Diesel 10, or simply Diesel, is an evil diesel engine with a semi-sentient roof-top, hydraulic claw, which he has named "Pinchy".
Thomas & the Magic Railroad
Diesel 10 once visited the Island of Sodor a long time ago, and caused trouble for the steam engines while he was there. During his visit, he found Lady, the engine responsible for keeping Sodor alive, and chased her, making her crash. Following the accident, Lady's caretaker, Burnett Stone, hid Lady in his workshop and tried to restore her, but failed to bring her back up to steam.
Several years later, Diesel 10 came back to Sodor when the Fat Controller was on holiday, intending to destroy Lady forever. He was first seen by Thomas and Gordon when he raced past them at Killaban Station, and brought his two lapdogs, Splatter and Dodge, to the railway, who were present when he was scheming. He caused several problems for the steam engines, such as dumping sneezing powder around Tidmouth Sheds and later destroying the scaffolding that had been placed beside the shed.
When Mr. Conductor travelled across Sodor to find the windmill, Diesel 10 found him and held him over the Big Dipper, intending to drop him. However, Mr. Conductor managed to escape by cutting one of the hydraulics hoses to his claw with a pair of wire cutters, causing him to fling Mr. Conductor across the island and to the windmill. Diesel 10 was later present at the Coaling Plant, where he was covered in coal when he was teaching Splatter and Dodge “how to stop being stupid”. After Junior flew in the air after riding the windmill's sails, he landed on Diesel 10's cab, who raced across the island and to the smelter's yard, where he tried to push James and Junior into the melting pit. Fortunately, Junior and James managed to escape by using the last of the former's gold dust.
After Lady was brought back up into steam and returned to Sodor, Diesel 10 found her and began to chase her, Thomas and Burnett across the island, until they reached the viaduct, but not before Splatter and Dodge betrayed him. Lady, Burnett and Thomas managed to cross the viaduct safely while it was collapsing, but it had already done so by the time Diesel 10 came over it and he plunged into a barge of sludge below the bridge, and was sent away in disgrace.
Thomas & Friends
Diesel 10 later returned to Sodor years later under unknown circumstances. It can be assumed, however, that Sir Topham Hatt decided to give him a second chance. He was seen working at the scrapyard, loading piles of scrap into trucks. The very sight of his return caused Thomas and Percy to shudder in fright.
When the steam and diesel engines were holding a meeting at the coaling plant so that they could work on the Sodor Airport, Thomas was sent to the scrapyards to inform Diesel 10 of the meeting. However, Thomas was too frightened to meet Diesel 10 again, and sped away as fast as he could, not believing that Diesel 10 would want to help the steam engines due to their difficulties in the past.
Soon, the airport was nearly complete with its construction, until a water tower collapsed, cracking the runway and blocking the line. With Harvey all the way on the other side of the island, Thomas went to ask Diesel 10 for assistance. After some slight hesitation, Diesel 10 agreed to help clear the wreckage.
After Thomas was found prior to the reopening of Great Waterton, Diesel 10 was among the diesels present at the quarry when they heard the news. Later, when the Sodor Search and Rescue Centre was opened, Diesel 10 was present at the rescue centre's grand opening, standing on a cliffside overlooking the rescue centre and the steam engines below, threatening to return.
When Percy was experiencing a falling-out with Thomas, Diesel 10 decided to manipulate him into helping him restore the Vicarstown Dieselworks, by having him visit the Dieselworks and befriend him. Diesel 10 managed to convince Thomas to arrive at the Dieselworks, where he was held hostage while he, Percy and the other diesels went to the Sodor Steamworks. Once there, Diesel 10 betrayed Percy and took over the Steamworks. Percy returned to the Dieselworks to rescue Thomas, when he noticed that sparks from Pinchy had set the main building ablaze. Percy brought Belle and Flynn to put out the fire. After Thomas was saved and the fire was put out, Percy, Kevin and the rest of the Steam Team went to the Steamworks. After a brief argument with the diesels, Sir Topham Hatt arrived and, after being told about the state of the Dieselworks, agreed to have the place restored. Diesel 10 and the other diesels worked alongside the steam engines to restore the Dieselworks, and he became the new head of the Dieselworks, with Den and Dart taking over in his absence.
When it was Christmas time, Diesel 10 became jealous of the steam engines for having more decorations at Tidmouth Sheds than he and the diesels had at the Dieselworks. He began stealing decorations from the sheds to bring to the Dieselworks, enlisting a reluctant Paxton to help him. Diesel 10 was caught by Percy, who chased him back to the Dieselworks with the rest of the Steam Team, where Diesel 10 found out that Sir Topham Hatt had, in fact, had Paxton deliver some decorations to the Dieselworks, so he gave the decorations back to the Steam Team. But as most of them had been damaged, he gave them the Dieselworks' decorations to the next day, as he and the other diesels considered Sidney to be a good enough decoration.
