Page 14 - Cat Motor Grader Application Guide AEGQ0947-00

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the travel surface with the moldboard. When the motor grader is in the crab mode, the front axle is no longer running perpendicular to the direction of travel. This places one front tire slightly ahead of the other and allows one tire to be on top of a corrugation while the other is in the bottom. As the tires roll up and down through the washboard, the front axle will pivot up and down keeping the front mainframe stable. The degree of articulation required to make this technique work effectively will vary with the space between corrugations. CAUTION: Do not use the crab mode when scarifying washboarded areas. Crab mode could bend the scarifier shanks and/or linkage.

Winter snow plowing operations and traffic in all seasons forces gravel off the road onto the road shoulder and ditch slope. Traffic forces the shoulders to mushroom outward when roads are soft, widening the road. Ditches may require cleaning to restore drainage. Spring road maintenance normally includes repairing these problems.

Use straight or articulated frame for this work. Two examples are:

1. Move the linkbar to its maximum position toward the ditch. Side shift the drawbar to its maximum position.

With the frame in straight mode, position the motor grader on the road shoulder.

Circle the moldboard and side shift it to obtain the desired blade angle and desired reach into the ditch.

Raise the heel of the moldboard to match the ditch slope angle. Move the material up onto the road shoulder or onto the ditch slope as desired. When the shoulders are soft, using articulation to offset the heavy rear frame away from the shoulder will prevent rutting and trapped water that cause shoulder damage.

2. Using crab steer will allow running one front wheel in the road ditch or on the road shoulder slope to recover material moved there by traffic or snow plowing. Use crab steer to narrow shoulders, to maintain the desired road width, and to clean wet ditches.

The rear tandems can be kept on the road travel surface away from the shoulder.

Extend the blade into the ditch to open a drainage path. This reduces standing water and possible road damage.

Crab steer can be used to reopen culverts blocked by material. If the ditch bottom is solid, place the front wheels in the ditch with the rear frame on the road travel surface, as shown above. Shift the circle toward the toe of moldboard, with the moldboard square to the mainframe and tipped to nearly two-thirds of its maximum forward tip capability.

Place the moldboard cutting edge into the ditch at the blocked end of the culvert, and set the blade angle to match the shoulder slope. Be careful not to damage the end of culvert.

M S E R I E S M O T O R G R A D E R S A P P L I C A T I O N G U I D E

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Page 14 - Cat Motor Grader Application Guide AEGQ0947-00

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