Abstract: Two pairs of double-acting pistons are disposed in a hollow toroidal structure. Each pair of the double-acting pistons is operatively connected together and moves in the same rotational direction. Each of the pistons has two heads which cooperate with a head of an adjacently disposed piston to define a cylinder therebetween. Near the closest approach of two opposed heads, the fuel-air mixture is burned and the pistons recede from each other on an expansion stroke. Near their farthest separation, one of the opposed heads of the defined cylinder first opens an exhaust port and then the other one of the opposed heads opens an intake port. On a return compression stroke, during which the opposed heads move toward each other, the exhaust port is closed first and the intake port last.

Abstract: A heatable turntable is provided for efficiently warming and serving food. A deck is rotatably mounted on a base. Electrical current is supplied from a power supply in the deck to thermal pads located in the deck via wires connected to sliding pole pieces attached to the base and deck. Individual thermostats are provided for each thermal pad to prevent overheating when a pad is unoccupied. Each thermal pad is located within a recess in the deck such that each pad extends out of the recess to permit air to flow between the deck and an object placed on the pad, whereby efficient heat exchange is promoted. Also, each thermal pad has a heating element comprising a resistance plate sandwiched between two mica insulation plates. The heating surface of each pad can be concave shaped towards this sandwich and has a lower lip which compresses the sandwich towards the heating surface. In addition, the sandwich is biased towards the concave heating surface by a screw actuated bracket.

Abstract: A heatable turntable is provided for efficiently warming and serving food. A deck is rotatably mounted on a base. Electrical current is supplied from a power supply in the deck to thermal pads located in the deck via wires connected to sliding pole pieces attached to the base and deck. Individual thermostat is provided for each thermal pad to prevent overheating when a pad is unoccupied. Each thermal pad is located within a recess in the deck such that each pad extends out of the recess to permit air to flow between the deck and an object placed on the pad, whereby efficient heat exchange is promoted. Also, each thermal pad has a heating element comprising a resistance plate sandwiched between two mica insulation plates. The heating surface of each pad can be concave shaped towards this sandwich and has a lower lip which compresses the sandwich towards the heating surface. In addition, the sandwich is biased towards the concave heating surface by a screw actuated bracket.