This section archives a lot of theories and speculation, which usually occurs from pre-release media, or just things that are still unknown, so please keep that in mind while reading. The page will continue to be updated with the most accurate information as more solid evidence is supplied.
A springlock suit as seen in Five Nights at Freddy's: Sister Location.
The springlock suits, springlock hybrids, or springlock animatronics are unique but currently discontinued machinery in the Five Nights at Freddy's series. They are suits that function as animatronics and costumes in each different mode, which can be switched back and forth by using a crank which winds up the suit. This allows the mechanical gears surrounding the body of the wearer to deactivate, allowing the wearer to slip in-between them. If the suit activates whilst the wearer is inside of it, they will spin inwards and the wearer will be bludgeoned severely, causing them to be crushed and killed.
The springlock suits are composed of several individual spring-powered locking mechanisms, hence their name. When one wishes to change a springlock suit from its animatronic form into its suit form, they must insert a hand crank into its designated slot and proceed to turn it firmly into position. Doing so will proceed to coil the springs into their suit positions, causing the endoskeleton parts to be compressed and locked around the sides.
When operating a suit, one must be careful not to touch or lubricate any of the springlocks and keep them tightly wound. If these requirements are not met, the wearer of the suit has little chance of survival; the springlocks will come loose and the endoskeleton parts will rapidly recoil inwards, thus impaling the suit's user and causing a slow, painful death.
From the various springlock suit appearances, one can gather that this event has taken place at least twice within the history of the franchise. One event was the death of William Afton, as depicted in the end-of-night minigames of the third game. The other was mentioned by Ralph, being a "springlock failure". Little-to-no context is given as to this event, so it is mostly regarded as speculation. It is unknown if The Big Bite counts as a springlock failure despite a springlock suit being involved; this could be the incident Ralph mentioned.
“And, if you accidentally trigger those spring locks, two things will happen: First, all the locks will snap right into you, making deep cuts all over your body, and a split second later all the animatronic parts they've been holding back, all that sharp steel and hard plastic, will instantly be driven into your body. You will die, but it will be slow. You'll feel your organs punctured, the suit will grow wet with your blood, and you will know you're dying for long, long minutes. You'll try to scream, but you will be unable to. Your vocal cords will be severed, and your lungs will fill with your own blood until you drown in it...”
— The Silver Eyes, page 159
Internal Springlock mechanism seen inside the torso of the Captain suit.
Five Nights at Freddy's: Secret of the Mimic introduces a new design of springlock suit invented by Edwin Murray. Contrary to the previous suits, the updated models don't require a hand crank and are purely mechanical, opening a hatch for the operator to enter upon pressing the right button. These suits were presumably never used outside of the Manor.
“Fiona, the new springlocks are working well, even with the water damage. They should be ready for the diner soon. I'll just make sure to warn Hen about some of the more... odd behaviors they might have.”
— Secret of the Mimic, "Springlocks" note
History
Five Nights at Freddy's 3
William Afton wearing the Spring Bonnie suit before his demise during the final Five Nights at Freddy's 3 end-of-night minigame, animated.
The springlock suits were introduced to Fredbear's Family Diner at some point, likely before or during 1983 as seen in the television Easter Egg from Five Nights at Freddy's 4. Despite Ralph mentioning in the training tapes that the suits were incredibly dangerous, they were continued to be used until a springlock failure incident occurred at an unnamed sister location. Due to this unfortunate event, the suits were decommissioned permanently.
In the end-of-night minigames of Five Nights at Freddy's 3, William Afton seemingly meets his death within the Spring Bonnie suit he used to commit most of his murders due to his labored breathing and moisture throughout the building. Within the suit, William is reanimated as Springtrap during the third game's events after decades.
From there, the suits go essentially untouched before employees from Fazbear's Fright: The Horror Attraction unearth Springtrap from the Safe Room and place him as the star attraction at the location, setting up the events of Five Nights at Freddy's 3. Fredbear has currently not been discovered at this point.
Ralph mentions that there were "temporary" suits used after the decommissioning of the springlock ones, with a possible example being a cartoonish Spring Bonnie suit that is implied to have served as the basis for Glitchtrap.
It is generally assumed that the Spring Bonnie suit was the mentioned "cartoon mascot" used to instigate the Missing Children Incident due to the fact that the suits are the only wearable costumes present throughout the series.
Five Nights at Freddy's 4
William Afton is seen putting a mask on a springlock suit-wearing employee in one of the Five Nights at Freddy's 4 end-of-night minigames. The springlock suits are mostly seen in the end-of-night minigames of the fourth game, found within Fredbear's Family Diner.
The silhouette of Spring Bonnie on stage
Fredbear's head being removed
Spring bonnie without his head
An Employee wearing the Springlock suit
From the end-of-night minigame after completing Night 2, if the player walks back to right of the entrance room of the diner after going to the dining area, William can be witnessed inside the spare parts room, putting the Spring Bonnie head on an employee, who is seen wearing a springlock suit. The moment shows William holding the Spring Bonnie costume head over the springlock suit-wearing employee before fully putting it on the employee. As soon as this happens, the doors close, hiding both of them from view.
It is noteworthy that another employee from the end-of-night minigames on Night 2 and 3 is seen wearing Fredbear's springlock suit.
Inside the spare room on Night 4, several parts for the springlock suits (besides the endoskeletons) are seen, consisting of a headless springlock suit to the left of the door, and a table with an endoskeleton skull to the left and an endoskeleton hand to the right. There are two shelves above them; the lower shelf has a costume-arm to the right, Fredbear's head in the left and an endoskeleton torso in the middle, the upper shelf has Spring Bonnie's head to the right and an endoskeleton skull to the left.
