Platform service vehicle

Claim 1

In a platform type service truck suitable for use upon and travel along public highways; the truck having a chassis including parallel frame members for supporting truck portions including a cab mounted upon the chassis, an engine and drive train for powering the truck, at least one powered source of hydraulic fluid under pressure for operating hydraulic devices mounted on the truck, and a work platform mounted to the frame members and capable of being telescopingly elevated from a lowered position for transporting the truck along public roadways to at least one elevated working position, the improvement comprising: a stationary telescopic tower section mounted atop the frame members, the stationary section including two opposing channel-like vertical members joined by at least three cross members, a cross member being positioned closely adjacent each end of the stationary telescopic tower section; at least one extendible telescopic tower section including opposing channel-like vertical members joined by at least three cross members, a crossmember being positioned closely adjacent each end of the extendible telescopic tower section, the extendible section being slidingly nested within the stationary section, and additional extendible sections being slidingly nested one within the next whereby the stationary section is outermost and an extendible section capable of being more elevated than any other section is innermost within the nest the more elevatable extendible section having a closed upper end forming a support plate and having a king post mounted to the support plate upwardly from the support plate; elevational stops between each telescoping tower section and the next innermost telescoping tower section positioned to prevent a telescoping tower section from being elevatably withdrawn from the nest, the elevational stops being configured as sliding pads for facilitating sliding between adjacent sections; a double acting hydraulic cylinder having a barrel including attachment tabs, and a number of telescopic extendible portions, including a most extendible having an attachment point, equalling the number of extendible telescopic tower sections, each telescopic extendible cylinder portion being attached to a corresponding tower section whereby longitudinal movement of the cylinder portions positively and correspondingly longitudinally moves the nested tower sections, the double acting hydraulic cylinder being affixed by its attachment point adjacent the mounting between frame members and stationary tower section and by its barrel to the support plate obversly from the king post, the cylinder including fluid interconnections to the source of hydraulic fluid; a platform rotatable in a horizontal plane, including safety rails and a work surface, the platform having an upper base to which the safety rails and work surface are attached, and a lower base, the platform bases being separated by insulators and by spacing with the separation being rated for at least 500 volts, the platform lower base including a circular recess configured to receive the king post snugly, and a ring worm gear affixed to the lower base centerably surrounding the recess; a platform rotational drive, the rotational drive including a worm drive gear having a hydraulically driven motor affixed to the support plate and engaging the ring worm gear, the engagement being self locking while the drive gear is not under power regardless of rotational position of the platform, and a hydraulically driven motor including fluid interconnections to the source of hydraulic fluid for powering the worm drive gear in either direction; and at least one set of controls for regulating the flow of hydraulic fluid under pressure separately to the cylinder and the hydraulically driven worm gear drive motor, any controls mounted above the lower platform base being interconnected in a manner preserving the electrical insulative integrity of the platform.