| 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 that is adapted to engage a support surface on which the apparatus is placed, a length that is adjustable, and a telescoping portion that enables the load-engaging portion to be raised and lowered relative to the ground-engaging portion, wherein the telescoping portion is releasably connectable to the ground-engaging portion and moveable with respect to the ground-engaging portion; and a support portion-engaging unit that is releasably connectable to each of the plurality of vertical support members, the support portion-engaging unit having a first configuration in which the position of the support portion-engaging unit is fixed relative to the telescoping portion of each of the plurality of vertical support members and a second configuration in which the support portion-engaging unit is vertically movable relative to the telescoping portion of each of the plurality of vertical support members; and at least one extension and retraction device connected at a first end to the support structure and at a second end to the support portion-engaging unit, wherein extension or retraction of the at least one extension and retraction device while the support portion-engaging unit is connected to at least one of the plurality of vertical support members causes the length of the at least one of the plurality of vertical support members to be adjusted. |
