主权项 |
1. An apparatus comprising:
a support structure comprising a plurality of vertical support members, each of the plurality of vertical support members having a load-engaging portion located at an upper end, a ground-engaging portion located at a lower end, and a telescoping portion that enables the load-engaging portion to be raised and lowered relative to the ground-engaging portion, wherein the load-engaging portion, ground-engaging portion, and telescoping portion are vertically aligned and the telescoping portion is releasably connectable to the ground-engaging portion and moveable with respect to the ground-engaging portion; and at least one extension and retraction device that is adapted to releasably engage the telescoping portion and to cause the telescoping portion to extend and retract with respect to the ground-engaging portion. |