Gearbox Flashcards
Name 3 transmissions you may encounter in everyday life
Gear, chain, belt
Which type of transmission is commonly used in a bicycle?
Chain transmission
Which type of transmission commonly used in power drills?
Gear transmission
Describe what a gear transmission looks like. Do the same for chain transmission and belt
A bunch of cogs connected together.
A chain wrapped around a cog at one end and a cog at the other.
A rubber belt wrapped around a cog at one end and a cog at the other.
What kind of transmission is used in an engine?
Belt transmission
What are gear teeth?
The things that jut out and connect the gears (like cogs)
Name the 2 types of gear teeth
Straight, involute
What is the term for 2 or more gear wheels in series?
A gear train
What do straight gear teeth look like? What do involute gear teeth look like?
Square/angled.
Rounded.
When gear teeth are diagonal across the gear, what are they called?
Helical gears
Give 3 benefits of helical gears
Transmit greater force
Smaller gear wheels can be used than with spur gears
Less noisy
List 4 types of commonly used gears
Straight cut gear
Bevel gear
Worm gear
Rack gear
Give 1 advantage of using gears
High power density
Give 2 disadvantages of using gears
High production cost, noisiness
What’s another name for belt transmission?
A belt drive
How is gear ratio connected in a belt drive/transmission?
By using pulleys of different sizes
Name the 3 modern belt shapes
V-belt
Poly belt
Toothed belt
Why are belts shapes to slot into their corresponding pulleys?
To increase the friction as much as possible, to reduce chance of slippage
Give 2 advantages of belt transmissions
Relatively quiet, because of flexible belt
No lubrication needed
Give 2 disadvantages of belt transmissions
Prone to slippage, other than toothed belt
Power transfer is limited
In chain transmission, there are 2 things on either end connected by a chain. In belt transmission, there are 2 things on either end connected by a belt. What are the name for the ‘things’ in chain transmission. What about belt transmission?
Sprockets
Pulleys
How do you create a gear ratio?
By using sprockets/pulleys of different sizes
List the 5 parts of a chain
Pin
Outer plate
Inner plate
Roller
Bush
List 2 advantages of chain transmission
Does not slip
Greater forces can be transferred
List 2 disadvantages of chain transmission
Heavier than a belt
More expensive
Where is the gearbox located in rear wheel drive?
Between the clutch and the differential
What are the x and y axes of an engine graph
x = engine speed (rpm x 1000)
y = torque (Nm)
To put car in motion in first gear, is a high or low torque required?
High torque
What do gears in a gearbox do to torque?
Increase it
What’s the name for a reduction ratio in a gearbox?
A low gear
What happens to the rotational speed of the output shaft of the gearbox when second gear is selected in the gearbox?
The rotational speed increases
What is the gear where input and output revs are equal called?
The direct drive
What is/are the gear(s) where the output rotational speed is higher than the input rotational speed called?
The overdrive(s)
In what direction are the engine and gearbox mounted in a rear wheel drive car?
Longitudinally
What are the 2 kinds of reduction ratios that are possible in a gearbox?
Single reduction
Double reduction
When higher gears are selected, what happens to the reduction ratio?
There is less reduction
In direct drive, what is the reduction ratio? What has changed?
1:1
From double reduction to single reduction
What is the spur gear that reverses rotational direction, used for reverse called?
The idler gear
Do fifth and sixth gear have a high or a low ratio?
Low ratio
List 6 of the main components of the gearbox
Input shaft
Output shaft
Secondary shaft
Reverse gear auxilary shaft
Gear stick
Selector mechanism
What’s another name for the gear stick?
The gear lever
What are the 3 ways the gear lever and gear box can be linked
Hydraulic
Rods
Cables
In linking the gear lever and gearbox, how does gear selector linkage work?
The gear lever is linked to the gearbox by a system of rods
When gear selector linkage is used to link the gear lever and gearbox, what is moved to engage a specific gear
A synchroniser sleeve
Name the 3 main components of gear selector linkage
Shafts
Gear-selector forks
Synchroniser sleeve
What does the gear-selector fork fit into?
