Propel - Straight Forward/Reverse

SWING MOTION

Swing motion is controlled by the operator’s right joystick. To swing in either direction, move the joystick lever in the direction of swing. Practice swinging in each direction until a “feel” is developed for start-up and stopping.

NOTE: The joy stick also controls the hoisting and lowering of the dipper through forward and backward motions.

DANGER: Each motion - hoist or swing - is fully operational throughout the complete movement of the other motion.

NOTE: When this joystick is used for propelling the machine, the hoist and swing motions are electrically locked out.

PROPER SWING MOTION

Proper swing motion means smooth control and an efficient swing cycle. The swing motion is begun toward the haulage unit when the dipper is filled and is clear of the bank.

DANGER: Extensive damage to the dipper handle and dipper can occur if the machine is swung before the dipper clears the bank. The swing motion begins with acceleration to an optimum point at which the excavator is brought to a stop over the haulage unit. Maximum efficiency and minimum swing machinery wear are direct results of mastering the swing motion.

NOTE: Improper swing motion results in erratic control, and an inefficient swing cycle.

DANGER: The dipper should never be swung over personnel, trail cables, related electrical equipment or other equipment. When the dipper is loaded, accidental tripping of the dipper door could result in death or serious injury to personnel, and extensive damage to equipment. Empty dippers may contain small fragments of material that can be extremely dangerous when dropped from a considerable height. On long moves it’s best to have the door open on an empty dipper and the dipper lowered to a point that permits moving without striking the ground.

Time is required to accelerate any motion from zero to working speed, and also to decelerate from working speed back to zero. The time expended for accelerating and decelerating the swing represents the major part of the entire dig cycle. Therefore, the swing arcs must be kept to a minimum to obtain maximum operating efficiency. As an example: assuming that a 90° swing results in 100 percent of the maximum output, increasing the swing arc to 180° reduces output to 70 percent, while decreasing the swing arc to 45° increased the output to 126 percent. Therefore, a swing arc of 90° or less should usually be used.

Haulage units should be positioned so their center line is approximately under or not more than slightly outside the swing path of the boom point. This substantially reduces the amount of dipper maneuvering required of the operator when positioning the dipper for dumping. Positioning of the haulage unit inside or outside the boom point makes it necessary to retract or crowd the dipper handle and dipper, which breaks the operator’s natural rhythm.

A clean, level pit floor must be maintained. A good operator will always clean the floor before moving into the bank. A clean and level floor grade is a requisite to safe and stable machine operation, and reduces damage to crawler links and related components.

DANGER: “Sweeping” should never be attempted with the machine. Sweeping consists of lowering the dipper to the ground and using the swing motion of the machine to move the dipper from side-to-side and “sweep” the pit floor. The dipper, dipper handle and boom structures can be damaged by this tactic. A bulldozer or loader should be used to help the machine operator maintain a clean pit floor in conjunction with the machine.

STEERING

To make a gradual forward right turn, move the LEFT joystick (crowd) forward and leave the right joystick (hoist) in neutral.

To make a gradual forward left turn, move the RIGHT joystick (hoist) forward and leave the left joystick (crowd) in neutral.

Whenever possible, gradual turns should be made in short increments of 15° to 20° maximum. Propel straight for a short distance (usually 1/2 the length of the crawler belts) to clear the crawler belts of stone and other debris; then make another 15° to 20° turn. Continue until the turn is completed.

NOTE: When steering in soft material such as sand, clay, etc. Increments of less than 15° to 20° might be used to minimize material build up on the crawler belt roller path.

A single sharp turn should be avoided to minimize material build up on the crawler belt roller path and subsequent high loading of crawler belt and associated propel components.

COUNTER-ROTATION TURNS

Although possible, a single sharp turn should be avoided to minimize material build up on the crawler belt roller path. This results in high loading of the crawler belt and associated propel components.

To make a sharp right turn, move the LEFT joystick forward and pull the RIGHT joystick to the rear.

To make a sharp left turn, move the RIGHT joystick forward and pull the LEFT joystick to the rear.

