PURPOSE: To simplify installation and removal of a hood while improving strength by a method wherein a support frame for supporting a hood sheet in a specified shape is constituted of an elastic support cylinder and gas filled inside, while exhaust gas of an engine is utilized as the gas.

CONSTITUTION: When a hood 6 is to be assembled on a load-carrying platform 3 of a truck 1, a sheet 7 is initially extended loosely with circular pipes 9 mounted on respective portions of a gate panel 4. Then, a cap 18 on one side of an exhaust pipe 15 is removed, and its portion having the largest diameter 17 is inserted into a tail pipe 13. With an engine driven, its exhaust gas is injected into a support cylinder 8 from the exhaust pipe 15 through a tube 12. This allows the support cylinder 8 to be filled with high pressure exhaust gas making the support cylinder 8 fully extend and molding the sheet 7 in a shape as shown in the figure. On the other hand, when the hood 6 is to be folded, negative pressure is generated by passing exhaust gas through an orifice portion 16 of the exhaust pipe 15, thereby sucking and discharging the exhaust gas in the support cylinder 8.