No Traction

I have the impression that back in the steam era, quite a bit of wheel slippage on the loco was common and expected.

Is this correct?

I can't imagine how someone in a locomotive cab could not realize there's slip going on ... you FEEL it (it's a noticeable jerk), you HEAR it (engine revs up), etc.

And on older equipment w/out the modern computer controls, it'll keep doing that until you max out on amps, and then it unloads on you.

Believe me, anyone who's ever tried to run a sizable train uphill in rain or in the fall leaf season (esp. in the rain), you know exactly what I'm talking about ...

I guess in this case, the fact that the slippage was in a different locomotive is what made the difference ... without the tactile feedback for the crew, and presumably a fault in the MU line to warn them, they had no idea ...

- litz

Brutal. That there is some extremely poor train handling. Guarantee you that little exercise left eight or so nice potholes in the rail. A professional train crew would have immediately realized the obvious, taken the loads out in two trips, or else waited patiently for the rescue power without chewing up the railroad.

thirdtrick wrote:Brutal. That there is some extremely poor train handling. Guarantee you that little exercise left eight or so nice potholes in the rail. A professional train crew would have immediately realized the obvious, taken the loads out in two trips, or else waited patiently for the rescue power without chewing up the railroad.

By any chance, do you work for Union Pacific?

And if you get CAUGHT allowing the engines to slip, thereby damaging the rail(s), you're gonna get some "whammy" time! (at least on NS) Plus you're gonna get a cussin' from the Track Supervisior if he sees you doing that. Of course, ALL engines slip at times, but its continuing to allow such that causes rail "cupping".

Personally, I never understood this fascination that rail buffs seem to have with slipping wheels. It's NOT funny, but occurred a LOT on our shop tracks where heavy machinery such as Tampers, and Ballast Regulators, and Cranes sometimes became stalled due to drive train failures and could not proceed. This required us---even using fork lifts---to come and shove them ahead into a stall or onto the transfer table.

One time, to show us how mechanical engineers sometimes make boo-boos, They got the bright idea to move the controls of a walking machine so they would be better accessed and the operator, walking along beside the RoW, didn't have to stretch to work the controls. All the heavy components were over the drive axle and provided proper wheel loading and traction. Not taking this into consideration, the engineer-in-charge moved the controls, and several other heavy components to the OTHER end of the machine, effectively removing all loading from the drive axle (it only used the one axle for propulsion). I came around the shop on a fork lift to find this machine just outside a work bay, its diesel engine roaring, hopelessly slipping its wheels and going NOWHERE! Clearly this wasn't going to work, and after shoving the machine into the back shop, the engineers and the workers set about correcting this faux pas!

Gadfly

I just saw this video of a steam engine struggling to make it, in Tyrone, PA.
Slowly craw through it, wait for assistance or reverse and start over with a little more momentum?

It would be interesting to see what that rail looked like. Here is a photo of some "rail burn" on the GTW.

From my experience in calibrating and troubleshooting wheelslip conditions a lot of the time, sand is the problem. Locomotives do not pull well without sand. Some units have intermediate sand and some units don't have intermediate sand. Intermediate sand for example is when you are in the forward direction and when second stage wheel slip condition happen or if you call for directional sand it will be applied to the # 1 & # 3 wheelset. If you don't have intermediate sand, sand will only flow on the # 1 wheelset. On an EMD unit you have 3 stages of wheelslip. # 1 is a slight reduction of power. # 2 the sand will automatically start flowing. # 3 if the 2nd does not correct it, you will get a wheelslip light on the control stand and a greater reduction in power with sand because ORS will be driving the Load Regulator to minimum field. If you have a meter hooked to the WS10 module on the AC scale on pins 8 & 21and you are monitoring the wheelslip system, at 30 VAC is when 2nd stage wheelslip happens and you should also get a (Red) led on the SA10 card for eight seconds. At this point you should not have a wheelslip light on the control stand.
There is also something called simultaneous wheelslip. This is a condition when all 4 wheelsets brake loose at the same time and start spinning. As long as all 4 wheelsets are spinning at the same speed, you will not get a wheelslip light, because there is no imbalance in current in the WST,s that are monitoring the system. Lets say that the wheelset start spinning faster then 70 mph, your Wheel Overspeed module will come into play and then you will get a wheelslip light and power will drop off.

We had a yard engine the other day, breaking the wheels free... the output from the WS module, one of the wires had come off... damn thing would spin the wheels til the overspeed kicked in. No output from teh WS module means no protection against wheel slip.. and Sparks a flyin'!

I have read that the older EMD units load regulators would put out more amps in a given notch. Using the older units takes getting used to. Once I had a Geep9. if I was giving a kick, I would just leave it in notch 3. The load meter would go almost to the red zone. If I used any higher notches, the unit would just loose traction and eventually unload. Who knows how much of this is due to design, and how much for the lack of maintenance to the wheel slip system. It seemed consistant to other old Chevys I have run.

For frequent light slips, doing just as the operators manual says -take a notch away and lay down sand until the drivers stick - works. Dragging 80 cars out of the bowl in the rain or 120x0 up a 1 % hill at 13mph taught me to put it in run-8 and grab 12-15... sometimes 20 lbs on the jammer, depending on the Indpendent pressure setting... cures any slips you may have with out sand. They don't teach you that in school...