Engine speed controlling system in construction machine

Claim 1

In a construction machine having an engine speed setting device, a throttle lever for instructing a set number of revolutions to said engine speed setting device, a plurality of actuators and a plurality of operation levers each for instructing the operation of a respective actuator, an engine speed controlling system including: lever neutral detecting means for detecting a neutral condition of said operating levers and outputting a lever neutral signal when all of said operating levers are in a neutral condition; deceleration command issuing means for outputting a deceleration command signal when operated by an operator; and control means for outputting to said engine speed setting device one of a normal operation command at the set number of revolutions provided by said throttle lever and a deceleration command at a small number of revolutions in accordance with the signals provided from said lever neutral detecting means and said deceleration command issuing means, said control means comprising means for outputting the deceleration command to said engine speed setting device only when said control means has received the deceleration command signal from said deceleration command issuing means during issuance of the lever neutral signal from said lever neutral detecting means, said control means further comprising means for outputting the normal operation command to said engine speed setting device when the lever neutral signal from said lever neutral detecting means has been extinguished.