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ashishbhagwat
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A vehicle's engine produces 100 hp at 4773 rpm. If the wheel radius is 12 inches, the final drive ratio is 3 and the transmission ratio is 3.00, calculate the tractive force at the wheel, in steady state.
Stovebolt said:1. Convert engine power and rpm to engine torque:
hp * [33000 (lb*ft/min)/hp] * [1 min / engine revolutions] * [1 rev / 2 (pi) rad] = engine torque
2. Multiply engine torque by transmission ratio and final drive ratio to get axle torque
engine torque * trans ratio * final drive ratio = axle torque
3. Divide axle torque by wheel radius to get tractive force
axle torque / wheel radius = tractive force
I hope I wrote the formulae clearly enough. Pay close attention to unit conversions. If you're not sure where I got the conversion factors, please let me know.
ashishbhagwat said:thanks, but could u please explain just the 1st step again?
ashishbhagwat said:A vehicle's engine rotates at 5640 rpm and produces 62 hp. If the final drive ratio is 4.00 and the transmission gear ratio is 3.00, calculate the vehicle speed, in mph. The tire radius is 10.1 inches. Vehicle is at constant speed.
Stovebolt said:This one is actually a bit simpler, just filter out the unnecessary information.
We assume the engine's rotation is directly coupled to the wheel rotation (if one turns, the other turns - no slipping). Since you have the engine speed, you do not need the power - you just need to know how many times the wheel will turn per engine revolution.
Engine RPM * Transmission ratio * final drive ratio = wheel rpm
After that, it's just a matter of multiplying the wheel rpm by the wheel circumference to get the distance traveled per minute. Convert the units to mph and you will have the answer.
ashishbhagwat said:when i multiply wheel rpm by wheel circumference i will get a value in terms of rpm*inches.
How do i convert that into mph?
ashishbhagwat said:A vehicle with a weight of 3000 lbf is accelerating at .7 gs in first gear. The vehicle shifts from first to second at 1721 rpm (speed before shift). If the final drive ratio is 3.56, first gear transmission ratio is 3, and second gear transmission ratio is 2.4, calculate the engine speed in rpm after the shift.
ashishbhagwat said:A 6 speed standard transmission has a 6th gear ratio of 1:1. if the first gear ratio is 4.86:1, calculate the 4th gear ratio, based on a geometric progression. Answer must be expresses as a single number, two decimal places.
Tractive force at the wheel is the force that is applied to the ground by the tires of a vehicle in order to move the vehicle forward.
Tractive force at the wheel is calculated by multiplying the coefficient of friction between the tires and the ground by the weight of the vehicle. This equation is then adjusted for any additional forces acting on the vehicle, such as aerodynamic drag or rolling resistance.
The tractive force at the wheel is affected by the weight of the vehicle, the coefficient of friction between the tires and the ground, and any additional forces acting on the vehicle such as aerodynamic drag or rolling resistance. The type and condition of the tires can also affect tractive force.
Yes, tractive force at the wheel can be increased by increasing the weight of the vehicle, increasing the coefficient of friction between the tires and the ground, or reducing any additional forces acting on the vehicle. Upgrading to high-performance tires can also increase tractive force.
Tractive force at the wheel is a key factor in determining a vehicle's acceleration and overall performance. The greater the tractive force, the faster the vehicle can accelerate and the better it can handle obstacles and terrain. It is an important consideration for vehicles that need to perform well in off-road or high-speed situations.