A regulator of air pressure within a hot or cold storage chamber which comprises a damper and frames. The damper is disposed within an opening provided at a wall of the storage chamber defining an air passage, and the frames are airtightly in contact with peripheral surfaces of the opening and the damper at the inside and outside of the storage chamber to close the air passage. The damper and either one of the frames are moveable in the inside or outside direction of the storage chamber in accordance with variations of air pressure within the storage chamber to thereby release the sealing of the air passage and establish pressure equilibrium between the inside and outside of the storage chamber.

A housing is divided into two chambers. A tube connects the two chambers. The end of the tube forms a valve seat on each end. The valve seat in one chamber angles upward and the valve seat in the opposite chamber angles downward. A flapper valve is attached above the top of the valve seat which angles upward, and at the bottom of the valve seat which angles downward. Gravity acting upon the flapper valves will hold one in the open position and the other in the closed position unless it is opened by a flow of fluid. Turning the housing upside down will reverse the position of the flapper valves so that the permitted fluid flow will be reversed.

This invention relates to a combination of multiple tires disposed adjacently parallel to each other on a single wheel, respective inner spaces of the multiple tires being communicated with each other by way of an airflow piping. The airflow piping comprises a pneumatic pressure control valve which can be opened or closed due to an air-leaking condition of the multiple tires. When one of the multiple tires leaks air rapidly, the pneumatic pressure of the other normal tire is also decreased, thereby allowing the driver to notice the puncture. If the former leaks air slowly, its air is supplied by the latter, respective pneumatic pressures are going to become equal, thereby the driver can drive for a certain time and be free from any serious accident that may occur when he is unaware of the puncture.

Multiple tires are mounted adjacently parallel to each other on a single wheel. Respective inner spaces of the multiple tires communicate with each other by way of an airflow pipe for the transfer of air. The airflow pipe includes a pneumatic pressure control valve that opens or closes in response to air leaking from one or more of the multiple tires. When one of the multiple tires leaks air rapidly, the pneumatic pressure of the other normal tire decreases, thereby forcing the driver to notice the puncture. If one tire leaks air slowly, its air is replenished from another tire. Thus the respective pneumatic pressures of the individual tires become equal, whereby the driver can continue to drive for a time without risking the serious accident that could occur if he were unaware of the leak.

Thermal conduction through a liquid line is deterred when liquid is not flowing through it by lodging a double-acting spring-centered plunger in a constricted section of a passage connecting opposite ends of a barrel in the line. Such plunger can be displaced from the passage constricted section in either direction to a passage expanded section automatically by pressure of liquid in the line resulting from opening a valve in the line.