Abstract: Apparatus for use in the measurement of a variable comprises a housing; a first transducer which is mounted within the housing and which is arranged to produce an electrical transducer output signal which depends both on the value of the variable and on the value of at least one calibration constant of the transducer; an encoder which is mounted within said housing and which is programmed with information relating to the value of said at least one calibration constant, said encoder being arranged to produce an electrical encoder output signal representative of the value of the said at least one calibration constant, and connector means carried by said housing and electrically connected to the first transducer and to the encoder to receive signals functionally related to the transducer and encoder output signals, the connector means being connectible to a second transducer for the transmission of the said functionally related signals thereto.

Abstract: In a vehicle detector installation employing an inductive sensing loop that is a frequency determining element of an oscillator, the oscillator is provided with a voltage controlled capacitor as another frequency determining element and is made the voltage controlled oscillator (VCO) of a phase locked loop whereby the VCO is locked to a reference frequency. The presence of a vehicle in the vicinity of the loop causes the capacitor voltage to vary to maintain lock. The varying voltage is applied to an auxiliary VCO whose frequency is accordingly varied and may be analyzed for vehicle detection purposes. The oscillator containing the sensing loop is thereby prevented from influencing nearby installations by the FM sidebands that would be produced in the absence of the frequency locking. A group of such installations may use a common reference frequency source with each installation operating at its own locked frequency by virtue of means providing a programmable frequency division ratio from the source.

Abstract: A stuffing box comprising a housing member having a threaded passage therethrough and having an internally threaded recess, an externally threaded stem which is threaded into and passes through the threaded passage, a gland nut which is disposed in said recess, the gland nut having corresponding internal and external threads which are respectively threaded onto the threaded stem and into the internally threaded recess, and sealing material disposed in said recess, said sealing material being in engagement with the housing member, the threaded stem and the gland nut.

Abstract: An electronic vehicle detection installation of the type using a detector loop laid in the roadway senses changes in the inductive time constant of the loop. The changes are sensed by determining the phase difference between a voltage impressed on the loop and the loop current or by making the time constant the predominant frequency determining parameter of an astable oscillator. A digital processing circuit is provided to sense vehicle-indicative changes in the oscillator frequency. Clock pulses are counted over a selected number of oscillator cycles, the scan cycle, and the number counted over one scan cycle is compared with that stored from the preceding cycle. Provision is made to adjust the stored value for ambient changes and for the continued presence of a vehicle after a selected presence period.