Product Application by Industry - Airflex - #2

Power rating capability is determined by engine design. Combined capability and durability of all engine components determine how much power can be produced in a particular application.

The power output of a basic engine model can be varied within its design ranges by changing the engine fuel setting or speed setting. Both of these settings affect the engine's maximum fuel rate and the power output capability.

Some of the application conditions considered by an engine manufacturer in determining a rat­ing for an application are:

• Load factor

• Duty cycle

• Operating hours

• Historical experience

The same basic engine model can have different ratings for different industries and applications. Usually, they are grouped into the following cate­gories:

• Industrial

• Truck

• Off-highway

• Power generation

• Petroleum

• Marine

Also, within these groupings, are ratings for con­tinuous and intermittent service. Continuous rat­ings are for continuous use without interruption or load cycling. Intermittent ratings apply to about one hour operation followed by one hour operation at or below the continuous rating.

Engine Clutches

The CB element is usually recommended for en­gine clutch applications. Selections are based on the horsepower transmitted by the clutch. In some cases, it may be much lower than the en­gine's horsepower rating due to other engine driven auxiliary loads. Extra loads imposed by a cooling fan, alternator, air compressor or hydrau­lic pumps may represent a significant proportion of total engine power available.

Selections for Engines Without Torque Converters

Clutch selection is based upon the power trans­mitted, clutch rpm, the appropriate service fac­tor, 110 psi (7,6 bar) actuating air pressure and clutch engagement at engine idle.

Torque loss due to centrifugal effect must be taken into account. Follow procedure given in Section B. The peripheral speed of our standard semi-steel spiders and drums should not exceed 8500 fpm (43 mps). If it does, a dual element and/or ductile iron components should be con­sidered. Single elements are preferred because of smaller overhung loads and ease of align­ment.

The Power Capacity Table can be used to make a selection for single CB clutch elements having a 1.8 service factor and an operating pressure of 110 psi (7,6 bar). Find the horsepower value that is equal or greater than that which must be transmitted in the appropriate rpm line and read the clutch size in the column heading. For dual elements, double the power values in the table.

Selections for Engines With Torque Converters

The selection procedure for engines with torque converters is the same as that discussed above for direct drives, but with one other major con­sideration. Under the stall conditions, i.e. con­verter output shaft at zero speed, the clutch must be able to transmit the torque multiplication of the converter.

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Copyright Eaton Corporation, 1997, All rights reserved.