Automotive Academy ZW

Final Drive Unit Adjustment The beauty of bevel gears is that we can adjust the gears relative to each other during overhaul and service. It is advisable to avoid disturbing the adjustments set by the manufacturer. However, if the unit is indeed faulty, it may be necessary to repair it. The process is so complex that some manufacturers recommend replacement of the entire unit instead of adjusting. PREPARATION Before disassembling, ensure that you'll be able to refit it as it was. You need to pay attention to: - the amount of backlash available before disassembly - the position and direction of crownwheel bearing caps (mark them to avoid interchanging them by mistake) - the tightness of the bearing adjustment sleeves on the bearing caps (mark them and count the number of exposed threads) - the location and thickness of all shims PROCEDURE ⚠️ these adjustments should be performed in a logical sequence, strictly adhering to manufacturer’s instructions. the order of adjusting is as follows: 1. Crownwheel bearing preload 2. Pinion depth/height/depth of mesh (with crownwheel & differential assembly removed) 3. Pinion bearing preload 4. (After refitting crownwheel) crownwheel and pinion backlash 5. Tooth contact/tooth profile/tooth pattern/tooth mesh If tooth contact is incorrect, readjust the pinion depth and then the backlash until desired specifications are achieved. Do you want to know how to perform each of these?

🛠️ *_the Final Drive Assembly_* The final drive assembly consists of the crownwheel and pinion. It is connected to the differential — it is not the differential unit. FUNCTIONS 1. The pinion has fewer teeth than the crownwheel. This arrangement multiplies torque. 2. The final drive also changes the direction of the drive. Through the use of bevel-type gearing, the final drive transmits drive at 90° from the longitudinal propeller shaft to the transverse axle shafts. In this way, the drive is redirected from the length of the vehicle to the wheels. 3. The crownwheel is normally bolted to the differential unit. So it houses and drives the differential, which then distributes torque to the axle shafts CONSTRUCTION There are 4 common types of gearing systems used in final drives - Straight bevel gears - Spiral bevel gears - Hypoid bevel gears (most common) - Worm and wheel The gears are mounted on bearings, usually taper roller bearings. Due to the way the gears mesh and carry load, they develop specific wear patterns. For this reason, correct adjustment during assembly and maintenance is necessary. Would you like to go deeper into the measurement and adjustments?

THE DIFFERENTIAL [THE DIFF] Many people refer to the whole centre of the axle as the differential, but this is incorrect. The differential is only one part of the final drive assembly (which also includes the crown wheel and pinion). THE DIFFERENTIAL UNIT IS THE PART THAT ALLOWS THE TWO DRIVE WHEELS TO ROTATE AT DIFFERENT SPEEDS This is necessary when a vehicle is turning. The inner wheel travels a shorter distance and must rotate more slowly, while the outer wheel travels a longer distance and must rotate faster. If both wheels were forced to rotate at the same speed, one would slip, causing tyre wear and poor handling. The differential uses a set of gears (arranged as a planetary gearset) to achieve this. These gears automatically adjust the speed of each wheel while still transmitting power. When the vehicle is moving in a straight line, both wheels rotate at the same speed. When turning, the differential allows the required difference in speed.