PROBLEM TO BE SOLVED: To prevent generation of failure in transportation caused by increase of grain culms scraped between scraping wheels through which the grain culms pass in the pre-processing unit of a combine which transports the grain culms backward by scraping ends of the grain culms by two or more scraping wheels arranged in parallel and engaged with gears. SOLUTION: In carrying out an engagement driving of scraping star wheels 18a, 18b, 18c, 18e, 18f equipped to scraping devices 20L, 20C, 20R, rates of engagement between the scraping star wheels 18a and 18b, 18c and 18d and 18e and 18f through which reaped grain culms pass are brought to be smaller than a rate of engagement between the scraping star wheels 18b and 18c through which reaped grain culms do not pass. COPYRIGHT: (C)2008,JPO&INPIT
