Transmission Fundamentals Flashcards
what are the three functions of a transmission
. to multiply torque from the engine through a series of gear options
. to provide a means of reversing the direction of torque delivery from the engine
. to provide an interruption in torque ( neutral ) while the clutch is still engaged
transmission classifications
. synchronized or non-synchronized . single or multiple countershaft . number of forward gear ratio . manual or automatic . final gear ratio ( direct or overdrive )
how do you calculate output torque on a transmission
input torque must be multiplied by the final gear ratio
how do you calculate output speed on a transmission
input speed must be divided by the final gear ratio
what are the main components in a heavy duty transmission
. Transmission input shaft and drive gear . Mainshaft and mainshaft gears . Synchronizers . a shift lever . shift rails and forks . detents . interlocks
what is the initial component to receive power from the engine
transmission input shaft also called the clutch shaft
what happens when the clutch is engaged
it is trapped between the flywheel and the pressure plate friction surface
what is the purpose of the tapered roller bearing located in the casting ahead of the input shaft gear
to center the shaft in the front of the transmission case and provides a means of adjusting mainshaft endplay
how is the input shaft bearing retainer cover adjusted to have the proper endplay on the bearing cup and cone
shims
what is the mainshaft and gear assembly is different from the countershaft how ?
the main shaft is a sperate shaft that operates independently of the main shaft gears
how are the helical gears on a mainshaft held in place
with thrust washers, snap rings and lock pins
why are more thrust washers needed on a mainshaft than a countershaft
because the gears are not connected to the mainshaft so each individual gear requires thrust washers
what is the tang on a thrust washer used for
as a locating device
what is a synchronizer
a type of clutch or brake that is used to match the speed of the mainshaft with a mainshaft gear during the shifting process
what are the three types of synchronizers
block type
plate and disc type
pin type
what is used to transmit the actions of the operator to the shift fork and rails
the shift lever
what is used to reduce transmission noise up into the cab in a shift lever assembly
an isolator
what is the purpose if the shift rails and fork
to take the operators input from the gear shift lever and move the sliding clutches to engage the desired mainshaft gear
what allows proper gear selection without clashing gears
by only allowing one sliding clutch to be moved at one time
what is the purpose of the detents in a heavy duty transmission
to hold a shift rail in the selected position whether in a neutral or engaged position
how many recesses are there in a shift rail
there are usually three recesses in each shift rail
why must the operator overcome a definite amount of force to shift into first or reverse
to prevent accidental shifting during operation
in order to prevent the operator from selecting more than one gear at a time
interlocks
what are some advantages of multiple countershaft transmissions
. smaller and lighter countershafts, Bearings and housings
. Floating design of mainshaft gear
. Narrower gear teeth width required
what type of synchronizer is a multi piece unit composed of a central hub, two soft metal blocker rings, a shift collar. a set of inserts and two insert springs
block type synchronizer
what is the first reduction device used to increase the available engine torque
the transmission
how is torque divided in a twin countershaft design
it is split evenly between both countershafts 180 degrees apart
how is torque divided in a triple countershaft design
between all three countershafts 120 degrees apart
what are some advantages of multiple countershaft transmissions
. smaller and lighter countershafts, bearings and housings
. floating design of mainshaft gear
. Narrower gear teeth width required
how many reverse idler gears are needed in a multi countershaft design
one for each countershaft
the mainshaft gears are located in place by
a set of double washers
the shift lever directly moves what in the shift bar housing
shift rail
multiple countershaft transmissions use several housings , these housings are kept in alignment through the use of .
precise dowelling
