PURPOSE: To dispense with an exclusive auxiliary brake device by shutting the pipeline of a fluid circuit for working device, and giving a resistance to a pump in the pipeline when an auxiliary brake is required at the time of running, thereby applying the braking force as the auxiliary brake to the vehicle.

CONSTITUTION: First and second hydraulic pumps 9, 10 for working device and third and fourth hydraulic pumps 11, 12 for steering are connected to the output shaft 2 of an engine 1 to operate the respective pumps by the output of the engine. In a vehicle such as constructing machine, a first shut-off valve 21 and a second shut-off valve are provided in the tank side circuit of a first hydraulic pipeline 7 and the tank side circuit of a second hydraulic pipeline 8, respectively. The hydraulic pipeline is shut by, for example, the first shut-off valve 21, whereby the pressure in the first hydraulic pipeline 7 to the shut-off valve 21 is raised, and this raised pressure is given, as the resistance of the first hydraulic pump 9, to the engine 1 driving the pump 9 to exhibit the braking effect as an auxiliary brake.