Abstract: This invention discloses improvements to a damper of the type used in industrial applications to open and close ducts carrying noxious or corrosive materials, such as combustion by-products. The improvements include a linear rack and wheeled pinion system to raise and lower a damper blade plate and improvements to the seal cartridge to prolong the life of the seal membrane and to prevent galling between the blade plate and the seal cartridge or damper frame.

Abstract: A damper valve includes a base, a valve blade pivotally mounted on the base and two serially arranged valve seats. Each valve seat comprises adjustable valve seat portions on opposite sides of a pivot axis of the valve blade, the valve seat portions being positioned on opposite sides of the blade. Each valve seat portion includes a stationary member fixed to the base, an adjustable element movable relative to the stationary member, and bolts fixing the adjustable element to the stationary member. Adjustment devices are provided for moving each adjustable element toward the valve element to provide a precise fit along the entire length of the valve seat. The valve seats and the valve blade define an annulus which can contain gas at a higher pressure than the fluid controlled by the valve, so that none of the controlled fluid flows past the valve.

Abstract: A damper valve includes a base, a valve element pivotally mounted on the base and adjustable valve seat portions on opposite sides of a pivot axis, the valve seat portions being positioned on opposite sides of the blade. Each valve seat portion includes a stationary member fixed to the base, an adjustable element movable relative to the stationary member, and bolts fixing the adjustable element to the stationary member. In addition, adjustment devices are provided for moving the adjustable element toward the valve element to provide a precise fit along the entire length of the valve seat.

Abstract: A modem is disclosed having a data transmission protocol involving lower-speed, full-duplex operation during the connect sequence with a remote modem and an automatic switch to higher-speed, half-duplex operation for data transfer. Further, the modem data transmission involves transparently changing between lower-speed, interactive operation and higher-speed operation based upon data transmission demands. The operation is controlled by a processor monitoring the contents of a transmit data buffer and providing a mode control command to the modem transmitter. The modem also adapts its speed to the quality of the telephone line by fallback or fallforward to a different speed based upon predetermined data frame retransmission criteria.

Abstract: A diverter valve for diverting the flow of hot gases has a valve door pivotable between two outlets, each of which is surrounded by a bellows seal having a sidewall of significant width for continuous with the valve door and defining with the door a seal of large area. The sidewall is flat and uninterrupted, and the bellows can be made in various shapes, including circular, rectangular with rounded corners, and rectangular with mitered corners.

Abstract: A modem is disclosed having a data transmission protocol involving lower-speed, full-duplex operation during the connect sequence with a remote modem and an automatic switch to higher-speed, half-duplex operation for data transfer. Further, the modem data transmission involves transparently changing between lower-speed, interactive operation and higher-speed operation based upon transmission demands. The operation is controlled by a processor monitoring the contents of a transmit data buffer and providing a mode control command to the modem transmitter. The modem also adapts its speed to the quality of the telephone line by fallback or fallforward to a different speed based upon predetermined data frame retransmission criteria.

Abstract: In a sealing mechanism for a damper plate for a duct, seal members are made in the form of multi-convoluted sheet metal bellows, which engage each side of the damper plate around the periphery of the duct. When the duct is moved from an open position to a closed position, it slides between the seal elements forcing them apart. When the plate is slid from a closed position to an open position, the spring bias in the bellows members will cause them to expand to engage each other.

Abstract: Apparatus for communicating between a number of remote use terminals and a central computer. The apparatus initially answers an incoming call under concentrator control, and transmits an answer tone to the calling terminal. The terminal user places the modem at the terminal in data mode. The apparatus detects which modem type called, conditions the concentrator port interface and connects an answering modem of the same type into the circuit between the telephone line and the concentrator port. The port automatically detects speed and code, and conditions the computer adapter clock and software appropriately to be compatible. The user experiences no change in existing connection sequences and only one telephone number is necessary for servicing a number of different modem types having common access to the computer.

Abstract: Apparatus for controlling an automatic dialer which, in response to dial digits, automatically establishes communication paths over a plurality of telephone lines. The apparatus includes interface logic connected to a computer port for receiving serial digital data from the computer. The data includes control characters and dial digits. The serial data is stored in parallel word format in a random access memory (RAM) buffer. The RAM is operated in three modes, a write mode in which addresses and digits are stored in the RAM, a read mode in which the addresses and digits are presented to the dialer and an abort mode in which a call in progress is interdicted and resumed later, or completely aborted. Control logic responds to the serial interface and stores successive digits in successive RAM address locations, the final word being a buffer empty character to signify the end of the stored data.

Abstract: A full duplex communication system including a pair of full duplex modems. Each modem has both a call originate mode of operation and a call answer mode of operation. In the call originate mode outgoing data is transmitted by modulation of a carrier frequency F2 and incoming data is received by demodulation of a data modulating carrier of frequency F1. When in the answer mode of operation, the data is received on frequency F2 and transmitted on frequency F1. Means are provided for injecting a carrier frequency F6 in the outgoing data transmission path. The frequency F6 is near the midpoint between F1 and F2. The amplitude is such that the distribution of power within the transmission band is balanced so that the power in the frequency band set aside for single frequency signaling systems does not exceed the power in the remainder of the transmission band.