Abstract: The disclosure is directed to a method and apparatus for precisely controlling the frequency of a laser, and for precise control of distance. In a disclosed embodiment, a laser beam is split, modulated to obtain a frequency differential, and coupled to an interferometer which is designed to produce two processed beams having intensities that vary at the same ac frequency, but at a phase difference that is indicative of the laser frequency. The processed beams are converted to ac electrical signals which are coupled to phase control circuitry. The phase control circuitry determines the phase between the electrical signals and produces a control signal for controlling the laser frequency. Phase offset increments are introduced in the phase detection process, these phase offset increments resulting in controlled changes in the laser frequency. The laser frequency can be computed and read out as a function of the phase offset increments.

Abstract: A clutch drive for a vehicle engine cooling fan includes a pulley portion which is driven by the vehicle engine, a fan plate which rotatably mounts the engine cooling fan, and a pressure plate which engages the fan plate to drive the latter when the clutch is engaged. Torque transmission from the pulley to the pressure plate is through a series of circumferentially spaced coiled springs which also yieldabel urge the pressure plate into driving engagement with the fan plate. A spring stabilizer defines a circumferentially extending cavity which receives several coils of the spring to stabilize the latter and to prevent displacement of the coils circumferentially with respect to each other during engagement and disengagement of the clutch. The stabilizer also slidably engages both the pressure plate and the pulley, thereby taking up clearances between the various members to prevent rattling and also to assist in the transmission of torque to the pressure plate.

Abstract: An external laser frequency stabilizer combines an acousto-optic frequency shifter and a fast electro-optic phase modulator. A compensating electronic delay line in a crossover network provides a near-ideal transducer response while keeping the voltage across the electro-optic crystal away from the amplifier limits.

Abstract: A method and apparatus are disclosed for precisely stabilizing a laser to a sub-Doppler resonance of an absorbing gas contained in a cell located external to the laser resonator. Stabilization is based on the detection of modulation transferred onto a previously unmodulated probe beam by the non-linear interactions of the absorbing gas located in a cell which is subject to a counter-running, frequency-modulated saturation beam. Alternatively, the further modulation of the saturation beam can be detected.

Abstract: A clutch assembly includes an input member, an output member, and clutch plates connected to the input and output members which are driven into drive engagement with one another when the clutch is engaged to connect the output member for rotation with the input member. The clutch plates carried on the input member are mounted on a separate clutch plate carrying member, which is machined before installation on the input member to thereby facilitate manufacture and assembly of the device. A fluid pressure responsive piston operates the clutch plates, and has an outer diameter slidingly and sealingly engaged with the wall to bore of the housing of the input or driving member, and its inner diameter slidingly engaged with an annular retainer which is mounted for rotation with the input member.

Abstract: A clutch drive mechanism (10) interconnects a vehicle engine (12) with a vehicle air compressor (14) to provide a driving connection therebetween when operation of the air compressor (14) is necessary to charge the vehicle reservoir (18) and to break the driving connection to the air compressor (14) when the reservoir (18) is fully charged. The drive mechanism (10) includes a clutch disc pack (82) which is controlled by a piston (52). Piston (52) responds to a pressure signal from a conventional unloader mechanism (20) to disengage the clutch mechanism (10) to disconnect the air compressor (14) from driving connection with the vehicle engine (12). A thrust bearing (68) provides a rotary connection between the piston (52) and the disc pack (82) and another thrust bearing (46) is provided between the output drive (36) and the clutch drive housing (26) so that axial forces or loads are transmitted to the housing (26) instead of to the compressor (14).

Abstract: The control mechanism is for pneumatic apparatus of the kind comprising a piston-and-cylinder motor coupled between two relatively-movable parts (such as door-leaves) for driving them, when energized, to a predetermined relative position. A pilot valve is actuated when required to switch the apparatus to an emergency mode by isolating the motor from its power source and discharging it into an emergency reservoir having a volume large compared with the maximum volume of gas in the motor. While the pilot valve is actuated, the relatively-movable parts are urged towards their predetermined relative positions by a force small compared with the normal operating force. The pilot valve may be arranged to operate operation of an emergency release bolt, on obstruction detected by a detector valve (in which case a timing reservoir provides time delay before full power is restored), on power failure, or as required.