Diesel 10 is an evil, conniving, manipulative, bullying and raving diesel locomotive. He absolutely despises steam engines, and would call them taunting names like "Puffball" and "Teapot". He is Sodor's strongest (but not quite largest) diesel, his power being enforced by his slightly malfunctioning claw, Pinchy. He can use this deftly, and is even able to use it to make a sculpture. Pinchy, though, seems to have a mind of its own, as it has been shown to "punch" Diesel 10 in the face from time to time, which he loathes. All engines, steam and diesel alike, fear or respect him.
Despite his brutality, some of his demeanor appears to have cooled, and his behavior has apparently approved enough that Sir Topham Hatt allowed him back to the Island. He gets along enough with the other Sudrian diesels, but his efforts to help are often only when it suits his personal interest and he still harbors his scheming ways and anti-steam sentiments.
Diesel 10 is based on a BR Class 42 diesel-hydraulic with an added non-regulation hydraulic claw. All but two members of the class were named after Royal Navy warships, so they, and the similar Class 43, were nicknamed "Warships". Two of these engines are preserved.
Diesel 10 is painted ochre with tan stripes along his sides. His buffers and "Pinchy" are painted dark brown.
- In an original version of the Thomas and the Magic Railroad script, Diesel 10 was to have been a new engine to the island, and Pinchy was going to be concealed beneath Diesel 10's roof. These were kept in the book, Diesel 10 Means Trouble, the magazine story Left Alone also possibly has him illustrated without his claw.
- "Pinchy" was originally built with no gaps between its buckets, which carried onto early promotional arts/illustrations.
- Diesel 10 only appeared in specials and movies until the seventeenth series, where he appeared in an episode for the first time. The seventeenth series also marked his final appearance in the series, though his popularity with the fanbase allows merchandise of him to continue production even after his discontinuation in media.
- Outside of Thomas and the Magic Railroad, Pinchy hasn't been named, and is simply referred to as a claw.
- Some of Diesel 10's production-made face masks are now owned by Twitter user @ThomasTankMerch.
- Diesel 10 has had a few modifications throughout the television series. These include:
- Calling All Engines!
- His brake pipe was removed.
- The wipers on his front windows were removed.
- His body is incorrectly fitted to his chassis at the front, leaving a gap above his front bufferbeam.
- Misty Island Rescue
- The 'teeth' on his claw now interlock.
- His upper bodywork is level once again, but fitted higher with gaps above both bufferbeams now.
- Calling All Engines!
- In early concept art, Diesel 10 had his name painted on his side. In addition, his claw bucket was smaller, his arm was designed differently, and he had three brake pipes, whereas his final model only had one.
- His Ertl toy depicts him as a BR Class 46 with added claw, this is due to re-using Diesel 199's tooling but with modifications.
- Diesel 10's claw was briefly used during Rebecca's imagination scene in What Rebecca Does.
- Diesel 10's number is a reference to him being the 10th diesel engine to be introduced into the television series.
Diesel 10: Get outta my way! I have unfinished business here and I want to finish it fast!
Gordon: The Diesel 10's back! Oh!"
Thomas: Yes, ten out of ten for devious deeds and brutal strength. The blast from the past who hates steam engines.
― Diesel 10's introduction, Thomas and the Magic Railroad
Thomas: Sir Topham Hatt says the harder we work the lesser will need diesels to help.
Diesel 10: Help you? [Evil laughs]
Thomas: UH OH!
Diesel 10: You always need help. Because steam engines are cowardly, cranky, worn out hunks of metals who couldn't hurt a fly!
James: NO, WE'RE NOT!
Diesel 10: Yes, you are!
Diesel 10: ARE! Now, I've come back to find a lost steam engine.
Diesel 10: I'm gonna destroy her, and dominate you, and then... you'll be nothing but useless scrap!
Diesel 10: Right, Pinchy? [Evil Laughs and leaves]
James: Big bully! STINKER!
Thomas: We're really useful engines! You won't dominate us, and you won't destroy her! We won't let you, neither will Mr. Conductor! I off to fetch him now!
James: What lost engine?
― Diesel 10 intimidates Thomas and James, Thomas and the Magic Railroad.
- “Hello, Twinkle Toes! Remember me? Fat Hat won't have much use for you looking like that! [Evil Laughes] Oh, i see you forgot to bring the sugar. How careless of you. Say hello to Pinchy”
- ―Diesel 10 confronting Mr. Conductor and seizing him in his claw
- “Puffball! Teapot!" (falls off the viaduct) "Tin kettle!" (lands in a barge at the bottom)
- ―Diesel 10 falling off the viaduct, Thomas and the Magic Railroad
- “Alright, I will help!”
- ―Diesel 10 when he listens to Thomas about the airport, Calling All Engines!
- “You'll be laughing on the other side of your boilers soon, silly steamies.”
- ―Diesel 10, Misty Island Rescue, foreshadowing his return in Day of the Diesels
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