Torque calculation on drive half shaft in coast downshift condition

Click For Summary

Discussion Overview

The discussion centers on calculating the torque experienced by a half shaft during a specific driving scenario involving a downshift from third to second gear while coasting. Participants explore the factors influencing torque during this event, including engine characteristics and clutch engagement.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks guidance on calculating the torque on a half shaft when downshifting while coasting, emphasizing the conditions of the event.
  • Another participant suggests drawing a free body diagram and notes that the braking torque is dependent on motor characteristics, highlighting the complexity of calculating torque against a closed throttle.
  • A participant provides specific torque values, indicating that the drag torque of the engine leads to approximately 200 Nm per shaft, while considering wheel slip torque with a coefficient of friction results in 830 Nm. They note that the torque during the downshift can vary between 1300 Nm and 1700 Nm based on the clutch release method.
  • The same participant mentions the need to account for the force required to accelerate the flywheel and the rotating/reciprocating mass of the engine in their calculations.

Areas of Agreement / Disagreement

Participants express varying views on the factors influencing torque calculations, and no consensus is reached regarding the exact methodology or values to be used. The discussion remains unresolved with multiple competing perspectives on the topic.

Contextual Notes

Participants reference specific torque values and conditions but do not provide a comprehensive framework for the calculations, leaving assumptions and dependencies on definitions unclear.

kkd
I want to calculate the torque coming onto a half shaft in a very particular event.

The event is I let's say I am in 3rd gear and have reached my max torque zone after which I have taken my foot of the acc pedal...nw I m letting the the vehicle coast as soon as it reaches say 60% of max power rpm I downshift to 2st gear and after downshift m still not pressing the acc pedal..m just letting the vehicle drive by its momentum..

Now during my downshift as soon as I engage the clutch I will have a very high amount of torque cmng onto the shaft...
Pls guide me how to proceed to calculate this torque..!
Thanx in advance... :)
 
Engineering news on Phys.org
As always, draw a free body diagram.
The braking torque depends on the motor characteristics.
You need to calculate how much torque is required to run the engine against a closed throttle... No easy task...
Do you know the fluid friction across the butterfly etc?
 
Thanx billy for your reply...
It is basically a fuel in injected engine...I had some some data regarding the drag torque of the engine... If I multiply that value to the gear ratios the torque which is coming is to the tune of 200 Nm per shaft..the wheel slip torque if I consider .8 coefficient of friction comes up to 830 Nm but the incident which I mentioned above the values of torque varies from 1300 Nm to 1700 Nm depending upon the way clutch is released...1300 for gradual & 1700 for sudden...
 
kkd said:
Thanx billy for your reply...
It is basically a fuel in injected engine...I had some some data regarding the drag torque of the engine... If I multiply that value to the gear ratios the torque which is coming is to the tune of 200 Nm per shaft..the wheel slip torque if I consider .8 coefficient of friction comes up to 830 Nm but the incident which I mentioned above the values of torque varies from 1300 Nm to 1700 Nm depending upon the way clutch is released...1300 for gradual & 1700 for sudden...
Also include the force needed to accelerate the flywheel and rotating/reciprocating mass of the engine.
 

Similar threads

Torque calculations: Rotating vertical shaft
  • · Replies 5 ·
Replies
5
Views
5K
Shaft and Torque Calculations with Mass
  • · Replies 9 ·
Replies
9
Views
4K
Turbine Design for fire-hose driven shaft
  • · Replies 9 ·
Replies
9
Views
3K
Help with flywheel / clutch calculations
  • · Replies 19 ·
Replies
19
Views
4K
Understanding Drive Shaft Stress and Deflection for Optimal Performance
  • · Replies 1 ·
Replies
1
Views
3K
Torque calculations for a small electric vehicle
  • · Replies 58 ·
2
Replies
58
Views
9K
Automotive Need help calculating load torque and acceleration torque of a vehicle
  • · Replies 8 ·
Replies
8
Views
7K
Automotive How to calculate hydraulic disc brake size using actuation force?
  • · Replies 15 ·
Replies
15
Views
7K
How do I select the right motor and gear ratio for a mid-drive e-Bike?
  • · Replies 2 ·
Replies
2
Views
4K
Torque specs for 6,000lb party bike
  • · Replies 7 ·
Replies
7
Views
3K