Jumping a long distance on a train question...

[*_ash_*]

Here's one I often ponder-

How should a moving car approach the task of driving on to a moving car transporter- like Knight Rider used to?

I had a wonder about this too.... (after your post)

Depends on whether you have FWD or RWD. I don't know if its possible with permanent 4WD. (nor have I ever tried doing it).

IIRC Kitt was 4WD. So... is there a differential mechanism that allows the front and rear wheels to travel at different speeds on standard cars? (as left and right wheels can do in normal FWD and RWDs)

I doubt it would be standard. A slip diff, is the only way you could mount the transporter. A permanent 4WD with no slip diff, couldn't possibly drive onto a moving transporter.

 

Will wait to find this out, before I ask what would happen to Cynics 'fly' if it was hovering in KITT when it hit the ramp.

[Cyclone]

P4WD must have a diff between front and back, but limited slip, as generally when a wheel looses traction or a pair the power shifts to the other pair.

If it's fixed ratio fixed 4WD then you'd have to approach at some speed and dip the clutch as you were about to hit the ramp.

[*_ash_*]

P4WD must have a diff between front and back, but limited slip, as generally when a wheel looses traction or a pair the power shifts to the other pair.

If it's fixed ratio fixed 4WD then you'd have to approach at some speed and dip the clutch as you were about to hit the ramp.

Aha, good point, didn't think of that. Not something I would like to try, even moreso if was an auto.

[HappyHoosier]

What color is the train? Where is it headed? And is there a decent dining car?

[theripsaw]

Depends on whether you have FWD or RWD. I don't know if its possible with permanent 4WD. (nor have I ever tried doing it).

 

So if you had RWD you could approach the truck slightly faster than the truck is going(say car at 32 / truck at 30mph). The front wheels would roll on, then as soon as the rear wheels are on hit the brakes, otherwise i presume you would drive along the transporter at 32 mph and quickly fly off the front??

[Code13]

Mike "Stevo" Stevenson on Sky Sports often uses an example of a ball thrown from a train backwards (but going forwards relative to the ground due to the speed of the train) to explain the "momentum rule" regarding forward passes in Rugby League. Usually confuses the hell out of people.

[cgksheff]

Still going to be hard to measure, but would gravity not be exerting a decelerating force?

 

To illustrate this .. having stood on a normal carpet in the carriage to attain the steady speed, if you then stepped over onto a frictionless surface and continued to travel for a long time, would you never start to slide backwards in the carriage?

[Cyclone]

Gravity only acts downwards. So long as the train is neither accelerating nor decelerating you would stay stationary (if you could stand up) on the frictionless surface.

 

Re the RWD car, it's only the momentum of the wheels you have to worry about in terms of throwing you forward. If you drove on in a high gear (as you'd expect) the most likely danger is that the car lurches and stalls the engine as the wheels are suddenly decelerated rapidly by floor of the flat bed. This is why you'd want to a) dip the clutch, b) have enough momentum to carry you a bit further forward. It's actually harder with the FWD as you need more momentum because the stall will happen much sooner (ie when the front wheels hit).

[HappyHoosier]

Reading this thread has given me insight into the dinner-table conversation at the Royal Society of Mechanical Engineers annual convention.

[cgksheff]

You need to hit the brakes as well as the clutch on the instant that the rear drive wheels mount the ramp.

 

 

Edit (after reading the post below): I haven't got this velocity/momentum thing at all. Have I?