Helix angle the helix angle. The efficiency can be plotted versus the helix angle for a constant friction, as shown in the adjacent diagram. The maximum efficiency is a helix angle between 40 and 45 degrees, however a reasonable efficiency is achieved above 15°. Due to difficulties in forming the thread, helix angle greater than 30° are rarely used. Moreover, above 30° the friction angle becomes smaller than the helix angle and the nut is no longer self-locking and the mechanical advantage disappears. In helical and worm gears, the helix angle denotes the standard pitch circle unless otherwise specified. Application of the
Type 90 Kyū-maru kW (1,500 horsepower). The hydropneumatic suspension units are mounted on the front and rear pair of road wheels, which can be adjusted on-the-fly to deal with uneven terrain, a requirement on Japan's rough, mountainous terrain. According to the Japanese Ministry of Defense official data report, the acceleration of the type is 0–200 m in 20 seconds. The Type 90 has an approximate unit cost of 790 million Japanese yen or approximately 7.4 million US dollars at 2008 exchange rates. 341 Type 90 tanks were produced between 1990 and 2009 with an average annual production number of 19 vehicles. The original