We observed no significant difficulty with rip-
A ripping depth of several inches was easily
ping, given the ground conditions that existed at
controlled with the JD550 and 750-H ripper by
the time of testing, which included some hard,
tilting the blade and letting the corner act as a
well-frozen soils. Ripping performance can vary
slide to limit the depth of cut. Forward progress
greatly, depending on the strength properties of
was smooth using this technique and overall pro-
the frozen ground, which is controlled by the soil
ductivity of the JD550 using the smaller 750-H
type, moisture content, and ground temperature.
ripper was similar to that of the JD750 with the
Much less than ideal traction was available at the
larger 1000-HL ripper. Smoother and uninter-
sites since grouser penetration was not possible.
rupted ripping was also possible with the CEV
However, after a few passes with the ripper, trac-
when depth of cut was controlled by using a skid
tion should have improved.
under the blade, which eliminated the influence
Full penetration (14 in. [36 cm]) of the large
of the suspension.
ripper in one pass was not possible when frost
For some tasks a blade-mounted ripper can be
thickness approached this depth. Asphalt pave-
more versatile than a rear-mounted ripper. With
ment and a seasonal frost layer, both varying from
slightly better visibility for the operator, it can be
3 to 5 in. (8 to 13 cm) thick, were ripped by the
more easily used to remove barriers, rocks,
CEV with little noticeable resistance to both ini-
stumps, and other obstacles; however, it can not
tial penetration and forward progress. In both
be expected to have the performance of a rugged
cases the ripper was placed at full depth and
rear-mounted ripper that is designed for produc-
the dozer blade was allowed to slide on the
tion ripping.
surface.
The rippers fit well on all of the machines, and
Multiple passes were required to rip to the full
neither the rippers nor machines were damaged
depth of the rippers when frost thickness was
during these observation. Once the rippers were
greater than about 6 in. (15 cm). The depth of
adequately tightened, they were stable on the
penetration for a single pass uninterrupted by
blades and moved only slightly.
stalling and catching was similar for the JD750
and the CEV using the model 1000-HL ripper and
ranged from 4 to 8 in. (10 to 20 cm); however, soil
LITERATURE CITED
properties were a little more difficult at the CEV
site. Three to four passes were required to make
Bates, R.E., and M.A. Bilello (1966) Defining the
the first cut to the depth of 14 in. (36 cm). The
cold regions of the Northern Hemisphere. USA
suspension on the CEV made maintaining opti-
Cold Regions Research and Engineering Labora-
mum depth of cut and smooth forward progress
tory, Technical Report 178.
a difficult task. Depth control was more easily
Blaisdell, G.L., E.J. Chamberlain, and M. Mellor
regulated with the JD750 and JD550, since the
(1987) Evaluation of the cold regions aspect of
machines were more rigid and tilt-blading could
mobility and hardening of the mobile test bed at
be used to control depth of cut.
Malmstrom Air Force Base. Report for U.S. Air
The more limited control over ripping depth
Force Ballistic Missile Office--Small ICBM Pro-
with the CEV did not prevent it from ripping. It
gram. USA Cold Regions Research and Engineer-
required a technique to minimize the effect of the
ing Laboratory, Internal Report 1004.
suspension system. This involved stopping for-
Caterpillar Inc. (1989) Caterpillar performance
ward progress as soon as the front of the machine
handbook. Peoria, Illinois.
started to drop and forward progress began to
Haynes, F.D. (1978) Effect of temperature on
slow. Starting again by reversing a short distance
strength of snow-ice. USA Cold Regions Research
to free the ripper, then advancing while slowly
and Engineering Laboratory, CRREL Report
lowering the ripper to a depth that allowed smooth
78-27.
forward progress was quite effective. Also, it is
Mellor, M. (1972) Strength and deformability of
important for an operator to work closely with a
rocks at low temperatures. USA Cold Regions
spotter on the ground for better control of depth
Research and Engineering Laboratory, Research
of cut and spacing of the paths to be ripped. A
Report 294.
number of shallower cuts can be made faster than
Monfore, G.E., and A.E. Lentz (1962) Physical
a few deeper ones.
properties of concrete at very low temperatures.
14
Previous Page