Abstract: Housing has a top and bottom and has a living hinge joining them so that the top and bottom are of monolithic construction of a thermoplastic polymer composition flexible material. The top and bottom are configured so that opposite the hinge an edge on the top with a catch thereon enters between a flange and latch on the bottom so that the latch resiliently engages over the catch to detachably hold the top and bottom in the closed position.

Abstract: Frequency stabilization is disclosed for a two-mode laser, such as a Zeeman aser. The emission frequency of the laser is servo-stabilized to the center of the atomic gain curve to provide a stable laser reference frequency that is independant of time and enviromental operating conditions. Stabilization in a longitudinal-field Zeeman laser is achieved by utilizing the mode-pulling effect which makes the frequency difference between the two circular polarization components have a parabolic dependence on the optical frequency of the laser. The detected intermode beat frequency from the laser is subjected to digital phase-sensitive, drift-free integration, utilizing a reversible counter, to provide a cumulative count with a rate of increase corresponding to the displacement of the average wavelength from the atomic center wavelength and an analog error-correction signal is generated therefrom which is coupled to the laser.

Abstract: In a panic bolt assembly for use on an emergency exit door, a horizontal elongate operating device comprises two elongate bodies hinged together along adjoining horizontal edges. Each body is pivotally mounted on the door about a horizontal axis adjacent the edge of the body remote from the hinged edges. At least one of these pivoted edges is constrained to move vertically with respect to the door to effect engagement or disengagement of a bolt of the door. Pressure imparted to the hinged edges of the device in a direction towards the door effects vertical movement of the pivoted edge or edges to disengage the bolt or bolts.

Abstract: An externally screw threaded member of the self-locking, prevailing torque type has a series of convolutions of a standard thread form, and a locking series of convolutions of the same thread pitch as the standard series but of wider section and with incomplete thread crests. When the member is mated with an internal thread of standard form complementary to the standard series, the locking series of convolutions have an interference fit with the internal thread. In consequence of the interference fit one or both flank portions of each convolution of the locking series are caused to be swaged to some extent towards the crest region.

Abstract: A fringe counting interferometric method and apparatus is disclosed. The aratus comprises a fringe-counting Michelson interferometer employing a velocity-stable carriage means for translating the two corner-cube retroreflectors, two phase locked oscillators and counting and control circuitry. Fringe intensity signals are counted for both a reference and unknown beam, and high accuracy is obtained by multiplying reference beam fringe signals by a fixed integral multiplier employing a phase-lock circuit. In comparing the unknown wavelength with the reference, the convenience of direct readout in wavelength units arises from the use of a high resolution preset counter.

Abstract: A clutched fan drive for a vehicle engine is disclosed which couples the engine cooling fan to a member driven by the vehicle engine when the engine coolant temperature exceeds a predetermined level, and which uncouples the fan when the engine temperature level falls below the predetermined level. The fan drive includes a driving member which is rotatably mounted on a fixed spindle, a ram piston which is slidably mounted on the spindle, and a driven member which is rotatably mounted on the ram piston and which is movable therewith. The engine coolant fan is coupled to the driven member, and both the driven member and the driving member are provided with a clutching mechanism which is engaged by a resilient spring which acts against the ram piston.

Abstract: An axially compliant injection nozzle for plastic molding machines incorporating a valve actuated by differential motion between the mold and the conditioning chamber comprises a tappet engaged on the stem of that valve and entrapping a valve spring between the valve seat and the tappet. The nozzle has a sliding fit with a bore in the tappet head and is biased away from the latter by a secondary spring. The action of the secondary spring aids in maintaining good sealing contact between the nozzle and the sprue bushing and during the injection period despite variations in the lock-up force between the nozzle and the sprue, and retains such contact subsequent to injection so as to prevent plastic drip due to backflow.