101
Maintenance
SP 500 / 750-15 / 750-18 / 1000 / 1250 Operation Manual
Weekly maintenance
Adjust the Rock Valve Tension Nut
Remove the 16-mm keeper bolt, grasp the tension nut
by hand, and turn it clockwise (Figure 11). There are
holes for the keeper bolt on the spacer behind the ten-
sion nut. The object is to place the keeper bolt in the
furthest hole that you can reach when you turn the ten-
sion nut by hand. If the tension nut will turn enough to
get all the way to the next hole, then turn it back to the
previous hole. Do not put a wrench on the tension nut
to get it to go to the next hole. Replace and tighten the
keeper bolt. Over-tightening the tension nut will cause
premature wear on the kidney seal.
The tension nut adjusts the spacing of the Rock Valve
on the kidney seal end. Spacing between the spectacle
plate and cutting ring is compensated for by the pres-
sure spring as the spectacle plate wears.
Keeper Bolt
Tension Nut
Spacer
Keeper Bolt
Figure 11
Adjusting the Rock Valve tension nut
Inspecting / Rotating the Cutting Ring
Needing to rotate the cutting ring depends more on the
type of concrete and the number of cubic yards pumped
than on a time schedule, but you should at check it for
wear at least once per week, and rotate it as needed.
To rotate the cutting ring:
1. Turn o the engine and put the key in your pocket.
2. Loosen the tension nut as explained in “Adjust the
Rock Valve Tension Nut”.
3. Loosen the eight cover bolts a couple of threads,
but do not remove the bolts (Figure 12).
4. Loosen the 12 x 30 bolt on the end of the rock
shaft by the slewing lever.
5. The Rock Valve will slide far enough out for you to
loosen the cutting ring.
12x30 Bolt
(end of Rock shaft)
Tension Nut
Figure 12
Loosen bolts on Rock valve cover and shaft
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