Motor pulley

The motor, pulley and the supports for the reaction vessel must be attached firmly to a heavy wooden stand which will allow as little motion as possible in the apparatus during shaking, thus reducing to a minimum the possibility of the gradual formation of leaks. 

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. 

This could also include supervisions such as midshaft overspeed, end of wind overspeed, overwind, underwind, wrong direction of rotation and stall, broken motor-pulley/drum drive chain, rope shp (for friction hoist) and slack rope switch (for drum hoist) supervisions. 

Broken motor-pulley/drum drive chain 3... 

Lifting devices are installed to enable change of motorized pulley without cutting the belt. 

Motor pulley The wheel fixed to the shaft on a motor used to turn a belt drive. 

Are there any mechanical hazards such as motors, pulleys, machinery or shop equipment, foik-lifts, hoists and cranes, or sources of kinetic or potential mechanical eneigy present in this operation ... 

Disadvantages. Again, a specialized probe-head is necessary to allow the rotor axis to be changed, usually usmg a stepper motor and a pulley system. Angle switching needs to be as fast as possible and reproducible. 

Backstops. A backstop is a device that permits rotation of the pulley in the forward direction but automatically prevents rotation in the opposite direction. A backstop should be installed at the headshaft of an inclined belt to prevent the belt from moving in reverse if the power to the motor is intermpted or if there is a failure in the mechanical drive system. 

FIG. 29-75 Conil.ined irialile-speed and motor drive. CRueres Pulley Co. from Kenl, Mechanical Engineers Handliook. 12th ed, Wiley, ew York, 1961. ... 

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. 

Figure 8.12 shows the arc of contact, i.e. the contact angle, the belt would make with the pulley. As for a motor a belt is also subject to unfavourable operating conditions that require deratings depending upon the working conditions, arc of contact and the length of the belt selected as noted below ... 

W = weight of complete rotor and driven masses on the motor shaft, such as the pulley and the belts (kg)... 

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...

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

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... 

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)... 

Weight of pulley on motor shaft (kg) Magnitude of pulley force P (kgf or N) Inclination /3of the pulley system to the horizontal plane as shown in Figure 8.18. 

This test is intended to determine the temperature rise in different parts of the motor windings while running at rated conditions and the permissible temperature rise limits are specified in Table 11.1. While preparing for the temperature rise test the motor should be shielded from currents of air coming from adjacent pulleys, belts and other components to avoid inaccurate results. Sufficient floor space should be left between the machines... 

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. 

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