Rolling-Contact Bearings

According to the American Bearing Manufacturers Association (ABMA) standard, what is the defined failure criterion for a rolling-contact bearing under ideal conditions?

The relationship between a bearing's load (F) and its life (L) at a constant reliability is given by the formula FL^(1/a) = constant. What is the value of the exponent 'a' for ball bearings?

What is the 'rating life' (also known as L10 life) of a group of nominally identical bearings?

A ball bearing is desired to have a life of 5000 hours at 1725 rev/min with a radial load of 400 lbf. The manufacturer's catalog rating life is 1 million revolutions. Assuming a reliability of 90 percent, what is the required catalog load rating, C10?

In the Weibull distribution used for rolling-contact bearing reliability, what does the parameter 'x0' represent?

When selecting a bearing, an application factor (af) is often used. What is the purpose of this factor?

For an angular-contact ball bearing, the equivalent radial load (Fe) is calculated using the equation Fe = XiVFr + YiFa. What does the rotation factor V equal when the inner ring rotates?

An SKF 6210 angular-contact ball bearing has an axial load Fa of 400 lbf and a radial load Fr of 500 lbf. The outer ring is stationary. The basic static load rating C0 is 4450 lbf. The bearing table provides the following data: for Fa/C0 = 0.084, e = 0.28 and Y2 = 1.55; for Fa/C0 = 0.110, e = 0.30 and Y2 = 1.45. What is the equivalent radial load Fe?

For a bearing subjected to a series of different loads for different fractions of its life, what is the formula for the equivalent steady load (Feq)?

What is the primary advantage of using a filling notch in a deep-groove ball bearing?

In selecting tapered roller bearings, what is meant by 'indirect mounting'?

A design load on a ball bearing is 413 lbf with an application factor of 1.2. The desired life is 30,000 hours at 300 rev/min, with a target reliability of 0.99. The bearing manufacturer's rating life is 1,000,000 revolutions. The Weibull parameters are x0 = 0.02, (θ - x0) = 4.439, and b = 1.483. What is the required catalog rating C10?

If two bearings, A and B, are used on a single shaft and the required reliability for the shaft is R, how are the individual bearing reliabilities RA and RB related?

What is the primary reason that straight or cylindrical roller bearings have a higher radial load capacity than ball bearings of the same size?

Under what condition should grease be used as a lubricant for a rolling-contact bearing instead of oil?

What is the main purpose of preloading in a bearing assembly?

When mounting bearings on a shaft, which ring is typically mounted with a press fit?

Which type of seal is described as being especially effective for high-speed installations and can be used with either oil or grease?

What is the recommended life in kilohours (kh) for machines in continuous 24-h service where reliability is of extreme importance?

According to Table 11-5, what is the recommended load-application factor for machinery with moderate impact?

The relationship between a bearing's load (F) and its life (L) at a constant reliability is given by the formula FL^(1/a) = constant. What is the value of the exponent 'a' for roller bearings (cylindrical and tapered)?

A roller bearing on a shaft has a radial load of 316.0 lbf. The life goal is 10,000 hours at 655.4 rev/min. The manufacturer's rating life is 1,000,000 revolutions. The application factor is 1.2, and the reliability is 0.99. For this bearing, the Weibull parameters are x0=0.02, (θ-x0)=4.439, and b=1.483. What is the required catalog rating C10?

What is the 'basic static load rating', C0, of a bearing?

In the context of tapered roller bearings, a radial load induces a thrust reaction within the bearing. According to Timken, what equation is provided to estimate this induced thrust load (Fi)?

When calculating the equivalent radial load for a tapered roller bearing, Timken recommends an equation of the form Fe = XFr + YFa. What value is recommended for the radial factor X in all cases?

In a pair of direct-mounted tapered roller bearings, an external thrust load Fae is applied. Bearing A is the 'squeezed' bearing. If the induced thrust from bearing A (FiA) is greater than the sum of the external thrust and the induced thrust from bearing B (FiB + Fae), which bearing carries the net thrust load?

