Rotary motion devices

One of the outstanding features of fluid power systems is that force, generated by the power supply, controlled and directed by suitable valving, and transported by lines, can be converted with ease to almost any kind of mechanical motion. Either linear or rotary motion can be obtained by using a suitable actuating device. 

A fluid power motor is a device that converts fluid power energy into rotary motion and force. The function of a motor is opposite that of a pump. However, the design and operation of fluid power motors are very similar to pumps. Therefore a thorough knowledge of pumps will help you understand the operation of fluid power motors. 

Couplings are mechanical devices used to connect the shaft of a driver (e.g., motor, turbine, etc.) to the shaft of a driven unit (e.g., fan, pump, etc.). The purpose of a coupling is to transmit rotary motion and/or torque on a continuous basis without slippage. 

Turbine flow meters are composed of some form of rotary device such as a helical rotor, Pelton wheel or a vane mounted in the flow stream. The fluid passing the rotor causes the rotor to turn at an angular velocity which is proportional to the flow velocity and hence the volumetric flowrate through the meter. The rotary motion of the rotor is sensed by some form of pick-up device that produces an electrical pulse output. The frequency of this signal is proportional to the flowrate and the total count of pulses is proportional to the total volume of liquid passed through the meter. 

Rotary Actuator A device for converting hydraulic energy into rotary motion. Ryton A polyphenylene sulfide elastomer. 

Sieve Shaker Use a mechanically operated sieve shaker that imparts to the set of sieves a horizontal rotary motion of between 270 and 300 rotations/min and a tapping action of between 140 and 160 taps/min. The sieve shaker is fitted with a plug to receive the impact of the tapping device. The entire apparatus is rigidly mounted—bolted to a solid foundation, preferably of concrete. Preferably a time switch is provided to ensure the accuracy of test duration. 

Mixed motional devices, where both rotary and linear (e.g. sliding or translation) motions should be in principle possible, like in rotaxanes. 

Molecular systems that exhibit controlled or coordinated rotary motion are discussed in this chapter. These systems represent a reproduction of a variety of macroscopic mechanical devices on the molecular scale. From gears to a motor, passing through a turnstile, a brake and a ratchet, we describe their design, synthesis and dynamic behavior. The importance of molecular motors in the biological realm and possible applications in nanotechnology are also discussed. 

An important feature of all these devices is that one or more vacuum feedthroughs are required for linear or rotary motion. A common problem with such feedthroughs is that small amounts of sorbed gases... 

Each paddle acts directly without transduction of force or motion, eliminating the need for complex transmission systems that, for example, convert rotary motion to linear motion, or increase/reduce speed through an intermediary device such as a gearbox or crank assembly. 

Have you ever wondered how pedaling moves your bicycle Have you ever thought about how the disc tray on your CD player opens and closes These processes and many more are made possible by people designing and controlling devices called mechanisms. A mechanism is a device that transmits movements so that the output movement is different from the input movement. Mechanisms can change the movement s speed, its direction, or its type of motion. Motion can be in the form of linear motion, rotary motion, or reciprocating motion. 

Cam and Follower A common mechanism used to convert rotary motion into a reciprocating motion is a cam and follower (Figure 10-20). The cam is always the input device for the cam and follower. The follower, sometimes called a lifter, is always the driven component of this mechanism. 

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