Figure 8. John Deere 550 with blade tilted to use its corner as a slide to limit depth of cut and control
ripping depth.
The 550 tractor was selected to help predict the
ness. The observations were made during field
potential ripping capability of the smaller mili-
demonstrations, and during runs planned for ob-
tary machines, such as the DEUCE, being tested
serving ripping characteristics. The observations
by the Army. Caterpillar indicated that the down
in frozen ground were made at sites in northern
pressure on the blade edge of the DEUCE is ap-
New England. The CEV was used at the site with
proximately 7900 lbf (35 kN), which is similar to
the strongest and most difficult ground conditions.
the John Deere 550 and some Caterpillar D4 and
D5 tractors. The 750-H provided an indication of
Rippers on commercial tractors
ripping performance of machines larger than the
The GH Hensley model 750-H and 1000-HL
550, but smaller than the D7 tractors used by the
rippers were used on the John Deere tractors. The
Army (Table 1).
1000-HL ripper was attached to the center of the
blade on the John Deere 750 without difficulty in
about 5 to 10 minutes. The 750-H used on the
Ripping with the John Deere 750
At the borrow pit, the seasonal frost was just
John Deere 550 could not be installed on the cen-
over 2 ft (60 cm) thick. The surface and this layer
ter of the blade because controls on the rear of the
were well frozen. Note in Figure 8 that the track
blade interfered with the attachment yoke. Also,
grousers do not penetrate the surface and only
this ripper's standard yoke was not long enough
mark the ground on high areas and in the turns.
to solidly engage the back of the blade. The 750-H
We initially tried to penetrate the frozen ground
was securely attached to the 550 blade by placing
by tilt dozing (no ripper) with the corner of the
it just off center and using the longer yoke from
blade. Tilt-dozing passes did not penetrate and
the larger 1000-HL ripper. The lighter weight of
only smoothed and polished the ground surface.
the 750-H ripper also made installation easier. As
mentioned, the ripper was installed in pieces to
With the 1000-HL ripper attached, continual
forward progress could be made when passes
reduce the weight of the equipment handled. The
were less than full ripping depth. At this site 5 to
ripper shank was first positioned on the blade,
6 in. (13 to 15 cm) was routinely ripped (Fig. 7a).
then the sleeve, followed by the yoke.
8
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