A grain cleaning system for receiving grain and residual crop material from a threshing system in an agricultural harvester, the grain cleaning system comprising: a set of sieves (46, 48, 50) for separation of the grain from the residual crop material that comes from the threshing system; and a chaff pan receiving some of the residual crop material from the set of sieves (46, 48, 50), the chaff pan having a pivotal axis near an end of the chaff pan; said chaff pan having: at least one chaff pan dual locking system (100, 200) coupled to the chaff pan for the holding of the chaff pan in two different positions when the chaff pan is pivoted about the pivotal axis relative to the grain cleaning system, characterized in that said chaff pan dual locking system (100, 200) has: a first over-center locking arrangement (102, 202) to hold the chaff pan in an upward engaged position when the first over-center locking arrangement (102, 202) is locked, the first over-center locking arrangement (102, 202) having: a first linkage element (110, 210) pivotally coupled to the chaff pan; a second linkage element (108, 208) pivotally coupled to the first linkage element (110, 210); and a third linkage element (106, 206) non-pivotally constrained about the pivotal axis, the second linkage element (108, 208) being pivotally coupled to the third linkage element (106, 206); and said chaff pan has a second over-center locking arrangement (104, 204) to hold the chaff pan in a downward disengaged position when the second over-center locking arrangement (104, 204) is locked, the second over-center locking arrangement (104, 204) having: a first linkage element (110, 210) pivotally coupled to the chaff pan; and a second linkage element (112, 74) pivotally coupled to the first linkage element (110, 210), the first linkage element (110, 210) of the first over-center locking arrangement (102, 202) being the first linkage element (110, 210) of the second over-center locking arrangement (104, 204). a set of sieves (46, 48, 50) for separation of the grain from the residual crop material that comes from the threshing system; and a chaff pan receiving some of the residual crop material from the set of sieves (46, 48, 50), the chaff pan having a pivotal axis near an end of the chaff pan; said chaff pan having: at least one chaff pan dual locking system (100, 200) coupled to the chaff pan for the holding of the chaff pan in two different positions when the chaff pan is pivoted about the pivotal axis relative to the grain cleaning system, characterized in that said chaff pan dual locking system (100, 200) has: a first over-center locking arrangement (102, 202) to hold the chaff pan in an upward engaged position when the first over-center locking arrangement (102, 202) is locked, the first over-center locking arrangement (102, 202) having: a first linkage element (110, 210) pivotally coupled to the chaff pan; a second linkage element (108, 208) pivotally coupled to the first linkage element (110, 210); and a third linkage element (106, 206) non-pivotally constrained about the pivotal axis, the second linkage element (108, 208) being pivotally coupled to the third linkage element (106, 206); and at least one chaff pan dual locking system (100, 200) coupled to the chaff pan for the holding of the chaff pan in two different positions when the chaff pan is pivoted about the pivotal axis relative to the grain cleaning system, characterized in that said chaff pan dual locking system (100, 200) has: a first over-center locking arrangement (102, 202) to hold the chaff pan in an upward engaged position when the first over-center locking arrangement (102, 202) is locked, the first over-center locking arrangement (102, 202) having: a first linkage element (110, 210) pivotally coupled to the chaff pan; a second linkage element (108, 208) pivotally coupled to the first linkage element (110, 210); and a third linkage element (106, 206) non-pivotally constrained about the pivotal axis, the second linkage element (108, 208) being pivotally coupled to the third linkage element (106, 206); and a first linkage element (110, 210) pivotally coupled to the chaff pan; a second linkage element (108, 208) pivotally coupled to the first linkage element (110, 210); and a third linkage element (106, 206) non-pivotally constrained about the pivotal axis, the second linkage element (108, 208) being pivotally coupled to the third linkage element (106, 206); and said chaff pan has a second over-center locking arrangement (104, 204) to hold the chaff pan in a downward disengaged position when the second over-center locking arrangement (104, 204) is locked, the second over-center locking arrangement (104, 204) having: a first linkage element (110, 210) pivotally coupled to the chaff pan; and a second linkage element (112, 74) pivotally coupled to the first linkage element (110, 210), the first linkage element (110, 210) of the first over-center locking arrangement (102, 202) being the first linkage element (110, 210) of the second over-center locking arrangement (104, 204). a first linkage element (110, 210) pivotally coupled to the chaff pan; and a second linkage element (112, 74) pivotally coupled to the first linkage element (110, 210), the first linkage element (110, 210) of the first over-center locking arrangement (102, 202) being the first linkage element (110, 210) of the second over-center locking arrangement (104, 204).