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A remote control system for an automotive transmission in an earth-moving vehicle which includes a fluidic variable frequency oscillator having a variable feedback loop controlled by a quadrant lever which acts as a gear shift control. When the lever is moved between spaced transmission control posi

A remote control system for an automotive transmission in an earth-moving vehicle which includes a fluidic variable frequency oscillator having a variable feedback loop controlled by a quadrant lever which acts as a gear shift control. When the lever is moved between spaced transmission control positions, the frequency of the signal at the output is swept through the frequencies corresponding to intermediate control positions. The waveform of the output signal is non-symmetrical having a fixed “off”time and an “on”time which varies in length as an inverse function of the frequency. The output signal is fed to a fluidic transmitter, then through a pair of conduits to a fluidic receiver. The “on”output port of the receiver feeds into a manifold developing pressure therein which varies with the degree of dissymmetry of the wave, that is, inversely with frequency. A plurality of Schmitt triggers have their control ports connected to the manifold and have reference ports progressively biased so that pressure is produced at their output ports in succession. A power actuator of the progressive indexing type is connected to the Schmitt trigger output ports and is mechanically coupled to the gear shift member of the transmission to provide smooth transition through the gears regardless of the magnitude of the change in gear ratio. The lowest gear is interlocked with engine speed to prevent going into this gear when the engine speed is too high. The reverse gear is effectively interlocked with a forward motion detector to insure that the vehicle is at standstill before the transmission may shift into reverse.

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In a remote control system for an automotive transmission in an earth-moving vehicle or the like having a plurality of forward gears as well as neutral and reverse and a progressively movable gear shift member for selecting the same, the combination comprising a fluidic variable frequency oscillator

In a remote control system for an automotive transmission in an earth-moving vehicle or the like having a plurality of forward gears as well as neutral and reverse and a progressively movable gear shift member for selecting the same, the combination comprising a fluidic variable frequency oscillator having a variable feedback loop and a fixed feedback loop as well as a pair of on and off output ports, the variable feedback loop having both resistance and capacitance and having associated means including a manual quadrant lever for progressively varying at least one of them and settable at a plurality of successive transmission control positions so that when the quadrant lever is moved between spaced control positions the frequency of the signal at the output ports is swept through the frequencies corresponding to intermediate control positions, the waveform of the output signal being non-symmetrical having an “off”time which is substantially constant and an “on”time which varies in length inversely in accordance with frequency, a transmitter in the form of a bistable fluidic amplifier having a pair of control ports and a pair of on and off output ports, the transmitter control ports being directly coupled to the respective oscillator output ports, a receiver in the form of a second bistable amplifier having a pair of control ports and a pair of on and off output ports, a pair of conduits for connecting the output ports of the transmitter to the control ports of the receiver for remote driving of the latter with substantial preservation of the oscillator waveform, a manifold, the off output port of the receiver being vented while the on output port of the receiver is connected to the manifold for developing a pressure therein which varies inversely with the frequency of the signal at the receiver output port, a plurality of Schmitt triggers corresponding to respective transmission settings, each of the Schmitt triggers having a control input port, a reference input port, a vent, and an output port, the control input ports of all of the Schmitt triggers being connected to the manifold, means for applying biasing pressure to each of the reference ports with the biasing pressures being progressively stepped so that pressure is produced at the output ports of the Schmitt triggers in succession in step with progressive movement of the manual quadrant lever into successive control positions, and a power actuator of the progressive indexing type having a series of ports and a plunger, the actuator ports being connected to the output ports of the respective Schmitt triggers, and the plunger of the actuator having a connection to the gear shift member of the transmission so that when the manual quadrant lever is moved between spaced control positions the transmission selectively goes through the gears corresponding to all of the intermediate positions thereby to provide smooth transition regardless of the magnitude of the change in gear ratio.