A hydraulic system is adapted to provide at least one of a fluid flow at a variable fluid pressure or a fluid flow at a variable fluid displacement. A pressure sensor measures a fluid pressure. A controller is in communication with the engine and the pressure sensor. Wherein, the controller sends an engine speed signal to operate the engine in an open state and controls the fluid displacement or the fluid pressure of the hydraulic system to a first load condition. Further wherein, the controller detects an engine speed and a fluid pressure of the hydraulic system with the pressure sensor when the engine is in the open state and the hydraulic system is in the first load condition. Further wherein, the controller operably calculates a total engine torque as a function of the detected engine speed and fluid pressure when the hydraulic system is in the first load condition.

A work vehicle having a plurality of working modes allowing working in accordance with a load state includes an engine, an exhaust gas purification apparatus, a reducing agent tank, a state determination portion, and an engine control unit. The exhaust gas purification apparatus purifies a nitrogen oxide in an exhaust gas. The reducing agent tank stores a reducing agent. The state determination portion determines a state of the reducing agent. The engine control unit controls output of the engine with the use of a restricted-operation engine output torque curve in which horsepower output from the engine is lower than horsepower output from the engine at the time when each of the plurality of working modes is selected, when a state of the reducing agent is equal to or lower than a reference value.

An engine idle control method of an off highway vehicle. The method including the steps of: detecting a static load on the engine; detecting a dynamic load on the engine; determining if the static load is below a predetermined static level; determining if the dynamic load is less than a predetermined range; and engaging an auto-idle feature dependent upon both of the determining steps being true.

A shovel includes a lower traveling body, an upper turning body turnably mounted on the lower traveling body, an engine mounted on the upper turning body, a hydraulic pump mounted on the upper turning body and configured to be driven by the engine, and processing circuitry configured to collect diagnostic data of the shovel, in response to detecting that the engine is driven under a constant driving condition.

A controller mounted on a small-sized hydraulic excavator includes an engine restart section that restarts an engine when a horn switch operation determining section determines that a horn switch is operated and a gate lock lever position determining section determines that a gate lock lever is at a lock position in a case where a restart standby time determining section determines that restart standby time does not yet elapse after the engine is automatically stopped by an idling stop function, and a power supply stopping section that stops an electric power supply of a vehicle body when the restart standby time determining section determines that the restart standby time has elapsed.

A work machine includes an engine power management system. The work machine includes an engine, a hydraulic temperature sensor, and a coolant temperature sensor. The hydraulic temperature sensor is configured to monitor and transmit a hydraulic fluid temperature, and the coolant temperature sensor is configured to monitor and transmit a coolant fluid temperature. The work machine also includes an engine controller and a machine controller. The engine controller includes a processor, and is operatively associated with the engine and the coolant fluid temperature sensor. The machine controller includes a processor, and is operatively associated with the hydraulic fluid temperature sensor and the engine controller. The machine controller is configured to transmit a torque limit command to the engine controller when the hydraulic fluid temperature or the coolant fluid temperature exceeds a predetermined temperature threshold.

A method is provided for controlling engine speed of a drive engine of a utility vehicle having a drivable loading apparatus. The method includes detecting or predicting a driving movement of the loading apparatus, and requesting an increase of engine speed if the movement of the loading apparatus is predicted or detected.

There is provided a construction machine that draws attention from the surroundings of the machine body when the prime mover is started and that can have the operator reliably confirm the surroundings of the machine body before the prime mover is started. An engine start control section 23 of a main controller 22 inhibits an engine 18 from starting when a key switch 12 is operated while a horn switch 21 is not operated, inhibits the engine 18 from starting when the key switch 12 is operated for the duration until a first set time T1 elapses after the operation of the horn switch 21 has been finished, permits the engine 18 to start in a case the key switch 12 is operated for the duration until a second set time T2 elapses after the first set time T1 has elapsed, and inhibits the engine 18 again from starting when the key switch 12 is operated if the engine 18 is not started for the duration until the second set time T2 elapses.

Provided is a construction machine capable of accurately notifying a worker that a prime mover is in a drive state. The construction machine includes a prime mover, a heat exchanger, a fan that blows air to the heat exchanger, a controller, and notification units. Only when all of a plurality of notification judgment conditions, which include a condition that the prime mover is in a drive state and a drive sound condition for judging that the drive sound of the fan is low, are satisfied, the controller inputs a notification instruction to the notification units. With input of the notification instruction, the notification units perform notification that the prime mover is in a drive state.

A work machine includes: a work device; an operation device operating the work device; a first controller controlling operation of the work device on the basis of operation of the operation device; and a second controller determining that an auto idle condition is satisfied and performing auto idle control that decreases an engine revolution speed to an idle revolution speed in case the operation device is not operated for a predetermined time. The first controller diagnoses presence or absence of a failure in the first controller when supply of power to the first controller is started. The second controller performs power interruption control that interrupts the supply of the power to the first controller in case the auto idle condition is satisfied, and performs power supply control that starts the supply of the power to the first controller afterward.