Gears Flashcards
Enclosed your drives are contained how
Contained in a gearbox with lubrication supply
Open gear drives are exposed to what and are suitable for what kind of application
Outside environment and are suitable for light duty applications
What are gear sets used for
To be meshed together in pairs and intended to mate
What is gear train
Two or more gears that mesh or mate together
What is a pinion
Two gears with different number of teeth
gear with fewer amount of teeth is the pinion
If the smaller gear is the pinion what is the larger gear in a bevel and hypoid mating gear
Crown gear
What is the drive gear
The gear the drives the output gear
What is the driven gear
Gear that is driven by the drive gear
What Kinda drive has the same speed as the input and output
Direct drive
What does a speed reducer do
If you have a fast input speed the output speed will be reduced
Ex
Input will have a small gear going into a big gear on the output
Speed increaser
Is the drive gear smaller or bigger
Bigger
What is an overhung gear
Bearing support only on one side of the gear
What is a straddle mounted gear
A bearing on both sides of the gear
Internal gears have teeth on the inside or outside of the gear plank and are they smoother or not as smooth
Inside
Smoother
Compound gear train has how many shafts and how many gears
Three or more shafts and four or more gears
Define end play
The gear or shaft can move axially
Pre-loads have how much axial clearance for proper gear mesh
Zero
What is the axis of rotation
Centerline around which gear or parts revolve
What causes gear wear
Lack of lubrication, abrasives and bad tooth contact
What is a floating gear or shaft
Where one gear or shaft is allowed to move axially to its best position kind of like bearing
Right and left-hand gears are called what kind of angle
Helix angle
How can you tell if you have a left or right hand gear
Which ever way the gear points away from centerline of the shaft
Describe a worm and worm wheel gear set
The worm is the smaller gear and looks like a screw the worm wheel is a larger circular gear
The clearance between gear teeth and the pitch line is called what
Back lash
Top half of the gear tooth is called what
Addendum
Bottom half of the gear tooth including the clearance is called what
Dedendum
Total depth of the tooth top to bottom including the clearance is called what
Whole Depth
Working depth includes what minus the clearance
Addendum + Dedendum
What are the two best pressure angles in degrees
20° and 14°
If you have a steep and smooth helix angle is this better or worse
Better
If you have more starts then less starts on a worm gear box will the worm wheel move faster or slower each revolution
Faster
example 3 starts equals three pitches each revolution
What is the formula to get diametral pitch
Number of teeth on your gear divided by pitch diameter
List three ways to have proper gear mesh
Have the same diametral pitch
same pressure angle
and correct your hand left or right
Same helix angle
Can idlers change the speed of the input and output gear
No because idlers only change the direction or keep it the same
What Kind of gears are suitable for shafts parallel to each other with no axial thrust unless misaligned (cowboy)
Spur gears
Where will external spur teeth be on a gear plank
On the outside
Where will the internal spur teeth be on a gear plank
On the inside
What kind of gear system is on a arbor press
Rack and pinion
How are single helical gears cut
They have the teeth cut at an angle to the shaft of the axis
Are helical gears stronger or not stronger then spur gears
Stronger because they have more teeth in contact at one time
Can helical gears be used on shafts that cross over 90° or other angles
Yes but the gears have to be left-hand and right-hand in order to mesh proper
What are the most common angles for helical gears
7° to 23°
most industrial gears have a 20° pressure angle
What kind of loads and speed applications are herringbone gears used for
High speeds and heavy loads
What kind of gear is similar to a doublecut helical gear
The herringbone gears
For bevel gears what is the most common intersection angle
90°
but some intersect at other angles
Give four types of bevel gears
Miter
straight
spiral
and zerol
On gears where the shafts must intersect at 90° are called what kind of bevel gear
Mitre gear
Worm bleed refers to the distance by which what
One tooth on the worm advances in one turn this is determined by the number of starts on the worm
Parallel
angle
compound
and planetary gear systems are all what kind of drives
Fixed speed gearbox drives
What kind of specific combination of gears can produce several speed and torque combinations from one set of gears in a small space
Ex: Sun gear, carrier with planet gears mounted to it and a ring gear
Planetary gear systems
What kind of methods do you use to check for acceptable mesh patterns while being reassembled
Prussian blue
Venetian red
Black light
pencil lead
What is a good practice before using Prussian blue on your gear teeth to measure mesh patterns
Clean both gears very thoroughly
What is the best tool to use to measure backlash
Dial indicator
Tie rod torque arms should be mounted in a position that forms what kind of angle
A 90° angle
