Lubrication and Journal Bearings

Which form of lubrication is defined by the load-carrying surfaces of a bearing being separated by a relatively thick film of lubricant, where the film pressure is created by the moving surface pulling the lubricant into a wedge-shaped zone?

In the ips (inch-pound-second) system, what is the name for the unit of dynamic viscosity, which is equivalent to pound-force-second per square inch?

What is a key assumption made in the derivation of Petroff's equation for bearing friction?

According to the principles of stable lubrication shown in Figure 12-7, what is the self-correcting response of a bearing operating in the thick-film region if the lubricant temperature increases?

In the nomenclature of a complete journal bearing, what is the term for the displacement of the journal center relative to the sleeve center?

Who is credited with developing the mathematical theory of lubrication based on the experimental results first obtained by Beauchamp Tower?

Using Trumpler's design criteria for journal bearings, what is the recommended minimum film thickness (h0) for a journal with a diameter (d) of 4 inches?

For a journal bearing subjected to a load W of 500 lbf, with a journal radius r of 0.75 in and a length l of 1.5 in, what is the nominal bearing pressure P?

According to Figure 12-15, which presents the Raimondi and Boyd chart for minimum film thickness, what is the value of the minimum film thickness variable (h0/c) for a bearing with a Sommerfeld number S = 0.135 and an l/d ratio of 1?

Using the Raimondi and Boyd chart for the coefficient-of-friction variable (Figure 12-17), what is the value of (r/c)f for a journal bearing with a Sommerfeld number S = 0.135 and an l/d ratio of 1?

In a self-contained bearing, the heat dissipated to the environment is estimated by the equation Hloss = h_CR * A * (Tb - T_infinity). What does the term h_CR represent?

For a self-contained bearing operating in still air, what is the representative value for the combined overall coefficient of heat transfer, h_CR, in Btu/(h·ft2·°F)?

For a 1.5-inch-diameter journal bearing designed with a close-running fit (H8/f7), what is the maximum specified clearance 'c' according to Table 12-3?

What is a common practice used in pressure-fed bearings to force a greater flow of lubricant through the bearing for increased cooling?

When analyzing a pressure-fed bearing with a central groove, the bearing is treated as two half-bearings. What formula is used to find the characteristic pressure P in each half-bearing?

According to Table 12-5, 'Range of Unit Loads in Current Use for Sleeve Bearings', what is the typical range of unit loads, in pounds per square inch (psi), for the main bearings of diesel engines?

In a dynamically loaded journal bearing where the load and speed vary, what is the term used to describe the path of the journal center as it moves over the entire clearance space?

In the analysis of a big-end connecting rod bearing using the design variables listed in Section 12-8, what does the term M_rec represent?

Which of the following operating conditions may prevent the buildup of a film thick enough for full-film lubrication, potentially leading to boundary lubrication?

A pin with a diameter D of 2 inches rotates at a speed N of 120 rev/min. What is its pitch-line velocity V in ft/min?

Which type of lubrication is characterized by introducing a lubricant, such as air or water, into the load-bearing area at a pressure high enough to separate the surfaces, and which does not require relative motion between the surfaces?

Using the conversion formula from Section 12-2, what is the dynamic viscosity in Pascal-seconds (Pa·s) for a lubricant with a viscosity Z of 1000 centipoise (cP)?

The Sommerfeld number, S, is a dimensionless parameter defined by the equation S = (r/c)^2 * (μN/P). What does the term r/c represent?

In a thick-film journal bearing, if the eccentricity ratio, epsilon, is defined as e/c and has a value of 0.6, what is the ratio of the minimum film thickness, h0, to the radial clearance, c?

To prevent lubricant degradation and potential bearing failure, what maximum film temperature, Tmax, does Trumpler's design criteria specify for light oils?

When calculating the temperature rise in a journal bearing, what value is typically used for the specific heat capacity, Cp, of common petroleum lubricants in the unit Btu/(lbm·°F)?

