Calling all Engineers...
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From: Flatland, Saskatchewan
Calling all Engineers...
Ok, me and a buddy got into a big argument whether a truck, specifically a 1987 4x4 Ranger would pull a rail car (box car) or not. I have researched and found that a box car ways anywhere in the 6.5 - 9.2 x 10<SUP>4</SUP> kg range. Now since I am not much of a math whiz, what kind of equations/calculations do we need to look at when trying to determine this? There has to be a formula out there to figure this out.. Thanks!
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From: Waukesha, WI
I'm an engineer, but only a lowly electrical so I can't help with this mechanical dilema. However I do remember seeing a video years ago of some stunt guy pulling a train car with his teeth, so I would think a Ranger could do it. I think it depends how fast you want to go...
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From: Flatland, Saskatchewan
Mainly I just want to move it to Point A to Point B. But lets say we want to get it up to 5 feet/second. Also, let assume that friction in wheel bearings, stretch in the tow rope/chain, etc, are not included. Mainly concerned with what will it take to intially move the box car and will it maintain the velocity, and what the truck pulling it exerts for force. I think..maybe theres more..
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Engineers with too much time on their hands.
Pulling a rail car on the level is cake. You can do it with a riding lawn mower if you can hold traction. There is very little rolling resistance with steel on steel.
A rolling rail car will go 40 times the distance of a truck running the same speed.
Where your lawn mower and Ranger will be in trouble is when you have to pull a hill. Then you are going to be fighting the gravity thing and the load of the car.
Where your lawn mower and Ranger are going to be in REAL trouble is any kind of downhill.
Why don't you fellers work on something like using a little more than 20% of the energy in the gasoline we burn to move the car instead of sending it out through the pipe and radiator.
Pulling a rail car on the level is cake. You can do it with a riding lawn mower if you can hold traction. There is very little rolling resistance with steel on steel.
A rolling rail car will go 40 times the distance of a truck running the same speed.
Where your lawn mower and Ranger will be in trouble is when you have to pull a hill. Then you are going to be fighting the gravity thing and the load of the car.
Where your lawn mower and Ranger are going to be in REAL trouble is any kind of downhill.
Why don't you fellers work on something like using a little more than 20% of the energy in the gasoline we burn to move the car instead of sending it out through the pipe and radiator.
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From: Michigan
Have you ever taken Physics class or Statics class? All about analyzing force. You can calculate that in Newtons or foot-pounds or whatever you want, then compare it with the max output of the Ranger. You'll come up with some nice theoretical numbers. Holding torque in the real world will be the big problem there. Keep in mind starting isn't the problem... the mass is constant. Momentum will bite you in the butt when you try to stop though... 
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The dreaded "double post"...
Last edited by D-ranged2.5; Sep 28, 2004 at 02:41 PM. Reason: duplicate
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From: fremont ohio
ah yes....newtons, force, acceleration, coefficient of friction....this is the stuff were currently doing in physics, and i cant stand any of it, lol. i would say you'd be fine, but like said above, stopping it could be a pretty big problem, since the steel/steel friction is low. Force= Mass x Accel.
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From: Houston/Hope BC
http://www.school-for-champions.com/...e/friction.htm
You will have to find published experimentally or theoretically derived co-efficients of static and dynamic friction or conduct your own experiments down at the local friendly rail yard to determine the actual exact threshold of the minimum force required to start, and I presume you want to know also, maintain the rail car rolling. Then you can start on the air drag co-efficient calculations of your box-car truck rolling assembly and determine the theoretical top speed. You may be on to a whole new sport.
I think I am busy that weekend so let me know how it turns out
.
You will have to find published experimentally or theoretically derived co-efficients of static and dynamic friction or conduct your own experiments down at the local friendly rail yard to determine the actual exact threshold of the minimum force required to start, and I presume you want to know also, maintain the rail car rolling. Then you can start on the air drag co-efficient calculations of your box-car truck rolling assembly and determine the theoretical top speed. You may be on to a whole new sport.
I think I am busy that weekend so let me know how it turns out
.
Tuned
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I see what the Ford engineers are doing,, figuring out if the Ranger can move a box car,,,,Here is what makes me wonder,,,,,,, we can send a man to the moon but we cant make a parking brake cable that works for more than 6 months.
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Will the pull cable be level?
In what distance do you want the rail car to get to the desired speed?
How much time is allotted to get the rail car up to the desired speed.
Is the truck a 5spd or an automatic (if it's a 5spd, in reality you'ld cook the clutch)
If the tow cable is perfectly level...
A quick answer to your question is, no, the pickup cannot get the rail car to 5'/sec.
Reason, lack of friction between the pickup tires and the rail bed.
If you negate that lack of friction, your answer is yes, but it will take several hundred yards on perfectly level tracks.
It will take approx. 112 footpounds of torque to get the 71.6 ton rail car moving on level frictionless rails. It will take approx 510 ft for a pickup (with at least the torque mentioned) to ge the rail car to 5 ft/sec. providing the torque applied is consistant and there is no wheel slippage.
In what distance do you want the rail car to get to the desired speed?
How much time is allotted to get the rail car up to the desired speed.
Is the truck a 5spd or an automatic (if it's a 5spd, in reality you'ld cook the clutch)
If the tow cable is perfectly level...
A quick answer to your question is, no, the pickup cannot get the rail car to 5'/sec.
Reason, lack of friction between the pickup tires and the rail bed.
If you negate that lack of friction, your answer is yes, but it will take several hundred yards on perfectly level tracks.
It will take approx. 112 footpounds of torque to get the 71.6 ton rail car moving on level frictionless rails. It will take approx 510 ft for a pickup (with at least the torque mentioned) to ge the rail car to 5 ft/sec. providing the torque applied is consistant and there is no wheel slippage.
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The original inquiry didn't ask about stopping.
The friction generated by the skidding tires is near impossible to calulate because the tires will be melting, the properties will be in constant change, and the friction applied will be variable.
Again, if the wheels are kept turning, the heat will cause brake fade, thus varying friction. There will be parabolic curve charting brake fade as a factor of heat. Meaning, eventually the brakes heat up to a point of destruction, at which point there will be no friction applied.
Those scenarios proposed, and with the formerly established frictionless level rails, the rail car will never stop.
The friction generated by the skidding tires is near impossible to calulate because the tires will be melting, the properties will be in constant change, and the friction applied will be variable.
Again, if the wheels are kept turning, the heat will cause brake fade, thus varying friction. There will be parabolic curve charting brake fade as a factor of heat. Meaning, eventually the brakes heat up to a point of destruction, at which point there will be no friction applied.
Those scenarios proposed, and with the formerly established frictionless level rails, the rail car will never stop.
Last edited by weymouth; Oct 5, 2004 at 03:20 PM. Reason: different info
