There is no shortage of rotation in today’s machinery. When transferring mechanical power, the most efficient and effective way is through rotation. Despite being a member of the three simple machines; the Inclined plane, the Lever and the Wheel, it took mankind a relatively long time to discover it. The wheel is so embedded into our way of life that one might have thought that it was invented shortly after the discovery of fire? However, there were several other things that you might not have thought preceded the wheel; the needle, rope, woven baskets and even the flute! The earliest evidence of the wheel dates back to 3500 BC, during the Bronze Age. And it wasn’t invented for transportation or power transmission, it was invented to create pottery. It turns out that using a wheel for transportation or energy transfer proved to be a greater challenge. The implementation of axles and circular bores was that challenge and wasn’t a trivial for those times. It took several hundreds of years later before evidence of tribes in Asia began making wagon wheels with axles.
During a time of I-phones, X-boxes and GPS it’s not surprising that the wheel is taken for granted. It’s clearly apparent how integrated the wheel is in our everyday lives, from bikes to trikes to automobiles. What’s not so apparent is that one of the wheels’ finest achievements is the gear. Gears are the unsung hero lurking in the depths of most things that move. Gears have even held star roles in major motion pictures, “The Curse of the Black Pearl”, Will’s first encounter with Captain Jack Sparrow at the black smith, where a mule driven cog (gear) is the central prop to their first of many sparing matches.…but, obviously I digress. Gears are truly one of an Engineers best friends. Interestingly enough, gears didn’t begin to appear until 2700 BC where they were introduced for navigation. A Chinese chariot incorporated a gear like mechanism that continually pointed south despite the direction the wheels of the chariot turned. During the 4th century BC Aristotle wrote about gears reversing the direction of rotation from one gear to the next, an often useful but sometimes bothersome reality while working with gears! In the 3rd century BC the Greeks used gears to turn water wheels and clocks. Then mysteriously, the history of gears appears to go dormant? Surprisingly it wasn’t until the 17th century when the first attempts at constant velocity ratios (conjugate profiles) were recorded and the involute curve was mentioned.
The involute curve, so simple in construction, yet so complex in implementation. This geometric shape is what modern gears are based on. For those of you that don’t know or understand the involute, simply put; on a piece of paper, take a spool of string, extend a length of string from the spool and hold it taught from the spool and place a pencil point at the end of the string….while keeping the string taught, draw a line that is generated while unwinding the string from the spool. This line is an involute and is the basis of why gears work and why they might not! During the 19th and 20th century inventors Joseph Whitworth and Herman Pfauter invented gear hobbing which revolutionized gear manufacture. In the 20th Century the Pfauter Company of Germany invented the first Numerically Controlled hobbing machine and to this date the Pfauter Company holds a very prestigious position in the gear manufacturing industry. Today, the highest level of gear profile generation is in Topological Gear Grinding, a subject covered in Adept’s first patent from 1993 as a way to improve gear efficiency and to reduce gear noise.
Gears might often be the centerpieces of rotating machinery. Bearings, shafts, clutches, housings, etc. all play important roles in making them rotate. If we were to choose the next most important element it would have to be the bearing. Bearings take many forms, but basically in its rawest sense, it’s a shaft in a hole dating back to 3000 BC when combining an axle with a wheel. Today the choices for bearings range from ceramics, magnetics, pneumatics or sometimes just a bushing in a hole. It comes down to position accuracy, friction and cost. Every machine has its own unique requirements. Whether it’s a 30,000 rpm turbine shaft or a hinge on next year’s latest toy, bearings play a very important role.
No matter what type of product or machine is being designed, it is infinitely important to understand the guidelines and specifications of that particular system. Here at Adept we have designed rotating elements spinning 10’s of thousands of RPM under extreme loads, as well as miniature gears transferring ounce inches of torque at a few RPM. If it spins we can design it effectively and efficiently. Call us now to discuss your need for rotation.