Bad analogy ... Timing belts are used because they are cheaper and lighter, but are a replaceable item. They stretch and sometimes jump the sprockets, and when they break can cause problems that can destroy an engine. Timing chains, which are even stronger, will sometimes stretch and need replacement if used in a powerful engine, although their replacement interval is usually longer than the belts. They, too, have been known to jump a sprocket. Older engines, with gear driven camshafts, last indefinitely and are more precise. You'll note that racing engines generally use gear drives because they must have absolute reliability and absolute timing accuracy.
Since we're talking about a "rubber" belt, my concern is that it will stretch or break after a while, causing misaligned frames or failed film transport. Gears do not have this problem, but they are more costly to manufacture and implement, which is most likely the real reason Pentax uses a belt drive. P�l Jensen wrote: > > Shel wrote: > > > More precise than what? > > More precise than 18 cogs. For the same reasing > they using timing belts on car engines. > The dataimprinting damand a precise film transport. -- Shel Belinkoff mailto:[EMAIL PROTECTED] - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
