Abstract: A protective device for a front of a large-size dump truck, in which a driver's cab (13) is secured on a front side of a truck body (10) and a vessel (15) is, liftably from its front side, secured on a rear side of the truck body, is characterized in that a front protective guard (20) protruding forward from a position of the driver's cab is attached on a front end portion of the vessel.

Abstract: An electrical circuit for driving an electrically driven vehicle such as a dump truck is capable of preventing occurrence of accidents caused by an erroneous operation and thereby increasing safety by providing an arrangement such that the vehicle cannot start unless all necessary operations have been completed before starting. For this purpose, a power source of a control box controlling an exciting current for a generator is turned on to generate the exciting current only when all necessary operations have been completed. This is achieved by connecting a plurality of switches corresponding to various operations in series to a power source relay and thereby causing the power source relay to be actuated upon closing of all of these switches. The circuit also enables the motors to be utilized as generators to provide dynamic braking for the truck.

Abstract: A control device for controlling accelerator and brake switches is designed to prolong life of the accelerator and brake switches as well as life of electromagnetic contactors for the accelerator and brakes which are energized and deenergized by these switches. According to the invention, once the accelerator switch has been turned on by depression of an accelerator pedal, the ON state of the accelerator switch is maintained unless a brake pedal is subsequently depressed. Similarly, once the brake switch has been turned on by depression of the brake pedal, the ON state of the brake switch is maintained unless the accelerator pedal is subsequently depressed. To this end, the control device comprises changeover valves respectively actuated by the accelerator and brake pedals, bistable means for performing a mechanical bistable operation by means of air supplied through the changeover valves and accelerator and brake switches actuated in correspondence to two positions of the bistable means.