Manual Trans./Transaxles Basic Diagnosis and Maintenance
roller bearing
A long cylindrical roller held in position by a cage.
interlock mechanism
A mechanical device that prevents engagement of two different gears at the same time.
shift fork
A mechanism that moves the synchronizer sleeve to lock the gear to the main shaft.
power train control module (PCM)
A module used to control engine and/or transmission shifting.
spring-loaded key
A part of the synchronizer that helps hold the synchronizer collar in position.
selector shift rail
A rod that is attached to the shift fork. These rails move when the shifter lever is moved against them.
pocket bearing
A roller in the rear of the input shaft that supports the front of the main shaft.
chamfer
A rounded or angled edge located on the blocking ring, with ridges machined into it to help grab the cone surface of the gear.
garter spring lip seal
A sea that has a spring to maintain pressure on the seal's surface to prevent leakage.
O-ring seal
A seal that is a complete circle. If a cutaway is done, it will also be a complete circle. These seals are usually set into a grove that is machined into the housing or part that does not move and is intended to be sealed.
reverse shift fork
A shift fork used to engage the reverse gear.
paddle
A shifting mechanism or electronic control usually attached to the steering wheel
hard shifting
A shifting problem in which the shifter will not move smoothly into the desired gear, requiring excessive force by the driver to set it into gear.
selective thickness shim
A shim of a prescribed thickness that is used to control shaft clearance in a transmission
blocking ring
A synchronizer part that increase or decreases a gear's speed to match shaft speed so that the synchronizer sleeve can lock the gear to the shaft. Also called a baulk-ring.
Baulk-ring synchromesh unit
A synchronizer used in all current transmissions. It uses a blocking ring. Also called a blocker ring synchromesh unit.
double-clutching
A technique used to shift gears when a non-synchronized transmission is used. The driver must push the cutch in multiple times to change gears.
synchronizer
An assembly that allows for the selection of gears without grinding by matching the speed of the two assemblies.
vehicle speed sensor
An electronic sensor that reads the driveshaft speed and sends either a analog or a digital signal to the computer that corresponds to the road speed of the vehicle.
electronic reverse lockout
An electronic solenoid used to prevent accidental engagement into reverse gear while the vehicle is moving forward
Hydrodynamic seal
Oil seal flutes or swirls that are part of the oil seal and that create a pumping action to return oil to the transmission as the shaft rotates, enabling lubrication.
Gradient resistance
Resistance encountered when a vehicle travels up a hill, requiring torque to be applied to overcome it.
rolling resistance
Resistance that is present from tires contacting the road and wind resistance against the vehicle while rolling down the highway.
Selector gate
The U-shaped cutaway in shift shafts that the shifter lever fits into.
lockout solenoid
The cam and lock pin operation b an electronic solenoid that keeps the reverse gear in lockout until it is selected.
torque multiplication
The increase in torque.
gear shift lever
The lever that the driver uses to shift the transmission.
detent mechanism
The mechanism that holds or helps hold the shift rail into position to ensure that the gear does not pop out when selected and to let the driver feel when a shift is completed.
gear ratio
The ratio of the number of turns that a drive gear must complete to turn the driven gear one turn. Typically this a calculation of the driven gear to the drive gear. Ratios are listed, for example a 2:1 or 4.3:1.
synchronizer sleeve
The sleeve that slides to lock the selected gear to the main shaft. The synchronizer sleeve is part of the synchronizer assembly.
gear reduction
The use of a small gear to drive a large gear. The result is in an increase in torque but a decrease in speed.
needle roller bearing
Typically a small-diameter pin rolling bearing that can be held in a cage or placed into the inside diameter of a hole.
idler gear
A gear used in between two gears to change the direction of the rotation of the driveshaft or drive axles in the transmission.
hydraulic actuator
A hydraulically controlled cylinder that engages or disengages the clutch pedal.
direct drive
A condition in which the engine and transmission output are turning at the same rate of speed.
thrust washer
A copper or brass washer that controls clearances on all transmission shafts.
overdrive
A gear in which the output shaft is faster than the engine speed A gear ratio of less than 1:1.