gearing fundamentals Flashcards
what are two types of gear drives?
open gear drives and enclosed gear drives
what are open gear drives ?
gears that are exposed to the outside environment
whaat are enclosed gear drives?
gear drives contained with in a gearbox with lubrication supply
can be either oil or grease lubricated
what is a gear set?
matched pair of gears manufactured together
what is a gear train?
when two or more gear mesh or work together
what is a pinion?
when two gears that have different number of gears mesh or work together
what is a crown gear?
in beval and hypoid gear sets there are two mating gears
smaller one is a pinion
larger one is a ring gear (crown)
what is the drive gear power in and power out
power in is the input gear train that causes mating gears to turn
- power out is the output gear train that the drive gear forces to turn
what is direct drive?
when the input speed of the gearbox is the same as the output speed
what is a speed reducer?
a gear train with a slower output speed that input speed occurs when a small gear drives a larger gear out put has more torque but less speed
what is a speed increaser
a gear train with a faster output speed that input speed occurs when a large gear drives a smaller gear less torque but same speed
one issue with over hung gears?
tend to have more shaft deflection under heavy loads because of a bearing support on only one side of the gear
what are straddle mounted gears
are mounted between two bearings ,stronger and less shaft deflection than overhung gears
what are internal gears ?
have teeth on the inside diameter of the gear , operate more smoothly than external gears , more tooth contact
what is a compound gear train?
have 3 or more shafts and four or more gears,
useful where a higher reduction or speed increase is important
substantial gear reductions can be achieved by using what ?
compound gear trains
what is end play?
when the gear shaft is allowed to move axially
what is axis of rotation?
centre line around which a gear or parts revolve
usually centreline of shaft
what is a floating gear or shaft ?
lists when one gear os shaft is allowed to move axially to its best position
what gears can be right hand or left hand gears?
helix angle
what is chordal thickness?
the thickness of the gear tooth the pitch of circle indicated tooth strength
what does an involute do ?
makes meshing with the mating gear quieter and smoother, has radius across the flank and the face of the tooth
what is one method in checking contact pattern?
use Prussian blue mixed with oil or red lead
where should back lash be checked?
the point at closest engagement
what is diametral pitch?
is the number of teeth on the gear divided by the pitch diameter
lower the number bigger the gear teeth
what is AGMA stand for
american gear manufactures
what is binding and what causes it
check with out a load
binding is where tight spots are felt
lack of backlash
incorrect center distances
gear center out of tolerance
bent shafts
thermal expansion
what is a pressure angle?
angle of the gear tooth, gear trains have pressure angles of 14.5 deg to 20 deg