CAUTION:When using the counter-rotation method for turning, have a helper insure that the trail cable does not get fouled and/or torn from the machine.

NOTE: The ability of the machine to turn sharply is dependent on the surface on which the machine is setting. A soft surface will cause the crawlers to dig-in and machine to bogdown.

CAUTION:The propel brakes are released when either joystick is moved from neutral. The propel brakes are set when both joysticks are returned to neutral.

When moving the machine in a straight line, propel forward, which is in the direction of the take-up axle to reduce strain on the crawler belts and propel mechanism. When not possible and propelling to the rear, make sure the trail cable is clear of the machine and follow the signals given by the helper. The machine should be rotated in a position to allow the operator to face the direction of travel.

NOTE: Turning when propelling to the rear requires that the master control be positioned in a direction opposite the actual direction in which the turn takes place.

The machine should be moved close to the bank in short and frequent moves to maintain digging efficiency. Movement should occur between the loading of haul units.

POSITIONING THE MACHINE

There are two basic methods for positioning an excavator at a bank working face. The first method is the “back-up method”. The second method is the “drive-by method”. Both methods are acceptable and effective when set up correctly.

BACK-UP METHOD

When using the back-up method, the excavator is placed in the bank with the front of the machine turned directly toward the digging face. The haulage units are spotted on both sides of the machine. The bank is worked until a 180° semicircle has been excavated. When the point is reached where a 90° swing to either side is required to load haulage units, the excavator is moved to a new cut.

Move the machine right to left along the bank. The operator should set the left brake first. In increments, back the machine until the crawlers are at a 45° angle to the original digging path. Then, back the machine straight until the right crawler crosses the corner of the excavated semicircle.

Lock the left track, propel forward turning the crawler in increments. When the right crawler is in line with the corner of the semicircle, move forward and proceed to load the haulage units.

The back-up method will minimize the swing arc and reduce moving time. Other advantages are less bank toe area clean up and simplified handling of the trail cable, cable standard and trail cable boat.

DRIVE-BY METHOD

NOTE: If the machine and haulage units cannot be set up as described below, the drive-by method should be avoided.

Position the machine crawlers parallel to the bank with the inside edge of the outer set of crawler tracks directly in line with the bank toe.

The trucks must approach the machine from the front making a turn away from the machine as the front wheel approaches the outside crawler. The truck should stop in a position to allow backing toward the point of the bank for loading.

During the load cycle, the swing arc should not exceed 90°. The time between finishing one truck to the first digging cycle of the next should not exceed that of any cycle during a load.

START OF THE DIG CYCLE

The crowd motion forces the dipper lip into the bank at the start of the digging cycle. It is the crowd thrust which enables the dipper lip and front opening to get into a column of material of sufficient cross section to fill the dipper rapidly.

Force the Dipper Lip into the Bank

There is a direct relationship between crowd depth of bank penetration and the distance the dipper must rise in the bank to fill the dipper. The deeper the “bite” the quicker the dipper will be filled, providing the hoist force is sufficient to cut the column of material. Do not attempt to lift the entire bank with each pass. As soon as the dipper is full, retract it from the bank and swing the truck.

Crowd penetration should be rapid just at the arc of entry and rise as the dipper enters the bank. This will permit as much digging as possible near the base of the bank. This is of particular advantage when digging loose or blasted material. The greater the hoist force and crowd thrust, the faster the dipper filling time of the dig cycle. The crowd thrust should be maintained to hold the dipper in the bank while it is being hoisted. An added benefit of proper crowd thrust and hoist force is that the opposing vertical resistance of the bank material tends to have a “ramming” effect in the dipper front opening, minimizing voids and producing larger dipper loads.

It is important that the full cutting surface of the dipper contact the bank on each pass. A full face cut combined with deep bank penetration will result in a full dipper for the least amount of hoist. A partial cut, even with deep bank penetration, requires a greater rise, and tends to leave voids in the dipper. This could necessitate additional passes to fill the haulage unit.