This is the N Scale Walking Beam/Horse Head Oil Pump - Kit - 2-3/4 x 1 x 1-13/16'' from Walthers.
Finding oil is hard work - and so is getting it out of the ground. If the oil is thin enough and there's enough underground pressure, it may flow into the well on its own. This may continue for a few hours or a few years, but in time, the pressure drops. Today, nearly 95% of all US oil wells require pumps to stay in production and one of the most common is the walking beam or "horse head."
Seen alone or in groups wherever oil is found, this new kit is a great way to model a part of this vital industry anywhere on your layout. It's typical of American designs in use since the 1920s and includes a detailed stationary diesel power plant, walking beam, rear crank and counterweight, along with the odd-shaped "horse head" front counterweight that gives the machines their nickname
Designed from the ground up to be a WORKING model, the kit includes a hidden drive. Whenever you're ready, just add the Universal Gearbox and Motor Drive Kit #933-1050 sold separately, to power your pump. Complete instructions and precise engineering produce a great looking, easy to build replica.