| TABLE 4: SERVICE FACTORS FOR DESIGNING TIMING BELT DRIVES | ||||||
| Driven Machine Type | Driver Type | |||||
| ELECTRIC MOTORS | ELECTRIC MOTORS | |||||
| AC Normal Torque | AC High Torque, Hi-Slip | |||||
| Squirrel Cage | Induction and Single | |||||
| Please see the examples of various | Synchronous | Phase, Slip Ring | ||||
| machines below. Select the group | Split Phase | DC Compound Wound | ||||
| that most closely matches your | DC Shunt Wound | 1-3 Cylinder Internal Combustion | ||||
| application. | 4+ Cylinder Internal Combustion Engines | Line Shafts, Clutched | ||||
| Intermittent Service | Normal Service | Continuous Service | Intermittent Service | Normal Service | Continuous Service | |
| 3-5 Hours / Day or Seasonal | 8-10 Hours per Day | 16-24 Hours per Day | 3-5 Hours / Day or Seasonal | 8-10 Hours per Day | 16-24 Hours per Day | |
| Display Equipment | ||||||
| Dispensing Equipment | ||||||
| Instrumentation | 1.0 | 1.2 | 1.4 | 1.2 | 1.4 | 1.6 |
| Projection Equipment | ||||||
| Measuring Devices | ||||||
| Medical Equipment | ||||||
| Appliances, Sweepers, Sewing Machines | ||||||
| Office Equipment | 1.2 | 1.4 | 1.6 | 1.4 | 1.6 | 1.8 |
| Light Belt Conveyors, Light Package Screens | ||||||
| Oven Screens, Drum, Conical | 1.3 | 1.5 | 1.7 | 1.5 | 1.7 | 1.9 |
| Wood Lathes, Band Saws | ||||||
| Agitators for Liquids | ||||||
| Dough Mixers | ||||||
| Drill Press, Lathe | ||||||
| Screw Machines, Jointers | ||||||
| Circular Saws, Planers | 1.4 | 1.6 | 1.8 | 1.6 | 1.8 | 2.0 |
| Laundry Machinery | ||||||
| Paper Machinery except Pulpers | ||||||
| Printing Machinery | ||||||
| Agitators for Semi-Liquids | ||||||
| Conveyor Belt: Ore, Coal, Sand, Line Shafts | ||||||
| Machine Tools: Grinder, Shaper, Boring Mill | ||||||
| Milling Machines | ||||||
| Pumps: Centrifugal, Gear, Rotary Pipeline | 1.5 | 1.7 | 1.9 | 1.7 | 1.9 | 2.1 |
| Screens: Vibrating Cam Type | ||||||
| Textile: Warpers, Reels | ||||||
| Compressor: Centrifugal | ||||||
| Fans, Blowers, Centrifugal | ||||||
| Brick Machinery except Pug Mills | ||||||
| Conveyors: Apron, Pan, Bucket, Elevator | ||||||
| Elevators: Bucket | ||||||
| Extractors, Washers | ||||||
| Induced Draft Exhausters | 1.6 | 1.8 | 2.0 | 1.8 | 2.0 | 2.2 |
| Saw Mill Machinery | ||||||
| Generators and Exciters | ||||||
| Textile Machinery: Looms, Spinning Frames | ||||||
| Twisters | ||||||
| Rubber Calendars, Extruders, Mills | ||||||
| Centrifuges | ||||||
| Conveyors: Flight, Screw | ||||||
| Hammer Mills | 1.7 | 1.9 | 2.1 | 1.9 | 2.1 | 2.3 |
| Paper Pulpers | ||||||
| Brick and Clay Pug Mills | ||||||
| Fans, Blowers, Propeller Mine Fans | 1.8 | 2.0 | 2.2 | 2.0 | 2.2 | 2.4 |
| Positive Blowers | ||||||
| Reciprocating Compressor | ||||||
| Mills, Ball, Rod, Pebble, etc. | 1.9 | 2.1 | 2.3 | 2.1 | 2.3 | 2.5 |
| Pumps: Reciprocating | ||||||
| Notes: | ||||||
| 1. Equipment subject to choking should use a minimum of 2.0 service factor. | ||||||
| 2. Additional service factors are required for unusual conditions such as load reversal, heavy shock, plugged motor stop and electric brakes. Generally add 0.5 to 1.0 to the above, depending on the severity of the condition. | ||||||