Rougarou VALLIES at Cedar Point July 16th!

We'll wait till Mikey comes here and post his final thoughts, or did this discussion come to a conclusion?

[Mikey]

Someone should PM me when you want a dose of Mikeyisms. It's summertime and this is kinda the busy time for me...

So a trains friction value comprises of many things, some of which are controllable, others are not.

Wheel Stock (Material, Type, Manufacture, etc)
Axle Tightness - Depending on style this could be a straight thru axle, or a pressure plate that holds a floating axle, or any other number of implementations.
Bogie Trim - Value changes as the wheel stock material wears down.
Environmental - Temperature, Humidity, Wind, Rain, Dust
Operational - Weight, Cycle Count (Consumable Wear), Duty Cycle, Mechanical Defect, Operator Instruction


First, let me start off by saying a lot of the valleys that I see are contributed by one or more of the following values causing the overall friction value of a train to fall below the minimum values.

There is a common misconception in some maintenance departments that you can simply arrive in the morning, power up the ride, and start cycling trains and everything will work just like it did yesterday. Sure, sometimes you can get away with that. However if you had a big temperature swing, or it rained over night, your friction values are going to be off. When it's cold out, often times you have to place little heaters in front of each axle a few hours before opening to get the grease to go from jelly to a functional lubricant. Then you have to load up the train with sand bags to put some load on the axles to generate some heat. Chances are if you got more problems then temperature then your going to play Go-Fish with the crane.

The second most common set of issues is mixing wheel types and over tightening axle nuts. The industry is moving towards towards multi-piece wheels as they are easier and cheaper to service. When a a single piece wheel was pulled from service, we would send the entire unit back to the manufacturer and they would mill down the poly, punch out the bearings, and put new poly and bearings in and send it back. This was sometimes a waste as we would be sending a wheel back with perfect bearings and worn down poly, or poop bearings and good poly. The newer units allow us to swap only the bad component as required. However when we do a field replacement we replace the entire unit, but we take the old unit back to the shop and tear it down to send only the broken parts back. It saves time and money.

As materials have changed over the years the friction values from manufacturer to manufacturer have changed as well as values type to type. I have seen a lot of parks this year running half multi-part rims with newer compound and half legacy wheels with older compounds. Some are doing this because changing all the wheels out will result in the friction values going to positive and resulting in an overspeed, some are doing it because they are on a budget. A few are doing it just wrong. Like a car, for each row all the wheels on all the axles must be the same. Otherwise you can get pull which means the bogie is constantly cocked at an angle is is wearing down the guide wheels or in really bad cases the up stop wheels. This is all bad, and results in a rough ride, and if left unchecked for too long will cause component failure. After you burn the bearings up in about four or more wheels, then well there is a game your going to love, Go Fish!

Each ride manufacturer sets a specification for axle nut tightness some of which provide different values for different climates and seasons. I see this disregarded more times then I care to count.
Seen a lot of grab a three foot long beaker bar and tighten it till its good. If you over tighten your axle nuts not accounting for the temperature then when the metal heats up and expands it will start compressing components. Compressed components do not roll free and will have a higher friction value then ones that aren't being compressed. It doesn't take much, but when a certain percentage are over tightened and you start getting into the heat of the day with a good operations crew hitting numbers you can find yourself having to play Go-Fish.

The third set is somewhat rare to see, but it does happen. Mechanical failure such as a bearing failing in a way that the wheel can't move, a trim brake that won't open all the way, a vekoma boomerang that liked to release trains pre-maturely, a brake fin that fell off a train because a green grease monkey didn't put lock washers on the mounting pins.

[TTD03]

^ These are some of the most fun things to read on CoasterCrazy.

[mkingy]

Awesome Mikey - thanks for the insight!

Thanks Mikey for filling us in on train friction! Awesome to read all through!