MDSP Elements No. 2 - Mechanical Engineering Review

Comprehensive vocabulary flashcards covering Machine Design and Shop Practice (MDSP) review elements, including keys, bearings, gearing, welding methods, and shop processes.

Feather key

A key that allows the hub to move along the shaft but prevents the rotation of the shaft.

Involute serrations

Spline-like fasteners used for permanent fits that are similar to involute splines except that the pressure angle is $14.5^\circ$.

Shear pin

A protective device used as a coupling, or in addition to another coupling, where danger of injury to the machine or material in process exists in case of overload.

Flanged compression coupling

A coupling that transmits power via the frictional forces induced by pulling the flanges toward each other over slotted tapered sleeves.

Flexible coupling

A coupling used for absorbing shock and vibration on one shaft and preventing the occurrence of reversed stresses caused by shaft deflection at the coupling.

Radial clearance

The difference in the radii of the bearing and the journal.

Fitted bearing

A journal bearing in which the radii of the journal and the bearing are the same.

Line of centers

The line that passes through the centers of the bearing and the journal.

Deep-groove ball bearing

A type of ball bearing in which the balls are assembled by the eccentric displacement of the inner ring.

Spur gear

Toothed wheels whose tooth elements are straight and parallel to the shaft axis, used to transmit motion and power between parallel shafts.

Regular lay

A wire rope construction in which the individual wires and strands are twisted in opposite directions.

Lang lay

A wire rope construction in which the individual wires and strands are twisted in the same direction.

Brake fade

A condition where the effectiveness of a brake greatly decreases shortly after it begins to act continuously.

Band brake

A friction brake where a band wraps partly around the brake wheel or drum, and braking action is obtained by pulling the band tight onto the wheel.

Spot welds

Resistance welds, usually round, formed in the same shape as the electrodes that press the metal sheets together.

Intermittent weld

A weld consisting of short lengths ($2\text{ to }3\,\text{in}$ long) with spaces between them, such as $6\,\text{in}$ on centers.

Tack weld

An intermittent weld lightly applied to hold members in position for assembly purposes or prior to principal welding.

Submerged arc welding

An automatic welding method in which the arc is covered with a welding composition and bare electrode wire is fed automatically.

Tangential load

The average tangential force acting on gear teeth that is derived from horsepower.

Pitting

A form of gear tooth wear that occurs due to fatigue of the surface material as a result of high contact stresses.

Scoring

A failure mode occurring when the oil film breaks down under excessively high load and speed, causing surface metal to melt and smear down the profile.

Spalling

A form of surface fatigue in surface-hardened teeth that is of greater extent than pitting, producing much larger flakes.

Hunting tooth

An extra tooth incorporated into a gear set to distribute wear more evenly among meshing teeth.

Annular gear

A gear that has its teeth cut on the inside of the rim instead of on the outside.

Face contact ratio

The advance of the tooth in the face width divided by circular pitch.

Normal circular pitch

The distance between gear teeth measured on the pitch surface along a line normal to the helix.

Crossed helical gear

Helical gears mounted on non-parallel shafts.

Bevel gear

Gears used to connect intersecting shafts, usually but not necessarily at $90^\circ$.

Pitch cone

The reference cone structure with respect to which bevel gear teeth are built, analogous to the pitch cylinder of spur gears.

Back cone

An imaginary cone whose elements are perpendicular to the pitch cone elements at the large end of the bevel gear tooth.

Zerol bevel gear

A bevel gear having curved teeth similar to spiral bevel gears, but designed with a zero spiral angle.

Shaping

A machining operation whereby the cutting tool reciprocates while the feed motion is stationary.

Grinding machine

A machine used in shaping metal by means of an abrasive wheel or through the removal of metals with an abrasive.

Dead center

A lathe center attached and meshed to the tailstock spindle that remains stationary or static while the workpiece rotates.