Drive System on a 4-wheeled car
Drive System on a 4-wheeled car
(OP)
I am currently looking into designing a 4 wheeled car that will lift steel coils and transfer them to a different location. The following parameters are as follows:
Wt of Car w/Steel Coil: 125 kips
Velocity = 6 in/sec
Distance = 50 ft
Drive Shaft Dia = 3 in
Coeff of static friction (stl to stl) = 0.78
Wheel Diameters = 12 in
The car wheels will be steel and will be riding on steel rails. The drive system will consist of an electric motor with a shaft mounted reducer. The back car axle will be the drive axle. I am assuming that I will need to calculate the torque and power required to move the car from a static position. This would include overcoming the weight of the car as well as the frictional force from the steel wheel to steel rail contact. I believe I need to look at the total weight of the car when I am calculating the reducer torque. Is this correct? Is there any other item(s) that I need figure?
Wt of Car w/Steel Coil: 125 kips
Velocity = 6 in/sec
Distance = 50 ft
Drive Shaft Dia = 3 in
Coeff of static friction (stl to stl) = 0.78
Wheel Diameters = 12 in
The car wheels will be steel and will be riding on steel rails. The drive system will consist of an electric motor with a shaft mounted reducer. The back car axle will be the drive axle. I am assuming that I will need to calculate the torque and power required to move the car from a static position. This would include overcoming the weight of the car as well as the frictional force from the steel wheel to steel rail contact. I believe I need to look at the total weight of the car when I am calculating the reducer torque. Is this correct? Is there any other item(s) that I need figure?





RE: Drive System on a 4-wheeled car
You have asked a very broad question that makes it sound like you are in over your head.
There ought to be someone at your site who understands cars like this, and who can answer your questions. How do the coils get on and off this thing? How are you going to stop it rolling? Is there hardware at your site people would prefer you used? If nothing else, sixty tons of equipment rolling back and forth, sounds like a safety hazard. Perhaps you should refuse the work.
RE: Drive System on a 4-wheeled car
RE: Drive System on a 4-wheeled car
RE: Drive System on a 4-wheeled car
http://ww
I haven't hunted around, but they are likely to have some technical data/worked solutions for similar situations somewhere in their brochures.
Best,
Medeski
RE: Drive System on a 4-wheeled car
A good engineer knows what he doesn't know but can always eventually find the answer...Never be afraid of asking a question. Even if some of your peers might think it is stupid.
RE: Drive System on a 4-wheeled car
RE: Drive System on a 4-wheeled car
Engineering is about the details, not about the physics. The physics defines the boundary conditions. Engineering places the components within the boundaries. I would hope an 11 year engineer who is either studying for or has his P.E. would know that.
David
RE: Drive System on a 4-wheeled car
RE: Drive System on a 4-wheeled car
Mike Halloran
Pembroke Pines, FL, USA
RE: Drive System on a 4-wheeled car
RE: Drive System on a 4-wheeled car
That is a common value found on the 'web, however I've yet to see that in real life.
Could someone elaborate that for me, or give a situation where friciton as high as 0.78 (or about that) is happening?
my findings: www.youtube.com/watch?v=558Htmux6UE
And that shows a more common and realistic scenario.
RE: Drive System on a 4-wheeled car
RE: Drive System on a 4-wheeled car
Maybe rubber tires on dry concrete. A Cf of .78 for steel on steel is unheard off. That's why trains use steel wheels and steel rails. The Cf is very low which makes starting and stopping a bit of a problem - but once up to speed there is virtually no friction.
RE: Drive System on a 4-wheeled car
I'd say the hardness of the steel allows for low rolling resistance due to less deformation of the wheel. The crappy coefficient of friction is merely an unwanted side effect. Hence adding sand, grit, etc between wheel and rail when extra tractive effort is desirable.
RE: Drive System on a 4-wheeled car
Just a thought....