Manual Transmission/Transaxle: Description and Operation
NV1500 MANUAL TRANSMISSIONDESCRIPTION
The NV1500 (available for only the 2.4 engine)is a medium-duty, 5-speed, constant mesh, fully synchronized manual transmission. The Transmission is available in vehicles equipped with a 2.4L engine.
The transmission gear case consists of two aluminum gear housings and a detachable clutch housing.
The mainshaft is supported by two sealed ball bearings, and the countershaft is supported by two tapered roller bearings. The transmission gears all rotate on caged type needle bearings. A roller bearing is used between the input and output shaft.
The Transmission has a single shaft shift mechanism with three shift forks all mounted on the shaft. The shaft is supported in the front and rear housings by bushings. Internal shift components consist of the forks, shaft, shift lever socket, and detent components.
The drain plug in on the bottom of the transmission and fill plug is on the side.
NV1500 Manual Transmission:
Identification bar code tags are located on each side of the transmission, below the shift tower. The tag located on the right side has the part number and the tag located on the left side has the build sequence and date information.
OPERATION
The driver selects a particular gear by moving the shift lever to the desired gear position. This movement moves the internal transmission shift components to begin the shift sequence. As the shift lever moves the selected shift rail, the shift fork attached to that rail begins to move.
The fork is positioned in a groove in the outer circumference of the synchronizer sleeve. As the shift fork moves the synchronizer sleeve, the synchronizer begins to speed-up or slow down the selected gear (depending on whether we are up-shifting or down-shifting).
The synchronizer does this by having the synchronizer hub splined to the mainshaft, or the countershaft in some cases, and moving the blocker ring into contact with the gear's friction cone. As the blocker ring and friction cone come together, the gear speed is brought up or down to the speed of the synchronizer. As the two speeds match, the splines on the inside of the synchronizer sleeve become aligned with the teeth on the blocker ring and the friction cone and eventually will slide over the teeth, locking the gear to the mainshaft, or countershaft, through the synchronizer.