Car Transmission System
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Transcript of Car Transmission System
TRANSMISSION
OBJECTIVESOBJECTIVESTo understand the operational
principles and basic mechanisms of transmission system
Lecture – 1 hourWorkshop – 1 hour
TRANSMISSION SYSTEM (1)TRANSMISSION SYSTEM (1)
Manual gear knob
Manual gear box
Manual gear boxManual transmission system
5-speed manual gearbox
TRANSMISSION SYSTEM (2)TRANSMISSION SYSTEM (2) Green shaft (input shaft) & gear
turn at the same rpm as the engine
Red shaft (layshaft) & gears are directly connected to the input so it spins when input shaft spins
Yellow shaft (output shaft) is splined shaft connected directly to drive shaft through differential to drive wheels (If wheels are spinning output shaft spins)
If engine is off with car coasting output shaft turns inside blue gears (blue gears & layshaft are motionless)
Collar connects one of two blue gears to output shaft via dog teeth
TRANSMISSION SYSTEM (3)TRANSMISSION SYSTEM (3) Moving knob forward & backward
moves collar to engage the gears Reverse gear is handled by a
small idler gear (purple) Importance of transmission:–Engine redline (max. rpm
above which engine explodes)–Engines have narrow rpm
ranges (horsepower & torque are at their maximum)
Synchronizers allow collar & gear to make frictional contact before dog teeth make contact (collar & gear synchronize their speeds before teeth need to engage
TRANSMISSION SYSTEM (4)TRANSMISSION SYSTEM (4)A car engine spins all
the time & car wheels don't (to stop without killing the engine wheels, engine needs to be disconnected from the engine)
Flywheel connected to engine
Clutch plate connected to the transmission
Pressure plate
Clutch plate
Spring
Spring
TRANSMISSION SYSTEM (5)TRANSMISSION SYSTEM (5)Springs force on pressure plate Clutch plate springs - isolate
transmission from shock of clutch engaging
Friction material on the clutch disc wears out (similar to the friction material on the pads of a disc brake pads/shoes of a drum brake; clutch slips & lost of power)
Driver who slips the clutch a lot will wear out clutch a lot faster
Worn throw-out bearing (rumbling noise whenever the clutch engages)
TRANSMISSION SYSTEM (6)TRANSMISSION SYSTEM (6) Other clutches:–Automatic transmission with several
clutches used to engage and disengage various sets of planetary gears–Car air conditioning compressor with
magnetic clutch
–Engine-driven cooling fan with thermostatically controlled viscous clutch
TRANSMISSION SYSTEM (7)TRANSMISSION SYSTEM (7)Ideally, transmission should be
flexible in its ratios that engine runs at its single, best rpm value (continuously variable transmission - CVT) – Honda City
Manual transmission checklist:–Check for oil leaks (RM5000 new Kancil
gearbox) Manual transmission test drive–With transmission lever in neutral,
parking brake applied & engine idling, listen to any loud noises when clutch pedal pressed or released– Try to drive the car at all speeds one by
one - every speed should shift smooth & easily without any noises or jerks
TRANSMISSION SYSTEM (8)TRANSMISSION SYSTEM (8)
Manual transmission test drive–While driving at 2nd or 3rd gear, try to
press down sharply on the accelerator pedal for an instance (clutch should not slip, any slipping i.e., engine rpm increases but speed remains the same clutch most likely has to be replaced)–Try to drive with acceleration &
deceleration (there should be no whining or humming noise under any condition with all gears should shift easily & noiselessly)
TRANSMISSION SYSTEM (9)TRANSMISSION SYSTEM (9)
TRANSMISSION SYSTEM (10)TRANSMISSION SYSTEM (10)Automatic transmissions:–no clutch pedal–no gear shift
Automatic transmission (gearbox plus torque converter) – like manual gearbox & its clutch
Torqueconverter
Auto gearbox
Auto transmission system
TRANSMISSION SYSTEM (11)TRANSMISSION SYSTEM (11) In automatic transmission, same set of
gears produces all of the different gear ratios (planetary gearset)
Planetary gearset – A set of bands to lock parts of gearset – Three wet-plate clutches to lock other parts
of gearset – Hydraulic system controlling clutches &
bands – Large gear pump to move transmission fluid
around Planetary gearset has 3 main parts: – Sun gear – Planet gears & planet gears' carrier– Ring gear
TRANSMISSION SYSTEM (12)TRANSMISSION SYSTEM (12)
TRANSMISSION SYSTEM (13)TRANSMISSION SYSTEM (13)Each of these 3 parts can be input,
output or stationary (determines gear ratio)
First Gear - 2.4:1Second Gear - 0.67:13rd gear - 1:1 ratio in 3rd gearOverdrive has a faster output speed than
