Ball and Roller Bearings Machinery's Handbook, 31st Edition
2491
Typical Bearing Life for Various Design Applications
Design life in hours 3000–6000 500–2000 500–800 600–1200 1000–2000 1000–2000 1500–2500 1500–2500 2000–2500 2000–5000
Design life in hours
Uses
Uses
Agricultural equipment Aircraft equipment
Gearing units Automotive
600–5000 8000–15000
Automotive Race car
Multipurpose Machine tools Rail Vehicles Heavy rolling mill Beater mills Briquette presses Grinding spindles Machine tools Mining machinery Paper machines
20000
Light motorcycle Heavy motorcycle
15000–25000
> 50000
Light cars Heavy cars Light trucks Heavy trucks
Machines
20000–30000 20000–30000 1000–2000 10000–30000 4000–15000 50000–80000 5000–6000 8000–10000
Buses
Electrical
Household appliances
1000–2000 1000–2000 8000–10000 10000–15000 40000–60000 40000–50000 15000–25000
Rolling mills
Motors ≤ 1 ⁄ 2 hp Motors ≤ 3 hp Motors, medium Motors, large
Small cold mills
Large multipurpose mills
20000–30000 Rail vehicle axle
Elevator cables sheaves Mine ventilation fans Propeller thrust bearings Propeller shaft bearings
Mining cars Motor rail cars Streetcars Passenger cars Freight cars Open-pit mining cars
5000
16000–20000 20000–25000 20000–25000
> 80000
Gear drives
26000 35000
Boat gearing units Gear drives Ship gear drives
3000–5000 > 50000 20000–30000
Locomotive outer bearings Locomotive inner bearings
20000–25000 30000–40000
Machinery for short or intermittent operation where service interruption is of minor importance Machinery for intermittent service where reliable operation is of great importance
Machinery for 8 hour service which are not always fully utilized Machinery for 8 hour service which are fully utilized Machinery for continuous 24 hour service
14000–20000
4000–8000
20000–30000
8000–14000
50000–60000 Instruments and apparatus in frequent use 0–500 Roller bearings are generally designed to achieve optimized contact; however, they usu ally support loads other than the loading at which optimized contact is maintained. The 10 ⁄ 3 exponent in Rating Life Formulas (12) and (15) was selected to yield satisfactory Rating Life estimates for a broad spectrum from light to heavy loading. When loading exceeds that which develops optimized contact, e.g., loading greater than C /4 to C /2 or C a /4 to C a /2, the user should consult the bearing manufacturer to establish the adequacy of the Rating Life formulas for the particular application. Thrust Roller Bearings: The magnitude of the Rating Life, L 10 , in millions of revolutions for a thrust roller bearing application is given by the formula: (15) where C a = basic load rating, newtons (pounds). See Formulas (16) to (18) P a = equivalent thrust load, newtons (pounds). See Formula (19) For single row, single and double direction, thrust roller bearings, the magnitude of the basic load rating, C a , in newtons (pounds), is found by the formulas: (16) L P C a a 10 = c m 10 ⁄ 3 , C f l Z D 90 for a c eff α = = ° 7⁄9 3⁄4 29⁄27
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