Conditions Affecting Selection Non–Standard Selection Procedures Some applications require special procedures, or refer to factory. Excessive Overloads The maximum momentary or starting load applied to the gear drive must not exceed 200% of the rated load capacity of the gear drive (100% overload). Rated load capacity of the gear drive is defined as the power rating published in this selection guide with a mechanical service factor of 1.00. If the actual maximum momentary or starting load exceeds the conditions stated above, calculate an equivalent input power associated with the excessive overload by dividing the maximum overload by two. The gear drive selected must have a rated load capacity equal to or greater than the equivalent input power. Frequency of Starts Starting frequency is an important consideration when selecting a gear drive. Applications involving two to three equally spaced starts per hour must utilize a minimum 1.5 service factor for unloaded starts, and a minimum 1.75 service factor for fully loaded starts. For applications involving more than three starts per hour, refer to factory application specifics such as starting frequency and maximum starting torque. The addition of a fluid coupling as a soft start device would increase the number of allowable starts. Reversing Service Applications involving either more than 20 reversals per 10-hour period, or less than 20 reversals per 10-hour period with peak torques greater than 175% of normal load must be referred to factory. Brake-Equipped Applications When a gear drive is equipped with a “working” brake that is used to decelerate the motion of the system, and the brake is located between the prime mover and the gear drive, select the gear drive based on the brake rating or the highest equivalent input power, whichever is greater. If the brake is used for holding only and is applied after the motion of the system has come to rest, the brake rating must be less than 175% of the rated load capacity of the gear drive selected for the application. If the brake rating is greater than 175% of the rated load capacity, refer the application to the factory. Also refer to the factory all applications in which the brake is located at the output shaft of the gear drive. Oversize Prime Movers Recommended Mechanical Service Factors do not cover applications that require oversize prime movers for high energy or peak loads. Refer such applications to the Factory for selection of suitable gear drives. Speed Variation or Multi-Speed Applications The gear drives offered in this selection guide are designed to operate with splash lubrication on any single-speed application and any ratio shown in the selection guide unless otherwise noted. It is essential that all orders indicate the operating speed requirements and ratio so that the proper internal oil distribution accessories can be supplied for the specific speed. Falk Gear Drives use different oil levels for various gear drive sizes, speeds and ratios. Consequently, to operate an existing gear drive at different speeds from those shown on the nameplate, full application and nameplate information must be referred to the Factory for review of the lubrication system. All variable or multi-speed applications will be referred to Factory to specify lubrication components for adequate lubrication at the slowest speed, without excessive temperature or churning at the highest speed. It is essential that all orders indicate minimum and maximum speeds, as well as the speed duration cycles. A separate motor-driven oil pump (at an extra charge) may be required. When selecting gear drives for multi-speed or variable speed applications, determine the speed at which the greatest torque is developed, and select the gear drive on this basis. If the speed is not listed in the selection table, interpolate to determine the gear drive rating. Application-Adjusted Thermal Rating, page 8, The application- adjusted thermal rating is the actual power that a gear drive will transmit continually for three hours or more without overheating. Although it is not necessary to apply the mechanical service factor when determining thermal adequacy of a gear drive, the application-adjusted thermal rating considers thermal factors associated with the application that will affect the ability of the gear drive to dissipate thermal energy. These thermal factors include ambient temperature, altitude above sea level, ambient air velocity and duty cycle. Thermal factors on page 8 are used to adjust the Basic Thermal Rating when determining the application-adjusted thermal rating. A check of the application-adjusted thermal rating versus the actual motor horsepower is necessary for the following applications: • Continuous duty application where the gear drive runs continuously without shutdown for three hours or more per day. • Intermittent duty applications where the gear drive operates for three hours or more per day, and run time intervals exceed the duration of the immediately following shutdown intervals. If any run time interval equals or exceeds three hours, the application is considered continuous duty. The duty cycle factor permits an upward adjustment of the basic thermal rating associated with intermittent duty applications above, and takes into account the operating time per hour of the gear drive, regardless of duration relationship between run time intervals and down time intervals, and provided no specific run time interval exceeds one hour in duration. Other short-interval, intermittent duty applications not meeting criteria stated above may generate only modest thermal energy to be dissipated by the gear drive. Refer full application details to the Factory for selection of the minimum cooling method that is adequate. Effects of Solar Energy If a drive operates in the sun at ambient temperatures over 100ºF (38ºC), then special measures must be taken to protect the drive from solar energy. This protection can consist of a canopy over the gear drive or reflective paint on the gear drive. If neither is possible, a heat exchanger or other cooling device may be required. Overhung Loads and Thrust Loads Overhung loads and thrust loads must be taken into account when selecting a gear drive. If either an overhung load or thrust load is imposed on the gear drive, or if both an overhung load and thrust load are applied simultaneously, refer application details to the Factory for correct gear drive selection. Product Modifications The Factory can supply special product modifications to suit your application needs. Contact your local Representative for housing modifications, special ratios, special shafts, special mounting orientations, accessory modifications and other special application requirements. Seal Housing Grease All gear drives will be shipped with NLGI grade #2 grease in the seal housing cavities. Where this grease could contaminate products produced by customer processes, such as in the food and drug industries, refer to factory for special food grade grease options. Oil Pump-Equipped Application When a gear drive is equipped with an integral or external motor-driven oil pump, and the ambient temperature falls below 50°F (10°C), or the oil viscosity is in excess of 3250 cSt, an oil heater may be required to maintain a satisfactory flow rate at startup to prevent bearing failure. Consult the Factory. V-Class Catalog 171-110 3
