Abstract: An improved device useful for hurling baseballs or the like to players in practice ball-hitting sessions has been developed. It provides multi-directional spin control to make a ball curve in any chosen direction from a normal trajectory path, as well as speed control, and it can be carried as a substantially lighter-weight and more easily portable package than the massive and expensive electric-powered curve-ball hurlers such as are now used by professional teams. The spin control is provided by attaching one end of a strap to the ball-holding pouch of an elastic-powered slingshot, or catapult, such that the loose end of the strap may be wrapped in any chosen direction around the ball as it is nested into the pouch, and the strap will induce a spinning motion on the ball when it flies out. The speed control is provided by a light-weight flexible cord that limits the length to which the elastic members of a slingshot may be stretched back; variable settings are possible.

Abstract: A heat exchanger-combustion chamber construction includes a combustion chamber and a heat exchanger chamber. Disposed in the heat exchanger chamber is an array of inlet tubes, the outlets of which discharge into the combustion chamber. Combustion products discharged from the combustion chamber are flowed over the inlet tubes in heat exchange relation. An array of aspirator sleeves of larger inner dimension than the outer dimension of the inlet tubes is secured to divider structure between the heat exchanger chamber and the combustion chamber, each aspirator sleeve receiving the outlet end of a heat exchanger tube while permitting longitudinal movement of the heat exchanger tube within the sleeve (due to thermal expansion, for example).

Abstract: It has been known that volatile organic compounds evaporated in a substantially closed drying oven may be recovered by condensing part of the vapors in a cooler and recycling the mixture of the non-condensed vapor and inert gas back to the oven. However, non-steady state conditions tend to cause volume and pressure variations resulting in an out-breathing of oven atmosphere through the oven's entrance and exit ports, and an in-breathing of outside atmosphere. The invention provides a flexible expansion-contraction chamber to temporarily receive excess gas volume return it to the oven with minimal change in pressure. This reduces the loss of vapor, minimizes the need for inert gas addition, and conserves energy.

Abstract: A vacuum-insulated thin-wall panel requires internal spacers to resist the compressive force of the atmosphere and to hold the sides apart. Such spacers are paths for heat flow by conduction. However, in the panel of this invention, the sides are held apart by a web of relatively thin and long spacers stressed in pure tension. Heat flow through such spacers is substantially less than through the more massive spacers designed to be stressed in compression.

Abstract: Automatic gear shifters or speed changers for bicycles and the like have been described which are intended to be responsive to speed changes as sensed by centrifugal weights or force changes as sensed by chain tension. It is necessary to prevent excessive shifting due to cyclic pedal positions, vibrational conditions, or shock loads. The subject, a force responsive automatic shifter, employs a hydraulic damping system to limit the rate of shifting, and in a simplified arrangement, the force is sensed indirectly from that portion of the rider's weight which rests on the saddle seat.

Abstract: A ski boot molded to be relatively stiff in a lateral direction but independently flexible in the forward-backward direction, characterized by molded elastomeric hinges and corrugations.

Abstract: A hinged ski boot with relatively great flexibility in the forward-backward direction, as is preferred for walking and a stride type of skiing, and means to be substantially stiffened, as is preferred for down-hill skiing, by the addition of a removable interlocking stiffening collar, wherein the stiffening collar can be attached or detached easily by the skier.