A rolling-element bearing reduces friction using what?
A Sliding wedges only
B Gear teeth
C Balls or rollers
D Fluid jets only
Answer: C. Balls or rollers. Rolling elements reduce sliding friction between bearing races.
A radial bearing mainly supports load perpendicular to what?
A Shaft length
B Gravity only
C Shaft axis
D Bearing width
Answer: C. Shaft axis. Radial loads act perpendicular to the shaft axis.
A thrust bearing mainly supports which load?
A Radial load only
B Bending moment only
C Axial load
D Thermal load
Answer: C. Axial load. Thrust bearings are designed to support loads parallel to the shaft axis.
A deep-groove ball bearing can carry radial load and what?
A Only pure torque
B No axial load
C Moderate axial load
D Large bending only
Answer: C. Moderate axial load. Deep-groove ball bearings carry radial loads and moderate axial loads.
Roller bearings generally carry higher radial loads than what?
A Ball bearings
B Thrust washers
C Plain bushings only
D Flexible couplings
Answer: A. Ball bearings. Line contact gives roller bearings high radial load capacity.
L10 bearing life corresponds to what reliability?
A 50 percent reliability
B 99.9 percent reliability
C 100 percent reliability
D 90 percent reliability
Answer: D. 90 percent reliability. The basic rating life L10 is the life reached by 90 percent of a bearing population.
Ball-bearing rating life exponent is what?
A Two
B Three
C Five
D Ten-thirds
Answer: B. Three. For ball bearings, L10 in millions of revolutions follows (C/P)^3.
Lubrication mainly reduces friction and what?
A Shaft diameter
B Elastic modulus
C Gear ratio
D Wear
Answer: D. Wear. Lubricants separate surfaces and reduce friction, wear and heat.
A hydrodynamic journal bearing supports load with what?
A Rolling elements
B Fluid film pressure
C Magnetic teeth
D Dry friction only
Answer: B. Fluid film pressure. Relative motion creates pressure in a lubricant film that supports the journal.
A journal bearing supports which surface?
A Gear tooth tip
B Cam nose
C Rotating journal
D Shaft keyway
Answer: C. Rotating journal. A journal is the rotating shaft portion running within a plain bearing.
Gear tooth bending stress is often estimated with which equation?
A Lewis equation
B Bernoulli equation
C Euler buckling equation
D Darcy equation
Answer: A. Lewis equation. The Lewis equation estimates bending stress near the tooth root.
Gear tooth bending failure commonly starts near what?
A Pitch circle center
B Tooth root
C Hub face
D Bearing race
Answer: B. Tooth root. Bending stress concentrates near the tooth root or fillet.
A Lewis form factor accounts for tooth what?
A Shape
B Lubricant viscosity
C Shaft alignment
D Bearing clearance
Answer: A. Shape. The Lewis factor represents gear-tooth geometry in a simplified bending-strength model.
Gear contact stress is associated with what?
A Shaft torsion only
B Key shear only
C Bearing temperature
D Tooth surface pressure
Answer: D. Tooth surface pressure. Contact stress arises where mating tooth surfaces press against each other.
A clutch transmits torque through engaged what?
A Friction surfaces
B Gear tooth roots
C Bearing rollers
D Valve springs
Answer: A. Friction surfaces. A friction clutch transmits torque through friction between contacting plates.
A multi-plate clutch increases capacity by increasing what?
A Friction interfaces
B Shaft speed
C Flywheel radius only
D Gear module
Answer: A. Friction interfaces. More active friction interfaces allow more torque for similar clamp force and dimensions.
A brake converts mechanical energy mainly into what?
A Heat
B Electrical charge
C Elastic strain only
D Fluid pressure
Answer: A. Heat. Braking dissipates kinetic energy primarily as heat at friction surfaces.
A self-energizing shoe brake uses friction to do what?
A Increase actuating moment
B Reduce drum speed instantly
C Cancel normal force
D Raise spring index
Answer: A. Increase actuating moment. Friction assists the applied moment and increases braking force.
A band brake applies friction around what?
A Shaft center only
B Gear pitch circle
C Drum circumference
D Bearing raceway
Answer: C. Drum circumference. A flexible band wraps around a rotating drum to produce braking torque.
Spring rate is force divided by what?
A Wire diameter
B Coil count
C Spring index
D Deflection
Answer: D. Deflection. Spring stiffness k is load divided by deflection.
Spring index is mean coil diameter divided by what?
A Free length
B Wire diameter
C Coil count
D Pitch angle
Answer: B. Wire diameter. Spring index C = D/d, the ratio of mean coil diameter to wire diameter.
Wahl factor corrects helical spring stress for curvature and what?
A Thermal expansion
B Gear tooth load
C Bearing life
D Direct shear
Answer: D. Direct shear. The Wahl factor accounts for curvature and direct shear effects in helical spring stress.
A compression spring’s deflection increases with what?
A Wire diameter to fourth
B Active coil count
C Shear modulus only
D Spring index squared only
Answer: B. Active coil count. For a helical compression spring, deflection increases with active coils and applied load.
A spring surge is a form of what?
A Static buckling
B Longitudinal vibration
C Surface fatigue
D Gear backlash
Answer: B. Longitudinal vibration. Spring surge is a longitudinal vibration of the spring coils.
A plain bearing’s PV limit combines pressure with what?
A Shaft length
B Gear ratio
C Spring rate
D Sliding velocity
Answer: D. Sliding velocity. The pressure-velocity value helps limit heat and wear in plain bearings.