A recess in the synchroniser sleeve
Are the selector shafts stationary or moveable?
Moveable
How is the selector shaft moved?
Longitudinally
What is the function of the locking device on a selector shaft?
To keep the selector shaft in place
What are the 2 main components of the locking device on a selector shaft? What does the locking device fit into?
Ball, spring
A notch
If there are 6 gears including reverse and 3 selector shafts, why are there 3 notches for the locking device on each shaft rather than 2?
To select the neutral position
What happens if 2 gears were selected at the same time? What prevents that from happening? Where is it located?
The gearbox would be damaged
The interlocking device
In between each of the 3 selector shafts
What are the 2 main components of the interlocking device?
Ball, locking pin
The gearbox is in 3rd gear. In the interlocking device, what is it that stop other selector shafts from moving, the balls or the locking pin? What would the answer be in 1st gear
The balls
The balls and the locking pin
How many shafts are there in a gearbox? Name them
3
Input shaft
Output shaft
Secondary shaft
Where is the input shaft located?
Between the clutch plate and the secondary shaft
Where is the secondary shaft located?
Between the input and output shafts
Where is the output shaft located?
Between the secondary shaft and the drive shaft
How are the gear wheels for all gears except reverse mounted onto the output shaft?
With a needle bearing
How are the synchroniser devices mounted onto the output shaft?
With a spline
When neutral is selected, does the output shaft rotate or not?
It doesn’t
When the output shaft stops rotating, the gear wheels on the output shaft stop rotating.
True or false? Explain
False
They are not fixed to the output shaft, so they continue freewheeling
How are the gear wheels connected the output shaft?
They are mounted, using bearings, not fixed
The gear wheels are not fixed to the output shaft. Is this also true for the synchroniser devices?
No, they are fixed
What does a synchroniser device do to a gear wheel when a gear is engaged?
Links them to the output shaft
Which shaft in the gearbox is connected to the cardan shaft?
The output shaft
Lift the 4 shafts found in a gearbox
Input
Output
Secondary
Auxiliary
What component enables the selection of a specific gear?
The synchro hub sleeves
If there are gears used in the input & output shafts and the secondary shaft, what type of gear train is it?
A compound gear train
Which is the gear setting without a compound gear train? Why?
4th gear.
It’s direct drive.
Which shaft is freewheeling when the car is in neutral?
The output shaft
What is the gear ratio in 1st gear
1:1
Which gear wheel is fixed to the output shaft and not directly driven from the secondary shaft?
Reverse gear
List 2 differences between reverse gear and the rest of the gears
The gear wheel slides into gear, not the synchro hub
The gear wheel has straight cut teeth
The gear index is the ratio of the number of teeth on the gear wheels. What else is it?
The ratio between rotational speeds of the input shaft and output shaft
What’s the name for the ratio between rotational speeds of the input shaft and output shaft?
The gear index
The gear index is the ratio between rotational speeds of the input shaft and output shaft. What else is it?
The ratio of the number of the teeth of the gear wheels
Give 3 formulas to calculate the gear index
Number of teeth on driven wheel / number of teeth on driving wheel
Rotational speed in / rotational speed out
Torque out / torque in
In the formulas for gear index, what do each of these letters mean:
i
z1
z2
n
T
Gear index
Number of teeth on driving wheel
Number of teeth on driven wheel
Rotational speed
Torque
A gear index is just the ratio for one of the 6 or 7 gears. How do you calculate the total gear index (gear index for all gears together)
i1 x i2 x i3 etc.
If you know the input rotational speed, and you know the gear index, how do you calculate the output rotational speed?
Output rotational speed = input rotational speed / gear index
In compound gear trains other than reverse, how many gear indexes are there for each gear setting? How many gear wheels are involved in each index?
2
2
Name one other vehicle in which can a gear ratio be found?
Mountain bikes
How many gear wheels are needing to have a gear? What are these 2 gears called?
2
The driving wheel
The driven wheel
Is the driving wheel or the driven wheel driven by the electric motor?
