AUTOMOBILE DIFFERENTIAL

UNITA MECHANICAL GEAR ASSEMBLY UNIT WHICH PROVIDE DIFFERENT

SPEED/TORQUE TO SAME AXLE WHEELS By:

Parth vaishnavUdit kamboj

REQUIREMENT

• Transfers power from driveshaft to the wheels

• Provides final gear reduction

• Splits amount of torque going to each wheel

• Allow the wheels to rotate at different speeds in turns

TYPES

• Open Differential• Locked Differential• Active/Electronic Differential• Limited Slip Differential

OPEN DIFFERENTIAL

• These are commonly used differential to achieve Different Speeds atwheels of the same axle

• Application includes normal passenger car and bus

OPEN DIFFERENTIAL TYPICAL PARTS

• Pinion Drive Gear: Transfers power from the driveshaft to the ring gear• Ring Gear: Transfers power to the Differential case assembly• Side/spider gears: Help both wheels to turn independently when turning• Differential case assembly: Holds the Ring gear and other components

that drive the rear axle• Rear drive axles: Steel shafts that transfer torque from the differential

assembly to the drive wheels• Rear axle bearings: Ball or roller bearings that fit between the axles and

the inside of the axle housing• Axle housing: Metal body that encloses and supports parts of the rear

axle assembly

OPEN DIFFERENTIAL SCHEMATIC

OPEN DIFFERENTIAL IMAGE

LOCKED DIFFERENTIAL

These are used to achieve Different Torques at wheels of the same axle

• Locking means joining the two independent pinion gear

• Application includes race car and off-road vehicles and 4 Wheel Drive

LOCKING DIFFERENTIAL NECESSITY

• To provide increased traction compared to

the normal differential unit

CASE :• When one rear axle wheel is stuck in the mud,

Open differential will concentrateinrotating the stuck wheel

Locked differential will push the vehicle with the help of torque available at the free wheel

ACTIVE/ELECTRONIC DIFFERENTIAL

(Both Open & Locked)• Dynamically Locking the differential

using a electromagnetic clutch• When cornering, the inner and

outerwheels rotate at differentspeeds,because the inner wheels describeasmaller turning radius. The electronicdifferential uses the steering wheel command signal and the motor speed signals to control the power to each wheel so that all wheels are supplied with the torque they need

LIMITED SLIP DIFFERENTIAL

• A limited slip differential (LSD), is very similar to the open differential unit but has additional link that prevents wheel spin and loss of traction

• The standard differential delivers maximum torque to the wheel with minimum traction. The limited slip differential delivers maximum torque to the wheel with maximum traction

• It is mainly used in off road vehicles• TYPES :

i. Clutch Packii. Cone Clutchiii. Torsen

LIMITED SLIP DIFFERENTIAL - CLUTCH

• The clutch pack limited slip differential uses a set of friction discs and steel plates to lock the axles together whenever one drive wheel experiences uncontrolled slippage. The friction discs are sandwiched between the steel plates inside the differential case. The friction disc is splined and turns with the differential side gears. The steel plates turn with the differential case.

• Springs (bellville springs, coil springs, or leaf springs) force the friction disc and steel plates together. As a result, both rear axles try to turn with the differential case.

• Spring force and thrust action of the spider gears applies the clutch pack. Under high torque conditions, the rotation of the differential pinion gears PUSHES OUT on the axle side gears. The axle side gears then push on the clutch discs. This action helps lock the disc and keeps both wheels turning.

LIMITED SLIP DIFFERENTIAL - CLUTCH

LIMITED SLIP DIFFERENTIAL – CLUTCH WORKING

• When driving normally, the vehicle can turn a comer without bothwheels rotating at the same speed.

• As the vehicle turns a corner, the inner drive wheel must slow down.• The unequal speed between the side gears causes the side gear

pinions to walk around the side gears.• This walking will cause the outer axle shaft to rotate faster than the

differential case, allowing the pinion shaft on the side to slide down a V-shaped ramp.

• This action releases the outer clutches causing the clutch pack to slipwhen the vehicle is turning.

LIMITED SLIP DIFFERENTIAL - CONE

• A cone clutch limited slip differential uses the friction produced by cone-shaped axle gears to provide improved traction. These cones fit behind and are splined to the axle shafts. With the axles splined to the cones. the axles tend to rotate with the differential case. Coil springs are situated between the side gears to wedge the clutches into the differential case.

• Under rapid acceleration or when one wheel loses traction. the differential pinion gears, as they drive the cones, push outward on the cone gears. This action increases friction between the cones and case, driving the wheels with even greater torque.

LIMITED SLIP DIFFERENTIAL - CONE

LIMITED SLIP DIFFERENTIAL – CONE WORKING

• When a vehicle goes around a corner, the inner drive wheel must slowdown.

• The unequal speed between the side gears will cause the side gear pinions to walk around the side gears.

• This walking action causes the outer axle shaft to rotate faster than the differential case. Because the cones have spiral grooves cut into their clutch surfaces, the inner cone will draw itself into the case and lock tight and the outer cone clutch will back itself out of the case.

• This action allows the outer drive axle to free wheel.• The end result is the majority of the engine torque is sent to the inner

drive wheel.

LIMITED SLIP DIFFERENTIAL - TORSEN

• Torsen differentials can be used in one or more positions on a motor vehicle:

• Center - used to apportion appropriate torque distribution between front and rear axles on an all-wheel drive vehicle.

• Rear - used to apportion appropriate torque distribution between left andright sides in rear axles. This may be on either a rear-wheel drive or four-wheel drive vehicle.

• Front - used to apportion appropriate torque distribution between left andright sides in front axles. This may be on either a front-wheel drive or four- wheel drive vehicle.

• A four-wheel-drive vehicle, for example, may use either one, two, or three Torsen differentials.

LIMITED SLIP DIFFERENTIAL - TORSEN

LIMITED SLIP DIFFERENTIAL – TORSEN WORKING

• The Torsen differential works just like a conventional differential but can lock up if a torque imbalance occurs, the maximum ratio of torque imbalance being defined by the Torque Bias Ratio (TBR).

• When a Torsen has a 3:1 TBR, that means that one side of the differential can handle up to 75% while the other side would have to only handle 25% of applied torque.

• During acceleration under asymmetric traction conditions, so long as the higher traction side can handle the higher percentage of applied torque, no relative wheel spin will occur.

• When the traction difference exceeds the TBR, the slower output side of the differential receives the tractive torque of the faster wheel multiplied by the TBR; any extra torque remaining from applied torque contributes to the angular acceleration of the faster output side of the differential.

DIFFERENTIAL PROBLEMS

• Bearings, humming sound gets louderwith

higher speeds– Clean the bearing setup if persist change it

• Ring and Pinion, show up as whining or howling noise that changes when going from acceleration to deceleration

• Lack of service or low fluid can causethis problem. Fill proper lubricant oil to avoid it

If backlash (clearance) between ring gear and pinion gear is too great. Adjust gear and pinion to avoid the noise

BEARING

RACK & PINION

Thank you !