DRIVETRAIN C549 14 CONSTRUCTION SPECIFICATIONS The C549 gearbox installed on the vehicle has features aimed at improving maneuverability. Its main features are: Excellent maneuverability of the gear control Quiet operation. The configuration is transverse with 2 shafts and a differential. The design is being made to improve the gearbox casing and the clutch casing in terms of strength and noise absorption. MAIN SHAFT The main shaft consists of: 1st, 2nd speed and Reverse gears directly on the shaft; 3rd, 4th and 5th speed gears fitted on the shaft. The main shaft is supported by two ball bearings. LAYSHAFT The lay shaft consists of: 1st, 2nd, 3rd, 4th and 5th speed gears fitted on the shaft. The lay shaft is mounted on: a front roller bearing a rear ball bearing. GEARS The gears are the following type: helical toothed for the forward gears Straight toothed for Reverse gear. The teeth for all the gears are HCR (High Contact Ratio). The 2nd and 5th speed and final drive gears are super finished after the thermal treatment to guarantee absolute precision for the teeth and quiet Operation. The kinematic components inside the gearbox casing are lubricated dynamically, by means of the oil flowing along channels and through ports in the casings, the 3rd/4th speed rod and the main shaft; this allows: improved torque transmission and greater efficiency against the effects of wear Maneuverability even at low temperatures thanks to the use of synthetic multi-grade oil. SYNCHRONIZERS The synchromesh for all the forward gears (there is no synchromesh for reverse which is always meshed on the main shaft to ensure smoothness during engagement) is the brass, baulk ring type (Borg- Warner) and is on the lay shaft for 1st and 2nd speeds, on the main shaft for 3rd, 4th and 5th speeds and on the idler shaft for reverse gear (for which there is no synchromesh). This solution reduces gearbox noise when stopped in neutral from the moment that 3 of the 5 pairs of gears are not driven. The engagement and synchronization loads are also reduced as a result of the corresponding reduction in the inert rotating masses downstream of the crankshaft. The synchronizer on 1st and 2nd speeds, the most used gears subject to the most stress, is the double cone type requiring far less engagement force compared with a single cone type traditional synchronizer of the same size. A new pre-synchronizer system comprising thrust bearings is used on all the gears to improve sliding and engagement: in 1st and 2nd speeds the free (neutral) gears are supported by roller chambers. The geometry of the teeth and the kinematic chain has been improved for the engagement of reverse gear producing better maneuverability. DIFFERENTIAL The differential unit is located in the rear part of the gearbox casing. It comprises: A crown wheel reduction A differential housing in a single piece which incorporates the planet and satellite gears. The differential is supported by two conical roller Bearings. The planet gears have a splined internal profile in which the two joints connected to the two driveshaft’s that transmit the drive to the wheels mesh. The speedometer idler drive gear is fitted on the outside of the differential housing
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