Hey y'all! Happy Saturday evening.
Just a thought lately.... as Muscle Machines could have posi traction what did locomotives do.
I know steam engines had a piston and driver arms operating the wheels. They were the same on both sides. This is a given.
On a radius the inside rail is shorter than outside rail. Did the drivers on the outside rail slip as the inside rail was being driven faster or did they both slip. Was the wear on the wheels equal?
Now new modern-day locomotives. Have they compensated for this. Do locomotives have posi traction or do they just wear out the wheels on one side or both are still slipping.
Your thoughts and knowledge on this? Very interesting to me....Thanks
Track Fiddler
I don´t think that locomotives had something similar to limited lip differentials and IMHO, they don´t need that. The minimum radius of curves on a mainline is >600 ft. so the effect is negligible.
Happy times!
Ulrich (aka The Tin Man)
"You´re never too old for a happy childhood!"
My understanding is that the wheel tread is not flat but has a radius. So when the loco goes around curves one rail is on a larger diameter and the other is on a smaller diameter and this compensates for the radius.
But I could be misunderstanding what I was told.
Its all in the taper:
https://www.scienceabc.com/eyeopeners/how-do-train-wheels-turn.html
Track fiddlerNow new modern-day locomotives. Have they compensated for this. Do locomotives have posi traction or do they just wear out the wheels on one side or both are still slipping.
Radial Steering Truck:
http://www.railway-technical.com/trains/rolling-stock-index-l/bogies.html
Cheers, Ed
The only locomotives that might have had differentials are the Heisler designs. Otherwise they had solid axles, which is kind of the ultimate in positraction. Kind of like welding the spider gears together on your Ford 9" rear end. No need for limited slip when there is zero slip.
.
Otherwise, the taper does the work, when it doesn't, you hear wheel squeal.
-Kevin
Living the dream.
This youtube explains it pretty well. It's not just Locos that need to go around curves. The graphic about 1 minute in shows it very well. My local Railway museum has different wheel contours you can roll along a curved track and it works just like this video.
https://www.youtube.com/watch?v=agd8B-31bjE
Alan Jones in Sunny Queensland (Oz)
Unless I am totaly missing the point the above site has the diagram backwards.
The larger wheel face should be on the outside rail.
Check it out.
Lee
I seen that too Lee. The stationary diagram is backwards.
The video makes a lot of sense though where the wider circumference of the Wheel flange rides up on the rail from centrifical Force, I never thought of that... makes perfect sense.
The video, while correct, is of course exaggerating the situation quite a lot.
The taper on the wheels is minimal, as you can see in the following picture:
It appears Ulrich, the engineers took some of the slip and wear off the wheels with the wheel taper. Certainly not all of it.
On tighter curves, flange oilers are also used to ease the friction and wear on both the rail and the wheel flange. On more gradual curves the flange should not make hard contact with the rail.
I have a video of the Union Pacific Challenger steam locomotive when it made a tour on what was the Clinchfield Railroad some years ago. The plan was to turn the locomotive on a tight wye at one location. The crew swabbed the rails with grease in an attempt to slip the wheels around the tight curve, but to no avail. The flanges kept climbing the rail. The locomotive was run (or towed) backwards on the return.
George V.