A type of articulated locomotive, in which there are two powered trucks, with the rear truck being rigidly attached to the main body and boiler of the locomotive, while the front powered truck is attached to the rear by a hinge, so that it may swing from side to side, and with the front end of the boiler resting upon a sliding bearing on the swinging front truck.
Often the malicious party in examples of threat scenarios. See Alice and Bob.
A wheel, propelled by running or falling water, used to power machinery.
A wheel with buckets used to raise water.