- "What is a removable link? Well, to start with it's the main safety feature required on every robot that enters the Robot Wars arena. It's a plug that goes directly in line with the batteries of the robot, which when taken out removes all power from the machine. Without this link in place it's impossible to drive the robot or activate its weapons accidentally."
- — Robot Wars: Build Your Own Robot
Removable links (often just called links and sometimes referred to as safety links, keys or killswitches) are small detachable power switches which are used to activate and deactivate all robots participating in Robot Wars and other robot combat events, including House Robots.
Once removed, a removable link automatically cuts off power to the robot's drivetrain and weapons, rendering it immobile and making it safe for transportation, inspection and maintenance in The Pits. It was not uncommon for them to either come loose or fall out completely mid-way through a battle, if a robot was hit in the area where the link was housed. This, in turn, would instantly immobilise the affected robot, with notable cases including Bulldog Breed 3's loss to Hypno-Disc in Series 5 and Apollo's loss to Carbide in the Head-to-Head rounds of the Series 8 Grand Final.
The term failsafe - referring to a completely different component - was frequently conflated with link even on Robot Wars itself, leading to occasional confusion. While both serve to make robots safe for handling by roboteers and other personnel, the most important difference is that while a failsafe cuts off power to a robot when it loses radio signal from its transmitter, a link cuts off power entirely upon being disconnected from the robot's systems.
- "A safety link that every robot has, so it can be immobilised, in The Pits, for security reasons. Pull that out, and the machine will stop."
- — Jonathan Pearce
Removable links are roughly rectangular-shaped with power sockets at one end and a wire forming a solid hoop-like extension on the other; the latter feature gives the device a close resemblance to a padlock. They can either be custom-designed or made out of commercially-available power connectors, such as Anderson connectors. The design of removable links allow them to be easily attached to or detached from the robot's electrical system.
Although most robots only required a single removable link, it is not uncommon for robots - especially in the rebooted series - to have two or more independent links for the drive and weapon systems. Additionally, duplicate links are required in order to allow invertible robots to be disabled from the inverted position (see Rules). For Series 8-10, the link was also required to demonstrate that the mandatory LED power light turned off whenever it was disconnected from the robot, confirming its deactivation.
Removable links or keys became a required safety device from Series 4 onwards, but in series prior to that the robot's main power switch could take any form. Some pre-Series 4 competitors - such as Disruptor - did not even feature a power switch or removable link at all.
By contrast, the design of Mortis incorporated a removable link for safety from as early as Series 1, and it was Random Violence Technologies' implementation of the device that compelled Senior Technical Consultant Derek Foxwell to encourage its wider use. Another early competitor to use a link was Dreadnaut; during its Series 2 Heat Semi-Final against Oblivion, it was unable to move at all due to its link falling out while being prepared for the battle.
From Series 5 onwards, the rules were clarified to only allow links as the main cutoff switch. Sometimes, however, links still continue to be referred to as 'keys' by roboteers, such as Pete Collier following Hot Pants' loss in Series 6.
Removable links are required to be positioned in a visible part of the robot's bodywork, accessible to members of the Robot Wars technical crew from behind the arena wall. They must also be clearly marked, kept away from any moving components such as weapons and drive systems, and able to be removed even while the robot is inverted. Most robots - especially in the original series - would have links concealed behind a hinged cover within their armour, which roboteers were required to be able to open without the use of tools.
For the rebooted series, additional rules were introduced regarding links on invertible robots; in the Series 8, 9 and 10 build rules, robots built this way were required to have a duplicate link 'fitted in the opposite panel' which could be accessible from the inverted position.
- Robot Wars: Build Your Own Robot, p.40.
- ibid, p.42.
- Series 4 Build Rules
- Arthur Chilcott's comment in the Unofficial Robot Wars Facebook group
- Series 5 Build Rules
- Series 8 Build Rules
- Series 9 Build Rules
- Series 10 Build Rules