Flexible drive

A powerful stirrer, driven by a flexible driving shaft between the motor (I h.p.) and the stirrer, is depicted in Fig. II, 7, 3. The motor may be placed at a distance from the stirrer head and reaction vessel, thus enabling the assembly to be used for inflammable, corrosive or fuming liquids without damage to the motor. Furthermore, any laboratory retort stand and clamp may be used since the stirrer head weighs only about 250 grams. A variable speed control (500-2000 r.p.m.) is provided. 

The bowl is suspended from an upper bearing and drive (electric or turbine motor) assembly through a flexible-drive spindle with a loose guide in a controlled damping assembly at the bottom. The unit finds its axis of rotation if it becomes slightly unbalanced due to process load. 

Besides the inherent lateral natural frequency characteristic, compressors are also influenced by torsional natural frequencies. All torsionally flexible drive trains are subject to non-steady or oscillatory excitation torques during normal operation of the system. These excitation torques can be an inherent function of either the driver or the driven equipment and, when superimposed on the normal operating torque, may appear to be of negligible concern. However, when combined with the high inertia loads of many turbomachinery trains and a torsional resonant frequency of the system, these diminutive ripples can result in a tidal wave of problems. 

Most of the failure modes associated with jackshafts and spindles are the result of lubrication problems or fatigue failure resulting from overloading. However, the actual failure mode generally depends on the configuration of the flexible drive. 

Spindles and jackshafts are designed to transmit torsional power between a driver and driven unit that are not in the same plane or that have a radical variation in torsional power. Typically, both conditions are present when these flexible drives are used. 

Repeated twisting of the spindle s tube or the solid shaft used in jackshafts results in a reduction in the flexible drive s stiffness. When this occurs, the drive loses some of its ability to absorb torsional transients. As a result, damage may result to the driven unit. Unfortunately, the limits of single-channel, frequency-domain data acquisition prevents accurate measurement of this failure mode. Most of the abnormal vibration that results from fatigue occurs in the relatively brief time interval associated with startup, when radical speed changes occur, or during shutdown of the machine-train. As a result, this type of data acquisition and analysis cannot adequately capture these... 

This section is an overview of flexible drive chains and sprockets. It provides the basic knowledge required to install, operate, and service this means of power transmission. 

The usual precautions regarding temperature and vibration control also apply to the ultracentrifuge. To overcome air resistance and the attendant frictional heating, the compartment in which the rotor spins is evacuated and may be thermostated over a wide range of temperatures. The rotor is mounted on a flexible drive shaft that minimizes the need for precise balancing as a requirement for vibration-free operation. Finally, the rotor assembly is enclosed in an armored steel chamber for safety. At these speeds, a runaway rotor is deadly ... 

Self-managed (empowered). Whilst a consequence of the flatter management organisations that exist in most companies. These types of team are now the cornerstones of the management of many R D projects. Self-managed teams are designed to improve flexibility, drive customer service improvement, speed up product delivery and maintain motivation. 

Their idea was that if they could develop a cheap, flexible drive system, people would buy it. They were more right than they realized. That solution, known as Integrated Drive Electronics (IDE) because its major feature was a controller located right on the disk, is one of the most popular drive interfaces on the market today. 

The Pensky-Marten apparatus consists of a brass cup mounted in an air bath and heated by a gas flame. A propeUer-type stirrer, operated by a flexible drive, extends from the center of the cover into the cup. The cover has four openings one for a thermometer and the others fitted with sliding shutters for the introduction of a pilot flame and for ventilation. The tern-... 

The stirrers can be driven individually by small electric motors, or power can be taken from a single large motor by means of belts, gear trains, or flexible drives as required. The optimum speed of rotation varies with the... 

Jensen JF. Remote center positioning device with flexible drive. October 6, 1998. US Patent 5817084. 

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