striking feature of this prototype was the amount of armor plating which had been added.  The rider was protected by a "metal fairing" which just had a small porthole in the front.  This might be usable when riding in a straight line on flat ground, but just imagine trying to maneuver over rough terrain looking through that tiny window.  The front tire was protected with an extended front fender and another plate protects the front of the motor.  Probably not the best design for a motorcycle powered by an air cooled motor.

The gun carriage was a great piece of engineering.  Most likely Harley's engineers started with the frame from a package truck, which had a higher payload than a standard sidecar.  This rig would need to carry quite a bit of extra weight, including the gunner, the machine gun, armor plating and of course lots of ammunition, so the heavy duty suspension used on package trucks was necessary.  To the package truck frame, they added a custom seat and sidecar-like body, along with the machine gun mount and front armor plating.  Notice how the front plate has been designed to deflect bullets using a curved profile.

The machine gun chosen for this prototype was a Browning M1917.  As the name would suggest, this heavy machine gun went into production in 1917, which meant it saw some action at the very tail end of WWI.  The M1917 used a .30 caliber belt fed cartridge and by the time this motorcycle was built, was capable of firing 600 rounds per minute.  The barrel's odd shape is due to a water jacket which surrounds the barrel, keeping it cool during extended firing.

It's obvious that Harley designed this motorcycle to attack the enemy head on, but I don't think they envisioned it charging across the battlefield with it's gun blazing.  The rig would have been slow and unwieldy, so it is most likely that it would be in a fixed position during battle.  It's advantage would be that it could be instantly deployed and it saved someone from lugging around the 100+lbs M1917.  Of course if they used the M1917 in the picture below, weight would not have been an issue.

Unfortunately, this motorcycle never made it into production.  Like many prototypes from this period, it was dropped in favor of the WLA.