Abstract: A tractor includes a working motor, a work machine including a roller configured to rotate by an output from the working motor, a support mechanism configured to support the work machine such that a working posture and a retracting posture are achievable, and a control device. The control device executes: an adherence amount acquisition process of acquiring an estimated adherence amount as an estimated value for the amount of mud attached to the roller; and a mud removal process of, when the estimated adherence amount is equal to or more than a determination adherence amount, removing the mud from the roller by driving the working motor in a state where the work machine takes the retracting posture.

Abstract: An oscillosope operation supporting device which assures easy and correct use of an oscilloscope by an operator unfamilar with such an instrument. The device is used in combination with an oscilloscope and comprises a controlling means, an operator guide display unit, and a confirmation signal inputting means. Operation procedures for individual functions of initialization, calibration, measurement and data storage of the oscilloscope are indicated in a predetermined order on the operator guide display unit. An operator will operate the oscilloscope only in accordance with the operation procedures indicated on the display unit.

Abstract: There is provided a cylinder power balance diagnostic apparatus for an internal combustion engine, in which all of the diagnostic procedures are automatically conducted. An ignition signal generated in synchronism with an ignition pulse to be supplied to each cylinder is taken out. On the basis of the ignition signal, at least one cylinder to be misfired is designated. The designated cylinder is misfired for a predetermined period and the number of engine rotations is detected when the period has elapsed. Such operation is successively conducted for respective cylinders. On the basis of the number of engine rotations when misfiring of each cylinder has been finished, a detective cylinder is determined.