input speed (output of engine goes straight to transmission)
Ratio = 1 / (1 + S/R) = 1 / ( 1 + 36/72) = 0.67:1 (an engine turning at 2000 rev/min output speed is 3000 RPM allowing cars to drive at freeway speed while the engine speed stays nice and slow
TRANSMISSION SYSTEM (14)TRANSMISSION SYSTEM (14) Differentials (where engine power, in most
cars, makes its last stop before spinning the wheels) –Aim engine power at the wheels –Act as final gear reduction in the car
(reduce rotational speed of transmission one final time before it hits the wheels) – Transmit power to the wheels while
allowing them to rotate at different speeds during turning
Device that splits engine torque two ways, allowing each output to spin at a different speed
Differential is found on all modern cars & trucks, and also in many all-wheel-drive (full-time 4WD vehicles)
TRANSMISSION SYSTEM (15)TRANSMISSION SYSTEM (15)
Differential
TRANSMISSION SYSTEM (16)TRANSMISSION SYSTEM (16)Final drive ratio (gear ratio in the
differential)Open differential always applies the
same amount of torque to each wheelTwo factors determining how much
torque can be applied to the wheels:–equipment– traction
Dry conditions - torque applied to wheels limited by engine & gearing
TRANSMISSION SYSTEM (17)TRANSMISSION SYSTEM (17) In low traction - amount of torque limited
to greatest amount that will not cause a wheel to slip under those conditions (if you give the car more gas after the wheels start to slip, the wheels will just spin faster – problem with open differentials
Limited slip differential (LSD) – positraction - allows more torque to be transferred to the non-slipping wheel
TRANSMISSION SYSTEM (18)TRANSMISSION SYSTEM (18)Automatic transmission checklist–Place your car at a level surface, start
engine, set transmission lever to "P“ & let engine idle –Pull transmission dipstick–Wipe it off with a lint free clean
rag/tissue– Insert it back carefully all the way
down into its place–Pull again & check fluid level
TRANSMISSION SYSTEM (19)TRANSMISSION SYSTEM (19)Automatic transmission
checklist –Pull again & check fluid
levelEngine cold fluid within
"COLD" marksEngine hot fluid level at
upper end of "HOT" mark (top it up if it is lower)
Check fluid condition also: too black & a burnt smell -transmission may not last
TRANSMISSION SYSTEM (20)TRANSMISSION SYSTEM (20)Automatic transmission
checklist –Pull again & check fluid
levelThere should not be any
metal filings or black flakes
Topping up transmission fluid–Use only specified
transmission fluid (check your manual)
TRANSMISSION SYSTEM (21)TRANSMISSION SYSTEM (21)Topping up transmission
fluid–Add a small amount of
fluid through dipstick pipe as shown in the image & do not overfill it–Wait for a few minutes
to let fluid to flow down –Start engine & check
level again
TRANSMISSION SYSTEM (22)TRANSMISSION SYSTEM (22)Transmission maintenance–Most of transmission troubles start
after overheating Under heavy loadContinuous stop & go traffic in hot
weatherRacingAccelerating too hard to free the car At higher temperatures transmission fluid
burns loosing its lubricating qualities & becomes oxidized leaving deposits all over inside
Exposed to heat rubber seals & gaskets inside transmission become hardened causing leaks
TRANSMISSION SYSTEM (23)TRANSMISSION SYSTEM (23)Transmission maintenance–Most of transmission troubles start
after overheating Metal parts warp & loose their strength
–Poor design–After being rebuilt by inexperienced
technician–Harsh driving–Too low or too high transmission
fluid level–Wrong transmission fluid type
TRANSMISSION SYSTEM (24)TRANSMISSION SYSTEM (24)How to prevent the transmission from
damage–Always check your parking space for
leaks (get it fixed before it caused something serious) –Once in a while check transmission
fluid level & condition –Use only same type of the
transmission fluid as specified in owner's manual–Never shift to “R” or “P” until car
comes to a complete stop
TRANSMISSION SYSTEM (24)TRANSMISSION SYSTEM (24)How to prevent the transmission from
damage–Never shift from “P” mode when
engine rpm is higher than normal idle –Always hold a brake down when
shifting from “P”–Do not tow with drive wheels on the
road–Go to transmission shop when you
experience any problems with your transmission such as leaks, noises, problems with shifting, etc.
TRANSMISSION SYSTEM (25)TRANSMISSION SYSTEM (25)ATF (owner’s manual)Fluid change (40,000 km or so)Good conditions – clean & odorless Transmission screen/filter
THE ENDTHE ENDIQ + EQ + SQ = TQ*