Pulleys motor loads

Bending moment at the motor shaft due to pulley and load... 

Diameter of pulley on motor shaft D1 (mm) Width of pulley on motor shaft W1 (mm) Diameter of pulley on load side D2 (mm) Width of pulley on load side W2 (mm)... 

Determine the width of a heavy-duty double-leather flat belt for transmitting a load of 18.5 kW at 1480 r.p.m. from a squirrel cage motor to be switched directly on line. Diameters of pulleys are 250 mm on the motor side and 200 mm on the load side. The centre distance between the pulley may be considered as 800 mm. 

The allowable pulley loads for standard motors are given in Table 8.10. These are recommended by a few manufacturers for their motors, but they are generally true for other motors also. 

Table B.10 Allowable pulley loads for standard motors...

Note The shaft deflection should not be more lhan 11% of the air gap between the stator and the rotor. For loads that exert more force and torsional stress on the motor shaft and bearings than is permissible, due to the larger width of pulleys which may shift the... 

Brake and pulley method (usually for very small motors). Considerable care needs be taken in the construction and use of the brake and pulley. When conducting this test conditions should be such that a scale pointer remains practically stationary at any given load. Proper cooling, preferably water cooling, should be provided for the pulley. 

Calibrated machine. When brake and pulley or dynamometer methods are not possible, the test motor may be loaded onto a calibrated generator. The efficiency curve of the generator must be available. 

The mechanical seal on the radiator water pump of your car has to work under severe conditions. This seal must resist the pressures and temperatures, corresponding to the velocities of the motor, and the variable operating times. This seal is not a precision seal (it has stamped parts rather than machined components) and the pump is a portable pump. The pump doesn t use a direct coupling but a v-belt pulley with radial loading. The seal must resist many vibrations commencing with the v-belt slapping and whipping. 

The National Electrical Manufacturers Association (NEMA) has developed a standard that specifies minimum pulley diameters that should be used on electric motors. Since motor bearings are specified using a relatively small maximum overhung load, minimum pulley diameters can have a dramatic effect on motor bearings. The increase in tension that is created by smaller pulleys can transmit a potentially destructive side-load on the bearings. 

The revolutions per minute (RPM) (or rotational speed) of a fan can be increased by increasing the size of the motor pulley, which is the grooved wheel on the motor shaft. A small increase in the diameter of this pulley will greatly increase airflow through the cooling bundle. But, according to the affinity or fan laws, doubling the diameter of a pulley increases the driver amp load by 800 percent. That is, driver horsepower increases to the cube (third power) of the fan s speed. 

The motor 256 is so designed as to slip electrically when the rack 251 is in contact with the stop 277 and the weight of the rack 251, line 250, and safety rod 176 are counterbalanced through the magnetic clutch 257 by weight 280 attached to the periphery of a pulley 281 mounted on the extension 282 of the sh 254 to reduce the load on the motor. 

Means to drive the belt/chain and driving system for top pulley gear box and electric motor. The system should be designed for at least 150-200% of fully loaded condition at maximum speed. 

In several respects our design problem with the belt is somewhat simpler than with the other units in the drive train. The primary load on the belt is a tensile load used to transmit the torque from the motor shaft to the cam pulley. There is a bending force needed to move... 

Single-rotor and twin-rotor hammer crushers are usually driven by slip-ring motors via a V-belt transmission system. As a rule, slip resistors are provided in order to ensure flexible behaviour of the drive motor. In the event of a drop in rotation speed due to impact loading of the rotor, the motor will still develop a high torque and the V-belt drive will be less severely strained. The drive pulley, which serves as a flywheel, is overhung-mounted on the rotor shaft - even on the largest crushers hitherto built - and is fixed by means of locking sleeves or similar devices. 

Use larger pulleys (both motor and load). Check belt tension. 

Different designs for converting rotary motion of a motor to the linear motion of the neutron absorber are in existence. These include rope and pulley mechanisms, rack and pinion drives and screw and nut mechanisms with split nuts for scramming. Use of linear induction motor or a linear synchronous motor eliminates use of a rotary prime mover thereby providing more reliability. However, these mechanisms are larger in size for the same load capacity and are not very popular for reactor applications. Rope and pulley mechanisms permit flexible layout of drive mechanisms with respect to the neutron absorber and can be accommodated within a very small >ace. While using rope and pulley mechanisms, proper tools ate necessary for retrieval of neutron absorber assembly subsequent to incidental rope snapping. 

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