Decades: 1240s 1250s 1260s 1270s 1280s - 1290s - 1300s 1310s 1320s 1330s 1340s
Years: 1289 1290 1291 1292 1293 - 1294 - 1295 1296 1297 1298 1299
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... when the axis starts "rolling" inside the groove. (Compare with graphic below.) Since this friction force is essential for the device's operation, the groove must not be ...