Hyperkinesia
A tic can be defined as a repeated, individually recognizable, intermittent movement or movement fragments that are almost always briefly suppressible and are usually associated with awareness of an urge to perform the movement. These abnormal movements occur with intervening periods of normal movement. These movements are predictable, often triggered by stress, excitement, suggestion, or brief voluntary suppressibility. Many children say that the onset of tics can stem from the strong urge to move. Tics can be either muscular (alter normal motor function) or vocal (alter normal speech) in nature and most commonly involve the face, mouth, eyes, head, neck or shoulder muscles. Tics can also be classified as simple motor tics (a single brief stereotyped movement or movement fragment), complex motor tics (a more complex or sequential movement involving multiple muscle
groups), or phonic tics (including simple, brief phonations or vocalizations).
Cush drive
A cush drive is a part of a motorcycle or scooter drive-train that is designed to reduce stress from engine torque damaging other components during gear or throttle changes. A common design used by almost all street motorcycles, it has three major pieces: the wheel, the sprocket assembly, and the rubber damper. The wheel and the sprocket assembly fit together with five or more sections much like two hands woven together. In between the contact of the two assembly are rubber blocks. This makes it so the wheel and the sprocket have a dampening layer between them, and the rubber blocks reduce wear and fatigue of the metal assemblies. Another popular system incorporates metallic compression type coil springs placed between the input and output shafts of the cush drive assembly.