by replacing the lifting platform with a wide box open at the front and top. An opponent maneuvered into the box may then be restrained with an arm or claw from above. Some designs use only the box with no restraining claw. BattleBots middleweight runner-up S.O.B. used a dustpan in conjunction with a saw blade mounted on an arm, with the more recent 2018 BattleBots competitor SawBlaze using a 180º pivoted-arm-mounted circular saw on their trident-style dustpan design to cut downwards into an opponent. Crusher – Like flywheels, crushers can be separated into horizontal and vertical variants. Vertical crushers use a hydraulic cylinder attached to a sharp piercing arm to pin and slowly penetrate the top armor of the opponent. Robot Wars Series 5 Champion and two-time world champion Razer was the first vertical crusher, and by far the most successful. Horizontal crushers feature two of these arms, which act like pincers to crush robots between them. Two-time Robot Wars Annihilator champion Kan-Opener armed with horizontal claws, and King of Bots Champion "Spectre" armed with a vertical 'biting fang' - or like the Dutch-fielded, hydraulically-powered ten tonne-force "toucan-billed" robot Petunia in recent seasons of Discovery Channel's Battlebots are other examples of successful crushers. Overhead Axe – Swinging a high-speed axe, spike, or hammer forcefully down onto your opponent offers another method of attacking the vulnerable top surface. The weapon is typically driven by a pneumatic actuator via a rack and pinion or direct mechanical linkage. The attack may damage the opposing robot directly, or may lodge in their robot and provide a handle for dragging them toward a hazard. BattleBots heavyweight runner-up and Robot Wars competitor Killerhurtz was armed with an overhead axe. Some axes are double-sided, and can strike opponents both in front of and behind the robot; Killerhurtz' successor Terrorhurtz, and Robot Wars Series 2 Grand Finalist Killertron, were examples of this. The heavyweight pneumatically powered, bifurcated-armed pickaxe of Chomp from the 2016 and 2018 Battlebots competitions also incorporated short metal "wing" levers at the pickaxe-arms' rear ends to upright its bulky chassis if knocked onto its side during combat, and pioneered a hardware design that autonomously turned Chomp to always face its opponent during a match. SRiMech – Many robots are incapable of running inverted, due to their shape, weaponry, or both. A SRiMech (self-righting mechanism) is an Active Design element that returns an inverted robot to