Abstract: Apparatus for indicating, to the operator of a combine, that a sieve overload or blockage has developed comprises wind sensors responsive to the fan air flow within the cleaning section of the harvester. The flow sensor signals are compensated for the ambient temperature within the combine such that they are independent thereof. The apparatus includes a monitor circuit for detecting a low flow indicative of blockage or overload and warning means responsive thereto to alert the operator.

Abstract: A defrosting control for a heat pump system utilizes a first temperature sensor mounted to the outdoor coil fan motor windings, a second sensor mounted to sense the outdoor ambient air temperature and a third sensor to sense the refrigerant temperature in the outdoor coil. The control circuitry determines the temperature difference of the first two sensors, representing the fan motor temperature rise, which increases dramatically when the outdoor coil is frosted; if the difference exceeds a selected abnormal temperature rise and the temperature sensed by the third sensor indicates frosting is likely to have occurred, the defrost cycle is initiated. The cycle is terminated when the temperature sensed by the third sensor indicates that all frost is likely to have melted.

Abstract: The invention concerns a device indicating a state due to the pressure modification, in particular an overpressure or a vacuum pressure switch for the indication of the fullness of the dust bags in household or industrial vacuum cleaners with a diaphragm exposed on one side to the variable pressure and with a contacting action between two contact elements as caused by the diaphragm's movement.

Abstract: A vibration isolator is connected in line between an air intake tube (22) of an engine (14) and a pressure-responsive switch (30) to isolate the pressure-responsive switch from vibration during operation of the engine. The isolator includes a pair of metallic coupling members (52, 54) connected together by a resilient tube (50) providing fluid communication between the air tube (22) and the pressure-responsive switch (30). A conductive wire is disposed within the resilient tube for electrically connecting the switch in its associated indicator or warning light (32) circuit.

Abstract: A restriction indicator having a contactless switch device for indicating a restriction in filter elements of fluid filters having an intake side and a negative pressure side. The restriction indicator includes a photointerrupter having a light emitting device and a light receiving device. The light receiving device provides an electrical signal indicative of increased negative pressure in the negative pressure side.

Abstract: A system for warning an operator when the vacuum in a system, such as a diesel engine air intake system, exceeds a predetermined maximum because of clogging of the air cleaner or other reasons, and when the vacuum falls below a predetermined minimum value indicating loss of air cleaning action as, e.g., because of damage to the air cleaner or because of a hole or leak in the air intake system. The system includes a vacuum gauge having spaced, adjustable electrical contacts, an electrically conductive indicator movable between the contacts, and means responsive to the change in air intake system vacuum to move the indicator; and an electrical circuit having one or more visual or audible warning signal devices. The electrical contacts are connected to the circuit and the indicator is electrically grounded such that when the indicator engages one or the other of the electrical contacts on an unacceptable rise or loss of vacuum, respectively, it closes the circuit to actuate the warning signal device.

Abstract: A Poppet valve is disclosed of the type in which a valve member located in a flow passage is biased to the closed position on a valve seat, and in which an electrical indication is provided, when the valve seats or unseats, by an indicator circuit which includes a current path through the valve and valve seat which is opened and closed by seating and unseating respectively of the valve. The valve construction includes a conductive rubber seal which insures a positive seal while allowing the passage of electric current for activating the indicator circuit. In one embodiment, a thin metal contact washer is used in conjunction with the rubber seal to enhance its conductivity, the configuration of the contact washer allowing good sealing contact while greatly improving the contact conductivity.The indicator circuit activates an indicator device such as a panel light in response to the making or breaking of the current path caused by seating or unseating of the valve.