Machine Elements in Mechanical Design FIFTH EDITION CHAPTER

Keys • Key § Machinery component placed at interface between a shaft and hub

Keys • Types of Keys § § Square and rectangular parallel Taper and gib

Table 11 -1 Key Size vs. Shaft Diameter Machine Elements in Mechanical Design ,

Table 11 -2 Suggested Fillet Radii and Key Chamfers Machine Elements in Mechanical Design

Table 11 -3 Woodruff Key Dimensions Machine Elements in Mechanical Design , Fifth Edition

Materials for Keys • Selection and Installation of Keys and Keyseats § Length of

Table 11 -4 Selection of Materials Used for Keys Machine Elements in Mechanical Design

Stress Analysis to Determine Key Length • Modes of failure for keys transmitting power:

Splines • Spline § Series of axial keys machined into a shaft, with corresponding

Splines • Straight-Sided Splines § Made according to specifications of Society of Automotive Engineers

Table 11 -5 Formulas for SAE Straight Splines Machine Elements in Mechanical Design ,

Splines • Involute Splines § Made with pressure angles of 30°, 37. 5°, 45°.

Other Methods of Fastening Elements to Shafts • Methods of Fastening Elements to Shafts

Table 11 -7 Capacities of Selected Sizes of Ringfeder Locking Assemblies Machine Elements in

Couplings • Device to connect two shafts together at their ends for purpose of

Universal Joints • When application calls for accommodating misalignment between mating shafts greater than

Retaining Rings and Other Means of Axial Location • • • Retaining rings Collar

Types of Seals • Contaminants must be excluded from critical areas of a machine.

Types of Seals • Pressurized fluids must be contained within a component (valve or

Seal Materials • • • Elastomers Rigid materials Packings Gaskets Shafts Machine Elements in

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Machine Elements in Mechanical Design FIFTH EDITION CHAPTER 11 Keys, Couplings, and Seals Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Keys • Key § Machinery component placed at interface between a shaft and hub of power-transmitting element for purpose of transmitting torque. § Demountable to facilitate assembly and disassembly of shaft system. § Installed into shaft keyseat first; then hub keyseat aligned with key; hub slid into position. Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Keys • Types of Keys § § Square and rectangular parallel Taper and gib head Pin Woodruff Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Materials for Keys • Selection and Installation of Keys and Keyseats § Length of key specified to be substantial portion of hub length of the element in which it is installed to provide good alignment and stable operation. • Materials: plain carbon steel, alloy steels, stainless steels, non-ferrous metals, plastics. Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Stress Analysis to Determine Key Length • Modes of failure for keys transmitting power: § Shear across shaft/hub interface § Compression failure due to bearing action between sides of key and shaft or hub material § Analysis for either failure mode requires an understanding of the forces that act on the key Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Splines • Spline § Series of axial keys machined into a shaft, with corresponding grooves machined into bore of mating part § Perform same function as a key in transmitting torque from shaft to mating element § Can be either straight-sided or involute. Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Splines • Straight-Sided Splines § Made according to specifications of Society of Automotive Engineers (SAE) § Torque capacity for SAE splines based on limit of 1000 -psi bearing stress on sides of the splines Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Splines • Involute Splines § Made with pressure angles of 30°, 37. 5°, 45°. § Standard diametral pitches § Length of splines § Metric module splines § Standard modules Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Other Methods of Fastening Elements to Shafts • Methods of Fastening Elements to Shafts § Pinning § Keyless hub to shaft connections Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Table 11 -7 Capacities of Selected Sizes of Ringfeder Locking Assemblies Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Other Methods of Fastening Elements to Shafts • Methods of Fastening Elements to Shafts § Polygon hub to shaft connection § Split taper bushing Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Other Methods of Fastening Elements to Shafts • Methods of Fastening Elements to Shafts § § Set screws Taper and screw Press fit Molding Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Couplings • Device to connect two shafts together at their ends for purpose of transmitting power § Rigid couplings: draw two shafts together tightly so no relative motion can occur between them § Flexible couplings: transmit torque smoothly while permitting some axial, radial, angular misalignment Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Universal Joints • When application calls for accommodating misalignment between mating shafts greater than the three degrees provided by flexible couplings, a universal joint often employed. § Single § Double § Vehicular Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Universal Joints • When application calls for accommodating misalignment between mating shafts greater than the three degrees provided by flexible couplings, a universal joint often employed. § Constant velocity (CV) § Heavy-duty industrial double § Cornay™ Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Retaining Rings and Other Means of Axial Location • • • Retaining rings Collar Shoulders Spacers Locknuts Caution against overconstraint Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Types of Seals • Contaminants must be excluded from critical areas of a machine. • Lubricants must be contained within a space. Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Types of Seals • Pressurized fluids must be contained within a component (valve or a hydraulic cylinder). • Choice of type of sealing system depends on function that it must perform. Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved

Seal Materials • • • Elastomers Rigid materials Packings Gaskets Shafts Machine Elements in Mechanical Design , Fifth Edition Robert L. Mott Copyright © 2014 by Pearson Education, Inc. All Rights Reserved