High-torque

Small ultrasonic motors such as the rotary actuator shown in Figure 10 have also been made and can be used for automobile windows, seats, and windshield wipers. Many small industrial motors could make use of the high torque, low speed, and precise stepping character of these actuators. 

Extmsion accounts for about 30% of nylon produced and is used in various processes (24). Nylons can be extmded on conventional equipment having the following characteristics. The extmder drive should be capable of continuous variation over a range of screw speeds. Nylon often requires a high torque at low screw speeds typical power requirements would be a 7.5-kW motor for a 30-mm machine or 25-kW for 60-mm. A nylon screw is necessary and should not be cooled. Recommended compression ratios ate between 3.5 1 and 4 1 for nylon-6,6 and nylon-6 between 3 1 and 3.5 1 for nylon-11 and nylon-12. The length-to-diameter ratio, T/D should be greater than 15 1 at least 20 1 is recommended for nylon-6,6, and 25 1 for nylon-12. 

For dry traction more contact is desired and the stopping distance is directiy related, ie, the more contact area the shorter the stopping distance. A softer, more pHable compound conforms to the road surface topography. Too soft a compound (low mechanical strength) abrades more easily and can therefore acts as a roUer and not allow sufficient contact area to be maintained. This is not readily encountered in nominal tires and conditions but has been encountered in cases of extremely high torque conditions for very fast acceleration and sudden stops. 

Rake drive controls protec t the drive mechanism from damage and usually incorporate an alarm to indicate high torque with an interlock to shut down the drive at a higher torque level. They can have an automated rake raising and lowering feature with a device to indicate the elevation of the rakes. 

For reversing drives, except where high torque is not present on starting, add 20% to these factors. 

The split-shaft regenerative turbine is very similar to the split-shaft cycle. The advantage of this turbine is the same as that mentioned before namely, high torque at low rpm. The cycle efficiencies are also about the same. Figure 2-14 indicates the performance that may be expected from such a cycle. 

Water injection, or steam injection systems, are being used extensively to augment power. Corrosion problems in the compressor diffuser and combustor have not been found to be major problems. The increase in work and efficiency with a reduction in NO makes the process very attractive. Split-shaft cycles are attractive for use in variable-speed mechanical drives. The off-design characteristics of such an engine are high efficiency and high torque at low speeds. 

The gas turbine is a high-speed, high-torque drive and requires that its coupling have the following characteristics ... 

Torque the rotating force developed by a motor for starting and carrying loads. Some loads require high torque motors. 

Note Classes A, B, and C listed under 1 are also applicable to multispeed motors. The listing (A, B, or C) for the constant-speed motor indicates the form of motor to use under 2. For example if the listing shows 1C-2B, then the multispeed, constant torque motor should also be high torque, low starting current. 

The tool features a spline assembly that transmits high torque loads to the bit through its outer tube, while the inner assembly absorbs vibration through a series of steel-disc springs. The spring system works in both suspension and compression. 

Air (or Gas) Downhole Motors. Some positive displacement mud motors can be operated on unstable foam. In general, these mud motors must be low-torque, high-rotalional-speed motors. Such motors have found limited use in air and gas drilling operations where directional boreholes are required. Recently a downhole turbine motor has been developed specifically for air and gas drilling operations. This downhole pneumatic turbine motor is a high-torque, low-rotational-speed motor. 

High torques and low speeds are obtainable with certain positive displacement motor designs, particularly, the higher lobe profiles (see Figure 4-203). 

The positive displacement motor whose performance characteristics are given in Table 4-115 is a 5 6 lobe profile motor. This lobe profile design is usually used for straight hole drilling with roller rock bits, or for deviation control operations where high torque polycrystalline diamond compact bit or diamond bits are used for deviation control operations. 

Chain couplings provide a good means of transmitting proportionately high torque at low speeds. Minor shaft misalignment is compensated for by means of clearances between the chain and sprocket teeth and the clearance that exists within the chain itself. 

Torque requirements are a primary concern during the selection process. In all applications where variable or high torque is transmitted from the driver to the driven unit, a flexible coupling rated for the maximum torque requirement must be used. Rigid couplings are not designed to absorb variations in torque and should not be used. 

Variable, high-torque machine hains operating at moderate speeds Run-out table rolls Vertical pump shafting... 

Variable or high torque and/or speed transmission Greater misalignment compensation... 

Because of their proximity to the wall, anchor agitators are more effective in maintaining heat transfer coefficients to higher viscosities. Relatively high torques and larger gear reducers are required, however. Studies by Uhl and Voznick ( ) correlated the heat transfer coefficient in a manner similar to that used with turbine agitators ... 

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