Topics Introduction Shaft Design Stresses and Loads on Shafts Shaft Fits Shaft Locking Devices Exercise Questions Note: Refer to Chapter 7 in the text.

Introduction Shafts are used to transmit mechanical power such as the propeller shafts in vehicles. Applications of shafts: - To transmit power - To extend other shafts - To provide the rotary motion needed by other components such as in rollers and printing press machines. Shafts are usually made of steel. Some materials are used in making shafts: - Cold Rolled Steel: most common due to its low cost - Hardened Steel: heated rolled steel. Stronger than the cold rolled shaft. - Stainless steel Reference: Amatrol Mechanical Drives 1, LAP 3

Shaft Design Shafts may be designed with ‘turn downs’ These shafts have smaller diameters at the ends. When shafts are turned down, a large shaft fillet is used to reduce stresses as possible. Refer to figures 7-2 and 7-3 in the text (pp. 134-135)

Loads and Stresses on Shafts Shear Forces Tensile Forces Compressive Forces Bending Moments Torsions

Shaft Fits Clearance fit: the mating parts have a clearance between them. Also known as slip, slide, or loose fit. Transition fit: no clearance is present. It is also known as line-to-line fit. In this case pressing is required. Interference fit: The shaft diameter is larger than the diameter of the hole of the component to be mounted. Some types of it are: press and shrink fits. An Arbor Press is used to mount the components onto the shafts

Shaft Locking Devices Taper-Lock Bushings (see figure7-11 in text) Quick Detachable (QD) Tapered Bushings Split-Taper Bushing Keyless/Compression Bushings A Quick Detachable (QD) Tapered Bushing

Exercise Questions What is the purpose of the propeller shaft in a car? Transmitting mechanical power in the form of torque to the rear axle. Name five types of loading and moments that shafts can be subjected to: 1) Compressive forces 2) Tensile forces 3) Shear forces 4) Bending moments 5) Torsion

What three types of shaft fits? Clearance, line-to-line, and interference fits Name three types of bushings that can be used to mount components on shafts? 1. Taper-Lock Bushuings 2. Quick Detachable Tapered Bushings 3. Split-Taper Bushings 4. Keyless/Compression Bushings 5. Describe how to mount a component on a shaft with a shrink fit? The shaft may be freezed in liquid nitrogen to shrink, then the component is mounted on it. 6. What is a disadvantage of shrink fitting? You are limited by time needed to mount the component on the shaft before the shaft retains its regular dimensions.