Question

Given SKF rates for various revolutions if the desired life is 6000 hrs at 1780 rpm

a) 10000 hrs rating at 70 rev/min rating speed

b) 500,00 revolutions

c) 1000 hrs rating live at 600 rev/min rating speed

Answer 1

a) The SKF rated life for 10,000 hours at 70 rpm is determined by the proportion
`\((C)/(P) = (1780)/(70) * (6000)/(10000)\)` , and then using the SKF life formula.

b) The SKF rated life for 500,000 revolutions is directly given as
`\(L_(10) = 500,000\)`.

c) For 1000 hours at 600 rpm, the SKF rated life is calculated using
`\((C)/(P) = (1780)/(600) * (6000)/(1000)\)` and applying the SKF life formula.

Step-by-step explanation:

To determine the SKF rated life for various operating conditions, the basic dynamic load rating (C) and equivalent dynamic bearing load (P)play a crucial role. In scenario a), where a 10,000-hour rating at 70 rpm is desired, a proportion
`\((C)/(P) = (1780)/(70) * (6000)/(10000)\)` is established to find the ratio. This ratio is then employed in the SKF rated life formula to calculate the bearing's life expectancy under these specific conditions.

In scenario b), the SKF rated life is directly given as 500,000 revolutions, providing a clear measure of the bearing's longevity under the stated operating conditions.

For scenario c), aiming for a 1000-hour rating at 600 rpm, a similar proportion
`\((C)/(P) = (1780)/(600) * (6000)/(1000)\)` is utilized to find the necessary ratio. Subsequently, this ratio is employed in the SKF rated life formula to estimate the bearing's life expectancy.

It is essential to note that accurate values for the basic dynamic load rating (C) and other pertinent parameters for the specific bearing are required to conduct precise calculations for SKF rated life in each scenario.

Answer 2

a) The 10,000 hrs rating at 70 rev/min rating speed is not directly comparable to the desired life of 6000 hrs at 1780 rpm.

b) To find the equivalent life at 1780 rpm for 500,000 revolutions, the SKF rates can be used to calculate the corresponding hours.

c) The 1000 hrs rating life at 600 rev/min rating speed can be converted to an equivalent life at 1780 rpm using the SKF rates.

Step-by-step explanation:

a) The given information provides SKF rates for 1780 rpm, and the desired life is specified at this speed. To directly compare, we need rates for 70 rev/min. Unfortunately, the provided rates are not applicable in this case. The discrepancy in speed prevents a straightforward conversion, making it difficult to determine an equivalent life.

b) To calculate the equivalent life for 500,000 revolutions at 1780 rpm, the SKF rates can be utilized. Using the formula
`\(L_(10h) = \left((C)/((n/60)^p)\right)\)`, where
`\(L_(10h)\)` is the rated life, (C) is the basic dynamic load rating, (n) is the speed in revolutions per minute, and (p) is the exponent for the bearing life equation.

c) The 1000 hrs rating life at 600 rev/min rating speed can be converted to an equivalent life at 1780 rpm using the SKF rates. Applying the SKF formula
`\(L_(10h) = \left((C)/((n/60)^p)\right)\)`, the rated life at 1780 rpm can be calculated, providing a basis for comparison with the desired life of 6000 hrs.