Electronic traction control system

An electronic traction control for a vehicle having multiple hydraulically driven wheels comprising:

• a hydraulic pump;
• a plurality of hydraulic drive motors each fluidly connected to the pump for driving one of the wheels;
• a plurality of speed sensors corresponding in number to the plurality of drive motors for generating a motor speed signal for each of the drive motors;
• an electronic flow control valve comprising a microcontroller electrically connected to the speed sensors for receiving and comparing the motor speed signals and a plurality of normally open proportional solenoid-operated spool valves each electrically connected to the microcontroller for receiving a flow restricting command signal therefrom based upon comparison of the motor speed signals, the anti-slip valve being fluidly connected to one of the drive motors and operatively located between said drive motor and the pump;
• the spool valves including a housing having a spool bore and first and second ports therein, the spool valve including an elongated hollow valve spool slidably mounted in the spool bore and having a predetermined range of travel therewithin, the valve spool including a first plurality of metering holes extending therethrough and in fluid communication with the first port and a second plurality of metering holes extending therethrough and in fluid communication with the second port, the first and second plurality of metering holes being spaced apart and at least partially registered with the first and second ports respectively such that some fluid flow is permitted from the second port to the first port through the metering holes throughout the entire range of travel of the valve spool.