"The Soviet “railroad torpedo” ЖДТ-3 (ZhDT-3) was developed by the Ordzhonikidze Machine Plant of Podolsk in 1935 as a weapon against enemy armored trains.
It consisted of a small, two-axle, battery-powered trolley armed with a 495lb (225 kg) bomb containing a 220lb (100 kg) high-explosive charge. The ZhDT-3 had a top speed of 37 mph (60 km/h) and a range of about 6 miles (10 km). Production started in 1938 and it was planned to equip each armored train with five of these devices. While many of these were in service in 1941 at the outset of the war, there is no record of their actual use in combat."

Photo source: Нам есть о чём помолчать…/Eastern Front studies group

Railroad torpedo

Red Army soldiers inspect the captured Finnish artillery systems and small arms; Karelian Isthmus, north-western Russia, Winter War, 30 November 1939-13 March 1940.
   The weapons from left to right: M/09-21 machine gun, 37-mm anti-tank gun PstK/36, 45-mm anti-tank gun 53-K (Soviet, previously captured by the Finns), 37-mm anti-tank gun PstK/36 without a shield, several 150 mm howitzers H/14j (150 mm howitzers of the Krupp system of Japanese manufacture) previously armed with the 2nd Separate Heavy Artillery Division of the Finnish army.

 

Captured Finnish Armament

Member of the Military Council of the 1st Belorussian Front, Lieutenant General Konstantin Fedorovich Telegin (left) and Front commander, Army General Konstantin Konstantinovich Rokossovsky at the map at the Front command post. 