Security system of construction machinery

A security system for a construction machine, comprising:

• a construction machine equipped with a body controller for storing a first password;
• and
• a portable communications unit for storing a second password,
• wherein
• the body controller determines whether the second password output from the portable communications unit coincides with the first password and inhibits a predetermined operation of the construction machine in the case of mismatch between the passwords;
• the system comprises a management apparatus for storing the first password and communicating with the body controller and the portable communications unit, the management apparatus being arranged in a location apart from the construction machine,
• upon receiving the first password from the management apparatus, the portable communications unit changes the second password to the first password;
• the predetermined operation of the construction machine is starting an engine installed on the construction machine,
• the construction machine comprises an engine start instruction section for instructing the body controller to start the engine,
• the management apparatus comprises an input section for receiving a communication signal output from the portable communications unit, a database for storing the first password, an arithmetic operation section for selecting the first password stored in the database in accordance with a communication signal received by the input section, and an output section for outputting the first password selected by the arithmetic operation section,
• the portable communications unit is owned by an operator of the construction machine and comprises a first output section for outputting the communication signal to the management apparatus, a first input section for receiving the first password output from the management apparatus, a memory for storing the first password received by the first input section as a second password, and a second output section for outputting the second password to the body controller,
• the body controller of the construction machine comprises a memory for storing in advance the first password stored in the database of the management apparatus, an input section for receiving the second password output from the second output section of the portable communications unit, an arithmetic operation section for determining whether the second password output from the second output section of the portable communications unit coincides with the first password stored in the memory of the body controller and outputting an engine drive permission signal when matching is made, and an engine start controller for outputting an engine drive signal in accordance with the engine drive permission signal output from the arithmetic operation section;
• and
• the portable communications unit and the management apparatus perform communications via a public circuit.