Steering System for Crawler Track Machine

A linear actuator control system comprising:

• a machine including first and second pairs of steerable tracks for effecting movement of the machine;
• a tie rod coupled between each of the first and second pairs of tracks;
• a linear actuator positioned on each tie rod for adjusting the length of the respective tie rod;
• a steering mode selector configured to transmit a steering mode for selectively orienting the first and second pairs of tracks, the steering mode selected from one of at least a crab steering mode and a coordinated steering mode;
• and
• a controller coupled to the steering mode selector and the linear actuator, the controller configured to receive the steering mode and communicate with the linear actuator with respect to tie rod length according to the steering mode;
• wherein when the steering mode selected is the crab steering mode, the controller determines each tie rod length according to a steering angle such that the tie rod lengths are adapted to be adjusted in real time to orient each of the first and second tracks parallel to one another for the steering angle, and to communicate with the linear actuator to adjust the tie rod to the determined length;
• and
• wherein when the steering mode selected is the coordinated steering mode, each of the tie rods are fixed to a predetermined coordinated steering length and the first and second pairs of tracks are adapted to achieve coordinated steering turning angles through steering linkage.

A method of steering a machine including first and second pairs of steerable tracks, comprising the steps of:

• selectably engaging a steering mode selected from one of at least a crab steering mode and a coordinated steering mode;
• and
• when the crab steering mode is engaged:
• determining a steering actuator length for each of the pairs of steerable tracks according to a steering angle,
• determining a desired tie rod length for each of the pairs of steerable tracks to achieve the steering angle as a function of the determined steering actuator length,
• comparing the tie rod length for each of the pairs of steerable tracks with the desired tie rod length for each of the pairs of steerable tracks,
• adjusting the tie rod to the desired length for each of the pairs of steerable tracks, such that all tracks are oriented parallel to one another for the steering angle;
• and
• when the coordinated steering mode is engaged;
• fixing the steering actuator and tie rod to predetermined coordinated steering mode length for each of the pairs of steerable tracks.