Section 3
OPERATION
3-22
785 Motor Grader
Back Filling
The moldboard can be used to backfill a trench
and the rear tandem can be used to compact the
backfill material.
Vee Ditching
Vee ditching requires at least three passes; The
first pass shapes the ditch, the second pass
deepens the ditch, and the third pass cleans up the
materials. The material is then spread to form the
roadbed and shoulder. The final step is cutting the
back slope.
First Pass
1. Center the circle.
2. Position toe of blade just outside edge of front
tire.
3. Tilt blade and pitch forward until top of blade is
in line with center of front tire.
4. Raise blade heel just ahead of tandem tires so
dirt will spill out between them.
5. Lead front wheels slightly toward discharge end
of blade.
6. Engage the differential lock.
7. Travel in 1st or 2nd gear.
8. Make first pass very shallow in order to
establish line of ditch.
Second Pass
Position wheels in vee ditch made on first pass to
compensate for side thrust.
NOTE: This allows a deeper cut at higher
speed during second pass.
Third Pass
This is the clean-up pass. The cleanup pass is
used to reduce the build-up of dirt between the
tandem wheels from successive passes. After the
cleanup pass the material can be spread to
establish the roadbed and the shoulder.
1. Sideshift circle and blade toward ditch.
2. Position front wheels outside windrow.
3. Set blade at an angle that positions heel
between tandems with blade pitched slightly
forward.
4. Position toe of blade well beyond windrow to
minimize spillage back into the vee ditch;.
5. Articulate grader slightly to deposit windrow
between tandems.
Spreading Material
1. Use a straight frame position to spread
windrow left from cleanup pass.
2. Position circle and moldboard to deposit
material evenly. Use material to establish
roadbed and shoulder.
Cutting Back Slope
1. Sideshift circle and blade toward bank.
2. Position heel of blade in center of rear tire.
3. Pitch blade slightly forward.
4. Blade angle is toward direction of travel at
approximately 40° depending upon degree and
height of slope.
5. Drive wheels of machine in established vee
ditch.
NOTE: This will deposit dirt from back slope
slightly up onto shoulder slope when a
cleanup pass will pull it up onto
roadbed for spreading.
6. To finish vee ditch; pull windrow up from
shoulder slope, clean it away from edge of
ditch and spread it.
7. Repeat steps as necessary.
Cleaning Ditches
If ditch is soft or wet and can not support the full
weight of the grader, proceed as follows:
1. Offset tandems so that the tandems ride on
shoulder of road.
2. Lift material from ditch and dump it outside of
tandems.
3. By articulating tandems on road and front
wheels into ditch, the grader can be backed up
until toe of blade is at end of culvert. Then start
cut, windrowing material onto shoulder of
roadbed.
NOTE: When filling washouts on existing back
slopes, blade can be angled back and
side-shifted enough so that material
can be rolled up slope.
Road Crowning
1. Blade material inward from shoulders of
ditches.
2. Cut top of crown with blade at a 0° angle, or a
slight angle to side cast material to whichever
side might require it.
Courtesy of Machine.Market
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