Drive Axles Flashcards
What is torque reaction?
When the vehicle rotates around the wheel as opposed to the wheels rotating
What drive systems have been developed to suit modern requirements?
- De-Dion Type Drive
- Torque Tube Drive
- Hotchkiss open-Type Drive
- Four-Link (Semi-Hotchkiss) Drive
- Front Wheel Drive (FWD)
What drive system uses an upper control arm and a lower control arm?
4 link (semi-hotchkiss)
What drive assembly doesn’t have an exposed prop shaft?
Torque tube
What drive assembly has exposed drive shafts?
De dion
Why is there a seal on a final drive assembly?
Because oil is encased
What are the 2 main gears in a final drive assembly?
Pinion and crown wheel
What are the purposes of a final drive?
- To transmit drive through an angle of 90 degrees
- To provide a gear ration that reduces the speed at which the gearbox output shaft rotates
- Permit an additional system and constant gear reduction in the transmission system
How is the taper decided on a final drive?
The point of the taper needs to meet the centre of the crown wheel
Why don’t final drive assemblies use straight gears?
unacceptable noise levels
What type of oil is used to lubricate final drive?
Extreme pressure oil
Where should hypoid pinions be offset in light and heavy vehicles?
Light - Below the centre line
Heavy - Above the centre line
What is used to cool worm drives?
A large well cooled sump
What types of worm drive final assemblies are there?
- Overhead
- Underslung
- Hindley worm
What two ways are there to measure the pre loading of pinion bearings?
- Spring balance
- Pre-loading gauge
What two types of spacer is used to determine pre load of a pinion bearing?
- Rigid spacer
- Ductile spacer
What type of nut signifies that you have a ductile spacer?
Castellated nut
What must you do prior to replacing the oil seal on a final drive assembly when there is a ductile spacer?
Ensure you draw a line on the nut
What is backlash?
The gap between the pinion and the flywheel
What is crown wheel run out?
Deviation from the centre as it rotates
What are the components of a differential?
- Sun wheels for each axle
- Axle shafts
- Planet pinions
- Cross pin
Where is the differential housed?
In the differential cage
What are the two main types of limited slip differential?
- Mechanical LSD
- Visco LSD
What two ways can viscous control be installed and connected in a differential?
- Shaft to shaft: hub of coupling joined to one axle shaft and the housing joined to the other axle
- Shaft to cage: hub of coupling joined to one axle shaft, housing is integral with the differential cage
What two types of live axle are there?
- Banjo-type casing
- Carrier-type casing
What type of casing is used more often to support a hypoid gear?
Carrier type casing
What is transmission wind up?
A condition in which a positive torque occurs in one axle and a negative torque in the other
What can transmission wind up occur in?
4WD vehicles
Tandem drive vehicles (HGV)
What’s the difference between axle wind up and transmission wind up?
Axle wind up is side to side and transmission wind up is front to rear
What three main groups do axle shafts fall in to?
- Semi Floating
- Three Quarter Floating
- Fully floating
What forces act on a semi floating axle?
Torsion, bending, compressive and tensile, shear
What forces act on a semi floating axle?
Torsion, bending, compressive and tensile, shear
What forces act on a three quarter floating axle?
- Torsion
- Bending
- Tensile and compressive
What forces act on a fully floating axle?
Torsional
What forces act on a fully floating axle?
Torsional
What is the purpose of hub reduction axles?
To increase torque at the wheel hub
What is the purpose of hub reduction axles?
To increase torque at the wheel hub
What advantages are there for using a tubular prop shaft?
- Light weight
- High resistance to misalignment
- Good torsional strength
- Low resistance to changes in angular speed
What advantages are there for using a tubular prop shaft?
- Light weight
- High resistance to misalignment
- Good torsional strength
- Low resistance to changes in angular speed
What advantages are there for using a tubular prop shaft?
- Light weight
- High resistance to misalignment
- Good torsional strength
- Low resistance to changes in angular speed
What is implemented on a prop shaft to correct any imbalances?
Spot welding small patches on to the shaft
What is implemented on a prop shaft to correct any imbalances?
Spot welding small patches on to the shaft
What is excessive whip at high speeds in a prop shaft known as?
Whirling speed
What is excessive whip at high speeds in a prop shaft known as?
Whirling speed
What is whip of a prop shaft caused by?
Sagging due to its own weight
What is whip of a prop shaft caused by?
Sagging due to its own weight
What 3 things can we do to eliminate the sag and whirling speed caused at the drop shaft?
- The length of the shaft
- The diameter of the shaft
- Making the shaft out of two smaller pieces
What are the requirements for modern joints for a propshaft?
- Strength
- Compactness
- Large drive angles
- Shaft balance
- Operating speed
What groups of modern joints do we have?
- Cross type/Universal joint
- Rubber joint
- Constant velocity joint (CV)
What groups of modern joints do we have?
- Cross type/Universal joint
- Rubber joint
- Constant velocity joint (CV)
What type of bearings are used in a hardy Spicer UJ?
Needle roller bearings
What type of bearings are used in a hardy Spicer UJ?
Needle roller bearings
What 3 ways can a Hardy Spicer UJ be retained?
- Circlip
- Peening
- Bolted
What 3 ways can a Hardy Spicer UJ be retained?
- Circlip
- Peening
- Bolted
What is the disadvantage of using a Hardy Spicer joint?
Lacks ability to absorb torsional shock
What is the disadvantage of using a Hardy Spicer joint?
Lacks ability to absorb torsional shock
What types of rubber universal joints are there?
- Moulton
- Layrub
- Doughnut
What types of rubber universal joints are there?
- Moulton
- Layrub
- Doughnut
What type of CV joints do we have?
- Weiss
- Tracta
- Rzeppa
- Tripode
- Plunge
What type of CV joints do we have?
- Weiss
- Tracta
- Rzeppa
- Tripode
- Plunge
What is the purpose of a CV joint?
To provide an output shaft speed equal to that of the input in all shaft positions within the working range of the joint
Why is a plunge joint needed in a CV joint?
To allow for up and down suspension movement causing a change in length of the driveshafts
Why is a plunge joint needed in a CV joint?
To allow for up and down suspension movement causing a change in length of the driveshafts
What plunge joint arrangement would you have on front and rear axles?
Front - CV joint at the wheel end and plunge at the other
Rear - Plunge at both ends
What plunge joint arrangement would you have on front and rear axles?
Front - Plunge at the wheel end and CV at the other
Rear - Plunge at both ends
