powershift and automatic transmission Flashcards
what are the two types of transmission applications
cycling transmissions - hauling transmissions
what are the two classifications of powershift transmissions based on the internal gearing
planetary - countershaft type
the function of the transmission is to
modify engine power to propel heavy equipment
what can powershift transmissions also provide
a place to mount a PTO
what is a major advantage to powershift transmissions over manual transmissions
allow speed and directional changes with no interruption in the flow of power that is propelling the machine
how do powershift transmissions and automatic transmissions differ
powershift transmissions require speed and directional changes to be made solely at the discretion of the operator
automatic transmissions has the ability to
receive information on machine ground speed as well as operator demand for power and automatically makes up or downshifts
machines equipped with powershift transmissions are most often used in what type of application
cycling
what is a cycling application
a repeated forward and reverse motion
most power shift transmissions will feature
the same number of gears in forward as reverse
automatic transmissions are normally used in
hauling applications
why is a planetary capable of transmitting the same amount of torque as a larger spur gear set
because gear tooth loading is spread among all the contact points in the gear set
in most cases what do the gears in a planetary rotate on
needle bearings
the greater the number of the planetary pinion gears in a planetary
the greater the amount of torque the planetary is able to transmit
how do you achieve direct drive in a planetary gear set
any two members locked together or rotating the same rpm in the same direction
when can you achieve neutral in a planetary gear set
when there is an input but no held member or when there is no input
how are clutches always released
spring
when multiple clutches are on a powershift transmission gear set
only one clutch at a time per gear set can be applied at any one time
a differential planetary set is by definition a simple planetary set with
three rotating members and dual inputs with a single output
what is the turbine shaft
is the output shaft of the torque converter
the mainshaft is
internal in the transmission and connected to two of the planetary gear sets
what are the most commonly used clutch assemblies
multiple disc clutch
how are multiple disc clutches applied
by pressurized oil flow from the transmission - charging pump
what are the components of multiple disc clutches
clutch discs and clutch plates
clutch discs
are steel discs that have a friction material bonded to both sides
what are the grooves on the friction material that produce ridges called
lands
what is the purpose of the grooves in a clutch disc
to allow oil to lubricate the disc when disengaged and squeeze out when applied
clutch discs have teeth cut in the
internal circumference
the teeth on the clutch disc engage
the splines on the component that is to be held
clutch plates are located
between every pair of clutch discs
the plates provide
a reaction surface on witch the clutch discs can act on
what would a clutch plate have on the outside circumference if it was intended to hold a components of a planetary gear set
tangs
what would a clutch plate have on the outside circumference if it was intended to hold two rotating components together
teeth
what is used to apply the clutch
hydraulically actuated pistons
how is the actuating piston of a clutch held in the piston housing
by teeth that are machined into its outer surface
what type of seal is used on the clutch actuation piston to ensure good sealing
a lip type seal
in general the bearings and shafts of a countershaft transmission will have to be
larger than the planetary design
