Abstract: A control panel enabling and automatically disabling system is coupled between a source of electrical power and a plurality of motion controls on an aerial work platform. Upon activation of a pushbutton type power enabling switch, power is coupled to all the motion controls for a predetermined fixed time period which when activated will couple power to a respective motion producing mechanism such as a boom actuator. If none of the motion controls are activated by an operator within this time period, a timer times out and the panel thereafter becomes inactive by interrupting the electrical power. However, if a motion command is effected by actuation of any one of the motion controls during this time period, the timer is automatically reset to zero time and held thereat until all motion commands cease, at which time the timer is restarted. The enabling switch cannot be defeated by a continuous activation thereof. The enabling switch must be released and pushed again to start a new cycle.

Abstract: An electrical deactivation circuit and a two piece overhead guard assembly including two separately movable bar members which extends upward and over the head of an operator located on the upper work platform of an aerial work platform. The guard bar members are connected to the frame of the upper work platform by a pair of movable support assemblies, the movement of which actuates impact detection induction type proximity switch means to interrupt electrical power applied to the electrical control circuits and stop the engine powering the aerial work platform. Each movable support assembly includes a pair of spring loaded mechanical subassemblies including a pair of clamp members between which is located an elongated coil spring whose stiffness is varied in accordance with the distance separation of the clamps. An inductive type proximity switch is located in the lower end portion of each spring to sense movement of the inner end of a respective guard bar member.

Abstract: A welding control circuit for induction heating of a pair of articles to a welding temperature and for pressing the heated articles together. A pair of induction coils are positioned in a gap between the portions of the articles to be heated and a pair of temperature sensors monitor the temperature of both articles and controls heating rates so both articles reach a welding temperature at approximately the same time. The temperature sensors provide signals which cause the coils to be retracted from the gap and cause the heated articles to be pressed together to form a welded pair. When similar articles are to be welded together a single coil can be used to provide induction currents which heat the articles.