Crown Equipment Corporation

Crown Controls Corporation

Ned E Dammeyer

Michael P Gallagher

Harold A Stammen

Timothy A Wellman

Todd M Fullenkamp

Nicholas D Thobe

Walter Conley, Iii

Mark E Schumacher

Kevin Anthony Gilliland

Nicholas J Sherman

Bradley A Burns

Donald E Luebrecht

John C Wilkinson, Jr

Leif A Norland

William J Heidemann

John R Harman

Timothy S Quellhorst

John F McClusky

David B Smith

Joseph H Knapschaefer

Robert J Stauffer

Tim A Wellman

Ronald A Grisez

Kim A Klopfleisch

Paul J Leasor

Matthew P Ranly

Forrest A Haverfield

Daniel L Sherman

Pieter C Kruithof, Jr

Thomas W Linn

Nick D Thobe

John F Mcclusky

Thomas C Bidwell

Pieter C Kruithof Jr

A steering tiller and a steered wheel(s) of a steer-by-wire steering system of a materials handling vehicle are synchronized with one another and a virtual coupling force is exerted on the steering tiller to maintain synchronization. A motor or brake is associated with the steering tiller and the positions of the tiller and the steered wheel(s) are monitored and used to control the motor or brake to apply the virtual coupling force to the tiller. Thus, an operator of the vehicle receives feedback corresponding approximately to that experienced in a mechanically coupled steering system so that synchronism is maintained between the tiller and the steered wheel(s). In this way, if the operator attempts to oversteer or outrun the steered wheel(s) by rapid rotation of the tiller, a force proportional to the operator's action is applied to oppose that action. Synchronization can be set up with the tiller set to a desired position selected by the operator, for example to selected a desired tiller spinner straight ahead position.

Synchronized/variable force feedback power steering

A fork lift truck includes a fork level sensor located in the forks, away from the vertical mast of a lift truck for detecting the true level of the forks, and a vision system including a camera which may take several forms. In one form, a single camera is mounted in a housing which may be moved to a protected location vertically either by sliding in the carriage assembly, or by use of a parallelogram device. In another form, multiple cameras are employed where a second camera may be either mounted above the first camera in the same housing or mounted between the forks. Alternatively, the first camera may perform multiple roles by being moved vertically from a first predetermined location below the bottom of the forks to a higher elevation a second predetermined location relative to the forks. A video display terminal, which shows the view observed by the camera, may also include a fork level indicator, a reticle for assisting in adjusting the vertical position of the forks, and an indicator showing the specific truck function selected by the operator.

Fork level indicator for lift trucks

A personnel carrying vehicle comprises a self propelled, steerable body, a telescoping mast attached to and extending upwardly from the body, and a personnel compartment attached to the mast. Two control handles are mounted within the personnel compartment, with one handle including a rocker mechanism mounted therein for pivotal movement within a generally horizontal plane to control steering and the other handle being rotated to controlling traction. Sensors ensure that the operator's hands are on both control handles and both feet are properly positioned on a floor of the operator's compartment before the vehicle can be moved or the platform raised; this ensures a four point stance, providing for operator stability and that the operator's hands and feet are within the operator's compartment anytime the vehicle is being moved or during lifting or lowering operations.

Personnel carrying vehicle

The operational fitness of a magnetic sensor for detecting buried magnets can be tested from time to time by an electromagnet installed in proximity to the sensor. The electromagnet is a small coil of wire mounted near the sensor, such as a Hall effect device, which when energized, generates a test magnetic field. The analog output of the sensor is compared with preestablished values when the electromagnet is energized to verify the proper operation of the sensor; it is also compared with preestablished values when sensing buried magnets to confirm operation of the sensor, the strength of the buried magnet, and the alignment of the sensor with respect to the magnet. A threshold detector senses the output of the sensor to indicate when a magnetic field is detected, and the peak analog output of the sensor is stored and compared to a reference after the sensor passes the magnet. The sensors are normally tested whenever the vehicle is initially powered up or after the vehicle has been stopped for a predetermined time.

Method and apparatus for monitoring the proper operation of a control

A lift truck control system which utilizes a distributed control network including at least a display module, a distribution module, a traction module, a brake module and a steering module. The display and steering modules each are configurable by software which controls the module and the various drivers in each module. In the preferred embodiment, the display module includes flash memory which stores application software and can be rewritten so that the performance characteristics of the modules are software configurable. The display module is connectable to a programmable cartridge which includes nonvolatile flash memory that carries application software for the display and steering modules. When connected, the cartridge downloads the particular application software which is written over the stored software in flash memory for the display and steering modules. The programmable cartridge also can be used to store and download boot software to the display and steering modules, so that the boot procedure performed by the display and steering modules is also software configurable. The system accepts modules which can be installed in a variety of different lift truck vehicles with minimal physical changes; the performance of the modules is configured by the application software written into the flash memory of the module.

Removable programmable cartridge for a lift truck control system

Lift truck control system

A fork lift truck includes a fork level sensor located in the forks, away from the vertical mast of a lift truck for detecting the true level of the forks, and a vision system including a camera which may take several forms. In one form, a single camera is mounted in a housing which may be moved to a protected location vertically either by sliding in the carriage assembly, or by use of a parallelogram device. In another form, multiple cameras are employed where a second camera may either mounted above the first camera in the same housing or mounted between the forks. Alternatively, the first camera may perform multiple roles by being moved vertically from a first predetermined location below the bottom of the forks to a higher elevation a second predetermined location relative to the forks. A video display terminal, which shows the view observed by the camera, may also include a fork level indicator, a reticle for assisting in adjusting the vertical position of the forks, and an indicator showing the specific truck function selected by the operator.

