Mechanical Components

Shafting

high precision, expensive shafts

Round stock

irregular, lower costs shafts

Split, Setscrew, flange

Rigid Shaft Couplings

spline

coupling which enables axial sliding

paired U-joint

pivoting coupling for shafts at different locations (not concentric)

CV joint

constant velocity join ensures same velocity, even when angle

spline and pivoting

coupling for shafts at different locations (not concentric) which move axially

bellows, loop, beam, disc

flexible coupling

spider

coupling with flexible elastomer insert to absorb shock and vibration

mulitflex

made of multiple flexible elements and metal bushing to enable flexibility

oldham coupling

flexible coupling which compensates for parallel misalignment

clutches

connect two shafts and are used to intermittently bring them to the same rotation speed

threaded fasteners

standardized connections that can be taken apart and reassembled

rivets

metal deformed to create permanent joints

adhesives

tend to be best in shear, poor in tension, good load distribution and do not introduce stress concentrations

welds

join materials by fusing them into a continuous solid

soldering and brazing

involve melting the filler material only

quieter, gradual engagement, high cost, axial reaction

Helical vs Spur

bevel gears

intersecting axes, tangential, radial, and axial reactions

worm gears

sliding, high axial reactions on worm (and radial, tangential, and axial on gear), high wear, high ratios possible

wobble

gear’s rotation is off-centre

backlash

gap/play between mating gear teeth

asynchronous

transmit power using friction (V-belt, rounded belt)

synchronous

belts which prevent slipping, input/output moves at a fixed ratio (roller chain, timing belt)

T = D/2(F1-F2)

Tension in Asynchronous Belt Operation

Lower cost, long distance, quieter, lower precision requirements

Flex Drive Pros

lower stiffness, larger volume for same torque, tighter speed limits, degradation (sliding, rubbing)

Flex Drive Cons

high load for compact size, simple and inexpensive, heat resistant

Plain Bearing Characteristics

Rolling Element Bearings Characteristics

low friction, reliable, expensive

Hydrodynamics Bearing Characteristics

no wear (theoretically), high maintenance (lube upkeep), good at high loads

Tilting Pad Journal Bearing

internal pads tilt ensuring there is no moment at equilibrium, minimizing destabilizing forces

Cylindrical and Spherical

Cylindrical and Tapered

Tapered and Angular Contact

Best at Axial Loads

small contact area between balls and casing

Why are spherical and ball bearings worse at axial/radial loads

flexures

depend on temporary deformation, limited ROM and Bulky but high lifespan and low cost