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barcode generator vb.net source code CLUTCHES AND BRAKES 8.27 in Software
CLUTCHES AND BRAKES 8.27 Decoding EAN13 In None Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications. Printing GS1  13 In None Using Barcode drawer for Software Control to generate, create EAN / UCC  13 image in Software applications. CLUTCHES AND BRAKES
European Article Number 13 Scanner In None Using Barcode reader for Software Control to read, scan read, scan image in Software applications. GTIN  13 Generator In C# Using Barcode creator for .NET Control to generate, create UPC  13 image in .NET applications. FIGURE 8.16 Equivalent force system on a long internal shoe.
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Bar Code Generator In None Using Barcode maker for Software Control to generate, create bar code image in Software applications. Print EAN / UCC  14 In None Using Barcode maker for Software Control to generate, create EAN / UCC  13 image in Software applications. (8.24) Making EAN8 In None Using Barcode printer for Software Control to generate, create EAN8 image in Software applications. Barcode Encoder In None Using Barcode encoder for Word Control to generate, create bar code image in Microsoft Word applications. where b = width of lining. Substituting for p from Eq. (8.23) and integrating, we get T= pmax fbr 2 (cos 1 cos 2) (sin )max (8.25) Data Matrix 2d Barcode Creation In ObjectiveC Using Barcode creator for iPhone Control to generate, create DataMatrix image in iPhone applications. Drawing EAN13 In ObjectiveC Using Barcode generator for iPad Control to generate, create EAN13 image in iPad applications. Normal Force. To determine the actuating force and the pin reaction, it is necessary first to find the normal force P. The components of P are Px = Py = Make GS1  13 In None Using Barcode creator for Microsoft Word Control to generate, create EAN13 image in Microsoft Word applications. Generating USS Code 39 In Java Using Barcode creation for Java Control to generate, create Code 3/9 image in Java applications. 2 1 2 1 Recognizing EAN 13 In Java Using Barcode decoder for Java Control to read, scan read, scan image in Java applications. GTIN  13 Creation In Java Using Barcode creation for Java Control to generate, create EAN13 image in Java applications. pbr d sin pbr d cos
(8.26) (8.27) Downloaded from Digital Engineering Library @ McGrawHill (www.digitalengineeringlibrary.com) Copyright 2004 The McGrawHill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. CLUTCHES AND BRAKES 8.28
MACHINE ELEMENTS THAT ABSORB AND STORE ENERGY
Again, substituting for p from Eq. (8.23) and integrating, we find Px = and Py = brpmax (cos2 1 cos2 2 ) 2(sin )max (8.29) brpmax ( 2 1 + sin 1 cos 1 sin 2 cos 2 ) 2(sin )max (8.28) The resultant normal force P has the magnitude
2 P = (P x + P 2 )1/2 y
(8.30) and is located at the angle p, where p = tan 1 Px Py (8.31) Effective Friction Radius. The location rf of the center of pressure C is found by equating the moment of a concentrated frictional force fP to the torque capacity T: T = fPrf or rf = T fP (8.32) BrakeShoe Moments. The last basic task is to find a relation among actuating force F, normal force P, and the equivalent friction force fP. The moments about the pivot point A are Ma Mn + Mf = 0 where Ma = F Mn = Pa sin p Mf = P(rf a cos p) (8.34) (8.35) (8.36) (8.33) Selfenergizing Shoes. The brake shoe in Fig. 8.16 is said to be selfenergizing, for the frictional force fP exerts a clockwise moment about point A, thus assisting the actuating force. On vehicle brakes, this would also be called a leading shoe. Suppose a second shoe, a trailing shoe, were placed to the left of the one shown in Fig. 8.16. For this shoe, the frictional force would exert a counterclockwise moment and oppose the action of the actuating force. Equation (8.33) can be written in a form general enough to apply to both shoes and to external shoes as well: Ma Mn Mf = 0 (8.37) Burr [8.2], p. 84, proposes this simple rule for using Eq. (8.37): If to seat a shoe more firmly against the drum it would have to be rotated in the same sense as the Downloaded from Digital Engineering Library @ McGrawHill (www.digitalengineeringlibrary.com) Copyright 2004 The McGrawHill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. CLUTCHES AND BRAKES 8.29
CLUTCHES AND BRAKES
drum s rotation, use the positive sign for the Mf term. Otherwise, use the negative sign. Pin Reaction. At this point in the analysis, the designer should sketch a freebody diagram of each shoe, showing the components of the actuating force F, the normal force P, and the friction force fP. Then the components of the pin reaction can be found by setting to zero the sum of the force components in each direction (x and y). Design. The design challenge is to produce a brake with a required torque capacity T. A scale layout will suggest tentative values for the dimensions 1, 2, a, , and . From the lining manufacturer we learn the upper limit on maximum contact pressure pmax and the expected range for values of the frictional coefficient f. The designer must then determine values for lining width b and the actuating force F for each shoe. Since the friction force assists in seating the shoe for a selfenergizing shoe but opposes the actuating moment for a selfdeenergizing shoe, a much larger actuating force would be needed to provide as large a contact pressure for a trailing shoe as for a leading shoe. Or if, as is often the case, the same actuating force is used for each shoe, a smaller contact pressure and a smaller torque capacity are achieved for the trailing shoe. The lining manufacturer will usually specify a likely range of values for the coefficient of friction. It is wise to use a low value in estimating the torque capacity of the shoe. In checking the design, make sure that a selfenergizing shoe is not, in fact, selflocking. For a selflocking shoe, the required actuating force is zero or negative. That is, the lightest touch would cause the brake to seize. A brake is selflocking when M n Mf (8.38) As a design rule, make sure that selflocking could occur only if the coefficient of friction were 25 to 50 percent higher than the maximum value cited by the lining manufacturer. Example 6. Figure 8.17 shows a preliminary layout of an automotive brake with one leading shoe and one trailing shoe. The contact pressure on the lining shall not exceed 1000 kilopascals (kPa). The lining manufacturer lists the coefficient of friction as 0.34 0.02. The brake must be able to provide a braking torque of 550 N m. Two basic design decisions have already been made: The same actuating force is used on each shoe, and the lining width is the same for each. Check dimension a to make sure that selflocking will not occur. Determine the lining width b, the actuating force F, and the maximum contact pressure pmax for each shoe. Solution. One way to proceed is to express the braking torque T, the normal moment Mn, and the frictional moment Mf in terms of lining width b and maximum contact pressure pmax. Then the design can be completed by equating the actuating force for the two shoes, setting the sum of the braking torques to 550 N m, and selecting the lining width b so that the maximum contact pressure is within bounds. 1. The dimension a is a = (832 + 252)1/2 = 86.7 mm = 0.0867 m Downloaded from Digital Engineering Library @ McGrawHill (www.digitalengineeringlibrary.com) Copyright 2004 The McGrawHill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website.

