Drive gear

Right-angle gear drive is preferred for fans over 3 m (10 ft) in diameter, for electric motors over 22.4 kW (30 hp), and with steam-turbine drives. 

Disk Filters A disk filter is a vacuum filter consisting of a number of vertical disks attached at intervals on a continuously rotating horizontal hollow central shaft (Fig. 18-127). Rotation is by a gear drive. Each disk consists of 10 to 30 sectors of metal, plastic, or wood, ribbed on both sides to support a filter cloth and provide drainage via an outlet nipple into the central shaft. Each sector may be replaced individually. The filter medium is usually a cloth bag slipped over the sectors and sealed to the discharge nipple. For some heavy-duty applications on ores, stainless-steel screens may be used. 

Girth-gear drives can cause the concrete foundations to fail if not designed to resist harmonic vibrations (Saxer and Van der Heuvel, 31st IEEE Cement Industiy Conference, 1989). 

Synchronous speeds are calculated by Eq. (29-10). Speeds above the limits given are obtained through step-up gears large high-speed centrifugal compressors are examples. Two-pole (3600 r/min at 60 Hz) synchronous motors can be built but are uneconomical in comparison with geared drives. 

Bearings of aii types ean be used to support gears. Normaiiy, gear drives proposed for turbine-driven appiieations, whether they are singie- or doubie-iieiieai, wiii be supported in sieeve-type bearings. 

Phinney, J.M., Selection and Application of High-Speed Gear Drives, Proceedings of the 1st Turbomachinery Symposium, Texas A M University, October 1972, pp. 62-66. 

Portable or fixed mixers up to 5hp normally use propellers and run at either direct drive speeds of 1,150 or l,750rpm or at single reduction gear drive speeds between 300 and 420 rpm. They may either be clamped on the rim of open tanks or mounted with a fixed assembly for open or closed tank operation. These mixers are the most economical and are usually used in tanks without baffles. They are rugged and long-lasting. 

Large towers often have the motor mounted horizontally connected to a right angle gear drive. The motor can be closely coupled- in the air stream- or connected with a drive shaft with the motor outside the air stream. Maintenance personnel typically prefer the external TEFC motor- when available- for its easier access. Cooling tower fans- like all fans- operate in accordance with the fan laws one of which states that the horsepower required to drive a fan increases to the cube of fan speed. 

Gear boxes are used on just about all large field erected cooling towers and many factory assembled towers- all of the propeller ty e fan, draw-through type. Almost all are right angle gear drives with the input shaft horizontal and the output... 

Gear drives, power transmission AIA, ANSI, NSC, USCG... 

R er-antrieb, m. gear drive, -fahrzeug, n. wheeled vehicle. 

Normal electric motor speeds run from the standard induction speeds for direct connection of 3600, 1800 and 1200 rpm to the lower speed standards of the synchronous motors, and then to the somewhat arbitrary speeds established by V-belt or gear drives. For some cases, the pump speed is set by the type of drivers available, such as a gasoline engine. 

Usual practice, particularly for good estimating is to assume that the gear drive requires 5% of the impeller horsepower and that system surging or variations require a minimum of 10% of this impeller horsepower. Thus... 

This relation includes a 50% static efficiency of the fan and gear losses, assuming a gear drive [19]. If belt driven the difference will not be great. 

Estimated fan brake horsepower Assume gear drive... 

Figure 10-175 illustrates the assembly of a typical forced draft unit with electric motor and gear drive. Note that walkways and access ladders are necessary to reach the exchanger connections where valves are usually installed. If... 

Figure 12-39C. Single-stage gas compressor with integrally geared drive shaft. (Used by permission Bui. 1.10, Jan 1994. Sunstrand Compressors, Sunstrand Fluid Handling.)...

P , = mechanical loses, such as belt drive, gear drive, bearings... 

Elevators of this type are of a configuration similar to the geared drive systems mentioned above. The difference lies in the increase in the physical size of the drive as the required operating torque of a gearless d.c. motor is produced at a fraction of the rpm of a geared a.c. motor. 

The cost of these drives is significantly greater than that of a comparable geared drive, but the quality of ride and maximum speed of car travel are much improved. Gearless drives usually have applications in prestige offices and hotels where the elevator travel is in excess of 35 m. 

Source Adapted by Integrated Systems, Inc. from Gears and Gear Drives, 1996 Power. Transmission Design, Penton Publishing Inc., Ohio, pp. A199-A211. 

Table 52.5 Lubrication of industrial enclosed gear drives. AGMA Lubricant Number recommendations for helical, herringbone, straight bevel, spiral bevel and spur ...

Table 52.6 Enclosed cylindrical and double enveloping worm-gear drives...

Warning Worm gear drives operate satisfactorily on R O gear oils, sulfur phosphorus EP oils or lead naphthenate EP oils. These oils, however, should be used only with the approval of the gear manufacturer. 

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