slowing because of increased rip-
ping resistance, instead of making a
blade adjustment, it was best to stop,
reverse, and let the suspension un-
load, then advance again, essentially
starting over with a shallow cut. In
hard ground productivity was great-
est with successive shallow cuts
compared to fewer deep cuts.
Since the blade of the CEV can
not be tilted, this means of control-
ling depth of cut and reducing the
influence of the suspension was not
available. However, to see if overall
performance could be improved
with better control of ripping depth,
a skid was used on the blade to make
depth of cut independent of the sus-
pension. This was done in a very
expedient manner. A section of rail-
road tie, approximately 3 ft (90 cm)
long, was used as a skid and placed
under the blade like a ski. The front
was cut with a ramp, and a shallow
notch in the top engaged the blade
(Fig. 13). The blade was lowered into
the notch, limiting penetration to
about 8 in. (20 cm). Passes made with
the skid were noticeably different
from those made when depth was
controlled by blade adjustments
a l o n e . With the skid, forward
progress was smooth with no stall-
ing and loss of traction.
Considering the poor traction
usually attributed to the CEV when
it is operated on packed snow with
Figure 14. GH Hensley 1000-HL ripper attached to the outer part of
road pads, we found that perfor-
the blade on an Army Caterpillar D7 tractor. This model was also
mance was good. Traction was lost
used on the CEV and John Deere 750.
only a few times, and on those oc-
casions it usually could be antici-
pated. Ripping was resumed by re-
versing the machine for a new start
CONCLUSIONS AND
at a shallower depth.
RECOMMENDATIONS
Ripper on the Caterpillar D7
The moldboard ripper attached to the blades
The model 1000-HL can also be attached (fully
of commercial and military dozers provided a
extended) to the outer part of the 7-S dozer blade
rapid, low cost means of developing a ripping
used on some Army D7 tractors (Fig. 14). The
capability. The rippers were easily attached in the
ripper was used to rip compacted gravel and as-
field in less than 10 minutes with no modification
phalt pavement; no frozen ground was available
required to the tractor or the ripper. At our sites
at the time. However, with the tractor's weight,
the ripper attachment provided the dozers a means
power, and blade control, good ripping perfor-
of ripping hard and frozen ground.
mance in frozen ground would be expected.
13
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