I take it you're talking about the centre gear on the A3456. The centre gear has a pitch trimmer assembly just like that on the main gears. The assembly has been designed to move the centre gear bogie to the trail position to allow the gear to retract into the fuselage bay. It's also required to move the bogie to the dip position to allow the centre forward doors to close without fouling the gear. By keeping the bogie in this position rather than to move it back to the trail position like the main gear would require an extra command in the LGCIU sequence logic which would add to its complexity.