The driving wheel
List 3 qualities that the gear ratio can change
Torque
Rotational speed
Direction of rotation
When considering the only 2 gears needed to produce a gear ratio, what is the gearbox’s equivalent to the driving wheel. What about the driven wheel?
The input shaft
The output shaft
If the number of teeth on the driving wheel is 40 and the number of teeth on the driven wheel is 20, what is the gear ratio? Is it 1:2 or 2:1?
1:2
If you are given the gear ratio (a:b), how do you calculate the gear index?
a:b
b / a = gear index
When an extra gear wheel is added in between the driving wheel and driven wheel, what happens to the rotational direction of the driven wheel?
It rotates in the same direction as the driving wheel, rather than the opposite
When an extra gear wheel is added in between the driving wheel and driven wheel, what is the name for this extra wheel? What effect does the number of teeth on the intermediate wheel have on the rotational speed of the driven wheel?
Stud wheel
No effect
There can be more than 1 stud wheel in a gear train. Is the driven wheel the same or the opposite rotational direction of the driving wheel if there are 9 wheels in total? Why?
The rotational direction is the same.
There is an odd number of gear wheels.
There can be more than 1 stud wheel in a gear train. Is the driven wheel the same or the opposite rotational direction of the driving wheel if there are 10 wheels in total? Why?
The rotational direction is the opposite.
There is an even number of gear wheels.
There are 2 connected gear wheels rotating opposite directions. Wheel A is larger than Wheel B. Which one is rotating faster?
Wheel B
If the driving wheel is larger than the driven wheel, is the transmission a reduction or an overdrive?
Overdrive
If the driven wheel is larger than the driving wheel, is the transmission a reduction or an overdrive?
Reduction
When dealing with a transmission with just a driving wheel and a driven wheel, which unit is a better way to calculate rotational speed?
Number of teeth
You are given the gear index of 2 and the input speed of 20 rpm. How would you calculate the output speed and what is the answer?
Output speed = input speed / index
20 / 2 = 10 rpm
If the gear index is greater than 1, is the transmission an overdrive or a reduction?
A reduction
What is torque measured in?
Newton metres
Take 2 of the formulas for gear index, one involving number of teeth and other involving torque. Which one is out divided by in? Which one is in divided by out?
Torque
Number of teeth
Fill in the gaps:
Gear index = no. of teeth on [___] wheel / no. of teeth on [___] wheel
Driven
Driving
Define dual transmission
2 transmissions, operating consecutively
If there is a stud wheel in between the driving wheel and the driven wheel, are there 2 gear indexes or is the stud wheel factored in to produce one index?
There are 2 gear indexes, where the stud acts as the driven wheel in the first and the driving wheel in the second
When there is a stud wheel in between the driving wheel and driven wheel, there are 2 gear indexes. How do you calculate the total gear index?
Multiply them together
What effect does having a dual transmission have? (2 points)
A much greater acceleration or deceleration, therefore much higher or lower torque
How can you calculate output torque?
Multiplying input torque and gear index
When you shift up in gear, what happens to the engine speed?
It decreases
Why are gear ratios applied?
Different cars have uses for different ratios
What is true about a vehicle with a lot of power?
A) There need to be more gears
B) There can be less gears
List the 3 main types of sequences found in gearboxes
Progressive gear change
Geometric gear change
Reciprocal arithmetic gear change
What is a different name for geometric gear jump?
Geometric sequence
What is the x axis on a gear graph? What is the y axis? (Also name the units of measurement)
Rotational speed (engine speed) in rpm
Car speed in km/h or mph
What kind of vehicle is a geometric gear jump applied to?
Trucks
What is another name for a progressive gear jump?
Adjusted geometric sequence
Out of progressive gear jumps and geometric gear jumps, which one is running horizontally? Which one is linear?
Geometric gear jump
Progressive gear jump
What kind of vehicle is the progressive gear jump (adjusted geometric sequence) used on?
Cars
Give 2 facts about the progressive gear jump
The gear jump is greater in lower gears
The gear jump is smaller in higher gears
Will a less powerful engine require more or less gears?
More gears
Which is determined first, the number of gears or the power of the engine?
The engine power