For a self-contained bearing with an oil ring lubrication system operating in moving air, what is the typical range for the proportionality constant alpha according to Table 12-2?

A pressure-fed bearing with a central groove has a journal diameter of 1.750 inches, is subjected to a steady radial load of 900 lbf, and has an l'/d ratio of 1/2 for its half-bearings. What is the characteristic pressure P due to the load?

According to Table 12-6, 'Some Characteristics of Bearing Alloys', what is the recommended clearance ratio range (r/c) for a bearing made of Tin-base babbitt with a thickness of 0.022 inches?

For a bearing made of Teflon fabric, what is the specified maximum allowable operating temperature in degrees Fahrenheit according to Table 12-8?

The ASTM standard method for determining viscosity using a Saybolt Universal Viscosimeter measures the time in seconds for 60 mL of lubricant to flow through a standardized tube. What property of the lubricant is this measurement used to determine?

Petroff's equation for the coefficient of friction, f = 2*pi^2 * (μN/P) * (r/c), shows that the coefficient of friction is directly proportional to which dimensionless parameter?

In the context of a thick-film journal bearing, what is the name for the included angle between the eccentricity vector and the load vector?

The classical one-dimensional Reynolds equation is derived from the continuity equation dQ/dx = 0. What physical principle does this mathematical statement represent?

In Example 12-3, for a bearing with S = 0.135 and l/d = 1, the total volumetric flow rate Q was found to be 0.217 cubic inches per second. Given a flow ratio Qs/Q of 0.655 from Figure 12-19, what is the side flow rate Qs?

In Example 12-4, for a bearing with S = 0.135 and l/d = 1, the pressure ratio P/p_max is found from Figure 12-20 to be 0.42. If the nominal bearing pressure P is 222 psi, what is the maximum film pressure p_max?

A pillow-block bearing from Example 12-5 has a journal diameter of 2.000 inches and a length of 2.000 inches (since l/d = 1). If the radial load is 100 lbf, what is the bearing pressure P in psi?

According to Table 12-4, for a 1.5-inch-diameter journal bearing operating with a radial clearance 'c' of 0.00175 inches, what is the resulting minimum film thickness 'h0' in inches?

What is the formula for the total side flow, Qs, for a pressure-fed bearing, expressed in terms of supply pressure (ps), geometry (r, l', c), eccentricity ratio (epsilon), and viscosity (mu)?

In the mobility method used for analyzing dynamically loaded bearings, what does the mobility vector M relate the bearing load F to?

According to Table 12-7, what is the recommended minimum film thickness danger level (h_min) for an industrial diesel engine bearing with a typical diameter of 250 mm?

The equation for linear sliding wear in a boundary-lubricated bearing is w = KPVt. What does the proportionality factor K, known as the wear factor, represent?

When does elastohydrodynamic lubrication (EHL) occur?

The cgs unit for dynamic viscosity is the poise (P). How does it relate to the SI unit, the pascal-second (Pa·s)?

To ensure stable, thick-film lubrication and avoid metal-to-metal contact, what is the recommended minimum design value for the bearing modulus (μN/P) in reyn * rev/s / psi?

In addition to criteria for film thickness and temperature, what limit does Trumpler's design criteria place on the starting load divided by the projected area?

Given the result from Example 12-1 that the minimum film thickness variable h0/c = 0.42 for a bearing with a radial clearance c = 0.0015 in, what is the minimum film thickness h0?

How does the addition of a central circumferential groove in a pressure-fed bearing affect its analysis compared to a non-grooved bearing?

According to Table 12-5, 'Range of Unit Loads in Current Use for Sleeve Bearings', what is the typical unit load range in psi for crankpin bearings in automotive engines?

For a boundary-lubricated bushing, what is the rate of heat generation, H_gen, in Btu per hour, if the load F is 50 lbf, the journal speed N is 300 rev/min, the journal diameter D is 0.75 in, the coefficient of friction fs is 0.03, and the Joulean equivalent J is 778 ft-lbf per Btu?