Casey Junior

Casey Junior is a fictional anthropomorphic steam locomotive who is numbered 1 and is among the more memorable characters in the 1941 Disney animated feature film Dumbo, but has also appeared in other Walt Disney productions.

His name is a direct reference to Casey Jones, the famous railroad engineer who died in a train collision in 1900.

Physical appearance
Casey, as a 2-4-0 steam locomotive, has a small four-wheeled tender at the back, a big, tall, old-fashioned smokestack in place of his old, broken one, a little lamp hat, a short stumpy boiler, a short stumpy dome with a whistle on the top and a small cowcatcher at his front.

Dumbo
Casey is a tender engine hauling the circus train, and even has his own song. He appears frequently throughout the film, and is shown to be somewhat sapient. For example, when the Ringmaster calls "All aboard! All aboard!", his whistle can be heard calling "All aboard! Let's go!"

As is the case with most Disney vehicles, Casey has the ability to move in a more fluid way than actual locomotives, and his boiler is often seen bending and twisting like rubber when in motion.

In addition, Casey can twist and flex his metal body to express motion. He uses his steam cylinders like limbs, giving him the ability to shrug, point and make other gestures.

Although Casey is a male (according to his song, being referenced as he or him), his whistle was originally voiced by Margaret Wright and he is currently voiced by Cathy Cavadini. While the sound of the voice resembles that of one processed through a vocoder, it was actually done with a more primitive device, a Sonovox, which uses one or two small loudspeakers in contact with the throat, which allowed Wright to "speak" by modulating an artificially produced sound with her mouth.

Earlier Work
In The Reluctant Dragon, according to a deleted scene from Dumbo, Casey was, in fact, pulling a passenger train to Cleaveland, Ohio. He unfortunately crashed after an effort to jump the chasm left by a broken bridge in a storm. In this film, he was of different wheel arrangement, 2-4-0 with the main rod on the forward driving wheel. He also had a bell and wasn't quite as stubby. When he was hired as a circus engine, he had a few changes: his rod arrangement changed to the back wheel, his bell removed, and himself becoming more stubby. This leads people to learn that he was overhauled after the accident and bought to a railroad in Florida that he can call his very own.

Disney Parks
A Disneyland attraction, Casey Jr. Circus Train, is based on Casey, with an updated version running at Disneyland Paris. Casey Jr. Splash & Soak Station, a water play area themed around him, was added to the Magic Kingdom in 2012 in the Storybook Circus section of that park's new Fantasyland.

Trivia

 * Casey makes a cameo appearance in a Donald Duck cartoon Spare the Rod as a black train.
 * Casey is the second float in the Main Street Electrical Parade and its versions. He, driven by Goofy, pulls a drum with the parade logo and Mickey Mouse and Minnie Mouse.
 * Casey makes a brief cameo in the 1988 film Who Framed Roger Rabbit. He is spotted during the final scene.
 * The wagons that transport P.T. Flea's Circus in A Bug's Life are old boxes of Casey Jr. cookies.
 * In the film Kronk's New Groove, a sequel to The Emperor's New Groove, Kronk has a miniature model train set of Casey in his new home, complete with scaled-down models of the carriages featured in Dumbo.
 * Casey was named after John Luther Jones a.k.a. Casey Jones, an engineer from the late 1800's famous for driving trains at great speeds (sometimes dangerous speeds) in order keep on schedule.
 * It appears that, in the film, Casey does not have an engineer in his cab, so it's unknown of how he is able to move on his own in the first place, unless he is a sentient being.
 * Casey makes a cameo appearance in the Mickey Mouse episode "Tokyo Go".
 * When Casey climbs up the mountain, he chants, "I think I can," over and over again, and on the way down he chants repeatedly, "I thought I could." This is a reference to the classic children's book The Little Engine that Could. He was also based on the story "The Little Engine That Could".
 * The "Casey Junior" segment was originally much longer. It was drawn and animated, then heavily edited, cutting several minutes from its run time. The full length segment can be seen on Disney's The Reluctant Dragon DVD.
 * Casey's train, for some reason, is constantly gaining and losing cars as he makes his journey: the only time he is ever seen with all of his cars intact is when he crosses a bridge before climbing up the mountain.
 * The train Casey pulls in the film, from front to back, is made up of a yellow coach (carrying the clowns and other circus performers), a flatcar with a calliope organ, two more several flatcars (carrying various circus wagons), an orange stock car (carrying the elephants), a blue stock car (carrying animals like monkeys, horses, zebras, and camels), one more flatcar (carrying the tent and its supports), a light blue stock car (carrying the giraffes (whose heads are clearly sticking through the roof)), a pink stock car (carrying predators like hyenas, apes, bears, lions, and tigers), a light green stock (carrying animals like ostriches, seals, hippos and kangaroos), a green coach (carrying the circus workmen), and a red caboose numbered 2 (carrying the ringmaster). Also, at the end of the film, the caboose is replaced with a silver coach reserved for Dumbo and Mrs. Jumbo.
 * Casey makes a cameo appearance in Where's My Mickey?
 * Casey, in real life, is a 2-6-0 steam locomotive that is numbered 271.