WALKING

WALKING

Some preparations are required before moving the dragline. Its travel path must be adequately prepared. See the previous sub-section GROUND PREPARATION. The bucket must be positioned to suit the ground conditions. The machine must be rotated so its rear faces the desired direction of travel. Provision must be made for safely and correctly handling the trail cable during the move. DO NOT USE A WALKING SHOE TO PULL OR MOVE THE TRAIL CABLE to avoid damaging the trail cable.

The position at which the bucket is carried when the machine is propelled contributes considerably to the walking operation and is dependent upon the condition of the ground. When traversing firm, level surfaces, the bucket should be suspended from the boom point approximately 1/3 the dump radius of the machine. The same position is used when propelling up a ramp. When propelling down a ramp, carry the bucket below the boom point. In all cases, the bucket should be high enough so that it will not touch the ground during a walking step.

“Heeling” the bucket while walking is done by letting the rear of the bucket contact the ground during the step and slide along when the tub slides rearward in the direction of travel. As the tub is lowered to the ground, the bucket is picked up as the boom point raises. THE BUCKET SHOULD NOT BE JERKED OFF THE GROUND. Heeling is useful while traversing dry, sandy, or powdery soil conditions to reduce the ground pressure under the sliding area of the tub and stop soil build up behind the tub’s front edge or to avoid shoe slippage on the ground.

Each operator will learn through experience where to carry the bucket while propelling to suit the ground conditions encountered. The above are general guidelines for any operator to follow initially for positioning the bucket for walking.

When all is ready for the machine to be moved, transfer the machine control from DIG to PROPEL mode. Refer to TYPICAL START-UP in this section for the procedure. Sound the signal horns to indicate the machine will propel.

IMPORTANT NOTE:

The operator should check that the drag machinery is inoperative and that the transfer to PROPEL is complete. This is done by moving the left controller (drag) slightly forward off neutral and then back to neutral to see if the drag or the propel machinery moves. This check can avoid inadvertent damage to the boom or front end in case the drag motion is still activated when the controller is moved full forward to take a step.

Move the left controller rearward and hold it there during the entire propel period. This controller is pushed forward from neutral while in PROPEL ONLY to realign the two shoes if they get out of sync or to position them at top dead center for parking. This is a warning at 10o error and the propel is shut down at 15o error.

Operator’s Seat and Controls

As the first walking step commences and the shoes move off their PARK position, the swing and hoist brakes will automatically set if they had not already been set manually. During extended travel over long distances, it sometimes becomes necessary to alter the direction of travel or reposition the bucket. This can be done without transferring to the DIG mode. Stop the walking shoes in their PARK position. Check that the CLEAR TO SWING indicator is lit and the propel brakes are set. Press the EXCITATION ON pushbutton, then release the Hoist and/or Swing brakes. To continue propelling, set the hoist and swing brakes, press the EXCITATION ON pushbutton and release the propel brakes.

During walking, if a ground roll develops at the front edge of the tub, “heel” the bucket for a couple of steps. If the tub roll persists, swing the machine 30o - 40o to one side and propel one or two steps. This will spread the roll over the ground. Then return to the line of travel desired.

When the machine is walking, both shoes should contact the ground at the same time. If one of the shoes sets down on a high spot, or does not contact the ground, or steps into a soft ground area that will not support it, then the machine will rotate in relation to the tub if the walking step is completed. If this occurs and the operator can, he should stop the step before the machine is lifted and reverse the shoes up to top dead center position. He can then change machine travel direction with the swing motion and walk around the problem ground area.

When the number of steps taken is completed and return to digging is required, the operator can press “SHOE PARK” in the second half of the last step. Keeping the master switch rearward, the machine will complete the step and slow the shoes as they approach their park position. The propel brakes will set when each shoe has reached its park position.