OPERATING PRINCIPLE OF ROLLER COASTERS: CRAZY WORM |
Updated 11.09.00
Click here to see how to assemble the Crazy Worm
Crazy Worm is only a short and low kiddie roller coaster but nevertheless it is still a proper roller coaster. Its technology is exactly the same as used in much bigger mobile coasters. Basically you could enlarge it simply by adding more track length and height. Once you understand how Crazy Worm and its components work you can also understand how the largest roller coasters work. As a matter of fact, the Crazy Worm is an excellent coaster to learn on. It's low, so you have easy access to all the components used for it.
Basic facts:
Step on board
The station slants slightly downwards. The train is sent along the
track by releasing the brakes on the platform. There is a drop after the station that
propels the train to the bottom of the lift hill.
Train on lift hill
Once it reaches the lift hill the initial energy of the train's
drop from the station has been used up so it must be pulled up the hill by a motor.
Installing the chain
This image illustrates the operation of the lift hill.
There is a chain revolving around the hill. It goes up above the track surface, and
returns down under the track. The train engages into the chain from its belly and
is hauled to the peak of the hill. The train moves clear of the chain at this point and is
propelled by gravity to the end of the circuit.
Detail of the chain lift
In this picture the chain is almost installed. In the middle of the chain
there are wheels that include ball bearings. These wheels make it possible for the
chain to roll up the hill with a minimum of friction. There are pegs going through the
wheels. The train engages to these pegs. Each peg can be installed and removed
by a special tool like a bench vice, so there are no specific "ends" of the chain.
You simply join the free ends and drive a peg through the holes. It's very easy
to shorten / extend the chain if necessary.
Under the car
Some essential parts of the car are illustrated here.
All these parts can be found in each car. The fork (A) is the "chain dog" which
engages into the lift chain. Its arm is hinged, so the chain dog is able to jump
over the first peg of the chain when the train
reaches the lift but not move backwards. The advancing chain engages a peg
into the fork and starts to push the train up. So, basically the chain lift is not
hauling the train, it pushes it up the hill instead. When the train reaches the
summit it requires no additional mechanism to release the chain.
Motor
This is the motor of the chain lift. The green part is an
electric motor which operates using 3-phase mains power. It requires 8kW when operating.
The blue part is a planetary transmission. It reduces the rotating speed of the motor
to a speed suitable for the chain lift and increases the torque. There is a gear at the
end of the shaft.
Gear
Detail of the same gear.
Chain, engine and tensioner
This is how the chain and the motor link together.
The curved part above the chain is a tensioner which keeps the chain tight.
Note the outgoing and returning chutes for the chain.
Gears on top of the lift hill
The chain rotates around these gears and returns
towards the motor, which is mounted below the track.
Roll back arresters
The train is not allowed to roll back the lift hill if there is a
malfunction. This is prevented by the anti-rollback device. The "ratcheted dog" is a
claw-toothed bar permanently welded along the track, to the left of the chain. In the bottom of the
car there is an arm (B in the image above) that is also hinged. It is able to jump over the
arresters as the train moves forward. If the train starts to roll back, this arm catches on the
ratcheted dogs and stops the train.
Train on circuit
After the lift hill the track falls away, propelling the train
by gravity. Roller coasters are designed in a way that
each downhill gives enough speed for the train to be able to climb the next incline.
The train has no engine, nor has it any brakes...
Trim brakes
...but the track does. Trim brakes are used to control
the speed of the train. The train goes faster if there are heavy passengers
riding it, and vice versa. Weather conditions can also affect the
speed of the train. The trim brakes are adjustable, so each train can be set to
travel at the same speed. Crazy Worm has only one set of trim brakes,
located in the middle of the "first drop". The adjustment is made by the ride
operator. Larger roller coasters may have automatically controlled trim brakes.
Operating principle of the brakes
As with most other roller coasters, this one uses fin brakes.
Like the brakes on a car, the train is slowed down by friction between the
parts of the brakes. One part is on the track, the other is attached to the
bottom of the train. This picture shows the brake segment of the
track. There is a groove between the pads. The brake fins underneath the train
run through this groove as the train passes over the brakes. The silver cylinder
uses compressed air to open or close the gap, and so change the amount the train
is slowed down by the amount the brakes grip the fin.
Brake fins
The picture is taken underneath the train. The brake fin (D)
is affixed to the car and runs through the groove of the trim brakes.
Wheels
How does the train stay on the track? First, the wheels are hollow
so they can withstand lateral forces on the bends without derailing. Second, there are
upstop pads that ride under the track. They prevent the car from jumping off the track.
Extreme hills on larger roller coasters might be able to throw the cars away from the tracks,
so upstop wheels under the track are used instead of the pads so that the train is
not slowed down.
Loading station
The brakes of the station (E) are similar to the trim brakes in the
middle of the track. The bar (F) is used to release / lock the lap bars of the train.
The bar is powered by pneumatics and it goes up or down accordingly.
Restraint locking device
The picture is taken at the station, underneath the train.
The release bar (F) goes up and presses the release arms (C), thus unlocking the lap bars.
When the bar goes down, all the lap bars are locked at the same time.
Each lap bar has an individual release mechanism. If the train is stranded
in the middle of the circuit, each lap bar must be manually released under the train.
Control panel
Welcome to roller coaster control. The buttons are:
EMERGENCY stops the lift hill motor and engages the brakes.
START / STOP controls the lift hill motor.
COMPRESSOR ON / OFF switches ON the compressor
for the pneumatics that drive the brakes and lap bar locking device.
LIGHT ON / OFF is a switch for the decorative lights.
LAPBAR RELEASE locks / releases the lap bars.
PARKING BRAKE switches ON the brakes in the station.
The potentiometers
ADJUSTER preset the station brakes or the
DESCENT BRAKE (trim brakes). The braking powers are indicated
by meters.
Bottom of the control panel
This picture shows the pneumatic hoses from the control panel.
There is an input from the compressor, and outputs for both brakes and for lap bars.
Train
It's time to board again, engage the lap bar and start another circuit.
The pictures were taken in Kerava, between 6-7.9.2000. Many thanks to Petri Sariola for the technical details of the ride, and also to the magnificent build up team Ossi, Jyri, Vesku and Luki, whose work I terrorized for two days with my camera. Special thanks to Mark Cook for helping me out with the translation.
Click here to see how to build up the Crazy Worm