Remote viewing apparatus for fork lift trucks

A brake control apparatus for controlling the application of braking torque to a permanent magnet brake of the type wherein a permanent magnet creates a magnetic flux path for applying a braking torque and an electromagnet provides a continuously variable flux in opposition to the permanent magnet. Braking torque is controlled in response to a braking command signal from an operator controlled floor pedal or hand grip which varies in relation to the amount of braking desired. A control circuit responsive to the braking command signal causes braking torque to be generated in direct proportion to the amount of braking desired. The control circuit including a device for applying either direct current or pulses of current to the electromagnet, the pulse width of which varies from a minimum pulse width representing maximum braking to a maximum pulse width representing no braking. The pulses are monitored to insure proper operation. The current in the pulses is used as an indication of brake temperature and is used to control the pulse width of any given desired brake torque. A tachometer monitors the direction and speed of rotation of the braked wheel and an anti-skid algorithm modifies the pulses applied to prevent wheel lockup. The brake is fail safe since removal of current to the electromagnet either by operation of the control circuit or by an emergency removal of power will cause the permanent magnet to apply full braking torque.

Proportional control of a permanent magnet brake

Method and apparatus for monitoring the proper operation of a hall

A materials handling vehicle employs a two step braking process where full brakes are applied to stop the vehicle quickly when it is traveling at a fast rate, and partial braking force is applied to stop the vehicle smoothly when it is traveling slowly. The amount of the braking force is controlled by the spring force applied to the braking shoes. Whenever the vehicle is moving at or less than a predetermined speed, only the brakes on one pair of wheels, typically the load wheel brakes, that is the brakes on the wheels under the load, will be used when braking action is requested. This will permit the vehicle to stop smoothly, and not abruptly as would be the case if full braking were to be applied. If the vehicle is moving faster than the predetermined speed, then full braking force will be applied by actuating the brakes on both pairs of wheels whenever requested by the operator or by the vehicle control system. Both the load wheel brakes and the steered wheel brakes are conventional spring applied brakes which are released by hydraulic pressure applied to individual brake cylinders.

Two force levels of mechanical braking for materials handling vehicles

A digital height encoder on a turret stockpicker is used to determine platform height. A pair of fixed reference switches are provided, one to reset a digital height memory to a predetermined height value each time the switch transitions either on or off, the other at a predetermined height near the staging point of telescoping masts for initial calibration of the encoder and for verification of proper operation during normal operations. If the height measurement indicated by the encoder upon the transition of the second or verificaiton switch is not within predetermined limits, an error signal is generated and recalibration will be required. Motion of the platform is also required if the control handle is in the upward direction and the platform has not reached its predetermined upper limits.

Height sensor for turret stockpicker

A variable braking force electric brake for materials handling vehicles, such as fork lift trucks, utilizes two sets of springs to urge brake pads against a rotor of a disc brake. The first set of springs provide a first level of braking force, typically one-third of the total braking force. The second set of springs provide a second level of braking force, typically two-thirds of the total. A pair of electromagnetic elements act on armatures placed between the springs and a non-magnetic brake pad support plate to selectively permit either the first set of springs alone to provide braking, the second set of springs alone, or both sets together. Initially, the current to the electromagnetic elements is strong, to insure that the associated armature is pulled toward the electromagnet, and afterwards, the current is reduced to minimize heating and power requirements. The space or gap between the electromagnets and the armatures may be ascertained by means of a feeler gauge, or be examining a plunger, the end of which extends through the outer housing of the brake. The gap is determined by a set of three adjusting screws placed around the periphery of the brake housing.

Three step electric brake

A materials handling vehicle, such as a turret stockpicker, is provided with control circuits and hardware to allow an operator to control the vehicle from either a standing or seated position while providing all of the safety interlocks that ensure proper operation of the vehicle. All functions of the vehicle, including raising and lowering of forks and moving the vehicle, are affected by the operator's position. The switch associated with the operator's seat indicates whether the operator is in the standing or seated position, and the control of the vehicle is appropriately modified to conform to industry standards according to the mode selected from the operator. An electronic circuit is responsive to an operator actuated seat switch to control the mode of operation wherein, a) if the operator is standing, floor operated switches control the braking of the vehicle, with braking being applied upon release of either of said switches, and b) if the operator is sitting, a pair of pedestal switches must both be activated to permit selected operations of the vehicle and lift truck functions, and wherein braking is controlled by the operation of a pedestal brake switch.

Dual operator position for material handling vehicle

A fork extension and retraction system for use with stockpickers automatically extends and retracts hydraulically extendable forks of a stockpicker when the load handler carrying the forks has moved to its extended position on the load side of the vehicle, and it also automatically retracts the forks if they have drifted from a home position before performing other fork related activities. Switches in the fork carriage assembly sense when the extendable forks are in the home position and near the home position. Other switches sense when the load handler assembly has reached its extreme positions on either side of the operator's platform. Still other switches are used to slow the traverse movement of the load handler assembly as it approaches its extreme positions, thus to cushion the shock of the load handler stopping. A control circuit senses the condition of these switches and controls the operation of both the load handle and the fork extension hydraulic system.

Extend and retract control for fork lifts

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New Bremen, OH, United States of America

Ned E Dammeyer