Difference between revisions of "Differential"
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| − | + | A differential is a mechanism that allows the two driven wheels to rotate at different speeds to assist in cornering. | |
| + | =Function= | ||
When turning a corner, the outer wheels will follow a path with a greater radius of curvature. This difference in radius means the outside wheels will have to travel a longer distance, and rotate faster than the inside wheels.in a rear wheel drive car, the front two wheels are allowed to rotate at a different rate, so this does not pose a problem. The rear wheels, however, both have to be driven by the engine, and therefore are mechanically connected to each other, so there is no freedom of movement between them inherent in the design. | When turning a corner, the outer wheels will follow a path with a greater radius of curvature. This difference in radius means the outside wheels will have to travel a longer distance, and rotate faster than the inside wheels.in a rear wheel drive car, the front two wheels are allowed to rotate at a different rate, so this does not pose a problem. The rear wheels, however, both have to be driven by the engine, and therefore are mechanically connected to each other, so there is no freedom of movement between them inherent in the design. | ||
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[need a pic of cornering to demonstrate wheel travel difference] | [need a pic of cornering to demonstrate wheel travel difference] | ||
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{{#evt:service=youtube|id=https://www.youtube.com/watch?v=yYAw79386WI}} | {{#evt:service=youtube|id=https://www.youtube.com/watch?v=yYAw79386WI}} | ||
| − | + | =Types= | |
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==Open Differential== | ==Open Differential== | ||
An open differential is a gear assembly that allows the two rear wheels to spin independently of each other, while maintaining the average rotational speed. If the outside wheel spins faster than it would without the differential, the inside wheel must spin and equivalent amount slower. Similarly, the torque transferred to the ground, but is split in varying amounts between the two rear wheels depending on their relative velocities. The faster spinning wheel will see a proportionally greater amount of torque from the engine. | An open differential is a gear assembly that allows the two rear wheels to spin independently of each other, while maintaining the average rotational speed. If the outside wheel spins faster than it would without the differential, the inside wheel must spin and equivalent amount slower. Similarly, the torque transferred to the ground, but is split in varying amounts between the two rear wheels depending on their relative velocities. The faster spinning wheel will see a proportionally greater amount of torque from the engine. | ||
| + | This torque differential between the two wheels can become problematic in high torque applications where the torque is desired to go to the wheel with the greatest amount of traction, not the greatest rotational velocity, such as corner exit, or corner entry if using an inboard brake. To solve this problem, a differential that can limit the amount of slip is desired. | ||
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==Limited Slip Differential== | ==Limited Slip Differential== | ||
| − | + | A limited slip differential (LSD) allows the two wheels to rotate at different speeds, but is limited to a maximum difference. The maximum limit is the ratio of the LSD. | |
| − | + | ===Clutch=== | |
| − | + | ===2-Way, 1-Way, 1.5-Way=== | |
| − | + | ===Geared=== | |
| − | + | ====Torsen==== | |
| − | + | ===Locking=== | |
| − | + | ====Detroit Locker==== | |
| − | + | ====Cam and Pawl==== | |
| − | + | ===Viscous=== | |
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==Spool== | ==Spool== | ||
not really a kind of differential, just a way to lock the half shafts together | not really a kind of differential, just a way to lock the half shafts together | ||
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not sure if anyone uses eLSDs but they're common in industry, dont know if this is the right section or the LSD section is better | not sure if anyone uses eLSDs but they're common in industry, dont know if this is the right section or the LSD section is better | ||
| − | + | =Differentials used in Formula= | |
| − | + | Torsen University Special | |
| + | TRE MK1 | ||
| + | TRE MK2 | ||
| + | Drexler | ||
| + | =Further Reading= | ||
| + | * https://www.taylor-race.com/sites/default/files/DIFFERENTIAL%20ESSAY%20W%20PHOTOS2.pdf | ||
| + | =References= | ||
| + | <references /><br /> | ||
[[Category:Internal Combustion]] | [[Category:Internal Combustion]] | ||
[[Category:Electric Vehicle]] | [[Category:Electric Vehicle]] | ||
Revision as of 17:52, 4 June 2020
A differential is a mechanism that allows the two driven wheels to rotate at different speeds to assist in cornering.
Function
When turning a corner, the outer wheels will follow a path with a greater radius of curvature. This difference in radius means the outside wheels will have to travel a longer distance, and rotate faster than the inside wheels.in a rear wheel drive car, the front two wheels are allowed to rotate at a different rate, so this does not pose a problem. The rear wheels, however, both have to be driven by the engine, and therefore are mechanically connected to each other, so there is no freedom of movement between them inherent in the design.
[need a pic of cornering to demonstrate wheel travel difference]
Types
Open Differential
An open differential is a gear assembly that allows the two rear wheels to spin independently of each other, while maintaining the average rotational speed. If the outside wheel spins faster than it would without the differential, the inside wheel must spin and equivalent amount slower. Similarly, the torque transferred to the ground, but is split in varying amounts between the two rear wheels depending on their relative velocities. The faster spinning wheel will see a proportionally greater amount of torque from the engine.
This torque differential between the two wheels can become problematic in high torque applications where the torque is desired to go to the wheel with the greatest amount of traction, not the greatest rotational velocity, such as corner exit, or corner entry if using an inboard brake. To solve this problem, a differential that can limit the amount of slip is desired.
Limited Slip Differential
A limited slip differential (LSD) allows the two wheels to rotate at different speeds, but is limited to a maximum difference. The maximum limit is the ratio of the LSD.
Clutch
2-Way, 1-Way, 1.5-Way
Geared
Torsen
Locking
Detroit Locker
Cam and Pawl
Viscous
Spool
not really a kind of differential, just a way to lock the half shafts together
Electronic Differential
It is fairly common to find electric formulas where the battery pack powers more than one motor on each side of the car. These two motors are then controlled individually and behave like if a virtual electronic differential was separating each other.
not sure if anyone uses eLSDs but they're common in industry, dont know if this is the right section or the LSD section is better
Differentials used in Formula
Torsen University Special TRE MK1 TRE MK2 Drexler
Further Reading
References
