Abstract: A lift truck having a frame and a two-stage telescopic mast in which an outer, movable mast is mounted to telescope over an inner mast which is fixed to the frame, each mast having a substantially continuous, unitary tubular body which provides superior strength characteristics in response to torsional loads and bending moments. The masts each include vertically extending beams, integral with the tubular bodies thereof, having tracks to receive rollers mounted to the beams so that the only contact between the masts is by the rollers. The beams of the outer mast include tracks which receive the rollers of a platform having a lifting fork structure and which is vertically movable relative to the outer mast.

Abstract: In a material handling vehicle having an operator platform, a sideshift carriage mounted for lateral movement relative to the platform, a traverse carriage mounted for lateral movement relative to the sideshift carriage and forks mounted to the traverse carriage, an improved sideshift control system monitors the position of the sideshift carriage to define home positions for the sideshift carriage relative to the platform. Two home positions are defined, one for the forks facing to each side of the vehicle. The home positions offset the sideshift carriage to one or the other side of the platform to substantially center the load on the vehicle such that a portion of the base of the forks extends a set distance beyond one side of the platform, and the load supported on the forks extends approximately an equal distance beyond the opposite side of the platform.

Abstract: An improved system for monitoring lift chains included within mast assemblies in material handling vehicles disables downward movement of the forks upon detection of a first level of slackness in a lift chain. Since upward movement of the forks is not disabled, the forks may be raised to clear any obstruction causing the chain slackness. A lift chain may also be monitored to detect a broken chain in which case all vertical movement of the forks is disabled. In a material handling vehicle wherein the operator is elevated along a first mast and the forks are elevated along a second mast connected to an operator's platform, dual lift chains in the first mast are individually monitored for both slackness and breakage while dual lift chains in the second mast are monitored in common primarily to detect slackness. Lateral and rotational movement of the forks is also disabled for detection of a slack or broken first mast lift chain, but not for detection of a slack or broken second mast lift chain.

Abstract: The height to which the forks of a lift truck are raised is measured by an ultrasonic height measuring arrangement including a downward facing transmitting transducer, positioned on the truck platform in fixed position with respect to the forks, and a downward facing ultrasonic receiving transducer which receives ultrasonic acoustic energy waves reflected by an upward facing parabolic reflector. The receiving transducer is positioned in a casing substantially at the focal point of the parabolic reflector and is mounted by means of springs which provide vibration isolation between the casing and the transducer.

Abstract: An output distance signal related to the distance between an ultrasonic transmitting transducer and an ultrasonic receiving transducer is provided by an apparatus including a reference oscillator and a burst generator responsive to the reference oscillator which periodically generates ultrasonic burst signals. The ultrasonic transmitting transducer is responsive to the generator for providing an ultrasonic acoustic energy burst in response to each of the ultrasonic burst signals. An ultrasonic receiving transducer receives the ultrasonic acoustic energy bursts and generates detection signals in response thereto. A range window circuit is responsive to detection of an acoustic energy burst by the receiving transducer, for providing a range window signal at a time period lagging the detection signal such that a range gate will be opened for passage of the next following detection signal.

Abstract: A cable and hose guide has a series of alternately staggered intrusions extending into the opening of an extended channel so that a cable or hose must be deflected alternately around the intrusions as it is laterally fed into or out of the channel, thereby preventing the hose from buckling and falling out of the channel while therein.

Abstract: A speed control circuit is provided for a lift truck which is driven by an electric truck drive motor powered from a power source through a motor controller. The motor controller is responsive to a power control signal generated by summing a speed sensor signal, which is derived by comparing a tachometer signal with a speed selection signal. A fork height sensor provides a fork height signal which is used to limit the maximum level of the speed control signal. A safety circuit monitors operation of the speed control circuit and disconnects the circuit from the motor controller upon occurrence of a malfunction.

Abstract: The lifting mast (20), frame (12), and outriggers (16) of a slip sheet lift truck (10) are fixed and immovable with respect to one another. The platen (30), push-pull mechanism (45), and back plate (31) are an integral unit mounted to permit side shifting on a tilt carriage (29), which is mounted on lower pivots (28) and tiltable thereabout with upper tilt cylinders (35). These are carried on a lifting carriage (25) which is vertically moveable and supported by a lifting cylinder (26) on the lifting mast (20). The lift truck outriggers (16) extend and slope forwardly and downwardly from the mast (20) to provide better truck stability, clearance for the platen (30), and good underclearance for ramps and dockboards.

Abstract: A control system for directing hydraulic fluid to selected cylinders on a lift truck to perform selective ones of a plurality of power truck functions, such as raising and lowering the lift forks on the truck mast, tilting the lift forks with respect to the truck mast, and extending the lift forks away from the truck mast, includes a control lever mounted on the truck control panel, having upper and lower control positions and a neutral position therebetween. A function control switch includes a manually actuatable switch button on the controlled lever. A counter means is responsive to the function control switch to cycle sequentially through a plurality of count states from an initial count state in response to actuation of the function control switch means.

Abstract: Apparatus for controlling the position of an antenna rotator from remote locations includes a sender unit which generates desired antenna position information and a control circuit associated with an antenna rotator. The sender includes a dial for selecting the desired antenna position, a control transmitter responsive to the position of the dial for providing an output at a first frequency containing the antenna position information and a holding circuit for continuing the output of the control transmitter until the antenna reaches the desired position. The sender also includes a receiver responsive to a signal at a second frequency from the control circuit for terminating the operation of the control transmitter.

Abstract: A control mechanism for a remotely mounted motor, such as an antenna rotator, is contained withi n a molded housing having a cover and base, and includes an indicator motor which rotates a switch assembly to a preselected location. The indicator motor is secured by a motor housing integrally molded in the housing base and a polyurethane pad cushions the motor. The motor housing includes side wall members and a cover attached thereto by an integrally molded hinge member on one side wall, and fastening means on the other side walls secures the cover and the motor within the housing.

Abstract: A fork lift with a retractable overhead guard has limit switches built into the mast and one rail of the retractable guard which prevent the fork lift from being raised above a predetermined height when the guard is lowered, and when the fork lift has been raised above the predetermined height with the guard raised, prevents the guard from being lowered.