A shaft is supported by two tapered roller bearings, A and B, in a direct mount. The radial loads are FrA = 2170 N and FrB = 2654 N. An external thrust Fae = 1690 N squeezes bearing A. For the first trial, K=1.5 is used for both bearings. What is the dynamic equivalent load on bearing A, FeA?

In Example 11-8, bearings A and B (cone 15100 and cup 15245) are selected, with a C10 rating of 12100 N. The desired life corresponds to xD = 2.67. For bearing A, the equivalent load was FeA = 4938 N. What is the calculated reliability of bearing A?

What is the primary function of the separator in a rolling-contact bearing?

A bearing is subjected to a continuous, periodic load variation described by F = F_bar + A*sin(theta). For a ball bearing (a=3), what is the application factor (af) if the average load F_bar is 100 lbf and the amplitude A is 40 lbf?

What is the typical value for the Weibull shape parameter 'b' for rolling-contact bearings?

The median life of a group of bearings is typically how many times greater than the L10 rating life?

For a 02-series deep-groove ball bearing with a 50 mm bore, what is the basic dynamic load rating, C10, in kN?

Which type of bearing mounting arrangement provides the greatest aligning stiffness and is good for heavy radial and thrust loads from either direction?

Which class of machinery has the shortest recommended bearing life according to Table 11-4?

What is the primary disadvantage of a straight roller bearing mentioned in the text?

If a ball bearing is subjected to four load cycles with the following fractions of revolution and equivalent loads (Fei): f1=0.077, Fe1=873 lbf; f2=0.115, Fe2=795 lbf; f3=0.346, Fe3=966 lbf; f4=0.462, Fe4=835 lbf. What is the overall equivalent radial load (Feq)?

What is the primary defining characteristic of an angular-contact bearing compared to a standard deep-groove bearing?

In the iterative procedure for selecting a ball bearing at location C in Example 11-7, after the first calculation yielded a required C10 of 53.2 kN, an 02-60 mm bearing with C10=55.9 kN and C0=35.5 kN was selected. Using this bearing's C0, a new Y2 factor was interpolated to be 1.84. What was the new calculated equivalent load, Fe?

If a pair of tapered roller bearings has a reliability goal of R=0.99, and the individual bearing reliabilities are assumed to be equal (RA=RB), what should be the target reliability for each individual bearing?

Which of the following terms is a synonym for 'rating life'?

For a 03-series cylindrical roller bearing with a 50 mm bore, what is the basic static load rating, C0, in kN?

What does a DT mounting arrangement for angular ball bearings, also known as a tandem arrangement, primarily accomplish?

A shaft is supported by a pair of tapered roller bearings. Bearing A has a reliability of 0.994791 and bearing B has a reliability of 0.999766. What is the combined reliability of the bearing pair?

A constrained housing uses two direct-mount tapered roller bearings to resist an external thrust of 8000 N, with no radial loads. The shaft speed is 950 rev/min and the desired life is 10,000 h. The reliability goal for the loaded bearing is 0.95. What is the required thrust rating, (C10)a, for the loaded bearing A?

What is the primary function of the lubricant in a rolling-contact bearing, as summarized in the text?

For a standard single-row deep-groove ball bearing with a 65 mm bore, what is the recommended shaft shoulder diameter, dS?

Which bearing type is described as being particularly useful where radial space is limited and having a high load capacity?

A 02-70 mm deep-groove ball bearing (C10 = 13888 lbf) is selected for an application requiring a C10 of 6696 lbf. The application has a load FD = 413 lbf, application factor af = 1.2, and life multiple xD = 540. The Weibull parameters are x0 = 0.02, (θ-x0) = 4.439, and b = 1.483. What is the resulting reliability of the selected bearing?

Why must at least two tapered roller bearings typically be used on a single shaft?