Coaster Trains

[AirFAN]

I've noticed this on Nemesis and subsequently googled images of other coasters and this seems to be true for the majority of them.

The front two carriages on a train are fixed in relation to each other - i.e. they still bank independently but the second car is always level with the lead car. This is difficult to explain so I'll use images to illustrate my point (i've included photos of other B&M inverts to further illustrate my point).

Anyone have any idea why this is?

The gap between train 1 and 2 is different than the gap between 2 and 3.

Car 1 & 2 are both at the exact same angle.

Again, gap between train 1 and 2 is different from the following carriages - both carriages are both at the same angle.

If anyone wants to explain this in a way that makes sense or has any idea why this is, feel free to say your piece.

 

[DiogoJ42]

It's because B&M invert trains don't have a zero car. The front two rows are joined so that they can't tilt relative to each other.

 

[Ted]

Alpengeist does have a zero car though.

The 2nd and 3rd rows don't look that far apart.

 

[DiogoJ42]

Oh, bloody Alpengeist would have to be different, wouldn't it? Such a hipster of a ride.

 

[AirFAN]

Is there a reason for this? Does it make the train more stable?

 

[Alexsutton]

Coaster cars only have one axle, like a caravan. If you had a caravan on its own the front or the back end would drag on the ground because it's not stable. It needs to be attached to a car to be stable. The zero car has two axles and is fixed on one axis, so it can't pitch like the other vehicles. The zero car is like a car on the road, and then the rest of the cars are attached like trailers, relying on the one in front of it to support it. If that made any sense!

 

[Cheese]

I'm sure somebody with a better grasp of physics or mechanics could explain this better or prove me wrong, but I'd imagine that it does make the train more stable. The wheelsets have to pivot up and down to be able to deal with the bottom of drops and the top of crests, so cars 1 and 2 have to be limited to just pivoting to the side to control the angle between the seats on those rows and keep them apart at the correct distance. The other rows are then dependant upon how the front two behave to control how they respond to gradient changes.

A more flexible connection between the front cars would presumably introduce unwelcome shuffly backwards and forwards forces through the train. Imagine a train without rows 1 and 2 fixed coming out of a loop onto level track; I guess that in the loop the rows of seats would be angled slightly away from each other due to the positive force, and then as it levelled out on exit the rows would rock back together the other way. That movement might not be much but it's still going to rock the other cars, affect ride comfort and potentially mess up how it takes the next track element.

I've no idea why Alpengeist would have a seatless zero car. Obviously it's very tall and fast by Invert standards, so perhaps B&M decided it'd be more comfortable for the riders if rows 1 and 2 moved more independently than on smaller examples.

 

[Leah]

I know this is probably not the reason, but aren't some rows (4 and 5 on nemesis if I remember right) are bigger for people who don't fit in the regular seats. I know I have been moved from row 4 to the back because they couldn't get someone on the back rows restraints down.

 

[Rob]

Moved this thread to a more suitable area of the forum as it is not specific to Alton Towers.

Also, Aplengeist FTW!

 

[Nemesis94]

This has been identified in the above posts, but just to reiterate it is to do with how articulated vehicles work.

For a rollercoaster car to be stable it needs two pairs of wheelsets that are rigid in at least two axes, otherwise it would just collapse under any force applied to it. Simple example: Imagine if the your car could pivot up and down through the middle: as soon as you sat in it, the centre would just fold in on itself and you'd end up sitting on the road.

Once you have one rigid car, you can add addition vehicles to this that only have one pair of wheelsets. For example, a car towing a trailer. Theoretically, you could keep adding trailers on to the back of each other to make what is in a effect a coaster train:

The rear two wheelsets can pivot up/down, left/right and rotate horizontally. Whilst the front two (on the van) only have a horizontal rotation (through the suspension). The image above shows the principle used on the Smiler's trains:

The front two wheelsets only pivot horizontally (as the track twists), but the rear two can pivot in any direction.

As others have othen pointed out, the front wheelset is often a Zero-Car, in that it doesn't have seats on it. This is down to designer's preference. The very front wheelset does have more forces on it: It is the first in to curves/twists and has to steer the rest of the train around the track. Obviously, the bigger and faster the ride, the higher these forces are. In the case of Alpengeist, when this opened in 1997, it was by far the largest inverter B&M had built, which is a possible reason for the lack of seats on the front car.

 

[bluesonichd]

Am i wrong but dont you get more Gs on the back row of Nemesis?

 

[Cheese]

I said somebody else would explain it better, and Nemesis94 has done so. However, I do slightly disagree with the terminology here:

The front two wheelsets only pivot horizontally (as the track twists), but the rear two can pivot in any direction.

That's how the cars are articulated, not the wheelsets. The wheelsets on each car can pivot vertically and to the side separately to this, and it's the combination of the two that makes modern coaster trains so agile.

Am i wrong but dont you get more Gs on the back row of Nemesis?

That I believe comes down to the back row being furthest from the train's centre of gravity, so you enter track elements where the train is being pulled down by gravity at a higher speed than in other rows (again, please step in and correct if necessary folks).