A common misconception is in the final minigame, (The child's tears loosen the mechanisms, causing the springlock animatronic to overpower and crush his skull.) But the reality is that Fredbear was ALREADY in Animatronic mode, therefore no Springlocks would be activated at the time, and Fredbear bit down likely due to a sudden, violent drop while the child’s head was trapped inside the jaw mechanism or even because Fredbear might have been possessed. This event is dubbed The Big Bite.
Five Nights at Freddy's: Sister Location
The springlock suit opening its faceplates, animated.
A springlock suit appears in the fifth game during the events of Night 4. Seen inside the Scooping Room, this springlock suit has faceplates similar to the "funtime" animatronics, with a face noticeably different from Fredbear and Spring Bonnie upon observing. The identity of the animatronic mascot based on this springlock suit remains undisclosed, with Scott Cawthon himself bluntly and candidly refusing to clarify who it is.
It was used by Circus Baby to hide the player after Funtime Foxy jumpscared the player at the end of Night 3. After witnessing Ballora getting scooped, Circus Baby opens up the faceplates so the cameras can find and rescue the player. During this time of waiting, Minireenas will crawl up the suit and attempt to kill the player.
Freddy Fazbear's Pizzeria Simulator
In the sixth game, the Spring Bonnie suit worn by William Afton is completely different, making it possible that there are differently-designed springlock suit models of Spring Bonnie or it was a prototype. It was hinted by Scott Cawthon that there is some in-universe explanation for the design change, but this has not since been elaborated on.
William Afton wearing a Spring Bonnie suit is seen standing next to the left side of a crying girl named Susie, which occurs after beating the Fruity Maze game twice.
Five Nights at Freddy's: Secret of the Mimic
Murray Co. produced five springlock suit characters that appears in the game, of a different design of springlock suit. Pieces of the updated Pirate Captain suit are found inside the workshop. Said suit was presumably the cause of various injuries in the theater (aswell as Nurse Dollie being equipped to clean organic material out of the suits). Upon the assembly and energizing Arnold is able to use it to enter the theater. Research and Development's mockup Freddy's features additional four suits. Prototype versions of Fredbear and Spring Bonnie as well as springlock version of Monty and Bub. Some of these suits may have been meant to be used at the original Freddy Fazbear's Pizza, before being changed by a last minute work order from Fazbear Entertainment, Inc.
Spring Bonnie is the precursor to Bonnie the Rabbit and a mascot of Fredbear's Family Diner alongside Fredbear. Afton used the suit during his killings, though it would eventually crush Afton to his death, and Spring Bonnie along with Afton would later become known as Springtrap. He used them during the killings because he felt powerful in it and the security cameras couldn't see his face, hence why he got away with it multiple times.
A prototype suit appears in Secret of the Mimic.
Unidentified Funtime/Springlock Suit
“Try not to wiggle, though. You’re inside something that came from my old pizzeria. I don’t think it was ever used– at least, not the way it was meant to be used. Too dangerous. It’s just big enough for one person to fit inside—but just...barely.”
— Circus Baby,Five Nights at Freddy's: Sister Location
A springlock suit appears in the events of Night 4 in Five Nights at Freddy's: Sister Location. Seen inside the Scooping Room, this springlock suit has faceplates similar to the Funtime Animatronics, with a face noticeably different from Fredbear and Spring Bonnie upon observing. The identity of the animatronic mascot based on this springlock suit remains undisclosed, with Scott Cawthon himself even refusing to clarify who it is. Circus Baby stated that this animatronic originated from her old pizzeria, Circus Baby's Pizza World.
It was used by Circus Baby to hide the player after Funtime Foxy jumpscared the player at the end of Night 3. After witnessing Ballora getting scooped, Circus Baby opens up the faceplates so the cameras can find and rescue the player. During this time of waiting, Minireenas will crawl up the suit and attempt to kill the player.
In Dawko's interview with Scott Cawthon, he stated that he did not want to reveal the identity of animatronic. Why Scott refuses to clarify this is unknown. However, Scott's reasoning of preventing to reveal the identity of the animatronic is to possibly prevent spoilers for lore purposes.
It was once speculated that this costume may belong to Funtime Chica, however, since the character was revealed in Freddy Fazbear's Pizzeria Simulator, her design was shown to be entirely different (notably, the eye sockets are a different shape, the mouth-hole is more of an oval shape instead of a typical smile, and the horizontal line bisecting the face curves upward as opposed to being straight. The space between the horizontal line and the beak is also much narrower on Funtime Chica.)
Pirate Captain is a bulldog animatronic and the leader of the Puppet Crew, a group of puppet-like animatronics. He first appeared in Secret of the Mimic as a buildable suit, with Arnold being required to wear the suit.
Monty is an alligator animatronic present in a recreation of Freddy Fazbear's Pizza. He first appeared in Secret of the Mimic in the later stages of the game, as a suit that Arnold can wear to avoid The Mimic.
Bub is a dog animatronic present in a recreation of Freddy Fazbear's Pizza. She first appeared in Secret of the Mimic in the later stages of the game, as a suit that Arnold can wear to avoid The Mimic.
Trivia
Inside Inventor's House there are springlock endo legs (referred to as "Old Endo Part" in the files) using Nightmare Freddy's textures. Possibly to give them more "old" or "rusty" look.
