Gearing princibles Flashcards
what are the key areas of the gear tooth
Face - flank - heel - toe - centerline - pitch line
once a gear tooth has been divided lengthwise, what is the name of the upper half of the tooth
face
once a gear tooth has been divided lengthwise, what is the name of the lower half of the tooth
flank
when a gear tooth has a larger end and a smaller end what is the smaller end of the tooth called
toe
when a gear tooth has a larger end and a smaller end what is the larger end of the tooth called
heel
why is the root fillet of a gear tooth rounded slightly
to give the tooth strength and reduce the chances of cracking in this area
when the engine is driving a tractor the driving force acting on the gears in mesh is happening on what side of the gear tooth
drive side of the gear tooth
when the throttle has been let off and a tractor is coasting down a highway . with the loaded vehicle pushing the powertrain what side of the gear teeth are being used
the coast side
what are the three dimensions when looking at a pitch circle of a gear
. root diameter = shortest measurement
. outside diameter = greatest measurement
. pitch diameter = starts at the line that divides face and flank
in order to determine circular gear pitch what must first be established
pitch circle
why is it important to have the pitch circles of gears in mesh intersect
this relationship provides great gear strength, maximum force can then be delivered through the gears
wat is the purpose of having clearance between the root and tip of gear teeth in mesh
helps maintain a lubrication film between the teeth as they mesh together
what is the purpose of gear backlash
to allow for tooth expansion and lubrication
what is the purpose of having timed gear sets
this ensures that they always operate in a specific relationship with one another
what will proper timing of gears promote
long service life because they will develop distinctive wear patterns during operation
non - hunting gear sets
will have to be timed - will have a whole ratio 3:1 - 2:1 ect
partial - nonhunting gear sets
will have to be timed - will have a ratio without a run on number 4.50:1 - 3.75:1 ect
hunting gear sets
will not have to be timed . number of teeth will divide unequally into the crown gear 3.89: 1 - 2.333333:1 ect
direct drive
when two gear of identical size are in mesh with each other will have a one to one ratio 1:1
how is a gear ratio calculated
number of driven teeth over number of drive teeth
how is a reduction created in a gear set
small gear driving a big gear
how would a overdrive be created in a gear set
large gear driving a big gear
how can you change rotation of gears on mesh
by adding an idler gear
what is the most basic type of gears
straight spur cut gears
do straight cut spur gears require thrust washers
no because no end thrust is created
what is an advantage of internal gear design
very strong and they can handle high loads
what is an advantage of helical cut gears
provides great strength and less noise in operation
because of the design of helical cut gears what do they need to have
thrust washers because axial thrust is created when they are in mesh
what is a herringbone type of gear
a double helical cut gear . used for heavy torque loads
what type of gear set can be used to change rotary motion into linear motion
rack and pinion
in order to gain strength in design of angle cut gear sets what type of gear was developed
spiral cut gears . allows the contact to be more extensive and noise to be reduced
when would a hypoid gear configuration be used
where high torque loads are expected
when would a amboid gear configuration be used
when the vehicle is operating off road and this will allow for a higher drive line position
what is the difference between hypoid and amboid gear sets
. Hypoid gear sets are positioned so the centerline of the pinion shaft is below the centerline of the crown gear
. Amboid gear sets are positioned so the centerline of the pinon shaft is above the centerline of the crown gear
what are the components of a simple planetary
sun gear - pinion gears ( planets ) and internal gear
how is direct drive achieved in a planetary
any two members held
how is reverse achieved in a planetary
carrier held or planets
how is reduction achieved in a planetary
carrier driven
how is overdrive achieved in a planetary
carrier drive
how is neutral achieved in a planetary
no members held
