Abstract: An apparatus, for controllably driving a plurality of solenoids is provided. The apparatus includes a plurality of driver circuits. The plurality of driver circuits are configurable as one of proportional and binary driver circuits. A first number of the plurality of driver circuits include proportional driver circuits and a second number of the plurality of driver circuits include binary driver circuits. The apparatus controllably actuates the proportional driver circuits and the binary driver circuits. The apparatus detects failure conditions on the proportional driver circuits and the binary driver circuits and responsively produces respective failure condition signals. The apparatus is adapted to perform a proportional diagnostics routine on the proportional driver circuits and to perform a binary diagnostics routine on the binary driver circuits via the failure conditions detecting means.

Abstract: Vehicles having implements are typically used to perform repetitive functions in work cycles. An implement control system raises and lowers an implement relative to the vehicle and reduces the stresses applied to the vehicle from abruptly stopping the motion of the implement. A lever pilot signal is produced in response to the pivotal position of a control lever. An electrohydraulic pilot signal is also produced. The pilot signal having the greater pressure is directed to a main valve for controlling the position of the implement. The method and apparatus of the instant invention are applicable to a number of vehicles having a hydraulically operated implement.

Abstract: A communications network is adapted to provide communication between control modules on a vehicle. Each control module includes a first and second transceiver. A control module checks for the presence of a data message from another control module before transmitting a data message. If there is no other data message present, the control module transmits the data message around the network in both directions using the first and second transceivers. The other control modules receive the data message from the previous control module and pass the data message to the next control module in the network.

Abstract: An electrical transmission control mechanism includes first and second control members which are individually limitedly rotatable to respectively select the directional and neutral modes or the speed ratio modes of a transmission. First and second electrical rotary type switching devices which are respectively responsive to the movement of the control members are disposed within the mechanism for controllably disconnecting the supply and ground side leads of one of a plurality of transmission clutch actuating solenoids and connecting the supply and ground side leads of another one to minimize the possibility of any inadvertent electrical short in causing unexpected operation of the transmission. Each of the compact and reliable rotary switching devices has a plurality of upstanding contact members arranged at preselected radii and a plurality of radially oriented wiper members that make selected contact with pairs of the contact members to provide a multitude of desirable operating functions.

Abstract: Anti-spin control systems are useful, for example, in industrial off-road vehicles. It is desirable that such systems exhibit rapid response to adverse working conditions, and be capable of quickly applying braking forces to whichever driven wheel is rotating at a higher velocity at a given time. The instant invention includes an electrical circuit for producing first and second brake control signals having values responsive to a working condition wherein one of the vehicle wheels loses traction and rotates more rapidly than the other vehicle wheel. A first controllable valve receives the first brake control signal and responsively controllably engages a brake mechanism associated with the faster rotating wheel, while a second controllable valve receives the second brake control signal and responsively controllably moves a brake mechanism associated with the slower rotating wheel from a brake released position to a brake pre-engaged position.

Abstract: Clutch-brake steering systems are known to operate on track vehicles which are highly reliable and cost effective, but lacked the fine degree of controllability found in the more expensive differential steering. An electronically controlled clutch-brake steering control apparatus provides control signals to electrohydraulic proportional valves for accurately modulating the control pressures of a set of steering clutches and brakes. A pair of sensors deliver signals, which are indicative of track speed, to the control apparatus. The apparatus acts to adaptively adjust selected ones of the valves to maintain a desired track speed differential. Thus, the controllability of the clutch-brake steering system is enhanced to effectively compete with more expensive and complex systems.

Abstract: A hybridized solenoid driver circuit includes a first and second current sensing resistor. The first current sensing resistor is disposed within the flyback current path of the windings of an electrically actuated solenoid and provides a signal proportional to the flyback current only. Control of the solenoid current is effected by operation of a power transistor to controllably connect and disconnect the solenoid from the power supply at a preselected duty cycle. Operation of the driver circuit in the energization mode has no effect on the first current sensing resistor. Conversely, the second current sensing resistor is disposed within the energization current path and provides a signal proportional to the energization current only. Operation of the driver circuit in the flyback mode has no effect on the second current sensing resistor.

Abstract: Anti-wheel spin control systems are useful, for example, in industrial off-road vehicles. It is desirable that such systems operate automatically and not be unduly influenced by false slip signals caused by steering of the vehicle. It is further desirable that the operability of the control be readily determined by the operator. The instant anti-spin control includes an apparatus for producing a slip signal having a value responsive to the difference in rotational velocity between the vehicle wheels, and for producing a test signal. A processor receives the slip signal and test signal, compares the slip signal value with a first predetermined reference value in response to receiving the slip signal in the absence of the test signal, and compares the slip signal value with a second predetermined reference value in response to receiving both the slip signal and the test signal.

Abstract: A method and apparatus for controlling a coil (40) operated hydraulic valve (48) employs a constant current source (36) to consistently control valve response (P.sub.o) irrespective of variations in power supply voltage and coil resistance (R.sub.c). A switching circuit (58) controls the delivery of constant current pulses from the current source (36) to the coil (40) in accordance with a series of pulse width modulated control signals whose duty factors (t.sub.1 /t.sub.2) are proportionate to preselected values of hydraulic output pressures (P.sub.o) developed by the valve (48). A voltage regulator circuit (38) provides regulated supply voltage to the constant current source (36) in order to reduce variations in the coil current (I.sub.c) at small pulse widths.

Abstract: A slip control system for vehicles having spaced apart drive wheels (200,202) driven by an input shaft (204) through a differential unit (206) including means (220) for calculating wheel slip according to the ratio of wheel speeds, means (220,230,232) for entering a slip control mode wherein a braking force is applied to the slipping wheel and incrementally varied on a periodic review basis according to recalculated slip values. If slip increases or holds steady, the brake force is incrementally increased. As slip becomes less, the brake force is incrementally reduced, the particular increments of force reduction being selected in accordance with successive measurements of slip. A drive shaft signal (226) is compared to the high wheel speed signal to identify a wheel speed transducer failure.

Abstract: A slip control system for vehicles having spaced apart differentially driven wheels (200,202) including means (220) for calculating wheel slip according to the ratio of wheel speeds, means (242,230,232) for entering a slip control mode wherein a braking force is applied to the slipping wheel and incrementally varied on a periodic review basis according to recalculated slip values. If slip increases or holds steady, the brake force is incrementally increased. As slip becomes less, the brake force is incrementally reduced, the particular increments of force reduction being selected in accordance with successive measurements of slip. A drive shaft signal (226) is compared to the high wheel speed signal to identify a wheel speed transducer failure.

Abstract: Lift trucks (10) have many hand control levers which are manipulated to hoist a load, propel the lift truck (10) forward and rearward, and steer the lift truck (10). Some operations must be performed sequentially rather than simultaneously which increases loading time. An electronic directional control circuit (34) includes apparatus (36) for producing first and second command signals, apparatus (38) for producing first and second outputs in response to the first and second command signals, and apparatus (40) for delaying production of a preselected one of the first and second outputs a preselected time sufficient for the selected output to decrease to a preselected magnitude prior to the production of the other of the first and second outputs. The electronic directional control circuit (34) is useable with vehicles (10) which initiate the command signals with a foot operated pedal (12) while leaving the hands free for simultaneously operating other controls.