The camera perspective gives a false view of mass perhaps to this Reichswehr vehicle. Looks like a KD3 fitted with the standard 7,7cm M1914 Krupp gun. As you know , the treaty forbade AA weapons, and this system had the sights removed to comply. The KD3 was a post war developement from the KD1 tractor; increased HP and fitted with standard sized rear wheels.
I am no expert, but it looks like a Kraftwagen 19 als Geschutzkraftwagen (Sd. Kfz 1) used by the Friekorps and the Reichswehr, if you will look at the photos and drawings I have attached, especially the front end with the winch, you can see the resemblances.
Allow me to give further explanation to this vehicle. My information was provided by the late Walter Spielberger a good number of years ago.
Shortly before the war ended, the Germans had developed a new self-propelled AA gun chassis. To facilitate production, it was decided to utilize the KD1 chassis for the gun carrier. (Previously, these weapon systems were on either the Daimler, or Ehrhardt Modlel 1914 platform trucks.)
The new vehicle was virtually the same as the KD1 zugmaschine with reduced rear wheel diameter, and the armoured driver's compartment of the Daimler M1914 plataform truck. About 30 or so of the vehicles were delivered by the time fighting ceased.
Most were destroyed under the Armistice Agreement. Those remaining had inhibiting locks fitted to prevent extreme elevation to engage aircraft. Additionally, the laying gear was removed for the same reasons. None the less, the vehicle remained in limited production, and by 1930, a total of 49 had been built for the Reichswehr. Tactically, the vehicle functioned as mobil fire support in the Reichswehr.
The designation KW19 simply means "motor Vehicle 19".
Is this the same vehicle ? It is pretty thrashed, but it at least seems to mount a similar gun. It's some sort of war trophy, along with a smashed up German fighter you can see in the background.
The photo depicts a wrecked Ehrhardt platform lorry mounting the Rheinmetall 7,7cm L/30. (This piece was dsimounted, and taken to England for evaluation and is displayed in the IWM today.) The subject piece of this tread is a Krupp 7,7cm L/30.