Dolly and cart system with independently slidable jaws

A dolly (5) comprising:

• a caster/jaw support member (32) comprising:
• a first surface (25) opposite to a second surface (52);
• a sliding guide channel (30) within the first and second surfaces;
• and
• a slot (31) within the first and second surfaces;
• an upper jaw assembly (39) comprising:
• a first jaw (15) slidably mounted on the first surface (25);
• and
• a selectively engageable threading structure (65A, 65B, 65C) comprising a partially-threaded hole (65A-7, 65B-7, 65C-5), wherein the threading structure (65A, 65B, 65C) is disposed in a first hole (70,78) on the first jaw (15) and extending away from the first jaw (15) through the slot (31);
• a lower jaw assembly (38) comprising:
• a lower jaw carriage (50) slidably mounted on a second surface (52) and connected to the first jaw (15), wherein the selectively engageable threading structure (65A, 65B, 65C) is disposed in a second hole (75) on the lower jaw carriage (50);
• a threaded shaft (40) disposed in a receiver hole (62) on the lower jaw carriage (50) and disposed in the partially-threaded hole (65A-7, 65B-7, 65C-5);
• and
• an adjustment knob (45) connected to the threaded shaft (40);
• and
• a set of casters (10, 85) connected to and extending away from the caster/jaw support member (32).