Pallet transport device

1. A pallet transport device comprising:

a plurality of pallet rails configured to movably guide a pallet;

a plurality of moving mechanisms provided for the respective pallet rails, the plurality of moving mechanisms being configured to move the pallet along the pallet rails;

a transfer mechanism including a pivoting member and a retaining rail, the pivoting member being pivotable around a pivot axis in a horizontal direction, the retaining rail being mounted on the pivoting member and capable of retaining the pallet, the transfer mechanism being configured to transfer the pallet guided by one of the pallet rails to another one of the pallet rails using the pivoting member and the retaining rail;

a moving assistance mechanism configured to move the pallet from the pallet rails to the retaining rail, or from the retaining rail to the pallet rails; and

an elevator mechanism configured to cause the moving assistance mechanism to ascend and descend, wherein

when the elevator mechanism has caused the moving assistance mechanism to descend, the transfer mechanism becomes in a state where the transfer mechanism is capable of causing the pivoting member to pivot.

2. The pallet transport device according to claim 1 , wherein

the plurality of pallet rails are arranged in parallel to each other at a predetermined interval in the horizontal direction, or arranged in such a manner that a narrow angle formed thereby in the horizontal direction is a right angle or a predetermined angle.

3. The pallet transport device according to claim 1 , wherein

the moving assistance mechanism includes an endless auxiliary circulation belt arranged circulatably along the retaining rail and end portions of the pallet rails positioned collinearly with the retaining rail,

projection portions and recess portions are provided on an outer surface of the auxiliary circulation belt in an alternating manner along a longitudinal direction,

engagement portions engageable with the projection portions and the recess portions are provided on a lower surface of the pallet,

the ascent of the moving assistance mechanism brings the engagement portions of the pallet into engagement with the projection portions and the recess portions of the auxiliary circulation belt, and

the descent of the moving assistance mechanism releases the engagement between the engagement portions and the projection portions and the recess portions.

4. The pallet transport device according to claim 1 , further comprising:

an auxiliary rail provided continuously with the pallet rails, the auxiliary rail being provided along the moving assistance mechanism; and

an auxiliary rail elevator mechanism configured to cause the auxiliary rail to ascend and descend, wherein

the auxiliary rail elevator mechanism causes the auxiliary rail to ascend and descend between a first position where the auxiliary rail is collinear with the pallet rails and a second position lower than the first position.

5. The pallet transport device according to claim 4 , wherein

the auxiliary rail has a swing fulcrum point at a portion thereof near the pallet rails, and is provided swingably around the swing fulcrum point along a vertical plane, and the auxiliary rail elevator mechanism causes a portion of the auxiliary rail distant from the swing fulcrum point to ascend and descend.

6. The pallet transport device according to claim 1 , wherein

the retaining rail is provided in such a manner that a tilt thereof in a longitudinal direction is changeable with respect to a horizontal plane.

7. The pallet transport device according to claim 6 , wherein

the plurality of pallet rails include at least one tilted pallet rail tilted with respect to the horizontal plane, and

the moving mechanisms provided along the tilted pallet rail are tilted with respect to the horizontal plane in accordance with a tilt of the tilted pallet rail.