Boom angle indication system

Claim 2

Boom angle indicating apparatus comprising: a boom angle transducer for connection to a boom and operable to produce an angle signal indicative of the angle of the boom with respect to a reference plane; reference means operable to provide first and second reference signals indicative of respective angle limits of the boom to define a permissible range of boom position; first indicating means connected to said transducer for indicating boom angle; and seconD indicating means connected to said transducer and to said reference signal means and operable in response to an angle signal which is equal to said first or second reference signals to indicate that the boom is not within the permissible range, wherein said second indicating means comprises first and second differential amplifiers connected to receive respective ones of the first and second reference signals and to receive the angle signal, each of said differential amplifiers operable upon receipt of an angle signal of at least the magnitude of its respective reference signal; alarm means; and energizing means connected between said differential amplifiers and said alarm means operable to energize said alarm means in response to the operation of a differential amplifier.

Claim 3

The apparatus according to claim 1, wherein said boom angle transducer includes a pendulum-type potentiometer for connection to an electrical supply.

Claim 4

The apparatus according to claim 1, comprising an amplifier connected between said transducer and said first indicating means.

Claim 5

The apparatus according to claim 1, wherein said first indicating apparatus includes a meter having a dial calibrated in degrees.

Claim 6

The apparatus according to claim 4, comprising an amplifier connected between said transducer and said meter.

Claim 7

The apparatus according to claim 5, wherein said amplifier is an operational amplifier having unity gain.

Claim 8

The apparatus according to claim 1, wherein said reference means comprises an impedance network for connection to an electrical supply including first and second variable output means for providing said first and second reference signals.

Claim 9

The apparatus according to claim 1, wherein said energizing means includes gating means operable to perform an OR function.

Claim 10

The apparatus according to claim 1, wherein said energizing means includes relay means connected between said gating means and said alarm means and operable in response to the operation of said gating means.

Claim 11

The apparatus according to claim 8, wherein said alarm means includes a visual alarm device.

Claim 12

The apparatus according to claim 8, wherein said alarm means includes an audible alarm device.

Claim 13

The apparatus according to claim 9, wherein said relay means includes an electromechanical relay and an electronic relay driver.

Claim 14

Boom angle indicating apparatus comprising: a boom angle transducer for mounting on a boom, said transducer including a pendulum-type variable resistance for connection to an electrical supply and operable to produce an angle signal whose magnitude is indicative of the angle of the boom with respect to a reference plane; first indicating means including a meter calibrated in degrees; a unity gain amplifier connected to said transducer for coupling said transducer to said meter; a variable resistance network for connection to an electrical supply including first and second manually variable means operable to provide first and second reference signals to define a range of angle signal magnitudes representative of a permissible range of angular positions of the boom; switching means for receiving the angle signal and the first and second reference signals and operable to provide an electrical signal in response to an angle signal whose magnitude is outside the defined signal range; and alarm means connected to said switching means and operated in response to said electrical signal, wherein said switching means comprises a pair of differential amplifiers each of which is connected to said unity gain amplifier and to a respective manually variable means, and a gating circuit connected to each of said differential amplifiers and operable to provide said electrical signal.

Claim 15

Boom angle indicating apparatus comprising: a boom angle transducer for mounting on a boom, said transducer including a pendulum-type variable resistance for connection to an electrical supply and operable to produce an angle signal whose magnitude is indicative of the angle of the boom with respect to a reference plane; first indicating means including a meter calibrated in degrees; a unity gain amplifier connected to said transducer for coupling said transducer to said meter; a variable resistance network for connection to an electrical supply including first and second manually variable means operable to provide first and second reference signals to define a range of angle signal magnitudes representative of a permissible range of angular positions of the boom; switching means for receiving the angle signal and the first and second reference signals and operable to provide an electrical signal in response to an angle signal whose magnitude is outside the defined signal range; and alarm means connected to said switching means and operated in response to said electrical signal, wherein said switching means comprises a pair of differential amplifiers each of which is connected to said unity gain amplifier and to a respective manually variable means, and a gating circuit connected to each of said differential amplifiers and operable to provide said electrical signal.

Claim 16

The apparatus according to claim 13, wherein said switching means includes a relay connected to an energized by said gating circuit.

Claim 17

The apparatus according to claim 14, wherein said alarm means includes a visual alarm device connected to and operated by said relay.

Claim 18

The apparatus according to claim 15, wherein said alarm means includes an audible alarm device connected to and operated by said relay.