That's Wheely Weird: Pantherian's Wheel Debacle

What happened between Intimidator and Pantherian causing wheels to blow again?

Pantherian has just been painted, which believe it or not can cause issues with the wheels. Parks who opt to paint their coasters oftentimes will request that the running rails are not painted over. The paint will cause more friction and heat, as well as provide an insulating layer not allowing for heat transfer to the steel rails. Depending how careful the painters were with this request, there may be some overlap between the end of the paint lines and the running rails.

The ride also has not run very consistently yet; therefore the trains are not completely broken in. We used to fight "dirty track" at our park, where it took many cycles and a lot of track lube to clean all of the rust and dirt off the running rails, which would slow trains down. In this perspective, all of the buildup and debris also adds heat and friction to the wheels.

I have heard a rumor that the station misting system is also currently not in use, because it was painted over. If Baynum painting was contracted for the project, I would believe this statement as dumb as it may sound. Baynum came to our park to paint a coaster, and they painted over everything and anything that they could. This included wires, sensors, brakes, motors, etc. When we had to perform maintenance on certain things, it made it miserable, because we had to strip a thick layer of paint before we could even disassemble a component for repair. If they painted right over the misting system's nozzles, all the nozzles may have to be disassembled and cleaned of any paint to work properly.

All of this combined with the ride reopening in possibly the warmest part of the summer are leading to issues.

What about track lubrication?

Track lubrication is a very essential part of roller coaster wheel performance. The most popular product in the industry is Track Lube Plus, which is a biodegradable paste that lubricates wheels and track rails. It's even edible as some guys will show you, although I never tried it so I cannot give a good food review on that one. It does smell minty fresh though.

Anyways, back to the useful information, track lube can be a double-edged sword. One would think that more track lube is a good thing, but that's not always the case. Track lube is an insulator and can retain heat in the wheels if used in abundant quantities. Over time, excess track lube also seeps down the coaster rails and slings onto the structure. When dirt and debris collect and get stuck to the lubricant, it turns a very dark color, which would in effect ruin the brand-new paint job.

The best way to apply track lube is to start small and add more as needed. When polyurethane wheels begin to dry out, they turn into an almost "chalky" appearance. After a good day of running, this was the case on many high-speed rides. I would apply track lube almost every day, unless I was expecting a huge storm that would wash all the lubricant away anyways. The quantity varied depending how dry the wheels seemed. If I would do an inspection after somebody who was known to completely cover the wheels with too much lube, I would take excess from the edges and spread it around the wheel, not adding any additional lube. The park may have to dial in their lube quantity a little better if it is causing issues.

What safety issues may arise from a blown wheel?

The good news is that a single blown wheel on a car should not cause any immediate safety concerns. Two of the biggest issues that may arise are louder cycles and a rougher ride for the guests riding near that wheel. However, even if a polyurethane coating completely blows out, the aluminum hub is more than strong enough to support the weight of the car.

Intamin wheel bogies include a component that surrounds the rails that we called a "limit sheet". In the event of a severe issue with a wheel or the train itself, the limit sheet's job was to prevent the cars from derailing. There have been times where a blown wheel has caused the secondary to plow against the road steel of the track, which scrubs speed off the train. In normal operation, a train can run a while with a blown wheel without issue. However, on slower or colder days when trains are running slower, a blown wheel could put a train on the cusp of stalling somewhere mid-ride.

At least on the Intamin coaster that I worked, there was a fault for a slow run time. The first thing to do when dealing with a slow run fault was to look over the wheels and the bottom of the train for any deficiencies. The slow run fault will trigger at least 5 seconds before a train would stall to give enough warning time.

How do they change wheels?

On Pantherian specifically, it is pretty straightforward to change a wheel. For a road specifically, you need to take the weight of the frame off the wheels, so a good jack point must be found, usually under the center of the train. Certain modern transfer tracks also include jack points or sections of rails that slide off to obtain full clearance/movement.

The wheels are fastened onto the wheel bogies with a large locknut, machined washers, and a snap ring at the end of the wheel axle. These components are removed, and the pin is slid out of the wheel. A new wheel is placed into the bogie, and everything is put together in reverse order.

This may sound simple, but you would be surprised at the amount that can make this a difficult process. On Intamin coasters, the road wheel pin is usually too long to pull out straight, without hitting the coaster's frame. Therefore, you either need to turn the bogie somehow, or remove the pin with the eccentric cam that the pin goes through. Removing the inside cam with the axle gives you the ability to angle the pin and get it past all of the obstructions in the way.

I am not completely sure if Pantherian has eccentric cams, but most Intamin coasters of this type do. The eccentric cams allow you to set the height of each wheel, which affects the height of each frame as well. By rotating the cams around, the frame will either raise or lower. Therefore, replacing a wheel requires careful consideration of the position of the eccentric cams. If a really worn wheel is replaced with a brand new recoat, there may be a difference of several millimeters in the outside diameter. Therefore, if the cams are not adjusted right, it can throw off the heights of the frames, brake fins, etc.

Depending the location of the wheel on the train and how easy it is to remove will determine the time required to complete the replacement. I've had road wheels take 5-10 minutes to swap, and I've had wheels take the better part of an hour if they fought hard enough. Sometimes, the assembly lube will wash off the axle, causing the pin to seize in place on the bearings. Another holdup could be the pin hitting a burr on the dust covers and not coming through nicely. There are so many little things that you wouldn't expect that could take up a lot of time when performing maintenance.