Researchers at the Robotics Group at Sandia National Laboratories are developing energy efficient actuation and drive train technologies to dramatically improve the charge life of legged robots. The work is supported by DARPA, and Sandia will demonstrate an energy efficient bipedal robot at the technology exposition section of the DARPA Robotics Challenge Finals in June, 2015. This video describes early development and initial integration of the Sandia Transmission Efficient Prototype Promoting Research (STEPPR) robot. It is a fully functional research platform that allows developers to try different joint-level mechanisms that function like elbows and knees to quantify how much energy is used. The key to the testing is Sandia’s novel, energy-efficient actuators, which move the robots’ joints. The actuation system uses efficient, brushless DC motors with very high torque-to-weight ratios, very efficient low-ratio transmissions and specially designed passive mechanisms customized for each joint to ensure energy efficiency.