gearing principles Flashcards
when a gear tooth has been divided length wise this line is called
pitch line
what are the top and bottom sections on the gear tooth pitch line
upper is the face - lower is the flank
when a gear tooth has a larger end and a narrow end they are called
large is the heel - narrow is the toe
what part of the gear tooth profile is slightly rounded and gives the gear strength
the root fillet
what is path of power
can be used to determine which gears are actually in use and delivering power through the power train at a specific time
what is another name for the drive side of a gear
the convex side
what is another name for the coast side of a gear
the concave side
non-hunting gear sets
needs to be timed . will always be a whole number ratio 3:1 4:1 5:1 ect
partial non hunting gear sets
needs to be timed . will always be a ratio that equates to two decimal spots 4.35:1 2.25:1 3.75:1 ect
hunting gear sets
does not need to be timed . every tooth of the crown will come into contact with every tooth of the pinion . will be a run on decimal ratio 1.33333333:1 2.76555:1 ect
what is direct drive
1:1 ratio two identical gear in mesh
when two external gears are in mesh what happens to direction
they will be opposite of each other
how do you calculate gear ratio on a simple gear set
driven over drive
what is a gear reduction
small gear driving a larger gear . will always be > than 1
2:1 - 1.1:1 - 3:1 ect
what is another name for a gear reduction
underdrive
what is the relationship of speed and torque in a reduction gear set
speed decreases and torque increases
what happens with direction of rotation when idlers are added to a gear set
odd number of idlers will rotate the driven and the drive gears the same direction . even number of idlers will rotate the drive and the driven gears opposite direction
will adding idlers to a gear set change the overall speed and torque of the set
no they only affect direction of rotation
what thrust loads do spur cut gears create in mesh
vertical . they will try to push each other apart vertically
what thrust loads will helical gear sets create
axial thrust loads . they need to be used with thrust washers on either side of the gears
why are spur cut gears used on heavy equipment
cheap to make and strong
when an external gear is used with an internal gear what happens to direction of rotation
driven and drive will rotate the same direction
what is an advantage of a double helical gear design
no thrust washers are needed because thrust loads are equalized on either side of the gears
what gear set would be used to change rotary motion in gears to linear
rack and pinion
what are some disadvantages to straight cut bevel gears
noisy and may be limited to low torque load applications
in order to gain strength in design of angle gear sets
spiral gear sets can be used
what is the purpose of the short stub shaft on spiral that extends past the end of the pinion gear
is supported by a bearing and helps keep the pinion and crown gear in mesh during sudden shock loads
what is the advantage of a hypoid angle gears
can handle high torque loads due to its position on the crown gear . lower position on the crown centerline allows more pinion teeth to engage the crown
what is the advantage of an amboid gears
pinion is set above the center line of the crown gear allowing for a higher driveline position for clearance
what are some advantages to worm cut gears
can handle very high torque . and by design they can also act as a brake
what type of gear set is often used when the input shaft and output shaft are operate on the same plane
planetary gear sets
what are the three parts of a planetary gear set
the sun gear - the carrier gears or planetary - the internal gear
what is the held member of a planetary gear set also called
reactionary member
what is the acronym for planetary gear ratio calculations
P-I-O ( planetary input = overdrive )
P-O-R ( planetary output = reduction )
P-H-R ( planetary held = reverse )
how do you get direct drive on a planetary gear set
any two members held - or driven at the same rpm in the same direction
how do you get neutral on a planetary gear set
no members held
